RESEARCHERS Frontier Newsletter No.14 Jan.2001

Introduction of the researchers

Rao's photo

Anguluri Suruyachandra

Climate Variations Research Program

With the discovery of Indian Ocean Dipole (IOD), Indian Ocean has come into limelight of the international research community. Before this discovery, researchers worldwide believed that this Ocean is a slave to the Pacific ENSO. However, the discovery of IOD implies that the Indian Ocean has its own identity.

I have been working in FRSGC/IGCR since November, 1999. Till now most studies on the IOD were confined to the variability of SST. I, as a member of climate variations research program, am investigating the subsurface response to the Indian Ocean dipole using various tools such as Ocean General Circulation models, in-situ, and satellite altimetry measurements. My research shows that the major interannual variability in the subsurface Indian Ocean is associated with the IOD, rather than the ENSO.

It is well known that ENSO influence on the Indian Ocean is through the atmosphere and is due to the heat fluxes. This effects the SST in the Indian Ocean and is the dominant mode of interannual variability at the surface. However, at the subsurface we found that change in the absolute wind direction from westerlies to easterlies in the equatorial Indian Ocean during IOD events, contrary to the weakening of westerlies during an ENSO event, gives rise to change in polarity of the heat content anomalies in the tropical Indian Ocean. It is also found that the sub-surface phenomena significantly effects the surface phenomena in the subsequent years of IOD by reversing the polarity of SST.

Our ultimate goal is to look for subsurface heat storage signals to find how these interannual signals in the Indian Ocean are excited. Studies in this direction are presently underway. I am also involved in identifying the role of salinity in the evolution of SST in the Indian Ocean.

Prior to joining FRSGC, I worked in the Physical Oceanography Department of Institute of Marine Affairs (IMA) in Trinidad and Tobago (West Indies). My work at IMA involved describing the circulation in the Gulf of Paria, using simple numerical models and also providing consultancy to the oil and recreation industries around Trinidad and Tobago. Earlier, I worked at the National Institute of Oceanography, India to obtain my doctoral degree. During this period I carried out work on identifying the Rossby waves in the Bay of Bengal through numerical simulations and observations. This study enabled me to obtain the "Best Thesis Gold Medal" from the Andhra University.

Dr.Zhang's photo

Zhang Meigen

Atmospheric Composition Research Program

East Asia is a region of the world with large and rapidly increasing anthropogenic emissions from combustion. Ozone is a secondary pollutant whose production in nonurban areas is primarily controlled by nitrogen oxide concentrations, which are a primary product of combustion.

Tropospheric ozone has complex environmental effects. It is the primary precursor of the hydroxyl radical and thus plays a crucial role in controlling the oxidizing capacity of the atmosphere. At concentrations elevated above background levels ozone damages natural vegetation, reduces yields of agricultural crops, and is detrimental to human health.

Recent research suggests that tropospheric ozone concentrations have increased in the lower troposphere over East Asia in recent decades and that the rate of increase is larger than in other areas of the northern midlatitides. Photochemical production of ozone in East Asia may increase ozone levels both within the region and downwind as Asia pollution has been observed to be transported over the Pacific Ocean.

I joined the Atmospheric Composition Research Program in January 2000. As part of our program, I have been using the Models-3 Community Multiscale Air Quality (CMAQ) modeling system to investigate the transport and photochemical transformation of tropospheric ozone and its precursors over eastern Asia and western Pacific. I am also using the Regional Atmospheric Modeling System (RAMS) in order to provide a physically based description of boundary layer and meteorological fields for the CMAQ system.

Dr.Tsugawa's photo

Motohiko Tsugawa

Integrated Modeling Research Program

I joined the integrated modeling research program in May 1999. Before joining FRSGC, I was a graduate student of Tokyo University and my major was Astrophysics. I was interested in various fluid dynamics in astrophysics and Now, in FRSGC, I am fascinated by the stratified fluid and the various behavior of rotation.

As a member of integrated model research program, I participate in a development project of high resolution ocean general circulation model (OGCM) which will run on the Earth Simulator.

The OGCM will have very high resolution of about 0.1 degree and will be integrated long enough to predict global climate change. Unfortunately, The present model OGCMs takes a lot of time to run high resolution even on the earth simulator.

Therefore I'm trying to improve acceleration of OGCM by studying numerical schemes.The present model OGCMs which is using for predicting climate change does not have enough resolution to simulate meso-scale eddy behavior. Meso-scale eddy plays very important role and it causes uncertainty in prediction of future climate change. By using the high resolution OGCM, we expect to reduce the uncertainty. I think, it will be one of the most significant result which harnessed the capability of an Earth Simulator.

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