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MeghaMegha--TropiquesTropiques: Retrievals : Retrievals and Applicationsand Applications

R.M. R.M. GairolaGairola

Meteorology and Oceanography GroupMeteorology and Oceanography GroupSpace Applications Centre, ISROSpace Applications Centre, ISRO

AhmedabadAhmedabad, India, India

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MEGHA MEGHA -- TROPIQUES MISSIONTROPIQUES MISSION•• INDO INDO -- FRENCH COLLABORATION ( ISRO FRENCH COLLABORATION ( ISRO -- CNES )CNES )•• CLIMATE / ATMOSPHERE RESEARCH AND CLIMATE / ATMOSPHERE RESEARCH AND

APPLICATIONS SATELLTE FOR STUDIES OVER THE APPLICATIONS SATELLTE FOR STUDIES OVER THE TROPICSTROPICS

•• INCLINED ORBIT OF 20 DEGREES FOR HIGH INCLINED ORBIT OF 20 DEGREES FOR HIGH REPETITIVITYREPETITIVITY

•• ORBIT AT 866.4 KMORBIT AT 866.4 KM•• IRS BUS IRS BUS ––1500 KG CLASS1500 KG CLASS•• SHARED RESPONSIBILITY OF PAYLOADSSHARED RESPONSIBILITY OF PAYLOADS•• ISRO's PSLV LAUNCHERISRO's PSLV LAUNCHER•• SPACECRAFT CONTROL AND DATASPACECRAFT CONTROL AND DATA

RECEPTION FROM ISTRAC, BANGALORERECEPTION FROM ISTRAC, BANGALORE•• 2008/09 LAUNCH FROM SHAR2008/09 LAUNCH FROM SHAR

SHAR

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MEGHA MEGHA -- TROPIQUES MISSIONTROPIQUES MISSION

UNIQUENESS OF THE MISSIONUNIQUENESS OF THE MISSION

•• INCLINATIONINCLINATION: Low orbital inclination : Low orbital inclination 2020oo

•• SWATH:SWATH: Large swath Large swath 1700 to 2200 km1700 to 2200 km•• REPETIVITY:REPETIVITY: 6 times6 times a day over 10 a day over 10 –– 20 deg 20 deg

latitude band, latitude band, 4 times4 times at many other latitudesat many other latitudes•• PAYLOADS:PAYLOADS: 3 payloads: 3 payloads: A large number of climate/ A large number of climate/

atmospheric parameters from a common platform: atmospheric parameters from a common platform: -- Oceanic winds, humidity profile, liquid water, Oceanic winds, humidity profile, liquid water, clouds, iceclouds, ice--clouds, radiation budgetclouds, radiation budget

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MISSION OBJECTIVESMISSION OBJECTIVES

1. To collect a long-term set of measurements with a good sampling and coverage over Tropical latitudes to understand better the processes related to tropical convective systems and their life cycle.

2. To improve the determination of atmospheric energy and water budget in the tropical area at various time and space scales.

3. To study tropical climatic events and their predictability: droughts, monsoon variability, floods, tropical cyclones ...

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Science studies using MT dataScience studies using MT dataRadiation Budget (Climate variability & change )Cloud radiation interaction and feedback

Rainfall in tropics

Tropical Convective System (Thermal Eng)

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PAYLOAD CONFIGURATIONPAYLOAD CONFIGURATION

•• MADRAS (MICROWAVE ANALYSIS AND DETECTION OF RAIN MADRAS (MICROWAVE ANALYSIS AND DETECTION OF RAIN AND ATMOSPHERIC STRUCTURES)AND ATMOSPHERIC STRUCTURES)

-- Imaging microwave radiometer from 18.7 to 157 GHz Imaging microwave radiometer from 18.7 to 157 GHz (5 Frequencies and 9 channels)(5 Frequencies and 9 channels)

•• SAPHIR (Sounder for Atmospheric Profiling of Humidity in the SAPHIR (Sounder for Atmospheric Profiling of Humidity in the Intertropics by Radiometry)Intertropics by Radiometry)

(6 Channels Around 183 GHz)(6 Channels Around 183 GHz)

•• SCARAB (SCARAB (ScaScanner for nner for RaRadiation diation BBudget)udget)•• Broadband radiation measurement instrument in shortwave Broadband radiation measurement instrument in shortwave

(<4(<4μμm) and m) and longwavelongwave (>4 (>4 μμm)m)

•• The DualThe Dual--Frequency LFrequency L--Band, Integrated GPS Occultation Band, Integrated GPS Occultation Receiver (IGOR). Receiver (IGOR).

