Effects of ENSO on Temperature, Precipitation, and Potential Evapotranspiration of North India’s Monsoon: An Analysis of Trend and Entropy

Kazi Ali Tamaddun,Ajay Kalra,Miguel Bernardez,Sajjad Ahmad

doi:10.3390/w11020189

Abstract

The influence of El Niño Southern Oscillation (ENSO) on the north Indian temperature, precipitation, and potential evapotranspiration (PET) change patterns were evaluated during the monsoon season across the last century. Trends and shifts in 146 districts were assessed using nonparametric statistical tests. To quantify their temporal variation, the concept of apportionment entropy was applied to both the annual and seasonal scales. Results suggest that the El Niño years played a greater role in causing hydro-climatological changes compared to the La Niña or neutral years. El Niño was more influential in causing shifts compared to trends. For certain districts, a phase change in ENSO reversed the trend/shift direction. The century-wide analysis suggested that the vast majority of the districts experienced significant decreasing trends/shifts in temperature and PET. However, precipitation experienced both increasing and decreasing trends/shifts based on the location of the districts. Entropy results suggested a lower apportionment of precipitation compared to the other variables, indicating an intermittent deviation of precipitation pattern from the generic trend. The findings may help understand the effects of ENSO on the hydro-climatological variables during the monsoon season. Practitioners may find the results useful as monsoon is the most important season for India causing climate extremes.

Highlights

Studies on extreme climate events, i.e., droughts and floods, across the world, have found that such extremes are likely to be associated with the anomalies in zonal sea surface temperature (SST) fluctuations observed in the oceans
Considering the advantages of multi-variable analyses as a major motivation, the current study focused on understanding the influence of El Niño Southern Oscillation (ENSO) on the spatiotemporal change patterns of three hydro-climatological variables—temperature, precipitation, and potential evapotranspiration (PET)
The spatial distribution of trends suggested that the western regions, i.e., Chandigarh, Haryana, and Punjab, as well as a significant portion of Uttar Pradesh, experienced a decreasing trend in all the ENSO phases (Figure 3)

Summary

Introduction

Studies on extreme climate events, i.e., droughts and floods, across the world, have found that such extremes are likely to be associated with the anomalies in zonal sea surface temperature (SST) fluctuations observed in the oceans. These fluctuations cause severe changes in the temperature and precipitation patterns, global and regional atmospheric pressure systems, formation of surface winds, and moisture sources and evaporative demands [1,2]. Besides analyzing SST anomalies and precipitation patterns, recent studies have incorporated hydro-climatological variables like moisture sources, evaporative demand, and temperature in order to understand these climate extremes more thoroughly [7,8,9].

Methods

Results

Conclusion