An analysis of fog events in respect of winter season 2021-2022 using model reanalysis & INSAT-3D/3DR satellite data

The objective of the study was twofold (i) Review of INSAT-3D/3DR night time fog detection channel differencing (MIR- TIR1) scheme developed by Space Application Centre (SAC) Indian Space Research Centre (ISRO) thresholds  which were not uniform for winter season radiation fog and vary geographically over Indian domain & (ii) An analysis of Fog events of 2021-2022 winter season analysis using the anomalies (temperature, wind, moisture, inversion, geo-potential height etc) from NCEP reanalysis and ERA-5 data sets. This study is a way forward to look into the importance of recently introduced model reanalysis data sets to monitor and understand the recent changes of fog events behaviour. It is seen that the fog events winter season (2021-2022) was reduced appreciably and this change is really a concern but 2021-22 winter fog occurrences were very well captured in both models as well as INSAT-3D/3DR data analysis. The results brought out from the model as well as satellite data analysis were found to be very useful for forecasters and end users especially in monitoring and prediction of fog events.  However, to quantify the night time fog thresholds based on INSAT data for different regions of India and appreciable reduction of fog events in the recent past needs long term data sets study.