# Presentation: 695031

## Aura MLS Sensitivities to Dense Cirrus and Deep Convective Clouds

**Aura MLS Sensitivities to Dense Cirrus and Deep Convective Clouds**
- Dong L. Wu and Jonathan H. Jiang
- Jet Propulsion Laboratory
- California Institute of Technology, Pasadena, CA
- Aura Science Meeting,  Pasadena, CA, 2 March 2005

## Outline

- _Outline_
-  Cloud-induced radiances (Tcir) at 240 and 640 GHz
-  Dependence of MLS 240 and 640 GHz Tcir on particle size distributions
-  Clouds and pollution over Asia

**Acknowledgment**
- We thank our colleagues in MLS Science and Engineering teams for instrument development, operation, and data processing.

## Observed bimodal size distribution of ice crystals 

- Observed bimodal size distribution of ice crystals

- Parameterized size distributions based on tropical in-situ measurements (CEPEX)

**McFarquhar and Hymsfield (1997)**

- Mass-mean diameter

- Effective diameter

-  High *vs.* low altitudes
-  Large *vs.* small particles

**Cloud complexities:**

**Bulk properties**

## Limb radiance response to small-Dmm clouds

**Limb radiance response to small-D****mm**** clouds**
- (Dmm = 21 μm; De = 16 μm)

- Tcir

- Tcir

- Tcir

-  Good sensitivities at high tangent heights at both 240 and 640 GHz.
-  Weak sensitivities at low tangent heights.

## Limb radiance response to large-Dmm clouds

- Tcir

- Tcir

- Tcir

**Limb radiance response to large-D****mm**** clouds**
- (Dmm = 88 μm; De = 45 μm)

-  Good sensitivities at high tangent heights at 240, but poor at 640 GHz as the *scattered-in* and *scattered-out* radiances are about equal.
-  Good sensitivities at low tangent heights for 240 and 640 GHz radiances.
-  Deeper penetration at 240 GHz (~7 km) then at 640 GHz (~12 km).

- Small Tcir

## 15 km tangent height

## EOS MLS 

**Tcir Measurements**
**at 15 km**

**Large-*****D******mm***

**Small-*****D******mm***

**Clear**
**sky**

- Clouds
- over Asia

-  Tcir computed by removing zonal mean radiances
-  Significance of clouds ≡ abs(Tcir) > 3σ, which is
-     ~10 K for 640 GHz
-     ~5 K for 240 GHz
-  240:640 GHz correlation separating clouds with small- and large-Dmm.

***D******mm *****= ~30 *****μm***

## Clouds and pollution over South China and East Asia

- region1

- region2

-          Small-Dmm clouds

- Large-Dmm clouds

**Clouds and pollution over South China and East Asia**
**(****15 Aug - 14 Sep 2004)**

-  Collocated cloud and CO enhancements over South China.
-  Cloud variations in the two regions:
-     different causes and altitude-dependent.
-  Implications to regional cloud-pollution interaction and hydrological cycle.

- region1

- region2

- (from a quick-look 1D retrieval)

- Tcir (K)

- Tcir (K)

-              147 hPa MLS CO            (ppbv)

**15 km**

## MLS Tcir 

**30 August 2004**

**MLS Tcir **
**at low tangent heights **
**(15 Aug - 14 Sep 2004)**

-  Proxy of *hIWP* along MLS limb path.
-  Similar morphology in 240 and 640 GHz measurements except the 240 radiances penetrate deeper.
-  Additional information from comparisons of MLS and AIRS radiances along the *A-Train* orbits.

**4 km tangent height**

- region1

- region2

- Tcir (K)

- Tcir (K)

## Region 1

**South China**

**Region 2**
**East China Sea and Japan**

## Clouds over Asia

- Raining
- out

**15 km**
**640 GHz**

**4 km**
**240 GHz**

**Clouds over Asia**
**during 18 Aug-18 Sep 2004**

## The Big Picture 

**Water vapor**

**Water vapor**

**aerosols**

**aerosols**

**The Big Picture **
**& **
**Challenges**

**?**

**?**

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## Summary

-  MLS can separate between dense cirrus and deep convective clouds with simultaneous 240 and 640 GHz measurements at high tangent heights (> 13 km).
-  Radiances from high and low tangent heights provide further separation on the top height of deep convective clouds.
-  MLS observations show that clouds and pollution are correlated over South China during Asian summer monsoon.
- Lag of CO variation slightly behind dense cirrus peak at 15 km. Dense cirrus and convective clouds are enhanced coherently with slow buildup at the beginning and sharp rainout in a later period.
-  An indication of enhanced low clouds during the rainout of 15 km clouds.

## spare