What can we learn about tropical climate from MeghaTropiques

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What can we learn about tropical climate from
Megha-Tropiques? J.Srinivasan, Centre for
Atmospheric and Oceanic Sciences Indian Institute
of Science, Bangalore
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MEGHA-TROPIQUES Science To understand the
energy and water cycle in tropical convective
systems by simultaneous and frequent measurement
of Rainfall, water vapor, liquid water, ice,
humidity profile, surface winds and radiative
fluxes  
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Special Features

• Higher Temporal Sampling
• ( short cloud life times)
• Multi-Spectral Sampling
• visible, infrared and microwave
• Imager and Sounder ( vertical structure)
• Focus on the cloud scale

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TRMM
MEGHA-TROPIQUES
20O
35O
ORBIT INCLINATION
350 km
ALTITUDE
867 km
ScaRaB
CERES
RADIATION BUDGET
RADAR
NO
YES
18,24,37
10,18,21,37
PASSIVE MICROWAVE
89, 157
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PASSIVE MICROWAVE
NO
SOUNDER
183
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• SAMPLING ERROR IN RAINFALL MEASUREMENT FROM
  SATELLITES
• R Rainfall
• A Averaging Area
• S Number of visits/day

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MEGHA-TROPIQUES PAYLOADS
MADRAS Microwave Analysis and
Detection of Rain and Atmospheric Structures
Frequency Parameter
Resolution 18.7 GHz winds
50km 23.8 GHz water vapor 40km 36.5 GHz
liquid water 25km 89 GHz Rain
10km 157 GHz Ice
10km
SAPHIR(Humidity Sounder)
Resolution 10 km
6 Channels around 183.3 GHz
ScaRaB Radiation Budget
Visible 0.5 to 0.7? Solar 0.2 to 4.0? Total
0.2 to 200? IRW 10.5 to 12.5? Nadir Resolution
25 km
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Energy Budget of Tropical Convective Systems
FT
LqCpTgz
FB
Subtropical high
Equatorial Trough
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• P E QNET / ? - 1
• P RAINFALL
• E EVAPORATION
• QNET NET ENERGY CONVERGENCE
• VERTICAL STABILITY
• is inversely proportional to vertically
  integrated water vapor in the troposphere

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P E QNET / ? - 1 ? ?
? ? 89 Ghz 18 Ghz ScaRaB
Saphir MADRAS P RAINFALL E
EVAPORATION QNET NET ENERGY CONVERGENCE ?
VERTICAL STABILITY
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From L E C U Y E R A N D S T E P H E N S,
Journal of Climate , 2001
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Weckworth International H2O Project 2002

• Current understanding of convection initiation
  processes are impeded by a lack of
  high-resolution, high-accuracy water vapor
  measurements.
• water vapor is undersampled in space and time
  because existing observational techniques for
  mapping the three-dimensional distribution of
  water vapor are lacking

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MOZAIC project

• There may be a significant influence of
  subvisible cirrus clouds on the radiation budget
  in the vicinity of deep convective towers.
• Megha-Tropiques mission can test this by
• 157 Ghz ICE detection
• ScaRaB Radiation Budget

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CLOUD TYPES
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CLOUD RADAR SIGNATURE
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D19 TBV - TBH
Simulation by Liu Mausam, 2003
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Ocean
Land
From Liu , Mausam, 2003 for ASIAN REGION
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From Stephens Greenwald,1991Albedo vs LWP for
various re
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OPERATIONAL APPLICATIONS OF MEGHA-TROPIQUES
TMI TB-assimilation RR mm/h
From Peter Bauer Application in West Pacific
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• SYNERGY
• WITH OTHER
• RESEARCH
• AND
• OPERATIONAL
• SATELLITES ?

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The CloudSat Mission
Primary Objective To provide, from space, the
first global survey of cloud profiles and cloud
physical properties, with seasonal and
geographical variations needed to evaluate the
way clouds are parameterized in global models,
thereby contributing to weather predictions,
climate and the cloud-climate feedback problem.
The Cloud Profiling Radar

• Nadir pointing, 94 GHz radar
• 3.3?s pulse ? 500m vertical res.
• 1.4 km horizontal res.
• Sensitivity -28 dBZ
• Dynamic Range 80 dB
• Antenna Diameter 1.85 m
• Mass 250 kg
• Power 322 W

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The A-Train Constellation
Formation Flying

• Sun-synchronous orbit at 705 km altitude and
  98.2º inclination
• Nearly simultaneous views of the Earth from
  distinct payloads
• Of particular relevance to CloudSat are the
  MODIS, AMSR, and CERES instruments aboard Aqua,
  the lidar aboard CALIPSO, and the POLDER
  instrument aboard PARASOL

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• Global Precipitation Mission
  Objectives
• Improve ongoing efforts to predict climate
• by providing near-global measurement of
  precipitation
• Improve the accuracy of weather and precipitation
  forecasts
• through more accurate measurement of rain rates
  and latent heating.
• Provide more frequent and complete sampling of
  the Earth's precipitation.
• This will provide better prediction of flood
  hazards and management of life-sustaining
  activities dependent upon fresh water

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5-Order Magnitude Increase in Satellite Data
Over 10 Years
Satellite Instruments by Platform

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MEGHA-TROPIQUES MISSION

• WHAT ARE THE CHALLENGES?
• INTEGRATING MULTI-SPECTRAL DATA
• MULTI-SPECTRAL SATELLITE DATA VS MODELS
• TO INVOLVE A LARGER SCIENTIFIC COMMUNITY

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RESEARCH AREAS

• FOR DIFFERENT TYPES OF CLOUDS
• ALBEDO/EMISSIVITY AS A FUNCTION OF LWP
• NET RADIATION WITH LWP
• DAILY CLOUD RADIATIVE FORCING
• BI-DIRECTIONAL REFLECTANCE MODELS
• RAINFALL VS BRIGHTNESS TEMPERATURE
• CLOUD CLASSIFICATION FROM MICROWAVE CHANNELS
• VERTICAL PROFILE OF WATER VAPOR
• __________________________________________________
  ________
• MICROWAVE RADIATIVE TRANSFER SIMULATION USING
  CLOUD RESOLVING MODELS
• WATER VAPOR PROFILE IN SUBSIDENCE REGIONS AND
  LONGWAVE COOLING
• BROADBAND VS NARROW BAND RADIATIVE COOLING
• CONVECTION AND WATER VAPOR PROFILE

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