Transcript 080820Seattle_CloudSatSciTeamV09_Houze.ppt

Mesoscale Convective Systems
Observed by CloudSat
Robert A. Houze, PI
Study 1: Jasmine Cetrone
Study 2: Jian Yuan
CloudSat Science Team Meeting, Seattle, 20 August 2008
Goal: Structure and composition
of MCS Anvils
ANVIL
AC
ANVIL
AS
Study 1:
Identify MCSs by tracking
• West Africa
• Maritime Continent
• Bay of Bengal
Find MCS Anvils
• Find potential MCS signal in CPR data
• Track cloud systems in geostationary
satellite data to decide if MCS
– Tb<208K over 100-km scale at some point in its
lifetime
• Find anvil portion of CPR signal
–Non-precipitating anvil if less than -10 dBZ at
all levels below 5 km
Analysis of Anvils
• Number of cases:
– 82 over West Africa
– 78 over the Maritime Continent
– 42 over the Bay of Bengal
• Anvils stratified by thickness
– Thin (0-2 km), Medium (2-6 km) and Thick (>6 km)
• Plotted CFADs
All Anvil CFADs
West Africa
• Thin, medium, thick combined
• Diagonal mode
Mar. Cont.
• Not as high over West Africa
– Even though convection more
intense
– TRMM shows rain echoes
higher!
– Large ice particles?
Bay Bengal
Thick Anvil Results
West Africa
• West Africa thick anvils
– High reflectivity peak ~8 km
another indication of larger ice
Mar. Cont.
• Bimodal structure at lowreflectivity values
– Confirmed by ARM groundbased cloud radars
– Lower maximum may be a result
aggregation
Bay Bengal
ARM Thick Anvil Results
Niamey
Darwin
Study 2:
Objective Identification of MCSs
• Rain Rate: AMSR-E
– Aqua L2B Global Swath Rain Rate (AE_Rain).
• Horizontal Cloud Structure: MODIS
– MODIS/Aqua Clouds 1km and 5km 5-Min L2 Wide Swath Subset
along CloudSat V2 at GES DISC(GES_DISC_MAC06S1_v2)
• Vertical Cloud Structure: CloudSat
– Products 2B-GEOPROF; 2B-CWC-RO; 2B-FLXHR; …
Identification of High Cloud Features
MODIS Tb11 (K)
Cloud
Element
COMBINED
AMSR/E Rain (mm/h)
Rain Core
FEATURE MASK
Further Analysis


Identify MCSs:

Rain area 2,000-40,000 km2

Mean Tb11 <235 K

Rain area with R>10 mm/hr > 200km2
Stratify MCSs

Cold: Tb11_min<208 K

Warm: 208 Ko<Tb11_min<220 K

Subdivide Cold and Warm by size
Latitude Nº
Global-seasonal distribution of MCS
Largest 20 % of “Cold” MCSs (>14,000 km2)
Combined Analysis (CPR data in MCSs)
CFAD of thick and Thin Anvils of Cold MCS
Combined Analysis
Thickness-Distance Distribution for
Anvils of Cold MCSs
West Pacific
(100-160 E)
Conclusions & Future Work
• Temporally tracked MCSs
– Used manual tracking to identify MCSs
– CFADs suggest larger ice particles over Africa
– Thick anvils show a bimodal signature at low
reflectivity confirmed by ARM cloud radars
• Objective identification of MCSs
– Used MODIS and AMSR E to identify MCSs
– Reasonable global patterns of MCS types
– Vertical structure agrees with manually tracked MCSs
• Next work
– Statistics of structure, composition,
and radiative heating in MCS anvils
Thank You
Thank You
Study 2: Data
• AMSR-E/Aqua L2B Global Swath Rain
Rate (AE_Rain).
• MODIS/Aqua Clouds 1km and 5km 5-Min
L2 Wide Swath Subset along CloudSat
V2 at GES
DISC(GES_DISC_MAC06S1_v2)
• CloudSat products (2B-GEOPROF;2BCWC-RO; 2B-FLXHR…)
Latitude Nº
Global-seasonal distribution of MCS
Smallest 40 % of “Cold” MCSs (2000-4900 km2)
Vertical Structure Categories From CloudSat
54
%
5%
9
%
7%
3%
45%
Methodology




Build the data base of deep cloud system (precipitating and non precipitating)
basd on AMSR-E rain rate and MODIS Tb11.
Group deep cloud systems into different categories based on their
properties(size of the raining area, coldest Tb11, intense raining area etc.
Co-locate CloudSat data with the cloud database and determine their
parenting MCSs.
Composite cloud structures according to their parenting MCSs.
High Cloud System identification

Co-location of different datasets


Picking high cloud systems


'Nearest neighbor' matching, convert AE-Rain to
MODIS resolution
Determining high cloud boundary based on Tb11
gradients and rain fall pattern
Determining cloud cores (raining or non-raining
cold cores) in multi-core systems
MCS Definition


MCS1:Size>2000km2; Tb11_min<208Ko;
Tb11_mean<235Ko; area with R>10mm/hr
bigger than 200km2
MCS2:Size>2000km2,208Ko<Tb11_min<228Ko,
Tb11_mean<235Ko; area with R>10mm/hr
bigger than 200km2
Global-seasonal distribution of MCS
Large “Warm” MCSs (10000-21360km2)
Thick Anvil Results
West Africa
• Bimodal structure at lowreflectivity values
– Confirmed by ARM groundbased cloud radars
– Lower maximum may be a result
aggregation
• West Africa thick anvils
– Reach lower heights than other
regions despite having tallest
precipitation echoes
– High reflectivity peak ~8 km may
indicate larger ice
Mar. Cont.
Bay Bengal