;tw. GKSS il FOESCMUNGSZENT^UR/l ¥ —uj-. | Study on Earth Radiation Budget Mission Scenarios OtCl *U. ", •}- ' • i1' Autoren: R. Dlhopolsky R. Hollmann J. Muller R. Stuhlmann GKSS 97/E/71 ISSN 0344-9629 DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. GKSS 97/E/71 llLUlluiiiUiiuuinuiimuiiujti *DE011812925* Study on Earth Radiation Budget Mission Scenarios Autoren: R. DIhopolsky R. Hollmann J. Muller R. Stuhlmann (Institut fur Atmospharenphysik) GKSS-Forschungszentrum Geesthacht GmbH • Geesthacht • 1997 Die externen Berichte der GKSS werden kostenlos abgegeben. The delivery of the external GKSS reports is free of charge. Anforderungen /Requests: GKSS-Forschungszentrum Geesthacht GmbH Bibliothek/Library Postfach 11 60 D-21494 Geesthacht Germany Als Manuskript vervielfaltigt. Fur diesen Bericht behalten wir uns alle Rechte vor. GKSS-Forschungszentrum Geesthacht GmbH • Telefon (04152)87-0 Max-Planck-StraJ3e • D-21502 Geesthacht / Postfach 1160 • D-21494 Geesthacht *DE011812925* GKSS 97/E/71 Study on Earth Radiation Budget Mission Scenarios R. Dlhopolsky, R. Hollmann, J. Muller, R. Stuhlmann 126 pages with 21 figures and 29tables Abstract The goal of this study is to study optimized satellite configurations for observation of the radiation balanceof the Earth.We present a literature survey of Earth Radiation Budget missions and instruments. We develop a parametric tool to simulate realistic multiple satellite mission scenarios. This tool is a modular computer program which models satelliteorbits and scanning operation. We use Meteosat data sampled at three hour intervals as a databaseto simulate atmospheric scenes. Input variables are satellite equatorial crossing time and instrument characteristics. Regional, zonal and global monthly averages of shortwave and longwave fluxes for an ideal observing system and several realistic satellite scenarios are produced. Comparisons show that the three satellite combinations which have equatorial crossing times at mid-morning, noon and mid-afternoon provide the best shortwave monitoring. Crossing times near sunrise and sunset should be avoided for the shortwave. Longwave diurnal models are necessary over and surfaces and cloudy regions, if there are only two measurementsmade during daylight hours. We have found in the shortwave inversion comparison that at least 15 % of the monthly regional errors can be attributedto the shortwave anisotropic models used. Studie fiber optimale Satellitenkonfigurationen zur Besthnmung der Strahlungsbilanz der Erde Zusammenfassung Die Zielsetzung dieser Studie ist die Ermittlung einer optimierten Satellitenkonfiguration fur die Zwecke zukiinftiger Strahlungsbilanzmessungen der Erde. Zuerst wird in diesem Bericht eine Literaturstudie fiber die satellitengestiitzten Strahlungsbilanz-Missionen und deren verwendeten Instrumente der letzten Jahrzehnte gegeben. Zur Simulation von realistischen Satelliten- missionen wurde ein Programmpaket entwickelt. Als EingabegroBen dienen Orbitparameter, wie Aquatoruberflugszeit, und Instrumentspeziflkationen. Fur die Atmosphare werden als Datengrundlage ausMETEOSAT-Daten abgeleitete StrahlungsfluBdichten in dreistiindigen Intervallen verwendet. Als Ergebnis werden aus den fur die verschiedenen Szenarien simulierten Strahlungsbilanzmessungen Monats-, zonale sowie regionale und globale Mittelwerte derkurz- und langwelligen StrahlungsfluBdichten besthmnt und mit den tatsachlichen Feldem verglichen. Die Vergleiche zeigen, dafi die optimale Kombination aus drei Satelliten besteht: ein Satelht mit einem Vormittagsiiberflug des Aquators, einer am Mittag und einer am Nachmittag. Es zeigt sich, daJ3 Aquatoriiberflugszeiten in der Nahe des Sonnenaufgang und Sonnemmtergangs fur die kurz- wellige Komponente vermieden werden sollten. Fur bewolkte Szenen und Landbeobachtungen der langwelligen StrahlungsfluBdichte ist bei nur zwei Messungen am Tag ein Tagesgangmodell erforderlich. Es wird der Inversionsprozefi der kurzwelligen StrahlungsfluBdichte untersucht, wobei sich zeigt, daB 15 % des Fehlers im regionalen Monatsmittel aufdie verwendeten Anisotropiemodelle zuriickzufiihren ist. Masnuscript received / Manuskripteingang in der Redaktion: 18. Dezember 1997 Contents 1 Introduction 15 2 Review of ERB Mission objectives and Requirements 17 2.1 Previous, Current and Planned ERB Missions.............................................. 17 2.1.1 Nimbus 2,3,6 and 7................................................................................ 19 2.1.2 ERBE...................................................................................................... 21 2.1.3 ScaRaB - METEOR 3/7....................................................................... 