Investigating the impact of land-use land-cover change on Indian summer monsoon daily rainfall and temperature during 1951–2005 using a regional climate model

Abstract

Abstract. Daily moderate rainfall events, which constitute a major portion of seasonal summer monsoon rainfall over central India, have decreased significantly during the period 1951 through 2005. On the other hand, mean and extreme near-surface daily temperature during the monsoon season have increased by a maximum of 1–1.5 °C. Using simulations made with a high-resolution regional climate model (RegCM4) and prescribed land cover of years 1950 and 2005, it is demonstrated that part of the changes in moderate rainfall events and temperature have been caused by land-use/land-cover change (LULCC), which is mostly anthropogenic. Model simulations show that the increase in seasonal mean and extreme temperature over central India coincides with the region of decrease in forest and increase in crop cover. Our results also show that LULCC alone causes warming in the extremes of daily mean and maximum temperatures by a maximum of 1–1.2 °C, which is comparable with the observed increasing trend in the extremes. Decrease in forest cover and simultaneous increase in crops not only reduces the evapotranspiration over land and large-scale convective instability, but also contributes toward decrease in moisture convergence through reduced surface roughness. These factors act together in reducing significantly the moderate rainfall events and the amount of rainfall in that category over central India. Additionally, the model simulations are repeated by removing the warming trend in sea surface temperatures over the Indian Ocean. As a result, enhanced warming at the surface and greater decrease in moderate rainfall events over central India compared to the earlier set of simulations are noticed. Results from these additional experiments corroborate our initial findings and confirm the contribution of LULCC in the decrease in moderate rainfall events and increase in daily mean and extreme temperature over India. Therefore, this study demonstrates the important implications of LULCC over India during the monsoon season. Although, the regional climate model helps in better resolving land–atmosphere feedbacks over the Indian region, the inferences do depend on the fidelity of the model in capturing the features of Indian monsoon realistically. It is proposed that similar studies using a suite of climate models will further enrich our understanding about the role of LULCC in the Indian monsoon climate.

Impact of Land Surface Initialization and Land-Atmosphere Coupling on the Prediction of the Indian Summer Monsoon with the CFSv2

“…There could be several factors contributing to the enhanced skill in surface temperature over India on sub-seasonal to seasonal time scales, such as the ocean (Pokhrel et al, 2015), snowmelt and associated hydrological effect over Eastern Eurasia (Halder and Dirmeyer, 2017) or land-use land-cover changes (Halder et al, 2016) that needs further investigation. Here, we explore the LA coupling pathway that links skill in local soil moisture anomalies to that of temperature and precipitation.…”

“…The central and northwestern parts of India constitute one of the global "hot spots" of land-atmosphere coupling where soil moisture anomalies exert a significant control on temperature and precipitation via strongly coupled processes Guo et al, 2006;Dirmeyer, 2011;Halder et al, 2015). In addition, efforts to investigate the role of land-surface processes during the onset (Saha et al, 2011(Saha et al, , 2017Bollasina and Ming, 2013;Senan et al, 2016) and in the low-frequency variability of the Indian summer monsoon (Webster, 1983;Ferranti et al, 1999;Yasunari, 2007;Turner and Slingo, 2011;Saha et al, 2012;Halder et al, 2015Halder et al, , 2016Halder and Dirmeyer, 2017) have further added to the confidence that the prediction skill of the Indian summer monsoon can be further improved. However, the actual prediction skill arising from anomalies in the land surface state may depend on the methods of forecast initialization (Dirmeyer, 2005;Koster et al, 2011), errors in land surface initial conditions Halder, 2016, 2017) and the systematic errors in the model (Dirmeyer, 2003) that affect the land-atmosphere (LA) coupling strength (cf.…”

The Impact of China’s Grain for Green Program on Rural Economy and Precipitation: A Case Study of Yan River Basin in the Loess Plateau

“…Surface vegetation changes affect the concentration of greenhouse gases and aerosols in the atmosphere through the interaction of energy balance, water vapor exchange, and biogeochemical cycles between the ground and the atmosphere, which in turn affects climate change [15][16][17][18][19][20][21][22][23][24]. The state of vegetation growth is critical to the health of terrestrial ecosystems and biospheres, and is closely related to the rainfall [25].…”

On the contribution of internal variability and external forcing factors to the Cooling trend over the Humid Subtropical Indo-Gangetic Plain in India

“…31 . Moreover, using high-resolution regional climate model (RegCM4) simulations and prescribed land cover of years 1950 and 2005, it is demonstrated that part of the changes in moderate rainfall events and temperature have been caused by LULCC 32 (Halder et al . 32 On the other hand, a recent study by Joshi and Rai 33 reported that the opposite phases of AMO and IPO together modulates the total/moderate rainfall over west central and northeast regions in an asymmetric manner; whereas their warm phase stimulates the heavy rainfall over west central region, while their opposite phases together influences the precipitation extremes over the northeastern region.…”