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Vertical cloud structures of the boreal summer intraseasonal variability based on CloudSat observations and ERA-interim reanalysis Speaker : Li-Chiang.

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Presentation on theme: "Vertical cloud structures of the boreal summer intraseasonal variability based on CloudSat observations and ERA-interim reanalysis Speaker : Li-Chiang."— Presentation transcript:

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

2 Outline Introduction Datasets An index for the boreal summer intraseasonal variability (BSISV) Vertical cloud structures of the northward propagating BSISV Summary

3 The intraseasonal variability (ISV) plays a significant role for tropical climate Eastward propagating in boreal winter A period of 30–50 days, northward propagation over the Asian monsoon region in boreal summer MJO(Madden–Julian Oscillation)

4 EEOF Method (1) All the data were binned into pentad (5-day) values. (2) Intraseasonal anomalies were obtained by removing the annual cycle and data filtering through a 30–90-day band pass filter. (3) Perform an EEOF analysis on band-passed (30-90 day) rainfall data (e.g., TRMM, CMAP) over the tropical Indian Ocean and western Pacific. (4) Identify MJO events from the PC time series of 1st EEOF mode. (5) Composite MJO events in band-passed rainfall and target quantity (e.g., temperature, moisture, ozone, aerosols).

5 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 associated with the northward propagating BSISV.

6 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

7 The study focus on : Since three summer seasons from 2006 to 2008.Compared to Cloud structures from CloudSat data and ERA-interim reanalysis data. Now

8 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)

9 An index for the BSISV

10

11 Vertical cloud structures of the northward propagating BSISV CloudSat LWCCloudSat IWC

12 Vertical cloud structures of the northward propagating BSISV ERA-interim LWCERA-interim IWC

13 Vertical cloud structures of the northward propagating BSISV LWCIWC CloudSat ERA- interim 紅圈:不同的地方

14 Vertical cloud structures of the northward propagating BSISV CloudSat ERA- interim Total

15 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

16 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

17 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

18 Thanks for your attention !


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