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How can atmospheric variables such as temperature, wind, rain and ozone be measured by satellites? How are these measurements taken and what has been learned since the first measurements in the 1970s? What data are currently available and what data are expected in the future? The second volume of this encyclopedic book presents each field of application - meteorology, atmospheric composition and climate - with its main aims as well as the specific areas which can be addressed through the use of satellite remote sensing. This book presents the satellite products used for operational purposes as well as those that allow for the advancement of scientific knowledge. The instruments that are at their origin are described, as well as the processing, delivery times and the knowledge they provide. This book is completed by a glossary and appendices with a list of supporting instruments already in use.

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Table of Contents

Cover

Table of Contents

Title Page

Copyright Page

Acknowledgments

List of Acronyms

Introduction

PART 1: Meteorology

Introduction to Part 1: Meteorology and the Contribution of Satellite Observations

I1.1. From image use…

I1.2. …to measurement use

1 Operational Sounding of Thermodynamic Variables in the Atmosphere

1.1. Introduction

1.2. Operational use of TIR and MW sounders

1.3. Acknowledgments

1.4. References

2 Wind Observations

2.1. Introduction

2.2. AMVs

2.3. 3D winds derived from hyperspectral sounders

2.4. Measuring wind from space using Doppler lidar

2.5. References

3 Surface Variables

3.1. Observation of the Earth’s surface from space

3.2. Energy balances at the surface and at the top of the atmosphere

3.3. Ocean surfaces

3.4. Continental surfaces

3.5. Snow-covered surfaces

3.6. Expected changes

3.7. References

4 The Assimilation of Satellite Data in Numerical Weather Prediction Systems

4.1. Introduction

4.2. Early meteorological satellites

4.3. Assimilation of satellite soundings 1970–2000

4.4. Relevant aspects of data assimilation theory

4.5. The modern era (2000 to present)

4.6. Summary and conclusion

4.7. References

5 Nowcasting

5.1. Introduction

5.2. Satellite data for nowcasting

5.3. Observed phenomena

5.4. Nowcasting of detected phenomena

5.5. Perspectives

5.6. References

6 Observation and Monitoring of Tropical Cyclones from Space

6.1. Introduction

6.2. Visible and infrared imagery

6.3. Microwave imaging

6.4. Microwave sounding

6.5. Surface wind measurements

6.6. Ocean parameters

6.7. Climatology of cyclones

6.8. Conclusion

6.9. References

PART 2: Atmospheric Composition

Introduction to Part 2: Air Composition and the Contribution from Satellite Observations

I2.1. Air composition

I2.2. The ozone hole

I2.3. Air quality

I2.4. The greenhouse effect

I2.5. Dust and its impact

I2.6. Stratosphere

I2.7. References

7 Reactive Tropospheric Chemistry

7.1. Introduction

7.2. Methane

7.3. Reactive organic species

7.4. Reactive inorganic species

7.5. Conclusion

7.6. Acknowledgment

7.7. References

8 Major Pollutants: Ozone and Fine Particulate Matter

8.1. Introduction

8.2. Tropospheric ozone

8.3. Pollution aerosols

8.4. References

9 Desert Dust

9.1. Introduction

9.2. Qualitative satellite detection of desert dust

9.3. Satellite observation of the optical depth of desert dust

9.4. Vertical profiles of desert dust by spaceborne lidar

9.5. 3D distribution of desert dust by infrared spectrometer

9.6. Conclusion

9.7. References

10 Species Emitted by Fires

10.1. Introduction

10.2. Biomass burning gases

10.3. Biomass burning aerosols

10.4. Fire detection systems from space

10.5. Conclusion

10.6. Acknowledgments

10.7. References

11 Stratospheric Chemistry

11.1. Introduction

11.2. Stratospheric ozone chemistry

11.3. Stratospheric chemistry of other species

11.4. Satellite measurements of trace species in the stratosphere

11.5. Conclusion

11.6. Acknowledgments

11.7. References

PART 3: Atmosphere and Climate

Introduction to Part 3: Atmosphere and Climate and the Contribution of Space

I3.1. References

12 Climate Monitoring

12.1. General concepts about the climate

12.2. From space-based measurements to climate products

12.3. Climate data records and uncertainty estimates

12.4. The usage of climate data records in science and services

12.5. Looking ahead

12.6. References

12.7. References of the data sources cited in Figure 12.1

13 Anthropogenic Greenhouse Gases: CO

2

and CH

4

13.1. Monitoring anthropogenic greenhouse gases

13.2. Contribution of spatial observation of greenhouse gases

13.3. Measurement techniques

13.4. From radiation measurement to gas flux at the surface

13.5. Challenges for the future

13.6. References

14 Clouds and Water Vapor

14.1. Atmospheric water cycle and climate

14.2. Observations of water vapor

14.3. Observation of cloud properties

14.4. References

15 Precipitation

15.1. Need for global precipitation measurements

15.2. Satellite observation of rainfall

15.3. Observation of solid precipitation

15.4. Precipitation and the Earth water cycle

15.5. References

Appendices

Appendix 1: Atmospheric Profiles

A1.1. AFGL profiles

A1.2. Other profile databases

A1.3. References

Appendix 2: Spectroscopic Parameters for Radiative Transfer

A2.1. Spectroscopic parameters and line profiles

A2.2. Spectroscopic databases

A2.3. Atmospheric radiative transfer codes

A2.4. References

Appendix 3: List of Sensors and Satellites Cited in the Book

Appendix 4: Microwave Sensors and Infrared Hyperspectral Sounders

A4.1. Non-exhaustive list of passive microwave instruments

A4.2. Non-exhaustive list of active microwave instruments

A4.3. Non-exhaustive list of hyperspectral sounders

Glossary

List of Authors

Index

Summary of Volume 1

End User License Agreement

List of Tables

Chapter 4

Table 4.1. Early satellite sounding instruments

Chapter 10

Table 10.1. Global emission (Tg.a

-1

) of selected biomass burning species

Chapter 11

Table 11.1. Limb viewing instruments that provided interesting climatologies f...

Chapter 12

Table 12.1. Over 50 Essential Climate Variables are necessary to describe the ...

Chapter 14

Table 14.1. Methods for measuring atmospheric water vapor (see also Kämpfer (2...

Appendix 1

Table A1.1. AFGL profiles

List of Illustrations

Introduction

Figure I.1. The different compartments of the Earth System, taken into account...

Introduction to Part 1

Figure I1.1. Example of nephanalysis produced by the Météo-France Space Meteorology...

Figure I1.2. Example of an image in multispectral colored composition (March 4, 2...

Chapter 1

Figure 1.1. Upper stratospheric temperature sounding by IASI-B (left) and IASI...

Figure 1.2. Temperature weight functions of SEVIRI channels (left). Those of I...

Figure 1.3. Simulated spectra illustrating the coverage and spectral resolutio...

Figure 1.4. Simulation of an MTG-IRS observation in a window channel (cold clo...

