RESEACHERS Frontier Newsletter No.15 Jul.2001

Introduction of the researchers

Dr. Patra's photograph
Dr.Prabir Patra

Atmospheric Composition Research Program
My research in FRSGC is focussed on the study of global carbon cycle using the atmospheric transport models and inverse modeling techniques. This work is being carried out both as a part of an international effort (the TransCom-3 project) and by pursuing our own research interest in line with FRSGC's goal of predicting the global change. Presently we are working on evaluation of the inverse model estimation of regional carbon fluxes by using the transport model output of CO2 produced by TransCom-3 participants, and atmospheric CO2 observations. We aim to elucidate source uncertainty of CO2 and delineate possible ways for improvement.

We are also analysing the seasonal cycles, inter-annual variability and long-term trends of the greenhouse gases. Satellite observations of some of the species are being processed to derive their long-term trends and spatial variability. The analysed data will be used to study the roles of various circulation patterns on trace gas distribution as well as the impacts of the changing atmosphere.

Over the years I have been involved in various activities related to atmospheric sciences, which includes a) observation and modelling of various trace gases (e.g. CH4, N2O, and a number of halogenated compounds) in the atmospheric and oceanic environments, b) simulation of the tropical cyclones with the help of numerical weather prediction models, c) study of atmospheric teleconnections and statistics of the EOFs. Some of the studies continue to draw my interests even now.

Dr.Fukutomi's photograph
Dr.Yoshiki Fukutomi

Hydrological Cycle Research Program
I have been working in the Hydrological Cycle Research Program (Hydrological Cycle Process over a Wide Area Group) since February 2001. My present research interests are primarily in the atmospheric hydrological cycle process over the Asia-Pacific and Eurasian region at the intraseasonal through interannual timescales.

The hydrological cycle process over the Eurasian continent has been recognized as an important component that influences not only regional climate conditions but also various climate subsystems over the globe. In particular, it has been hypothesized that this process may significantly interact with other individual systems, for example, the Asia-Pacific (including ENSO and Monsoon), Atlantic, and Arctic climate. Then, our focus is placed on the characteristics of Eurasian hydrological cycle itself and the factor that plays an active role in its variability. What is the substantial influence on the variability of hydrological cycle in this continental region?

The precipitation is one of the representative indices of the climate variability in the continental region indeed, it is important to consider the process that controls its activity in order to manifest the linkages stated above. The occurrence of dry and wet events can be well associated with the specific large-scale circulation structure induced by atmospheric teleconnections. Modified circulations may cause a change in the moisture transport and their accumulation, and as a result, the regional atmosphere-land surface water balance may be modulated through precipitation and evaporation.

Our current subjects are the quantification of the broad-scale continental water balance associated with an above series of processes and the determination of the large-scale circulation which affects that. We are investigating the nature of interannual variability of the atmospheric water balance in the Eurasian region and its inter-relations to various climate subsystems with the statistical and dynamical methods based on some kinds of atmospheric objective analyses and satellite observational data. Recent analysis results indicate that the variability of summertime water balance of the two major river basins (the Lena and Ob river) over Siberia appeared to have 5-7-year timescale. And then, the occurrence of wet and dry extreme on this timescale over East Siberia shows out of phase with that over West Siberia. Further examination on this signal is ongoing.

Earth Science and Technology Organization Business Introduction

Bio-climate Feedback mechanism in carbon flux modelling in the ocean

Most of the solar radiation that reaches land or water is converted into thermal energy, but a significant part is diverted into photochemical and photobiological processes that affect the global carbon cycle. Here, we studied the effect of ocean phytoplankton on vertical penetration of solar radiation in the ocean mixed layer, using remotely sensed chlorophyll pigment concentrations and global ocean circulation model. We showed that a higher abundance of phytoplankton increases absorption of solar irradiance and heating rate in the upper ocean, comparing numerical modelling result with Joint Ocean Flux Study (JGOFS) observations during the 1994-1995 Arabian Sea experiment. We also showed such change of downward penetration of solar radiation by phytoplankton on the three dimensional Equatorial Pacific wave guide dynamics. We showed that space-time inhomogeniety of chlorophyll pigment concentration influences the mixed layer depth that may trigger geostrophic currents in the Equatorial Pacific wave guide region.

Back Cover Next