Global Variability of Mesoscale Convective System (MCS) Anvils Jian Yuan Robert A. Houze Department of Atmospheric Sciences, University of Washington CloudSat Science Team Meeting, 29 July 2009, Madison, WI

This Talk 1-MCS identification 2-Separation of MCS anvil from rain 3-MCS anvil cloud structure viewed by CloudSat

Data and Methodology Analysis of MCS anvil cloud composite CloudSat (GEOPROF-2B) AMSR-E rain & MODIS T B11 MODIS T B11 MCSs (raining center + non-raining anvil clouds) MCS Precipitating Cores High Cloud Systems 12 3

Step 1: Identify MCS Precipitating Cores T B11

Choosing Rain Rate Thresholds Ocean Land

Latent Heating within 1 mm/h threshold Areas of Different Sizes and Heights And At least 10% of the raining area has R>6 mm/hr MODIS AMSR-E  Define MCS Precipitating Core as 1 mm h -1 threshold area: covering > 2000 km 2 = (45 km) 2 with T B11 of the coldest decile of the raining area < 220 o K MCS

Annual Mean Occurrence of MCS Precipitating Cores

Step 2: Identify Total Cloud Area of MCS

CloudSat “high cloud” PDF (tops above 10 km) T B11 (K o ) High Cloud Thickness (km) CloudSat MODIS

High cloud systems Identification Raining systems Locate High Clouds Find Cold Centers Identify Cloud SystemsIdentify MCS Systems Length

Active MCSs and other cloud Features Two conditions for active MCS: 1.Total raining areas as a whole meets MCS requirements. 2.The largest raining element is a part of a MCS and it takes at least 70% of total raining areas within the system. Active MCS cloud system (meet both 1 and 2) Precipitating high cloud systems not associated with active MCSs -- contain active raining systems but do not satisfy 1. or 2. Non-Precipitating high cloud systems (no rain)

Comparison of Active MCS cloud systems Small: Rain +Anvil Area km 2 Small Large

Comparison of Active MCS cloud systems “Cold”: min Tb11 min Tb11  208  K Cold Warm Whole year

Step 3: Analyze anvil structure

To make sure we aren’t analyzing precipitating anvils-- Maximum reflectivity between 1.25 to 2.5 km to be < -10 dBZ Maximum reflectivity around the surface level to be > 25 dBZ Require

CFADs of thick anvil clouds (6-11 km) Sampled over open water in the West Pacific maritime continent area Broader distribution of reflectivity found in anvils closer to raining area

Continental thick anvil clouds (6-11 km) close to raining area suggests more “convective” microphysics

CFADs of thin anvil clouds (2-6 km) are less sensitive to geographical regions

Objective analysis of MODIS TB11 and AMSR-E rain product leads to reasonable global distribution of MCSs Anvils can be separated from the raining core of the MCS for analysis CloudSat GEOPROF-2b shows internal structure of anvils Thick anvils have broader distribution of reflectivity closer to raining area Continental anvils consistent with more convective microphysics Thin anvils are less impacted by convective core Summary

End This presentation was supported by NASA Grant NNX07AQ89G