Figure 1.5. On the left, conditional atmospheric instability highlighted by IA...

Figure 1.6. Vertical resolution of the three sounders IASI, IASI-NG and MTG-IR...

Figure 1.7. Cumulative degrees of freedom in temperature (left), humidity (cen...

Figure 1.8. Limitation of atmospheric sounding in the infrared in the presence...

Figure 1.9. At the top, coincidence of the in situ (radiosonde) and satellite ...

Figure 1.10. Evaluation of the quality of the operational products (IASI+AMSU+...

Figure 1.11. Schematic view of the dimensions and geometry of the footprints o...

Figure 1.12. Evaluation of operational sounding performance in the EPS program...

Figure 1.13. Coverage of the EARS-IASI regional service (left) and illustratio...

Chapter 2

Figure 2.1. All infrared winds extracted from geostationary and polar satellit...

Figure 2.2. Examples of wind vectors extracted from water vapor channels at 6....

Figure 2.3. Example of IASI 3D winds observed at 700, 500 and 100 hPa from the...

Figure 2.4. Principle of wind measurement by the Aeolus space mission

Figure 2.5. Geographical distribution of Aeolus wind data used at Météo-France...

Chapter 3

Figure 3.1. Schematic representation of the surface energy balance for estimat...

Figure 3.2. Example of a daily product (OSTIA analysis) of sea surface tempera...

Figure 3.3. Microwave emissivity of an ocean surface at 10.69 GHz without wind...

Figure 3.4. Representation of surface swaths (pink bands) of the ASCAT scatter...

Figure 3.5. Diurnal cycle of surface temperature before (curve without symbols...

Figure 3.6. Schematic dependency of the brightness temperature (a) and the bac...

Figure 3.7. Artist’s impression of the SMOS satellite launched in 2009 by ESA ...

Figure 3.8. Daily mean albedo produced by EUMETSAT’s LSA SAF for June 28, 2021...

Figure 3.9. Schematic representation of the spectral dependency of the surface...

Chapter 4

Figure 4.1. Increase in reforecast skill in the ERA-Interim and ERA5 reanalyse...

Figure 4.2. Satellite data coverage during FGGE: temperature retrievals from T...

Figure 4.3. Schematic of the assimilation of observations into an NWP model

Figure 4.4. Data coverage plot showing the AMVs assimilated into the Met Offic...

Figure 4.5. The geometry of a radio occultation measurement showing the refrac...

Figure 4.6. Impact of the various components of the global observing system in...

Chapter 5

Figure 5.1. Convective systems observed on the current MSG imagery (top), comp...

Figure 5.2. Main characteristics of a storm cell

Figure 5.3. RDT objects detected from SEVIRI channels in the western Mediterra...

Figure 5.4. Example of cloud types deduced from the SEVIRI imager onboard MSG,...

Figure 5.5. Observations (top line) and forecasts by machine learning (bottom ...

Chapter 6

Figure 6.1. Visible (a) and infrared (b) images of tropical cyclone (Hurricane...

Figure 6.2. Characteristic cloud structures for classifying tropical cyclones ...

Figure 6.3. Images of brightness temperatures in the 37 GHz (a) and 89 GHz (b)...

Figure 6.4. Vertical cross-section of the temperature anomaly associated with ...

Figure 6.5. Surface winds for the tropical cyclone (Super Typhoon) Noru on Aug...

Figure 6.6. Surface winds for tropical cyclone (typhoon) Hagibis on October 8,...

Figure 6.7. Trajectory and intensity of the tropical cyclone (Hurricane) Katri...

Chapter 7

Figure 7.1. The global reactive organic carbon (ROC) tropospheric budget

Figure 7.2. Means (on a 0.5 × 0.5 grid) of different VOC total columns retriev...

Figure 7.3. NO2 concentration differences (2020–2019) derived from TROPOMI ove...

Chapter 8

Figure 8.1. Average tropospheric ozone columns in Dobson units (DU) for the mo...

Figure 8.2. Annual tropospheric ozone column in Dobson units (DU) from OMI/MLS...

Figure 8.3. Observations of ozone in the very low troposphere (LMT: lowermost ...

Figure 8.4. Observations of the AOD at 550 nm retrieved from the measurements ...

Figure 8.5. Transects of the profiles of (a) attenuated backscattering of aero...

Chapter 9

Figure 9.1. Horizontal distribution of Saharan dust on June 18, 2011, observed...

Figure 9.2. Horizontal distribution of the optical depth of Saharan dust on Ju...

Figure 9.3. Transect of vertical profiles of desert dust extinction coefficien...

Figure 9.4. (Upper panel) IASI spectra simulated in the thermal infrared for f...

Figure 9.5. Distribution of dust over the Sahara on June 17, 2011, retrieved f...

Chapter 10

Figure 10.1. CO concentrations derived from IASI during California fires occur...

Figure 10.2. Vertical abundance (total column) of gas fire tracers over the Am...

Chapter 11

Figure 11.1. Total column ozone (TCO) in Dobson Units from the IASI instrument...

Figure 11.2. Total column ozone in Dobson units from the IASI instrument durin...

Figure 11.3. (a) Globally averaged CH4 dry air mole fractions and (b) instanta...

Figure 11.4. Vertical profiles for monthly mean CH4 for the period 2003–2006 a...

Introduction to Part 3

Figure I3.1. Infrared images (1978) illustrating the early days of operational ob...

Chapter 12

Figure 12.1. Variations in air temperature may be estimated from various data ...

Figure 12.2. Components of the Earth system relevant to climate timescales

Figure 12.3. Left: drifting buoy with high-precision calibrated platinum tempe...

Figure 12.4. Area extent of polar sea ice from 1979 to 2020. Thin blue lines s...

Figure 12.5. Timeline of observations, as assimilated in ERA5, from top to bot...

Figure 12.6. Time-series of (top) recalibrated top-of-atmosphere clear-sky ref...

Figure 12.7. Flowchart from satellite remote sensing to directly-usable climat...

Figure 12.8. Cover page of the WMO State of the Climate for the year 2020

Chapter 13

Figure 13.1. Example of weighting functions for CO2 in the case of nadir measu...

Figure 13.2. For the month of July 2019, CO2 field (top) and CH4 field (bottom...

Figure 13.3. Past, present and future missions observing CO2 (yellow), methane...

Figure 13.4. The three measurement principles aiming at the nadir for greenhou...

Figure 13.5. Monthly variation of integrated MT-CO2 measured by IASI from 2007...

Figure 13.6. Monthly variation of the integrated MT-CH4 columns measured by IA...

Figure 13.7. Monthly variation of XCO2 (left) and XCH4 (right) in three latitu...

Chapter 14

Figure 14.1. MSG images obtained on September 5, 2021 at 12:00 UTC. Left: 0.8 ...

Figure 14.2. Left: Spectra of emission (top) and absorption (bottom) by the at...

Figure 14.3. Total water vapor content (TCWV in cm, expressed as the height of...