21 2.1.4 CERES-EOS...................................................................................... 21 2.2 Review of Algorithms for Inversion................................................................. 22 2.2.1 Satellites with ERB Instruments........................................................... 22 2.2.2 Non-dedicated ERB Satellites.............................................................. 34 2.2.3 ERB Data by Synergy of Different Satellites..................................... 38 2.3 Summary............................................................................................................ 41 3 Review of existing and Planned ERB Instruments 43 3.1 Introduction......................................................................................................... 43 3.1.1 Top of Atmosphere Radiation budget ................................................. 43 3.1.2 Atmospheric Radiation budget .............................................................. 43 3.1.3 Surface Radiation Budget ........................................................................44 3.2 Summary of ERB Instruments.......................................................................... 44 3.2.1 Nimbus 2 and 3...................................................................................... 48 3.2.2 Nimbus 6 and Nimbus 7...........................................................................48 3.2.3 ERBE...................................................................................................... 48 v - vi - 3.2.4 ScaRaB................................................................................................... 49 3.2.5 CERES................................................................................................... 50 3.2.6 ISCCP: NOAA, METEOSAT, GOES, GMS......................................... 50 3.2.7 GERB...................................................................................................... 50 3.3 Instrument Types for multi-satellite ERB Missions............................................ 51 3.3.1 Measured Parameters............................................................................. 51 3.3.2 ISCCP as a Model ERB....................................................................... 54 3.4 ERB Monitoring at the Top of Atmosphere.................................................... 57 3.4.1 Random Error......................................................................................... 58 3.4.2 Systematic Error................................................................................... 59 3.4.3 Conversion to TOA Fluxes .................................................................... 61 3.4.4 Coverage of the Diurnal Cycle.............................................................. 61 3.5 Summary............................................................................................................ 62 4 Parametric Tool to model ERB Mission Scenarios 63 4.1 Development Strategy ...................................................................................... 63 4.1.1 Data Set and use in model.................................................................... 63 4.1.2 Temporal Colocation of Data: Treatment of Time in model............ 64 4.1.3 Spatial Colocation of Points................................................................. 68 4.1.4 Input Files............................................................................................... 69 4.1.5 Output Files............................................................................................ 72 4.1.6 Diurnal Averaging................................................................................ 72 4.2 Results of Parametric Tool application to Database .........................................76 4.2.1 Differences for SW Inversion................................................................. 78 4.2.2 Regional Flux Differences between Mission Scenarios..........................87 4.2.3 Zonal Flux Differences.......................................................................... 95 4.2.4 Global Flux Differences.......................................................................... 99 5 Recommendations for Future ERB Missions 103 5.1 Summary of Results ...........................................................................................103 - vii - 5.2 Results and Definition of Optimized Mission Scenarios ................................ 105 5.3 Discussion of Possible Application in other climatological Programs................106 References 109 Appendix 115 A.l User’s Manual........................................................................................................117 - vm - List of Figures 4.1 Definition of Pixel Boundaries.........................................................................