On the variability and climatology of Arunachal Pradesh: An observational study

Abstract

Abstract A comprehensive study on the variability and climatology of Arunachal Pradesh (study region) has been studied with the suite of automatic weather stations (AWS) and manual measured observations. Important meteorological variables such as air temperature (T), relative humidity (RH), wind speed (WS), wind direction (WD), and rainfall (RF) have been assessed, and explored the trend and variabilities for the study region. A very good correspondence is seen between two rainfall estimates (correlation coefficient value R = 0.77) over the study region, whilst during the monsoon season 10–20% higher R values were registered. The minimum (maximum) R value is 0.67 (0.92) at Ziro (Daporijo) station. Most of the stations in the study region exhibit significant monthly, seasonal, and diurnal variabilities in above mentioned meteorological attributes, whereas the diurnal variability is less significant in WD and RF. Spatial distribution of rainfall exhibits substantial season-to-season variation, where isolated (scattered) rainfalls are dominant during the cooler (warmer) seasons with values are almost 65% (40%). In addition, a higher percentage of fairly widespread (32%) and widespread rainfalls (8%) are noticed during the monsoon relative to other seasons, whereas dry percentage is higher during the cooler seasons. The frequency of heavy, very-heavy, and extremely heavy rainfall events is 2-times higher during with respect to the pre-monsoon season. Interestingly, the contribution of very light rain, light rain, and moderate rain to the total rainfall is ≈ 70%, whilst heavy, very heavy contributes about ≈ 30%. A significant negative trend in RF with a slope rate of -0.08 mm/year during the period 1976 to 2021, whereas the frequency of heavy and very-heavy rainfall events is increased with a slope rate of 1.28/year and 0.35/year, respectively for the study region.