Figure 14.4. Average upper tropospheric relative humidity (UTH, in %), for the...

Figure 14.5. Net radiative effect of clouds at the top of the atmosphere from ...

Figure 14.6. Average value of liquid water cloud path (in g/m2) from 1988 to 2...

Figure 14.7. Latitude/altitude transects observed by active instruments. On th...

Figure 14.8. Lidar scattering ratio histogram as a function of altitude observ...

Figure 14.9. Radiative heating rate in K/day related to different cloud types ...

Figure 14.10. Global average cloud cover (%) from left to right: for all cloud...

Figure 14.11. Geographic distribution of annual cloud cover for high-altitude ...

Chapter 15

Figure 15.1. The Global Precipitation Measurement (GPM) mission Core Observato...

Figure 15.2. Artist’s impression of the Tropical Rainfall Measuring Mission (T...

Figure 15.3. One of the first storms observed by the NASA/JAXA GPM Core Observ...

Figure 15.4. Global IMERG precipitation products on March 12, 2021 11:30 UTC. ...

Figure 15.5. Maps of the annual climatology of precipitation indexes for the p...

Appendix 1

Figure A1.1. Temperature variation as a function of altitude for the six AFGL ...

Figure A1.2. Pressure variation as a function of altitude for the six AFGL pro...

Figure A1.3. Variation of the H2O mixing ratio as a function of altitude for t...

Figure A1.4. Variation of the CH4 mixing ratio as a function of altitude for t...

Figure A1.5. Variation of the NO2 mixing ratio as a function of altitude for t...

Guide

Cover Page

Table of Contents

Title Page

Copyright Page

Acknowledgments

List of Authors

Introduction

Begin Reading

Appendix 1 Atmospheric Profiles

Appendix 2 Spectroscopic Parameters for Radiative Transfer

Appendix 3 List of Sensors and Satellites Cited in the Book

Appendix 4 Microwave Sensors and Infrared Hyperspectral Sounders

Glossary

List of Authors

Index

Summary of Volume 1

WILEY END USER LICENSE AGREEMENT

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SCIENCES

Space Exploration and Technology,Field Director – Jean-Luc Lefebvre

Space and Earth, Subject Head – Jean-Luc Lefebvre

Satellites for Atmospheric Sciences 2

Meteorology, Climate and Atmospheric Composition

Coordinated by

Thierry Phulpin

Didier Renaut

Hervé Roquet

Claude Camy-Peyret

First published 2023 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.

Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address:

ISTE Ltd27-37 St George’s RoadLondon SW19 4EUUK

www.iste.co.uk

John Wiley & Sons, Inc.111 River StreetHoboken, NJ 07030USA

www.wiley.com

© ISTE Ltd 2023The rights of Thierry Phulpin, Didier Renaut, Hervé Roquet and Claude Camy-Peyret to be identified as the authors of this work have been asserted by them in accordance with the Copyright, Designs and Patents Act 1988.

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s), contributor(s) or editor(s) and do not necessarily reflect the views of ISTE Group.

Library of Congress Control Number: 2023941805

British Library Cataloguing-in-Publication DataA CIP record for this book is available from the British LibraryISBN 978-1-78945-141-2

ERC code:

PE10 Earth System Science

 PE10_1 Atmospheric chemistry, atmospheric composition, air pollution

 PE10_2 Meteorology, atmospheric physics and dynamics

 PE10_14 Earth observations from space/remote sensing

PE9 Universe Sciences

 PE9_15 Space Sciences

 PE9_17 Instrumentation - telescopes, detectors and techniques

Acknowledgments

The coordinator is very grateful to Didier Renaut, Hervé Roquet and Claude Camy-Peyret for their significant help in editing this book through their advice, proofreading, corrections to chapters and help with the organization. Their support has been invaluable in bringing together quality contributions in a book that will cover the different facets of the topic Space and Atmosphere in a comprehensive manner. Gratitude is also expressed to Jérome Lafeuille and Jean Pailleux for their proofreading and improvements to various chapters. Finally, special thanks to the journal La Météorologie for having authorized the use of the glossary established for the special issue of the journal, No. 97 in 2019, devoted to satellite missions for meteorology and climate.

List of Acronyms

(3D/4D)-Var

(3/4 Dimensional) – Variational

4A/OP

Automatized Atmospheric Absorption Atlas/OPerational

AC-VC

Atmospheric Composition Virtual Constellation

ACCP

Aerosols, Clouds, Convection and Precipitation

ACX

GeoXO Atmospheric Composition

ADM

Atmospheric Dynamics Mission

AERIS

Data and Services for the Atmosphere

AERONET

AErosol RObotic NETwork

AI

Artificial Intelligence

AMV

Atmospheric Motion Vector

AOD

Aerosol Optical Depth

APHRODITE

Asian Precipitation – Highly-Resolved Observational Data Integration Towards Evaluation

APT

Automatic Picture Transmission

ARTS

Atmospheric Radiative Transfer Simulator

ASI

Agenzia Spaziale Italiana (Italian Space Agency)

