use of humidity data from mt and other platforms for science projects on monsoon cloud systems...
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Use of Humidity data from MT and other platforms for
Science projects on
Monsoon Cloud systems
KUSUMA G RAOSpace Sciences
Indian Space Research Organization Bangalore, India
“Life Cycle of Tropical Cloud Systems”
Indian Monsoon Variability as “manifestation” of the life cycle of these Tropical cloud systems.
Tropical Cloud Mesoscale Monsoon Systems Convective Systems Variability
Horizontal Scale: Ten’s of kilometers to several hundreds Life span: several hours to ~2 days
“Quasi permanent feature” observed every year
• Quasi-biennial• Interannual• Intra-seasonal-Active and Break Spells(4~25 Days)• Bi-weekly• 3~5 Days
Cloudiness - Precipitation organization
during
Southwest Monsoon Season
“Impact of Humidity variations”
DATA:METEOSAT measurements-- IR channel in the window region 10.5--12.5 m WV channel at 6.3μm 5x5km resolution, 1/2 hourly time interval
2. UTH (Upper Tropospheric Humidity)- at every hour, 150x150 km resolution2. TRMM PR (Precipitation radar) Rain 3. NCEP Re-Analysis, 4. PW from SSMI5. Temp and Hum profiles from Radiosonde 1999 &1998
75 85EArea AverageIRBRT > 270K Break< 270K Active
Active1: 10-24 JuneBreak: 26 June-4 JulyActive2:9 July-10 AugIMD Break:20 June-4 July
25N
15
Kusuma Rao, M Desbois, R Roca, K Nakamura, GRL, 2004
Spatial cloud pictures
TRMM pictures on ran and sampling Active
Days=48
In 1999
Active spells
10-24 June
9 July-10 Aug
Break:
26 June-4
JulyKusuma Rao and K Nakamura
Active
Days=48
In 1999
Active
Days=38
In 1998
Active spells
26 June-6 July
2-27 Aug
Break:
13 - 19 July
Active
Days=38
Active
spells
26 June-6 July
2-27 Aug
Break:
13 - 19 July
Break
Days=18
Break:
26 June-6 July, 1999
13 - 19 July,
1998
Deep clouds like to travel 100~1000 km per day, both over land and ocean
“Y” pattern“X” pattern
Webster et al, 2002Ohsawa et al.,2000
Central India
Indian Ocean
Indian Ocean
Rain superimposed on cloud
Kusuma Rao and K Nakamura, GRL (Submitted)
Overlapping TRMM passesOn METEOSATCloudImageries
Kusuma Rao and K Nakamura, GRL (Submitted)
Latitudinal Variation of PR Rain rate, mm/hour
Averaged[75-80E]
Kusuma Rao and K Nakamura, GRL (Submitted)
Vertical Distribution of PR Rain rate, mm/hour
Averaged[75-80E]And overLatitudinalExtentOf each TRMM pass
Kusuma Rao and K Nakamura
TRMM PR METEOSAT
Kusuma Rao and K Nakamura
Near simultaneous Rain-Cloudiness association
Individual Cloud system
Impact of Humidity variations on Monsoon Convection
Monsoon Variability on “Active” and “Break” spells
“Individual transitions from Active to Break conditions and Vice Versa” -------MORE COMPLEX
UTH derived from WV Brightness Temperatures
Schmetz et al, 1998
UTH is Mean HumidityBetween 600 to 200 mb
Drying sets inActiveSpell
Drying sets in Clear sky
Middle level clouds
Break
Kusuma Rao, M Desbois, R Roca, K Nakamura, GRL, 2004
Active
Number of Clear Sky Pixels
Transition to Clear SkyDrying Sets In
PRECIPITABLE WATER
Data Source: NCEP for land SSMI for Sea
Drying sets in
Break phaseActive phases
NCEP Humidity Profiles
Impact of Vertical Humidity Distribution on Precipitation
“A Special Experiment: Convection in Asian Monsoon System (CAMS–98)”
17 July- 14 August
Under the International GAME Programme
MST Radar Facility at station “GADANKI” (13.5N, 79.2E) East coast of southern Indian Peninsula
Investigators: Kusuma G Rao P B Rao A R Jain S C Chakravarty
GADANKI
ISRO LABORATORY“National Atmospheric Research Laboratory”Indian MST RadarWind ProfilerLidarDisdrometerOptical Rain GaugeAutomated Weather System
Specific Humidity distribution, 17 July-14 August
METEOSATBrightness Temperatures
Rain rate, from ORG
Gadanki
RADIO OCCULTATION TECHNIQUEThe GPS technology is anActive system A receiver on a Low EarthOrbit satellite measures the coherent GPS signals in the two carrier frequencies,L1 = 1575.42 MHz,L2 = 1227.6 MHz broadcasted fromGPS satellites.