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Channel No.Channel No. FrequenciesFrequencies PolarisationPolarisation Spatial Spatial resolutionresolution

MissionMission

M1M1 18.7 18.7 GHzGHz H+VH+V < 40 < 40 kmkm RainRain aboveabove oceansoceans, , WindWind speedspeed

M2M2 23.8 23.8 GHzGHz VV < 40 < 40 kmkm IntegratedIntegrated waterwater vapourvapour

M3M3 36.5 36.5 GHzGHz H + VH + V < 40 < 40 kmkm Liquid water in clouds, rain above seaLiquid water in clouds, rain above sea

M4M4 89 89 GHzGHz H + VH + V < 10 < 10 kmkm Convective rain areas over land and seaConvective rain areas over land and sea

M5M5 157 157 GHzGHz H+VH+V < 6 < 6 kmkm IceIce in in cloudsclouds

MADRAS CHANNELCHARACTERISTICS

MADRAS SCAN MECHANISM (MSM) by ISRO Rotates the Front End antenna and receiver of mass 90 kg with a speed stability of < 0.1 % @ 25 rpmProvides scan position with an accuracy of 10 arc-sec using 17 bit absolute optical encoder. Transfers power and signal via a 90-line PSTD with a life of 80 million revolutions. Status: EM tested successfully at IISU

MADRAS RF EQUIPMENT (MARFEQ) by CNES It is the 18 GHz – 157 GHz front end of MADRAS.It rotates at 25 RPM on a conical surface. In each scan the receivers are calibrated with an ambient blackbody reference and a sky-looking reflector. Status: FM under construction at ASTRIUM

ANTENNA

SATELLITE speedVECTOR

NADIR PATH

ON board ANGLE : 45,01°

INCIDENCE ANGLE : 50 to 55°

SWATH ANTENNA FOOTPRINTS1700 Km SCAN ANGLE : 65°

ALONG TRACKRESOLUTION

CROSS TRACKRESOLUTION

ANTENNA

SATELLITE speedVECTOR

NADIR PATH

ON board ANGLE : 45,01°

INCIDENCE ANGLE : 50 to 55°

SWATH ANTENNA FOOTPRINTS1700 Km SCAN ANGLE : 65°

ALONG TRACKRESOLUTION

CROSS TRACKRESOLUTION

MADRAS SCAN PATTERN

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SCARAB CHANNEL CHARACTERISTICS

Channel Wave length Signal dynamics Noise Sc 1 -Visible 0,5 to 0,7 μm 120 W.m².sr-1 < 1 W.m².sr-1 Sc 2 - Solar 0,2 to 4 μm 425 W.m².sr-1 < 0,5 W.m².sr-1 Sc3 - Total 0,2 to 100 μm 500 W.m².sr-1 < 0,5 W.m².sr-1

Sc 4 - IR Window 10,5 to 12,5 μm 30 W.m².sr-1 < 0,5 W.m².sr-1

Main channels : Sc2 and Sc3 Sc1 and Sc4 are for scene identification and for compatibility with operational satellites Longwave irradiance is calculated from the difference between Sc3 and Sc2

Channel Channel NN°°

Central Central Frequency Frequency

(GHz)(GHz)

Bandwidth Bandwidth (MHz)(MHz)

Lower bandwidth Lower bandwidth (GHz)(GHz)

Upper bandwidth Upper bandwidth (GHz)(GHz)

11 183.31 183.31 ±±

0.20.2 200200 183.010 183.010 -- 183.210183.210 183.410 183.410 -- 183.610183.610

22 183.31 183.31 ±±

1.11.1 350350 182.035 182.035 -- 182.385182.385 184.235 184.235 -- 184.585184.585

33 183.31 183.31 ±±

2.82.8 500500 180.260 180.260 -- 180.760180.760 185.860 185.860 -- 186.360186.360

44 183.31 183.31 ±±

4.24.2 700700 178.760 178.760 -- 179.460179.460 187.160 187.160 -- 187.860187.860

55 183.31 183.31 ±±

6.86.8 12001200 175.910 175.910 -- 177.110177.110 189.510 189.510 -- 190.710190.710

66 183.31 183.31 ±±

11.011.0 20002000 171.310 171.310 -- 173.310173.310 193.310 193.310 -- 195.310195.310

SAPHIR SCARAB

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Retrieval Retrieval –– MADRAS & MADRAS & SAPHIRSAPHIR

GEOPHYSICAL PARAMETER RETRIEVAL

KNOWN OCEAN & ATM. PARAMETERS

RADIATIVE TRANSFER MODEL

SENSOR PARAMETERS

NOISE (GAUSSIAN)

