Transcript 101027NewOrleans_ATrainV05_Houze.ppt

Multi-sensor Analysis of Tropical
Mesoscale Convective Systems
Jian Yuan and R. A. Houze [J. Clim., J. Atmos. Sci.]
NASA A-Train Symposium, New Orleans, 27 October 2010
Example of mesoscale convective systems
“MCSs”
Large areas
of cold top
Radar Echoes in the 3 MCSs
1458GMT 13 May 2004
Large rain
areas
Stratiform
Precipitation
Convective
Precipitation
Non-precipitating “anvil clouds” of MCSs
have not been studied very much
Mesoscale Convective
System
Extensively studied
Need to understand how
anvil is related to the
raining region
A-Train instruments make it possible to
observe both raining and anvil components
Three steps of analysis of multi-sensor data
1
(TB11)
2
(RAIN)
3
(GEOPROF-2B)
MODIS TB11 + AMSR-E
combined to find“cold centers” & “raining areas”
Locate 1st
closed
contour
Use 260 K
threshold
Use 1 mm/h
threshold for
rain rate
Associate
pixels with
nearest
cold center
Use 6 mm/h
threshold for
heavy rain
Define criteria for MCS that are reasonable
for all these regions
PDF of rain amount as a function of raining core properties
Min TB11 over raining core
MCS Criteria
Systems whose
raining cores have
•Area > 2000 km2
•Min TB11 ≤ 220
Must have one
dominant core
•with intense
cells, and
•accounting for
>70% rain area
220
°C
56% all
tropical rain
2000 km2
Size of raining core
MCSs Over the Whole Tropics
Smallest 25% (<12,000 km2)
Largest 25% (>40,000 km2)
“Superclusters”
MODIS/AMSR-E
identifies MCSs
separates out the anvil
component
CloudSat
structure of the anvils
Frequency of MCS anvils over tropics
Bulk Properties of MCS anvils
•identified by 3 A-Train instruments
•bulk width & thickness seen by CloudSat
Height (km)
Internal MCS anvil structure seen by CloudSat
Africa
Indian Ocean
Anvil structure shown by CloudSat
• Width and depth differs between land and
ocean
• Reflectivity distribution suggests larger particles
dominate at lower levels & smaller aloft
• Reflectivity distribution weakens with distance
from rain more quickly over land
• Anvil structure far from raining cores similar
everywhere
• Anvil structure close to raining cores differs land to
ocean
Conclusions
COMBINING 3 A-TRAIN INSTRUMENTS
• Identifies MCS
• Separates them into raining and anvil
components
• Allows anvils to be analyzed relative to raining
component
LEADS TO UNPRECEDENTED ANALYSES OF MCSs
• Global MCS climatology obtained
• Different categories of MCSs identified
• Anvil width, depth, and interior structure quantified
• Differences between land and ocean anvils identified
End
This research was supported by NASA grants
NNX07AQ89G and NNX10AM28G