In radio occultation, the radio path between an orbiting transmitterand an orbiting receiver, as it traverses the Earth’s atmosphere, getsrefracted primarily by the vertical gradient of atmospheric refractivity. From the Doppler shift in the refracted wave, the bending angle can be derived
Inter-comparison between GPS/MET and Other measurements
Anthes, Rocken, Kuo, Special issue on COSMIC of Terrestrial, Atmospheric and Oceanic Sciences
+/- 1 K, green>1 K, red< -1 k, blue
COSMIC Global Coverage
Typical Daily COSMIC Soundings- in Green,Locations of Radiosondes- in RedGlobal Snapshots with ~ 4000 profiles per day
Anthes, Rocken, Kuo, Special issue on COSMIC of Terrestrial, Atmospheric and Oceanic Sciences.
Constellation of8 LEO’s
Megha-Tropiques Coverage
M.R.Sivaraman, SAC, Ahmedabad
Advanced Microwave Sounding Unit (AMSU)
AMSU-A Operate on board NOAAAMSU-B Satellites since 1998 AMSU-A 12 Channels close to the Oxygen band below 60 GHZ 4 window channels 23.8, 31.4, 50.3, 89GHZ
Resolution at nadir ~ 48 km
AMSU-B 3 Channels at 183.31 ±1, 3, 7 GHZ, centered around Water Vapour line, 2 window channels 89 and 150 GHZ
Resolution at nadir ~ 16 km
Clay B. Blankenship*, Edward Barker, and Nancy L. Baker NRL, Monterey,California
Naval Research Laboratory, Monterey,California
Bakground: Navy Operational Global Atmospheric Prediction System1-D variational retrievals of humidityProfiles ( Clouds are turned off)
Observed GOES 6.7 μmTB’s for 12 March 2004
Simulated TB’s from NOGAPS background and retrievals relative to GOES Obs TB’s
Simulated 6.7 μm TB’sAt 15:00 UTC
From a retrieved atmosphere usingRTTOV-7 forward model (No clouds)
NAVDAS- NRL Atmospheric Data Assimilation System: The retrieved humidity profiles are assimilated in to NOGAPS
NOAA-16 & 17, ~ 9000 profiles at ~9 layers from 1005 to 122 mb Per update cycle
Rejections: Data over land, coast, sea ice, heavy cloud and precipitation scenes
At 400 mb
Control-AMSU-B
For Sept 2003
AMSU-B is Drier in middle& upper levels
Zonal mean specific humidity difference, Control - AMSU-B
ITCZ is more moist
Drier Sub tropics
Addition of AMSU-B Observations strengthens model moistureGradients, counteracting the model tendency to smooth out moisture
Clay B. Blankenship*, Edward Barker, and Nancy L. Baker
Location Error over a Number of forecasts ~106 at 24 hours to32 at 120 hoursReduced by an average of 6.9 %
Central PressureErrorReduced by 1.24 mbOn average
Validated against Best tracks reported byJoint Typhoon Warning Center and National Hurricane Center
Tropical Cyclone Simulation
GENESIS & PROPAGATION CHARECTERISTICS OF
DEEP CLOUDS
ACCURATE HUMIDITY MEASUREMENTSPARTICULARLY over OCEANS
Is Megha-Tropiques the Solution?Thank you
Profiles of Area Average Humidity based on NCEP data
Dry Midtroposphere
NCEP Data
Break
Active
Clear Sky Non-Precipitating cumulus Precipitating cumulus
Intense rain after launch
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