Elevation dependency of precipitation and temperature over northeast India

Abstract

The study inspects the elevation dependency of temperature and precipitation across northeast India. Various gridded observations and outputs from high-resolution Regional Climate Models under the CORDEX-CORE framework have been employed. The better representation of the topography leads to higher orographic precipitation in the model environment. Positive vorticity led to strong convergence of the moisture-laden air resulting in high precipitation along the slopes of the mountains, which is more intense above 1800 m. The variance in the magnitude of precipitation at different elevations indicates the role of other factors, such as the difference in the convection processes. The latitudinal and longitudinal analysis reflects that the precipitation follows the topography leading to higher orographic precipitation along the slopes of the Meghalaya Plateau and the mountains. The change of temperature with elevation is very shallow till 3000 m, particularly during monsoon and pre-monsoon, which can be attributed to the release of a huge amount of latent heat due to the condensation of water vapour during the convection process. Interestingly, all the model experiments indicate towards a higher warming signal between the elevation range 4000–5000 m. The temperature also shows a strong association with the elevation, with a decline in temperature over the Meghalaya plateau and higher elevations. The variability among model experiments as well as the decline of temperature with elevation is highest above 5000 m. Precipitation and temperature changes are found to be higher for fast-changing elevation profiles, while precipitation distribution is also dependent upon the local processes influencing the convection processes such as the vorticity, CAPE etc.