# Presentation: 710688

## Properties of Tropical Ice Clouds:

**Analyses Based on Terra/Aqua Measurements**

- P. Yang, G. Hong, K. Meyer, G. North, A. Dessler
- Texas A&M University
- B.-C. Gao
- Naval Research Laboratory
- B. Baum
- NASA Langley Research Center
- Baltimore, MD
- January 05, 2006

## This is a work in progress
We are attempting to establish links with the numerical modelling community to make use of the global satellite cloud products
In this talk, I will focus on the following points:
• 	Geographical distributions and seasonal variations of ice clouds
• 	Relationship between cirrus clouds and deep convections
•   PDFs and CDFs of cloud properties
• 	Comparison of the ice cloud properties derived from MODIS measurements and those from ECMWF simulations

- We are attempting to establish links with the numerical modelling community to make use of the global satellite cloud products
***In this talk, I will focus on the following points:***
- • 	Geographical distributions and seasonal variations of ice clouds
- • 	Relationship between cirrus clouds and deep convections
- •   PDFs and CDFs of cloud properties
- • 	Comparison of the ice cloud properties derived from MODIS measurements and those from ECMWF simulations

** ****Goals of the Investigation**

##  MOD08/MYD08 ice cloud properties (, De, , Tb) over the tropics from MODIS measurements (King et al., 2003; Platnick et al., 2003) 

-  Data from 3 years: 9/2002 - 8/2005

- Note: 	Poster of ice cloud properties based on the MODIS 0.66- and
- 	1.375-m bands, following Gao et al. (2002) and Dessler and 	Yang (2003).

** ****Data**

## In the literature, it is common to use the term “Cirrus Clouds” as a synonym of  “Cirroform clouds” or  “ice clouds” (e.g., Liou 1986, Fu et al. 1992...)
WMO: Cirrus, Cirrocumulus, and Cirrostratus
                 based on visual appearance during daytime
Classification based on visible optical thickness:
                 subvisual cirrus,  < 0.03 (Sassen et al., 1998)
                 thin cirrus, 0.03 <  < 0.3
                 thick cirrus, 0.3 < 
Cirroform clouds based on ISCCP:
                           Cirrus,  < 3.6
                   Cirrostratus,  3.6<  < 23.0

- WMO: Cirrus, Cirrocumulus, and Cirrostratus
-                  based on visual appearance during daytime
- Classification based on visible optical thickness:
-                  subvisual cirrus,  < 0.03 (Sassen et al., 1998)
-                  thin cirrus, 0.03 <  < 0.3
-                  thick cirrus, 0.3 < 
- Cirroform clouds based on ISCCP:
-                            Cirrus,  < 3.6
-                    Cirrostratus,  3.6<  < 23.0

** ****Ice Cloud Classification**

##  ISCCP Cloud Classification

- We will use the ISCCP classification system for our analyses because modelers are familiar with it.
- Rossow and Schiffer, 1999, Advances in understanding clouds from ISCCP.*Bull. Amer. Meteor. Soc*., 80, 2261–2287.

- Cirrus
- < 3.6 and
- Cloud top < 440 mb
-                    Cirrostratus
- 3.6<  < 23.0 and
- Cloud top < 440 mb
- Deep convection
- 23.0 <  and
- Cloud top < 440 mb

** ****ISCCP Cloud Classification**

- MAS BTD[8.5-11]

- Deep convection

- Thick cirrus

**Thin cirrus**

- Thin cirrus

- Thick Cirrus

- Below: CPL (Cloud Physics lidar) and CRS (Cloud Radar System) data with MODIS BTD color-coding
- Note: CPL data consistently places cirrus heights above CRS

** **
**BTD[8.5-11 ********m] for deep convective case from CRYSTAL-FACE case study**

## Terra

**Terra**

**Aqua**

** ****Geographical Distribution of Ice/Cirrus Cloud Fraction**

## Terra

**Terra**

**Aqua**

** ****Geographical Distribution of Cloud Fraction**

## Terra

**Terra**

**Aqua**

** ****Geographical Distribution of Ice/Cirrus Cloud Fraction**

## Cirrus and Deep Convection, over Ocean

## Cirrus and Deep Convection, over Land

## Ice Cloud: 30N to 30S; 3 years

##  Cloud Fraction

## Cloud Optical Thickness

## Cloud Effective Radius

## Seasonal Variations

**of Ice Clouds**

## Ice Cloud from ECMWF

- Cloud phase and ice cloud top

-  Using Model-to-Satellite method (Morcrelle, 1991) to
-      mitigate comparing properties incorrectly

- Cloud optical thickness

-  Directly derived from ECMWF

- Cirrus, cirrostrauts, deep convection

-  Classification based on cloud top and optical thickness
-     (in terms of the ISCCP definition)

## Cloud Phase and Top from ECMWF

## Comparison of Ice Clouds Derived from ECMWF and MODIS

- BTs at 8.5, 11.0, and 12.0 m
- derived from ECMWF

- Cloud phase
- (Baum et al, 2000)

- BTs at 11.0, 13.34, 13.64, 13.94,
- and 14.24 m derived from ECMWF

- Cloud top
- CO2 slicing technique
- (e.g., Wylie et al, 1986)

- IWC, LWC
- from ECMWF

- Cloud optical thickness
- from data base
- (Yang et al, 2005)

*ISCCP Classification*

- Ice cloud (cirrus, cirrostratus, deep convection)

- MODIS level-3 1°1° daily ice cloud products
- (http://modis.gsfc.nana.gov)

*ISCCP Classification*

- Ice De=60 m
- Water De=20 m

## Preliminary Comparison

- June 2003, MODIS vs ECMWF

## Ice Cloud Fraction

- MODIS — Southern Africa

- ECMWF — Southern Africa

- MODIS — West Pacific

- ECMWF — West Pacific

## Ice Cloud Optical Thickness

**Ice Cloud Optical Thickness**

- MODIS — Southern Africa

- MODIS — West Pacific

- ECMWF — Southern Africa

- ECMWF — West Pacific

## Ice Cloud Effective Emissivity

- MODIS — Southern Africa

- MODIS — West Pacific

- ECMWF — Southern Africa

- ECMWF — West Pacific

- ECMWF — Southern Africa

- ECMWF — West Pacific

## Ice Cloud Top Temperature

- MODIS — Southern Africa

- MODIS — West Pacific

- ECMWF — Southern Africa

- ECMWF — West Pacific

- ECMWF — Southern Africa

- ECMWF — West Pacific

## Reported on work in progress to put regional/global cloud properties in terms that a modeler may find useful.

In working with global cloud properties, we
	- investigated the relationship between cirrus clouds and deep convections
	- want to find a way to provide PDFs to global modelling community
	- also want to build links to data assimilation community
	- compared MODIS measurements and ECMWF simulations  (this work is                    --still ongoing).

- In working with global cloud properties, we
- 	- investigated the relationship between cirrus clouds and deep convections
- 	- want to find a way to provide PDFs to global modelling community
- 	- also want to build links to data assimilation community
- 	- compared MODIS measurements and ECMWF simulations  (this work is                    --still ongoing).

** ****Summary**