Why is the Indian summer monsoon in CFSv2 hypersensitive to moisture exchange with the Pacific Ocean?
by Priyanshi Singhai, Arindam Chakraborty, Kavirajan Rajendran & Sajani Surendran
CSIR Fourth Paradigm Institute
(Formerly CSIR Centre for Mathematical Modelling and Computer Simulation)
A constituent laboratory of Council of Scientific & Industrial Research (CSIR).
by Priyanshi Singhai, Arindam Chakraborty, Kavirajan Rajendran & Sajani Surendran
by P. Ipsita, V. Rakesh, Randhir Singh and G.N. Mohapatra
This study focuses to analyse the impact of land use changes on short range weather forecasts over Indian region. Weather Research and Forecasting (WRF) model simulation experiments are conducted by using land use data from Moderate Resolution Imaging Spectroradiometer (MODIS) and Indian Space Research Organization (ISRO) satellites for pre-monsoon and monsoon season. MODIS 2001 land use is used in control (CNT) experiment and updated land use with recent urban class from MODIS (EXP1) and ISRO (EXP2) for the year 2019 is used to generate model lower boundary conditions in other two experiments. Quantitative error measures and skill score computed for rainfall forecast showed that model skill is better with the use of realistic recent land use data from MODIS and ISRO during pre-monsoon and monsoon period. Extreme Dependency Index score computed also revealed that model skill in predicting extreme rare rainfall events is improved with recent landuse data. Model simulated surface meteorological variables and profiles at lower levels also found to be improved with the inclusion of realistic land use class from MODIS and ISRO. Between the two experiments, the one which used ISRO based land use showed larger improvement particularly during the monsoon season.
Source: https://doi.org/10.1016/j.uclim.2023.101558
by Raghavendra Prasad K, Kantha Rao Bhimala, G. K. Patra, Himesh S & Sheshakumar Goroshi
The present study analyzed the actual evapotranspiration (ETa) and its components [transpiration (Et), bare soil evaporation (Eb), interception loss (Ei), and open water evaporation (Eo)] data to study the long-term (1980–2018) trends over different meteorological sub-divisions in India. Quantitatively, all India average (µ) annual ETa is 573 mm (standard deviation (σ) = 29 mm), where Et (µ = 456 mm; σ = 30 mm) plays a major role compared to other evaporation processes like Eb (µ = 56 mm; σ = 9 mm), Ei (µ = 34 mm; σ = 3 mm), and Eo (µ = 27 mm). The Mann–Kendall (MK) test reveals an increasing trend (1.33 mm/yr) in annual ETa due to the rising trend in Et (1.91 mm/yr) and Ei (0.16 mm/yr). The sub-division-wise analysis shows the increasing trend in ETa observed over irrigated regions located in the south, north-west, and foothills of the Himalayas during pre-monsoon (March–May) and monsoon season (June–September). The correlation analysis observed a complex relationship between ETa and climatic factors (rainfall (RF), soil moisture (SM), surface temperature (T), relative humidity (RH), surface net solar radiation (SSR), and wind speed (WS)) during monsoon season such that the water-limited areas have a positive correlation with SM, RH and RF, and negative correlation with WS, T, and SSR, whereas, in energy-limited areas (east India), the ETa showed a positive correlation with SSR and T and negative correlation with RF. The main climatic drivers for the increasing trend of ETa are SM and rainfall over dry regions and SSR and T over densely vegetated regions in India.