AVCS

Advanced Vidicon Camera System

BC

Black Carbon

BIPM

International Bureau of Weights and Measures

BRDF

Bidirectional Reflectance Distribution Function

C3IEL

Cluster for Cloud evolution, ClImatE and Lightning

C3S

Copernicus Climate Change Service

CAMS

Copernicus Atmosphere Monitoring Service

CAPE

Convective Available Potential Energy

CALIPSO

Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation

CATS

Cloud-Aerosol Transport System

CCI

Climate Change Initiative

CCSDS

Consultative Committee on Space Data Systems

CDR

Climate Data Record

CDRD

Cloud Dynamics and Radiation Database

CEOS

Committee on Earth Observation Satellites

CFC

ChlorFluoroCarbon

CGMS

Coordination Group for Meteorological Satellites

CI

Convection Initiation

CIMSS

Cooperative Institute for Meteorological Satellite Studies

CLW

Cloud Liquid Water

CM

Cloud Mask

CM-SAF

Climate Monitoring – Satellite Application Facility

CMA

Chinese Meteorological Agency

CMEMS

Copernicus Marine Environment Monitoring Service

CMORPH

CPC MORPHing technique

CMV

Cloud Motion Vector

CNES

Centre national d’études spatiales France

CNRM

Centre national de la recherche météorologique France

CNRS

Centre national de la recherche scientifique France

CNSA

Chinese National Space Administration

COCCON

COllaborative Carbon Column Observing Network

CoMet

Carbon Dioxide and Methane field campaign

CONTRAIL

Comprehensive Observation Network for TRace gases by AIrLiner

COP

Conference Of the Parties

CORRA

COmbined Radar-Radiometer Algorithm

CPC

Climate Prediction Center

CRM

Cloud Resolving Model

CRTM

Community Radiative Transfer Model

CTTH

Cloud Top Temperature and Height

CWDP

Commercial Weather Data Pilot

CYGNSS

CYclone Global Navigation Satellite System

DAOD

Differential AOD

DBNet

Direct Broadcast NETwork WMO-OMM

DCS

Data Collection System

DDA

Discrete Dipole Approximation

DIAL

DIfferential Absorption Lidar

DISORT

DIScrete Ordinate Radiative Transfer

DLR

Deutsches Zentrum für Luft- und Raumfahrt Allemagne

DMSP

Defense Meteorological Satellite Program

DNB

Day and Night Band

DOFS

Degrees of Freedom for Signal

DU

Dobson Unit

DVB

Digital Video Broadcast

DVB-S

Digital Video Broadcast by Satellite

EC

European Commission

ECMWF

European Centre for Medium-term Weather Forecast

ECOSTRESS

Ecostress Spectral Library Database

ECV

Essential Climate Variable

EDR

Environmental Data Record

EE

Earth Explorer

EEA

European Environment Agency

EF

Emission Factor

ELDO

European Launcher Development Organisation

ENSO

El Niño Southern Oscillation

EOS

Earth Observing System

EOSDIS

EOS Data Information System

EPS

EUMETSAT Polar System

ERA

ECMWF ReAnalysis

ERB

Earth Radiation Budget

ESA

European Space Agency

ESE

Earth Science Enterprise

ESRO

European Space Research Organisation

ESSA

Environmental Science Services Administration

ESSP

Earth System Science Pathfinder

ESTO

Earth Science Technology Office

EUMETSAT

EUropean organisation for the exploitation of METeorological SATellites

EW

Earth Watch

EXIM

EXtrapolated IMagery products

FASTEM

FAST Emissivity Model

FCDR

Fundamental Climate Data Record

FCI

Flexible Combined Imager

FCover

Fractional Cover (of vegetation)

FDR

Fundamental Data Record

FGGE

First GARP Global Experiment

FFT

Fast Fourier Transform

FGGE

First Global GARP Experiment WMO-OMM

FIR

Far IR

FOR

Field Of Regard

FOV

Field Of View

FSOI

Forecast Sensitivity Observation Impact

FSR

Forecast Sensitivity to R (the observation error covariance matrix)

FT

Fourier Transform

FTS

Fourier Transform Spectrometer

FY

Feng Yun

GADS

Global Aerosol Data Set

GARP

Global Atmospheric Research Programme WMO-OMM

GAS

GMES Atmospheric Service

GASP

GOES Aerosol/Smoke Product

GAW

Global Atmospheric Watch

GCM

Global Climate Model

GCOS

Global Climate Observing System

GDP

Gross Domestic Product

GEO

GEostationary Orbit

GEO

Group on Earth Observation

GEOS-5

Goddard Earth Observing System model – version 5

GEOSS

Global Earth Observation System of Systems

GeoXO

GEOstationary eXtended Observations

GEWEX

Global Energy and Water Cycle Experiment

GHCN

Global Historical Climatology Network

GHG

GreenHouse Gas

GLM

Geostationary Lightning Mapper

GMES

Global Monitoring for Environment and Security

GMF

Geophysical Model Function

GNP

Gross National Product

GNSS

Global Navigation Satellite System

GOCCP

GCM-Oriented CALIPSO Cloud Product (CALIPSO-GOCCP)

GPCC

Global Precipitation Climatology Center

GPCP

Global Precipitation Climatology Project

GPI

GOES Precipitation Index

GPM-CO

GPM-Core Observatory

GPROF

Goddard PROFiling algorithm

GPS

Global Positioning System

GRUAN

Global Reference Upper-Air Network GCOS

GSFC

Goddard Space Flight Center

GSICS

Global Space-based Inter-Calibration System

GSIP

GOES Surface and Insolation Project

GSMaP

Global Satellite Mapping of Precipitation

GSOD

Global Summary Of the Day

GV

Ground Validation

H-SAF

Hydrology – Satellite Application Facility

HCFC

HydroChloroFluoroCarbon

HEO

High Eccentricty Orbit

HEPAD

High Energy Proton and Alpha Detector

HFC

HydroFluoroCarbon

HLOS

Horizontal Line Of Sight

HOAPS

Hamburg Ocean Atmosphere Parameters and fluxes from Satellite data

HRIT

High Rate Image Transmission

HRPT

High Resolution Picture Transmission

HSRL

High Spectral Resolution Lidar

IAGOS

In-service Aircraft for a Global Observing System

IBTrACS

International Best Track Archive for Climate Stewardship

ICOADS

International Comprehensive Ocean-Atmosphere Data Set

ICOS

Integrated Carbon Observation System

IEC

International Electrotechnical Commission

IF

Intermediate Frequency

IFS

Integrated Forecasting System

IIP

Instrument Incubator Program

IJSP

International Joint Polar System

ILS

Instrument Line Shape

IMD

Indian Meteorological Department

IMERG

Integrated Multi-satellitE Retrievals for GPM

IMS

Ice Mapping System

IMS

Interactive Multisensor Snow

INDOEX

INDian Ocean EXperiment

INPE

Instituto Nacional de Pesquisas Espaciais Brésil

InVEST

In-space Validation of Earth Science Technology

IOC

Intergovernmental Oceanographic Commission UNESCO

IODC

Indian Ocean Data Coverage

IPCC

Intergovernmental Panel on Climate Change

IPDA

Integrated Path Differential Absorption

IPSL

Institut Pierre-Simon Laplace France

IPWG

International Precipitation Working Group CGMS

IR

Infra-Red

IROWG

International Radio Occultation Working Group CGMS

ISA

Israel Space Agency

ISCCP

International Satellite Cloud Climatology Project

ISO

International Standardization Organization

ISRF

Instantaneous Spectral Response Function

ISRO

Indian Space Research Organization

ISS

International Space Station

ITOS

Improved TIROS Operational System

ITWG

International TOVS Working Group CGMS

IUPAC

International Union of Pure and Applied Chemistry

IWP

Ice Water Path

IWWG

International Winds Working Group CGMS

JAXA

Japan Aerospace eXploration Agency

JCSDA

Joint Center for Satellite Data Assimilation

JMA

Japan Meteorological Agency

JPL

Jet Propulsion Laboratory

JPSS

Joint Polar Satellite System

JRA

Japanese ReAnalysis

KMA

Korean Meteorological Agency

LAI

Leaf Area Index

LAMP

Laboratoire de météorologie physique France

LATMOS

Laboratoire atmosphères, milieux, observations spatiales France

LEO

Low Earth Orbit

LI

Lifted Index

LIDORT

LInearized Discrete Ordinate Radiative Transfer

LMD

Laboratoire de météorologie dynamique France

LMT

Local Mean solar Time

LMT

LowerMost Troposphere

LOA

Laboratoire d’optique atmosphérique France

LOS

Line Of Sight

LRIT

Low Rate Information Transmission

LRPT

Low Resolution Picture Transmission

LRR

Laser Retro-Reflector

LSE

Land Surface Emissivity

LSI

Low Stream Approximation

LST

Land Surface Temperature

LTE

Local Thermodynamic Equilibrium

LUT

Look-Up Table

MAG

Mission Advisory Group

MAGIC

Monitoring Atmospheric composition and Greenhouse gases through multi-Instrument Campaigns

