Sensitivity of convective precipitation to soil moisture and vegetation during break spell of Indian summer monsoon
- 149 Downloads
Indian summer monsoon rainfall is characterized by large intra-seasonal fluctuations in the form of active and break spells in rainfall. This study investigates the role of soil moisture and vegetation on 30-h precipitation forecasts during the break monsoon period using Weather Research and Forecast (WRF) model. The working hypothesis is that reduced rainfall, clear skies, and wet soil condition during the break monsoon period enhance land-atmosphere coupling over central India. Sensitivity experiments are conducted with modified initial soil moisture and vegetation. The results suggest that an increase in antecedent soil moisture would lead to an increase in precipitation, in general. The precipitation over the core monsoon region has increased by enhancing forest cover in the model simulations. Parameters such as Lifting Condensation Level, Level of Free Convection, and Convective Available Potential Energy indicate favorable atmospheric conditions for convection over forests, when wet soil conditions prevail. On spatial scales, the precipitation is more sensitive to soil moisture conditions over northeastern parts of India. Strong horizontal gradient in soil moisture and orographic uplift along the upslopes of Himalaya enhanced rainfall over the east of Indian subcontinent.
The research was supported primarily by the Indian Institute of Space Science and Technology. The authors thank the Indian Institute of Tropical Meteorology, Pune for providing computational resources.
- Betts AK, Ball JH (1998) FIFE surface climate and site-average dataset 1987–89. J Atmos Sci 72Google Scholar
- Guo Z, Dirmeyer PA, DelSole T (2011) Land surface impacts on subseasonal and seasonal predictability. Geophys Res Lett 38Google Scholar
- Hong S, Lakshmi V, Small EE, Chen F, Tewari M, Manning KW (2009) Effects of vegetation and soil moisture on the simulated land surface processes from the coupled WRF/Noah model. Atmospheres, Journal of Geophysical Research, p 114Google Scholar
- Saha SK, Halder S, Suryachandra Rao A, Goswami B 2012 Modulation of ISOs by land-atmosphere feedback and contribution to the interannual variability of Indian summer monsoon. J Geophys Res Atmos (1984–2012) 117Google Scholar
- Skamarock W, and et al. 2008 A description of the advanced research WRF version 3, 113 ppGoogle Scholar
- Tewari M, Chen F, Kusaka H, Miao S (2007) Coupled WRF/unified Noah/urban-canopy modeling system. NCAR WRF Documentation, NCAR, Boulder, pp 1–22Google Scholar