Trends in Precipitation Extremes over India - (IMD), Pune

Bihar. Over these regions, one day total rainfall has shown an increasing trend.Similar results are also observed for the highest Five day precipitation (RX5day).The regions of significant positive trends (Fig. 2d) are mainly along the west coastand some parts of west central India. The magnitude of trends is also higher in theseareas.R75p – Moderate wet days – Days with rainfall more than 75 percentile of the longperiod average.Seventeen percent of stations have shown significant positive trends. Thesestations are distributed (Fig. 3a) along the west coast of India, northern parts of Indiaand west central India (west Madhya Pradesh). Only 5% of stations have shownsignificant negative trends.R75pTOT – Precipitation fraction due to moderate wet daysThe index R75pTOT determines the contribution of moderate wet days(rainfall with more than 75 percentile) on the seasonal rainfall total. During themonsoon season, 19% of stations showed significant positive trend. These stations(Fig. 3b) are mainly over along the west coast, southwest parts of central India,northern peninsular India, and few stations in Orissa. Over these regions, thecontribution from the rainfall amount higher than 75 percentile has increased. Only3% stations have shown significant negative trend.In a similar fashion, two more indices for 95 percentile and 99 percentile arealso calculated. Similar to R75p, the R95p index also shows significant positivetrends for 16% of stations. Significant positive trends are also noticed for 15% of thestations during the monsoon season for the index R95pTOT. These significanttrends (Fig. 3c & 3d) are along the west coast and northwestern parts of PeninsularIndia, which includes Maharashtra and parts of northern Karnataka. The indices ofR99p and R99pTOT showed (Fig. 4a and 4b) significant positive trends along thefoothills of Himalayas and south peninsular India.8