MEO

Middle Earth Orbit

MEPED

Medium Energy Proton and Electron Detector

MERRA

Modern-Era Retrospective analysis for Research and Applications

MOP

Meteosat Operational Programme

MOZAIC

Measurement of OZone and water vapour by Airbus In-service airCraft)

MSWEP

Multi-Source Weighted-Ensemble Precipitation

MTP

Meteosat Transition Programme

MW

MicroWave

MWR

MW Radiometer

NASA

National Aeronautics and Space Administration

NCEP

National Center for Environmental Prediction

NDACC

Network for the Detection of Atmospheric Composition Change

NDVI

Normalized Difference Vegetation Index

NEDT

Noise Equivalent Differential Temperature

NESDIS

National Environmental Satellite, Data, and Information Service (NOAA)

NIR

Near InfraRed (~ 1.0 to 0.7 µm)

NMVOC

Non-Methane Volatile Organic Compounds

NOAA

National Oceanic and Atmospheric Administration

NOAA/NESDIS

National Oceanic and Atmospheric Administration Satellite and Information Service

NPP

NPOESS Preparatory Program

NRT

Near Real-Time

NSOAS

National Satellite Ocean Application Service

NSOSA

NOAA Satellite Observing System Architecture study

NSSDC

NASA Space Science Data Center

NUCAPS

NOAA Unique Combined Atmospheric Processing System

NWP

Numerical Weather Prediction

NWP-SAF

Numerical Weather Prediction – Satellite Application Facility

OceanRAIN

Ocean Rain And Ice-phase precipitation measurement Network

ODS

Ozone Depleting Substances

OI

Optimal Interpolation

OLR

Outgoing Longwave Radiation

OLS

Operational Linescan System

OPAC

Optical Properties of Aerosols and Clouds

OPD

Optical Path Difference

OSCAR

Observing Systems Capability Analysis and Review tool

OSE

Observing System Experiments

OSSA

Office of Space Science Applications

OSSE

Observing System Simulation Experiments

OSTIA

Operational Sea surface Temperature and Ice Analysis

PACRAIN

Pacific Rainfall Database

PAN

PeroxyAcetyl Nitrate

PAOB

PAid OBservation

PAR

Photosynthetically Active Radiation

PATMOS-x

Pathfinder ATMOSpheres – eXtended

PERSIANN

Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks

PERSIANN-CCS

PERSIANN-Cloud Classification System

PM

Particulate Matter

PM2.5

Particulate Matter (diameter smaller than 2.5 µm)

PMW

Passive MicroWave

PNPR

Passive microwave Neural network Precipitation Retrieval

POA

Primary Organic Aerosol

POEM

Polar-Orbit Earth-Observation Mission

PPS

Precipitation Processing System

PRPS

Precipitation Retrieval and Profiling Scheme

PSC

Polar Stratospheric Cloud

QA4EO

Quality Assurance Framework for Earth Observation

QI

Quality Index

QRNN

Quantile Residual Neural Network

R&T

Research & Technology

RDT

Rapidly Developing Thunderstorm

RF

RadioFrequency

RO

Radio Occultation

ROC

Reactive Organic Carbon

ROSCOSMOS

Russian Federal Space Agency

RR

Rain Rate

RSS

Rapid Scanning Service

RT

Radiative Transfer

RTE

Radiative Transfer Equation

RTTOV

Rapid Transmission for TOVs

RTTOV-SCAT

RTTOV with SCATtering

SAF

Satellite Application Facility

SAG

Science Advisory Group

SAGE

Stratospheric Aerosol and Gas Experiment

SAM-II

Stratospheric Aerosol Measurement II

SC

Snow Cover

SCaMPR

Self-Calibrating Multivariate Precipitation Retrieval

SEM

Space Environment Monitor

SFCG

Space Frequency Coordination Group

SI

International System

SIC

Sea Ice Concentration

SNPP

Suomi National Polar-orbiting Partnership

SNR

Signal to Noise Ratio

SOA

Secondary Organic Aerosol

SORCE

SOlar Radiation and Climate Experiment

SOS

Sum Of Squares

SPARC

Stratosphere-troposphere Processes And their Role in Climate

SR

Scattering Ratio

SRSOR

Super Rapid Scan Operations for GOES-R

SSA

Single Scattering Albedo

SSEC

Space Science and Engineering Center

SST

Sea Surface Temperature

STAR

(Center for) Satellite Applications and Research

SWE

Snow Water Equivalent

SWIR

ShortWave InfraRed (~ 2.5 to 1.0 µm)

SZA

Solar Zenithal Angle

Tb

Brightness temperature

TCCON

Total Carbon Column Observing Network

TCHP

Tropical Cyclone Heat Potential

TCWV

Total Column Water Vapor

TED

Total Energy Detector

TEMPEST-D

Temporal Experiment for Storms and Tropical Systems – Demonstration

TEMPO

Tropospheric Emissions: Monitoring of Pollution

TIR

Thermal InfraRed (~ 15 to 5 µm)

TLS

Temperature of the Lower Stratosphere

TLT

Temperature of the Lower Troposphere

TMPA

TRMM Multisatellite Precipitation Analysis

TMS

Temperature of the Mid-Stratosphere

TMT

Temperature of the Mid-Troposphere

TOAR

Tropospheric Ozone Assessment Report

TOR

Tropospheric Ozone Residual

TPW

Total Precipitable Water

TTS

Temperature of the Top Stratosphere

TUS

Temperature of the Upper Stratosphere

TUT

Temperature of the Upper Troposphere

TV

TeleVision

UMORA

Unified Microwave Ocean Retrieval Algorithm

UN

United Nations

UNESCO

United Nations Educational, Scientific and Cultural Organization

UNFCCC

United Nations Framework Convention on Climate Change

UT/LS

Upper Troposphere/Lower Stratosphere

UTH

Upper Tropospheric Humidity

UV

Ultraviolet (~ 400 to 200 nm)

UV-B

Ultraviolet-B (~ 315 to 280 nm)

