Ali Hasan Siddiqui

image: Lorenz's attractor, created as part of the course AS:303 Non-Linear Models in Climate Science at IISc.

Quantifying the role of surface elevation for assessing OLR over Antarctica

Master's project (August 2017 - present)

Unlike the Arctic, the average surface elevation of the Antarctic is around 2500 m. Thick ice sheets cover the vast expanse of the continent. In order to estimate the clear sky OLR over the region using an analytical model, parameterization of the surface emissivity is done based on surface inversion temperature and the column water vapor. In order to validate the model, CERES observations and reanalysis from MERRA-2, ERA-interim and NCEP-NCAR 2 are used to quantify the role of water vapor and temperature lapse rate. Verification for the observations are done using a radiative transfer code, SBDART and its performance is measured and statistically analyzed. Comparison with the Tibetan plateau is attempted to confirm the hypothesis.

Energy Budget calculations for the South Polar Cap using Reanalysis

Apr-2017 to July-2017

Estimate for the atmospheric energy budget is made for the period of 1981-2010 using NCEP-NCAR reanalysis 2. The project was carried out to get a broad understanding of the general circulation over Antarctica and study the time series and trends in the given data. Comparison was carried out with past studies of Nakamura and Oort 1988, Genthon and Krinner 1998 and Previdi et al., 2013. It was inferred that even though the budget was approximately closed and that too better than previous studies, however, the trend captured by NCEP data for precipitation and evaporation was considerably poor than that of ERA-interim and that captured in other studies.

fig : Climatological annual time series for energy components over Antarctica and comparison with Previdi et.al 2013.

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