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Daily rainfall datasets of 10 years (1998-2007) of Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) version 6 and India Meteorological Department (IMD) gridded rain gauge have been compared over the Indian landmass, both in large and small spatial scales. On the larger spatial scale, the pattern correlation between the two datasets on daily scales during individual years of the study period is ranging from 0.4 to 0.7. The correlation improved significantly (∼0.9) when the study was confined to specific wet and dry spells each of about 5-8 days. Wavelet analysis of intraseasonal oscillations (ISO) of the southwest monsoon rainfall show the percentage contribution of the major two modes (30-50 days and 10-20 days), to be ranging respectively between ∼30-40% and 5-10% for the various years. Analysis of inter-annual variability shows the satellite data to be underestimating seasonal rainfall by ∼110 mm during southwest monsoon and overestimating by ∼150 mm during northeast monsoon season. At high spatio-temporal scales, viz., 1 • ×1 • grid, TMPA data do not correspond to ground truth. We have proposed here a new analysis procedure to assess the minimum spatial scale at which the two datasets are compatible with each other. This has been done by studying the contribution to total seasonal rainfall from different rainfall rate windows (at 1 mm intervals) on different spatial scales (at daily time scale). The compatibility spatial scale is seen to be beyond 5 • ×5 • average spatial scale over the Indian landmass. This will help to decide the usability of TMPA products, if averaged at appropriate spatial scales, for specific process studies, e.g., cloud scale, meso scale or synoptic scale.

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The paper compares the final run of Integrated Multi-Satellite Retrieval of Global Precipitation Mission (IMERG) products with India Meteorological Department (IMD) gridded data over the Indian land mass during the southwest monsoon period (June-September) in the period 2014-2017. Spatiotemporal variations of the IMERG are evaluated with IMD rainfall by employing different statistical techniques, and the capability of the IMERG is examined using the categorical skill metrics. A region in central India is the focus in order to study the southwest monsoon's static and dynamic characteristics, such as rainfall distribution and monsoon activity, using the IMERG in conjunction with IMD rainfall data sets. The integrated condensation rate (ICR) was estimated using the specific humidity profiles, and it correlated with the IMERG and IMD rainfall. The IMERG is found to be a potential source for adequately reflecting the ground gauge-gridded data of categorical rainfall amounts, from very light rain (trace-2.4 mm) to very heavy rain (about 115.6-204.4 mm). However, the IMERG does not reflect satisfactorily the extreme heavy rain events (≥ 204.5 mmÁday -1 ) during the study period. The significant correlation between IMERG/IMD rainfall and the ICR suggests that improved adjustments methods are required for better results when depicting accurate extreme heavy rainfall events by the IMERG.

We have used 1 ∘ × 1 ∘ resolution maximum temperature (T MAX ) data sets developed by India Meteorological Department (IMD) to examine the summer time warming over India during the period 2001-2014 in comparison with the period 1971-2000. The two study periods have been arrived at based on the drastic change of Moisture Index (I M ) trends over India between the two epochs. The T MAX variations over India are discussed with the corresponding changes in Potential Evapotranspiration (PET) data of the Climate Research Unit (CRU) and Outgoing Longwave Radiation (OLR) data of NOAA ESRL. The study shows a considerable warming over northern parts of India compared to southern parts. Western Himalayas (WH) and Northwest (NW) regions experienced highest warming with 1.4 ∘ C and 0.8 ∘ C increases during Epoch 2 (2001-2014) as compared Epoch 1 during the summer (March, April and May). Using MERRA Black Carbon Surface Mass Concentration (BCSMC) data, we have analysed the relation of increasing BCSMC with the T MAX over different homogeneous temperature regions of India and found that BCSMC has increased upto 1.6 times between the two epochs. Strong linear association is found between T MAX , PET and OLR evidenced by Coherence Wavelet Spectral analysis. It is also found that the highest warming occurred in the month of March and is 2.2 ∘ C in WH and 1.4 ∘ C in NW parts of India. We calculated mass stream function based on zonal mean meridional velocity for the two periods. In the recent periods we observed the weakening of polar cell and northward expansion of Hadley cell. These changes may be related to warming conditions of the atmosphere which may explain the intensification and northward expansion of the Ferrel cell with favourable conditions during the summer season.