UVAI

Ultraviolet Aerosol Index

UVN

Ultraviolet, Visible and Near-infrared

VAAC

Volcanic Ash Advisory Centre

VarBC

Variational Bias Correction

VHI

Vegetation Health Index

VIS

VISible

VLIDORT

V-LInearized Discrete Ordinate Radiative Transfer

VOC

Volatile Organic Compound

WCRP

World Climate Research Program

WEFAX

Weather Facsimile

WF

Weighting Function

WMO

World Meteorological Organization

WWW

World Weather Watch

Introduction

Thierry PHULPIN

Retired from CNES and Météo-France, Toulouse, France

Observation of the Earth System from space

Satellite images are now in common use during television weather forecasts and are now also accessible on smartphones. Nowadays, everyone is introduced to this vision of the Earth from space at school. Thanks to satellites and their imagers, planet Earth appears to everyone as a familiar environment and is seen as a system in which all environments are interconnected. When a storm breaks out, its intensity is marked by the depth of the gyre formed by the depression and translates into very powerful winds whose impact on the ocean is very noticeable in data from oceanographic satellites. A volcanic eruption or an earthquake leaves traces in the atmosphere (ash clouds, ionospheric signals, etc.), which can be perceived and monitored. Heavy precipitation visualized using microwave instruments and droughts measured with sounders leave surface footprints that can be detected with satellites intended for monitoring continental resources. The relationship between the nature of the surface (oceans, desert, soil, bare ground, urban environment, crops, forests, etc.) and its state at a given moment (roughness, water state), in connection with atmospheric conditions, is decisive for meteorology via the mechanisms of thermal emission, or evaporation. All of these relationships can be characterized, inferred or measured by satellites, some intended for oceanography and others for monitoring land surfaces, or even for meteorology. These links between the various compartments of the Earth System began to be clearly highlighted as soon as the human or animal populations inhabiting the Earth began to move between the continents, thanks to discoveries by explorers. These discoveries, by allowing the development of a trade economy, led to the establishment of an interdependent system and had a major impact on a planetary scale, particularly on the various ecosystems. We could therefore already speak of an Earth System as early as the 16th century. However, it is the links between the observed natural phenomena that have made it possible to construct the notion of the climate system. Intuitively, we have perceived over the centuries that many phenomena responsible for the evolution of measurable variables were linked. These concepts can be visualized in diagrams, for example, Figure I.1. However, thanks to satellites, it has been possible to advance in the understanding of the processes (in addition to field studies), quantify certain phenomena at scales not possible from ground measurements alone, establish parametric links between certain variables and ultimately improve the physics of the models and then calibrate or validate these models.

Figure I.1.The different compartments of the Earth System, taken into account in a climate model.

It is therefore logical to address the various subsystems of the Earth in a work devoted to space science, and to consider them in a coherent approach.

The atmosphere

Volume 1 is devoted to satellite observation of the atmosphere and the sciences it has developed: meteorology, atmospheric composition, as well as knowledge of the climate and its evolution.

According to Blum (2019)1, it is the mastery of meteorology that would have allowed the WWII allies to land, demonstrating the major strategic importance of investing in an observation network. Space science and technology started early on, having been boosted by know-how of German engineers who developed the V2. The first photos of the Earth were taken in 1960, which highlighted how important the images were for providing an overview of the spatial distribution of cloud cover and its movement. The US then created a program of meteorological satellites, preceding the Soviets, followed by Europe and Japan. The history of these developments will be discussed in Chapter 1 of Volume 1. For meteorology, it is useful for the satellite measurements to be taken at the same solar time, to better follow the evolution of the thermodynamic parameters by comparing them with the readings of the previous day at the same time, hence the use of Sun-synchronous polar orbits. On the other hand, the ability to observe the Earth continuously from geostationary orbit is also very attractive for deducing information about the wind from the apparent movements of clouds and observing the development of storms or the movement of cyclones. The orbits used for these missions and their advantages are described in Chapter 8 of Volume 1. It quickly became clear that the long-term continuity of observations under identical conditions is necessary to integrate these observations into the international network of meteorological measurements and to facilitate their use in forecasting models. We then saw a dichotomy of missions appear; on the one hand, a series of identical operational satellites for a program spanning 20 or 30 years and, on the other hand, satellites equipped with innovative instruments for research. In the US, this dichotomy is reflected in the division of responsibilities between NOAA and NASA. These agencies pioneered meteorology from space. The history of their programs to date is presented in the first chapters of Part 1 of Volume 1. This part shows how the programs are developed to meet the needs of users, using the most advanced technologies whose developments are supported by the agencies that lead in this field. Following the American agencies, Chapters 4–6 of Volume 1 are devoted to the European programs of ESA, EUMETSAT and CNES. We see in Chapter 7 of Volume 1 the role played by the World Meteorological Organization in coordinating operational projects from the US, Europe or Asia. The chapter also discusses the issue of data acquisition anywhere on the planet for real-time use.

Part 2 of Volume 1 is devoted to the physical basis of satellite observations for atmospheric sciences. Chapter 8 of Volume 1 presents the principles of orbital mechanics to determine how to meet the need for observations by meteorologists or orbits more suited to different issues such as monitoring precipitation in intertropical zones or air quality in the most polluted regions. The first operational satellites only offered observation in a visible “channel”, similar to a photograph from the sky, and another in an infrared channel giving an idea of the temperature of the objects targeted. These passive observations have allowed advances in cloud mapping and sea temperature but have proven insufficient to access other meteorological information. The range of observations was quickly extended with observations in multiple optical channels, and the observation domain was extended to the microwave domain, allowing for, due to the digitization of measurements, the transition to the quantitative use of observations. Measurement physics, developed to propose passive or active measurement techniques and better use the resulting data, is presented in Chapter 9 of Volume 1. In Chapter 10 of Volume 1, we present the problem of finding atmospheric variables of interest from the observations and the main methods used for this purpose.

Part 1 of this book is more specifically devoted to meteorology. With regard to the three-dimensional distribution of temperature, humidity and wind, the main data useful for meteorology has long been provided by radiosondes. However, these observations are rare over the oceans and are therefore supplemented with satellite measurements of vertical distributions of temperature and humidity. The technique used is based on the selective absorption of carbon dioxide or oxygen, which is scarce but evenly distributed in the atmosphere (at least to the first order), and of water vapor and other greenhouse gases, which strongly absorb infrared or microwave radiation. This method, first tested by the Americans with the Infrared Interferometer Spectrometer (IRIS*) on the Nimbus IV satellite, then gave rise to the TIROS Operational Vertical Sounder (TOVS*) radiometric sounders, before technically evolving towards much more precise spectrometric measurements with the Atmospheric Infrared Sounder (AIRS*) and Infrared Atmospheric Sounding Interferometer (IASI*). Chapters 1 to 3 present the restitution of the main variables characterizing the state of the atmosphere, or that of the surface variables directly useful or necessary for the inversion of the atmospheric characteristics. Chapters 4 to 6 focus on the major applications of these observations: numerical weather forecasting, short-term forecasting and cyclone tracking.

Atmospheric sounding missions using spectrometry are successful by analyzing minority atmospheric components that are important for the planet or for human health, such as stratospheric ozone, gases and particles that are involved in air quality or the greenhouse effect.

The use of space observations and the benefits derived from them are presented in Part 2 of this book: detection of polluting species dangerous to health (Chapters 7 and 8), observation of clouds of desert dust and elements emitted by bush or forests. Chapter 11 is devoted to stratospheric chemistry, better known and understood thanks to the many satellite observations devoted to monitoring the hole in the ozone layer.