FREQ, INC ANG, POLARIZATION

BRIGHTNESS TEMPERATURE

SIMULATED DATA

SENSITIVITY STUDIES

OPTIMUM RETRIEVAL MODELS

RETRIEVAL COEFF. SAT DATARETRIEVAL ERRORS

GEOPHYSICAL PARAMETERS

INSITU DATA

VALIDATION & FINE-TUNNING

OPERATIONAL GEOPHYSICAL

PRODUCTS

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Rainfall Retrieval

Physical Approach: Forward Modelling Inverse Modelling

Atmospheric Data Base

Empirical Approach:

Radiative Transfer Model

Simulated TB’s

Rainfall

. Mult Regression

. Neural Network

TRMM-TB

Rainfall from:

• TRMM-Radar • Ground Radar • Rain gauge

• Multiple Regression • Neural Networks Synergistic Matching

Data Base

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MADRAS RetrievalsMADRAS Retrievals

•• Forward RT simulations using a data base from Forward RT simulations using a data base from TRMM and PR for on optimum spatial and TRMM and PR for on optimum spatial and temporal scales.temporal scales.

•• First version of rainfall using integrated First version of rainfall using integrated Scattering Index (SI) and Polarization Corrected Scattering Index (SI) and Polarization Corrected Temperature (PCT) methods in final stages of Temperature (PCT) methods in final stages of testing using DWR observations.testing using DWR observations.

•• Work has been initiated for blending GeoWork has been initiated for blending Geo--St. IR St. IR and lower orbiting MW observations from INSAT and lower orbiting MW observations from INSAT & MT& MT

•• Algorithm for inversion of MT measurements for Algorithm for inversion of MT measurements for WV and other geoWV and other geo--physical parameters in physical parameters in progressprogress

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MADRAS RetrievalMADRAS Retrieval

0.0 10.0 20.0 30.0 40.0 50.0

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10H

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19H

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21H

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37H

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85H

MWRT -- 4 Stream( Ice & Cloud Profiles from Smith et.al & Ice Density 0.25 gm/ cm**3)

Radiative Transfer Forward simulation

10 19

21 37

85

Non-raining atmosphere Scattering atmosphere

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COMPARISON OF RAINFALL FROM NASA, PR & PRESENT ALGORITHMSCOMPARISON OF RAINFALL FROM NASA, PR & PRESENT ALGORITHMS

GPROF TMI RAINRATE PR RAINRATE

TMI RAINRATE (PRESENT ALGORITHM)

OCTOBER 10, 2002

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New-SI (SSM/I) vs GPROF (TRMM) Based Rain Rate

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GPROF (TRMM) vs New-SI (SSM/I)Based Rain Rate

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GPROF (TRMM) vs New-SI (SSM/I)Based Rain Rate

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Scatter plot between GPROF algorithm and present technique

Rainfall from present technique

0 5 10 15 20 25 30

Rai

nfal

l fro

m G

PRO

F al

gorit

hm

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5

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25

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Scatter plot between the GPROF algorithm and present technique

Rainfall from present technique

0 2 4 6 8 10 12 14 16 18

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nfal

l fro

m G

PRO

F al

gorit

hm

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Histogram between the GPROF algorithm and the present technique over ocean

Rainfall range

0 3 6 9 12 15 18 21 24

Freq

uenc

y

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GPROF techniquePresent technique

Histogram between GPROF algorithm and Present technique over land

Rainfall range

0 3 6 9 12 15 18 21 24

Freq

uenc

y

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GPROF techniquePresent technique

Histogram of Rainfall over land

Rainfall range

3 6 9 12 15 18 21 24

Freq

uenc

y

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GPROF techniquePresent technique

Histogram of Rainfall over ocean

Rainfall range

2 4 6 8 10 12 14 16 18 20

Freq

uenc

y

020406080

100120140160180200220240260280300320

GPROF AlgorithmPresent technique

2020

VALIDATIONS: TRMM VS. DWR (IMD) RAINFALLVALIDATIONS: TRMM VS. DWR (IMD) RAINFALL

0 10 20 30 40 50 60DWR Rain Rate (mm/ h)

0

10

20

30

40

50

60

TMI R

ain

Rate

(mm

/h)

Comparison of TMI and DWR rain rates (17 October 2002)R (TMI) = 0.68 R (DWR) - 3.83No. of Pts.= 460r=0.80bias= -7.99 mm/ hrms diff=10.12 mm/ hrms after bias removal=6.31 mm/ h

OCTOBER 17, 2002

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PPI plot of Reflectivity and Radial velocity of the cyclone over SHAR on 29 October 2006 at 01:47:05 UT

