Vertical cloud structures of the boreal summer intraseasonal variability based on CloudSat obse

rvations and ERA-interim reanalysis

Speaker ： Li-Chiang Jiang

Xianan Jiang • Duane E. Waliser • Jui-Lin Li •Christopher Woods

X. Jiang • D. E. Waliser • J.-L. Li • C. Woods, Vertical cloud structures of the boreal summer intraseasonal variability based on CloudSat observations and ERA-interim reanalysis,2010

Outline

Introduction Datasets An index for the boreal summer intraseasonal

variability (BSISV) Vertical cloud structures of the northward pr

opagating BSISV Summary

Introduction

Sikka and Gadgil(1980);Cadet(1986); Lawrence and Webster(2002).

The meridional propagation of the BSISV is found to be intimately associated with active and break phases of the Asian summer monsoon

Jiang et al. (2004) Identified prominent meridional asymmetric structures associa

ted with the northward propagating BSISV.

Hsu et al.(2004);Fu et al.(2006)

The northward shift of low-level moisture perturbation relative to the BSISV convection, which may suggest a pre-conditioning process for its northward propagation.

An “easterly vertical wind shear” mechanism to explain the northward propagation of the BSISV.

Introduction

Datasets

European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-interim reanalysis

Liquid water content (LWC) and ice and water content (IWC) (2006 ~ 2008)

CloudSat dataset Liquid water content (LWC) and ice and water content (IWC)

(2006 ~ 2008) Tropical Rainfall Measuring Mission (TRMM)

Daily mean rainfall with a horizontal resolution of 1° × 1° (2006~2008)

An index for the BSISV

An index for the BSISV

Vertical cloud structures of the northward propagating BSISV

CloudSat LWC CloudSat IWC

Vertical cloud structures of the northward propagating BSISV

ERA-interim LWC ERA-interim IWC

Vertical cloud structures of the northward propagating BSISV

LWC IWC

CloudSat

ERA-interim

紅圈：不同的地方

Vertical cloud structures of the northward propagating BSISV

CloudSat

ERA-interim

Total

對流

雲

卷雲

高層

雲

高積

雲

積\

層積

雲

Increased LWC in the lower troposphere is located north of the BSISV rainfall maximum, and therefore leads the convection,so northward displacement.

Enhanced LWC anomalies to the north of the BSISV convection center are largely associated with low-level cumulus/stratocumulus clouds.

Summary and discussion

The maximum LWC anomalies are detected in the lower troposphere based on CloudSat, and in the middle troposphere in the ERA-interim.

Enhanced cloud IWC is evident in the upper troposphere corresponding to enhanced BSISV convection.

Summary and discussion

Aforementioned differences in LWC and IWC structures associated with the BSISV could be

ascribed to model biases and differences between CloudSat and ERA-interim datasets could be due to data sampling.

Summary and discussion

Thanks for your attention !