Because they offer precise and well-targeted observations with global spatial coverage, satellites have contributed significantly to better understanding the processes at play in the Earth’s climate. In addition, the continuity of long-term observations (more than 30 years of data!) makes it possible to monitor the evolution of the climate and to attribute certain phenomena to this evolution. Part 3 of this book concerns the use of satellite observations for the analysis of climatic processes and the monitoring of climatic variables. In its introduction, Chapter 12 recalls the importance of well-calibrated data, the need to reprocess the data acquired over time in a homogeneous manner and to repeat the reprocessing of the products as and when more efficient algorithms and processes become available. Chapter 13 is devoted to the restitution of the greenhouse gases CO2 and CH4 and to the location of the sinks and sources of these gases, which play a major role in the warming of the atmosphere. Clouds and water vapor also play an essential role. However, these variables have been monitored from the very first satellites. Analytical techniques have been refined and new data produced with more precise instruments have arrived, making it possible to more precisely estimate the spatio-temporal distribution of atmospheric water (Chapter 14). Clouds and water vapor are also involved in precipitation: the distribution and intensity of which are regularly monitored (Chapter 15).

In addition to an index, this book also includes a glossary to clarify the definition of certain concepts, appendices including a compilation of the names of instruments and satellites in question (to be updated as and when new missions occur), as well as a list of acronyms.

Notes

1

. Blum, A. (2019).

The Weather Machine. How We see in the Future

. The Bodley Head, London.

*

See

Glossary

.

PART 1Meteorology

Introduction to Part 1Meteorology and the Contribution of Satellite Observations

Hervé ROQUET

Direction de l’Enseignement Supérieur et de la Recherche de Météo-France, Saint-Mandé, France

I1.1. From image use…

Observation is an essential activity in meteorology. Observations are essential for real-time knowledge and monitoring of the main relevant atmospheric variables (pressure, temperature, humidity, wind, cloud variables and precipitation), as well as for the detection and monitoring of hazardous weather phenomena affecting human activities. They are also used for the preparation and monitoring of weather predictions. In particular, they make it possible to determine the initial state of the atmosphere from which numerical weather prediction models can predict its evolution. Finally, observations allow for continuous progress in the knowledge of meteorological phenomena and the physical processes that govern them.

In the history of meteorological observations, the advent of satellite imagery was a major milestone, giving meteorologists real-time access for the first time to a spatialized view of cloud systems and the meteorological phenomena they represent, such as fronts, mid-latitude weather disturbances, thunderstorms and tropical cyclones. The direct interpretation of an image by forecasters1 is still an important part of the use of satellite imagery in meteorology today, whether to analyze a situation or to assess predictions derived from numerical weather predicting models.

Figure I1.1.Example of nephanalysis produced by the Météo-France Space Meteorology Center on March 3, 1966 from images taken by the Vidicon camera of the American satellite ESSA-2

(source: Météo-France, Space Meteorology Center)

The instrument for observing on the first meteorological satellites was only a camera, which provided analog black and white photographs of the Earth and clouds of the regions they flew over. Their meteorological use was greatly limited not only by the image quality, but also by the fact that the identification of cloud types from a single black and white image in the visible domain is difficult even for an experienced user. An important step was the advent of the first radiometers with simultaneously a channel in the visible and in the thermal infrared, providing not only a usable observation at night, but also a better ability to distinguish the different types of clouds, the infrared channel providing information on the temperature and therefore on the altitude of their summit. For this reason, meteorologists have become accustomed to simultaneously exploiting images in the visible range in black and white with a natural dynamic (clouds appearing in white, because they are brighter than the surface), and images in the infrared range with an inverted dynamic (clouds also appearing in white, because they are cooler than the surface).

At the beginning of the operational use of satellite imagery in meteorology, the means of reception, processing and dissemination being essentially analogous, an operational production of nephanalyses was set up in some meteorological services (see Chapter 1). These maps, developed manually by experts in the meteorological interpretation of images (referred to as “nephanalysts”), made it possible to delineate the main cloud zones and the associated cloud cover, as well as the main types of clouds identified, and were distributed by facsimile to various weather prediction centers. This activity disappeared when computerized means of receiving, processing and displaying data became widespread, which made it possible not only to automate processing operations, such as the application of different dynamics to improve image display and the change of geographical projection, but also to transmit images via computer networks and direct display on forecasters’ workstations.

The advent of geostationary meteorological satellites was a crucial advance in providing access to visible and thermal infrared images with high temporal repetitiveness, enabling meteorologists to animate them to visualize the movements and evolution of cloud systems, and thus gain access to information on the dynamics of the atmosphere. In addition, the presence of an infrared channel in the water vapor absorption band (referred to by meteorologists as the “water vapor” channel) provided additional information on humidity in the mid-troposphere. The structure and evolution of the water vapor field is an important element in anticipating or monitoring the evolution of meteorological phenomena such as weather disturbances and convective systems, and indirectly provides information on the vertical movements of the atmosphere on a large scale; drying zones are associated with subsidence movements2 and vice versa.

Figure I1.2.Example of an image in multispectral colored composition (March 4, 2004, 10 am UT), obtained by combining the channels of the SEVIRI imager of the Meteosat Second Generation satellite. This image processing makes it possible to visually distinguish low clouds (ochre shades) from high clouds (white shades), as well as in the absence of clouds to detect the presence of snow on the ground (shiny white)

(source: Météo-France, Space Meteorology Center).

With the advent of recent generation meteorological satellites, carrying imaging radiometers with a large number of channels (e.g. the SEVIRI imager** of Meteosat Second Generation satellites, with 12 channels whose central wavelengths are distributed between 0.6 and 13.4 microns), the direct use by forecasters of all the individual images corresponding to each channel has become difficult, if not impossible, in an operational context. However, all of these channels and their combination can provide important additional information, for example, on the microphysical properties of clouds, on the presence of volcanic dust or ash or on the type of air mass. For this reason, false-color imaging products have been developed (often called multispectral colored compositions or “RGB” images), each red, green and blue color plane using the following as input: the data of a channel or a combination of channels, with the choice of channel depending on the type of information that it is desired to highlight through the color variations. In addition to basic images of a limited number of channels, RGB products dedicated to the general recognition of clouds, the identification of the air mass, the detection of low clouds and fog, and the detection of aerosols are nowadays often used operationally by forecasters.

I1.2. …to measurement use

But meteorologists do not just use satellite imagery. As will be shown in this section, they also use data from the various satellite instruments to access measurements of a large number of geophysical variables crucial for operational meteorology: vertical profiles of temperature and atmospheric humidity, physical and microphysical properties of clouds, wind, surface variables, etc. For this reason, satellite observations nowadays largely dominate in terms of data quantity of the other sources, and are particularly used intensively for Nowcasting and numerical weather prediction. However, despite their ever-increasing quality and diversity, they do not cover all the needs for meteorological observations, since measurements by remote sensing from space have limitations intrinsically linked to the physics of measurement, or to the current state of technology. Thus, at present, certain meteorological variables (such as atmospheric pressure) cannot be measured with sufficient accuracy, or certain regions (such as the atmospheric boundary layer) cannot be sampled with sufficient spatial or temporal resolution by satellite.