0.5º Elevation

SHAR

VALIDATIONS: DWR (SHAR) RAINFALLVALIDATIONS: DWR (SHAR) RAINFALL

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RHI plot of Reflectivity of the cyclone event of the cyclone over SHAR on 29 October 2006 at 01:47:05 UT

Azimuth No. 15

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Z = 211(R) 1.39 Z= 64 (R) 1.78

Scatter plots for Z vs R during (a) Startiform and (b) Convective rain

Z - R relation

(a) (b)

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Spatial distribution of (a) Reflectivity and (b) Rainfall rate

(a) (b)

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SAPHIR: Humidity profileSAPHIR: Humidity profile

• Emission based RT simulations using simulated atmospheres

• Retrievals using Statistical & EOF techniques

• Improvement in lower level humidity profile through total water vapour content

• Impact of viewing geometry & surface contamination on retrievals

•At nadir view with dry atmosphere, the low freq channels are contaminated by surface contributions

•At oblique view with moist atmosphere, the low freq channels are less sensitive to boundary layer humidity which contributes the most to many meteorological & oceanographic processes

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SAPHIR CHANNELSSAPHIR CHANNELS’’ RESPONSE (NADIR VIEW)RESPONSE (NADIR VIEW)

At nadir view with dry atmosphere, the low freq channels are contaminated by surface contributions

Dry Atmosphere Moist Atmosphere

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Long wave Flux (Wm-2) ScaRaB

(Resurs) 04 Mar 1999

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MM--T Validation AspectsT Validation Aspects

•• Participation in community field campaigns Participation in community field campaigns (similar to ARMEX, BOBMEX, AMMA, Ship (similar to ARMEX, BOBMEX, AMMA, Ship cruises/ cruises/ radiosondesradiosondes))

•• Comparison with high resolution model Comparison with high resolution model analysisanalysis

•• Collaboration with a worldwide effort to Collaboration with a worldwide effort to derive column derive column precipitableprecipitable water from a water from a network of surface GPS receiversnetwork of surface GPS receivers

•• Collaboration with regular observation Collaboration with regular observation agencies like IMD, NARL, NIOT, NIO, agencies like IMD, NARL, NIOT, NIO, INCOIS etc.INCOIS etc.

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DEPLOYED VIEWMEGHA-TROPIQUES SPACECRAFT

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Operational Meteorological Satellites

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INSAT-11982VHRR

INSAT-2A, 2B1992-93VHRR

INSAT-2E, 1998-99VHRRCCD Camera(1 km)

Metsat(Kalpana)2002VHRR

INSAT-3D, 2006/2007Advance Met PayloadImagerSounder

Indian Geostationary Satellites

INSAT-3A2003VHRRCCD Camera(1 km)

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Kalpana-1 INSAT-2EINSAT-3A

74o83o

93.5o

Current Indian Geostationary Meteorological Satellites

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INSATINSAT--3D3D ImagerImager

Channel No.

Wavelength Band Resolution(Km)

1 0.55 - 0.75 μm 12 1.55 - 1.70 μm 13 3.7 - 3.95 μm 44 6.5 - 7.1 μm 85 10.3 - 11.3 μm 46 11.3 - 12.50 μm 4

Channel No.

Wavelength Band Resolution(Km)

1 0.55 - 0.75 μm 12 1.55 - 1.70 μm 13 3.7 - 3.95 μm 44 6.5 - 7.1 μm 85 10.3 - 11.3 μm 46 11.3 - 12.50 μm 4

Channel No.

Wavelength Band Resolution(Km)

1 0.55 - 0.75 μm 12 1.55 - 1.70 μm 13 3.7 - 3.95 μm 44 6.5 - 7.1 μm 85 10.3 - 11.3 μm 46 11.3 - 12.50 μm 4

INSAT-3D 19 Channel Atmospheric Sounder

Channel No.

Central Wavelength(in μm)

Principal absorbing constituents

1 14.71 CO2 – band 2 14.37 CO2 – band 3 14.06 CO2 – band 4 13.64 CO2 – band 5 13.37 CO2 – band 6 12.66 water vapor 7 12.02 water vapor 8 11.03 window 9 9.71 ozone

10 7.43 water vapor 11 7.02 water vapor 12 6.51 water vapor 13 4.57 N2O 14 4.52 N2O 15 4.45 CO2 16 4.13 CO2 17 3.98 window 18 3.74 window 19 0.69 vis

INDIAN - INSAT-3D PROGRAM

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Case 4. Rainfall During GONU Cyclone: Present Techn. vs. 3B42

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Daily Rainfall fro GONU Cyclone 1. Present Techn. & 2. 3B42

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