The INSAT Multispectral Rainfall Algorithm (IMSRA) technique for rainfall estimation, has recently been developed to meet the shortcomings of the Global Precipitation Index (GPI) technique of rainfall estimation from the data of geostationary satellites; especially for accurate short period rainfall estimates. This study evaluates the 3-hourly precipitation estimates by this technique as well as the rainfall estimates by the GPI technique using data of the Kalpana-1 satellite, over the Indian region for the southwest monsoon season of 2010 to understand their relative strengths and weaknesses in estimating short period rainfall. The gridded 3 hourly accumulated TRMM satellite (3B42 V6 product or TMPA product) and surface raingauge data for stations over the Indian region for the same period is used as the standard measure of rainfall estimates. The Method for Object-based Diagnostic Evaluation (MODE) utility of the METv3.0 software, has been used for the evaluation purpose. The results show that the new IMSRA technique is closer to the TMPA rainfall estimate, in terms of areal spread, geometric shape and location of rainfall areas, as compared to the GPI technique. The overlap of matching rainfall areas with respect to TMPA rainfall patches is also higher for the IMSRA estimates as compared to the GPI values. However, both satellite rainfall estimates are observed to be generally higher compared to the TMPA measurements. However, the values for the highest 10% of the rainfall rates in any rainfall patch, is generally higher for rainfall measured by the IMSRA technique, as compared to the estimates by the GPI technique. This may partly be due to the capping maximum limit of 3 mm/hr for rainfall measured by the GPI technique limits the total 3-hour accumulation to 9 mm even during heavy rainfall episodes. This is not so with IMSRA technique, which has no such limiting value. However, this general overestimation of the rainfall amount, measured by both techniques, and the greater error in case of IMSRA estimates, is also validated independently with respect to surface raingauge observations. Hence the observed overestimation by the IMSRA technique for the highest 10th percentile rainfall rates in rainfall episodes, is real. This overestimation by the latter technique may become a significant source of error, if the IMSRA estimate is used for monitoring very heavy rainfall episodes. In all other respects, since the IMSRA method shows significant improvement over the GPI, the rainfall estimates by the IMSRA method may be used for operational short period rainfall estimation.

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A B S T R A C T Direct radiative forcing at top of the atmosphere for black carbon aerosols from two inventories comes out to be '0.33 W m (2 for Global Emission Inventory Activity (GEIA) and '0.14 W m (2 for BOND (Bond et al., 2004). However, for organic matter aerosols, it is simulated as (0.44 W m (2 for GEIA and (0.11 W m (2 with BOND inventory. Simulated annual global burden and aerosol optical depth of carbonaceous aerosols from GEIA and BOND are also compared. Normalised differences plots show that model simulates generally higher values of carbonaceous aerosols with GEIA, which are far superior in some parts of the globe as compared to those simulated with BOND emission inventory. An evaluation of these quantities with the median of the response of the AeroCom models is considered here as a benchmark Á shows that while simulations with GEIA inventory have closer agreement, values of radiative forcing with BOND inventory are comparatively of smaller magnitudes over most parts of the globe. The reasons for this disparity in results for the latter may possibly be attributed to key differences between the two inventories. The main conclusion of this study is that the radiative forcing appears to be highly sensitive to carbonaceous content in aerosol compositions.

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An efficient method for achieving the non-uniform grids on a spherical geometry is presented here. It uses the icosahedral-hexagonal grid with successive refinement to arrive at the target grid suitable for computational fluid dynamics (CFD) applications. It reduces the complexity of search from O(n 2 ) to O(n) on icosahedral-hexagonal grids where n refers to the refinement level. The numerical solution of the transport equation is performed using the initial conditions of a well-known problem (solid-body rotation); the numerical scheme is second-order accurate. Since advection of chemically active tracers in the atmosphere and their modelling are becoming a major area of concern within the climate change scenario, this study assures the efficiency and accuracy of the numerical scheme as tested here for tracer transport. 