Chapter 1 presents the atmospheric temperature and humidity profiles that are produced operationally from measurements of infrared and microwave sounders, and their main uses in meteorology.

Wind at altitude is a very important meteorological variable, for which direct observations are provided either by radio soundings, the spatial coverage of which is very inhomogeneous and limited essentially to continental areas, or by airliners, the spatial coverage of which is limited to the flight path and level of the aircraft. Chapter 2 shows the long-standing contribution of satellite imagery for estimating winds at altitude, which is obtained from the temporal tracking of targets such as clouds or water vapor field structures, as well as that of measurements by Doppler lidar, the operational demonstration of which has just been made thanks to the ADM-Aeolus satellite launched in 2018 by the European Space Agency.

Weather prediction requires not only knowledge of the state of the atmosphere at a given moment, but also knowledge of certain properties of the surface, on land or at sea, which will influence the exchanges of energy, matter and quantity of movement between the two environments. Chapter 3 provides an overview of the various surface variables that are important for weather forecasting, and to which different types of satellite measurements give access.

Chapter 4 shows the essential contribution of satellite observations for data assimilation into numerical weather prediction models. Data assimilation is a set of techniques which, using available observations, are intended to determine the initial state of numerical models, from which the evolution of the atmosphere is calculated to provide weather predictions. Much progress has been made in recent decades in this area, making it possible to take full advantage of satellite observations. These techniques also make it possible to produce re-analyses of past and present climate, thanks to the series of satellite observations which have now been available for more than 40 years.

In meteorology, Nowcasting refers to all methods aimed at predicting weather conditions in the next few hours, usually for alerting purposes with a few hours of anticipation. It requires the production of predictions as quickly as possible, and updated as frequently as possible to take into account the latest observations available, which represents a strong constraint with regard to numerical weather prediction systems. For this reason, the direct use of observations, often combined with temporal extrapolation techniques, also holds an important place. Chapter 5 presents the state of the art with regard to satellite observations and the methods used for Nowcasting.

Tropical cyclones are one of the most destructive meteorological phenomena, whose direct observation remains very difficult because of the extreme conditions prevailing there. Since the advent of the first geostationary meteorological satellites, images provided have enabled forecasters to identify and estimate the characteristics of cyclones, as well as to track their trajectory. As shown in Chapter 6, although geostationary imagery remains the main source of information today for the operational monitoring of tropical cyclones, other satellite measurement systems also provide valuable information on certain meteorological variables within them.

Notes

1

. Persons in charge within the meteorological services of the final development of expert forecasts.

**

See

Appendix 3

.

2

. In meteorology, subsidence is the vertical downward movement of air, which then compresses, and therefore warms and dries.

1Operational Sounding of Thermodynamic Variables in the Atmosphere

Thomas AUGUST

European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), Darmstadt, Germany

1.1. Introduction

Global knowledge of the vertical structure in temperature and humidity of the atmosphere is essential for weather forecasting and climate monitoring. These thermodynamic variables determine, for example, regional and large-scale air-mass circulation, as discussed in detail in Chapter 2. More locally, vertical thermal and humidity gradients are key ingredients of atmospheric stability. Knowledge of these gradients is critical to be able to alert populations and civil security components of the development of devastating weather events (massive hail, lightning, squall, flash floods, even tornadoes) or to monitor thermal inversions conducive to air quality degradation. It is also quite significant that these variables condition the storage capacity of water vapor (which is a powerful greenhouse gas) in the atmosphere as well as possible changes in the phase of the water, therefore microphysical processes associated with the formation of clouds (which are important in the global albedo of the Earth), fog layers, etc. More generally, these thermodynamic variables control the transfer of radiative energy between ground and atmosphere. They are therefore necessary to model radiative transfer, for example, for numerical weather prediction (Chapter 4), for modeling Earth’s radiation budget (Chapter 14) or finally to be able to detect and quantify other atmospheric constituents such as aerosols, greenhouse gases and molecules involved in air quality, etc.

This information was traditionally provided mainly by ground-based measurements or sounding balloon radiosondes, with consequently very limited spatio-temporal sampling and concentrated coverage on continental surfaces of the northern hemisphere. The development of satellite observation with TOVS instruments since the 1970s has made it possible to provide initial thermodynamic information on a synoptic scale thanks to radiometers operating in infrared (TIR) and microwaves (MW). But it was with the advent of hyperspectral sounders in polar orbit in the 2000s that a decisive step was taken to access temperature and humidity profiles with real vertical resolution.

In this chapter, we first present operational strategies at NOAA and EUMETSAT to operate passive vertical sounders and meet the needs of different users. They put into practice the theoretical principles of remote sensing explained in the two previous chapters with products of temperature, humidity, clouds and also ozone which is a tracer of the dynamics in the upper atmosphere. The sounders operating at nadir have a footprint ranging from about ten to a few tens of kilometers. They have maximum sensitivity and resolution in the free troposphere and also provide information in the stratosphere (Figure 1.1) and in a more limited manner in the planetary boundary layer. Atmospheric sampling of temperature and humidity using limb radio occultation (RO) signals from geo-positioning satellite systems (GNSS) has been described in Chapter 2. The RO technique makes it possible in particular to complete the knowledge of vertical structure in the upper layers of the atmosphere. It also offers a finer vertical resolution than the passive IR and MW nadir sounders, but on generally larger horizontal scales.

Figure 1.1.Upper stratospheric temperature sounding by IASI-B (left) and IASI-C (middle) after the explosion of the Hunga Tonga-Hunga Ha?apai volcano on January 14, 2022. On the right: temperature anomaly noted by IASI-B and IASI-C compared to previous days. Concentric circles reveal the propagation of gravity waves generated by the explosion to an altitude of 40 km

1.2. Operational use of TIR and MW sounders

1.2.1. Satisfying ever-more demanding users

The constant progress made in numerical weather prediction requires thermodynamic profiles that are increasingly resolved vertically. The same applies to very short-range prediction or nowcasting, as well as monitoring of climate, atmospheric composition and air quality.

As we have seen in Chapters 9 and 10 of Volume 1, the greater the spectral resolution of the measurements made by satellite sounders, the finer the vertical information restored. Deployed since the 1980s in polar orbit (Appendix 3), MW passive sounders operated in conjunction with broadband imagers and radiometers provided necessary vertical information until the late 1990s. Due to limited information content, however, the restitution of atmospheric profiles usually required the use of a priori information from numerical models.

The advent of hyperspectral sounders in TIR in the early 2000s made it possible to reach a milestone with vertical information content that allowed for the restitution of atmospheric profiles in temperature and humidity in a model-independent manner. They are operated in synergy with MW sounders. The respective information content of TIR and MW sounders have been discussed in Chapter 9 of Volume 1. The first hyperspectral instruments were launched in 2002 by the US with AIRS (Chapter 3 of Volume 1) on board Aqua (Aumann 2003