Mapping of coupling hot spots of satellite derived latent heat flux in indian agro-climatic regions

This study focuses on the understanding and mapping of coupling hotspots of LE versus terrestrial and meteorological parameters. Single source surface energy balance model was used to derive surface energy balance parameters. Agro climatic region wise monthly information of terrestrial, energy balance and meteorological parameters were derived during JuneSeptember from decadal analysis of MODIS data (2003-2012) over India (68‐100°E, 5‐40°N) at 5 km spatial resolution. Information on rainfall was obtained from gridded rainfall data (1°◊ 1° spatial resolution) from Indian Meteorological Department (IMD). The spatiotemporal variability of the parameters such as rainfall, evapotranspiration (ET), evaporative fraction (EF), soil water index (SWI), land surface temperature (LST) and air temperature (T a) showed strong influence on seasonal LE fluctuation. LE showed positive linear coupling with ET (0.52 <R 2 ≤ 0.91), EF (0.79 ≤ R 2 ≤0.96), SWI (0.80 ≤ R 2 ≤0.93) and negative exponential coupling with LST (0.63 ≤ R 2 ≤0.87), Ta (0.55 < R 2 ≤0.83). The pixel based knowledge of the parameters was incorporated into hierarchical decision rule algorithm and pixel-by-pixel segmentation of monthly coupling of LE versus parameters (ET, EF, SWI, LST, Ta) was generated. The rainfall zonations in a spatiotemporal domain were done based on the LE couplings that clearly demarcated the highest (West Coast Plains and Hills Region, Himalayan region), moderate (Gangetic Plains and Hills Regions, and the Plateau and Hills Regions) and lowest rainfall (Western dry region) areas. The transition of zone-wise availability of rainfall (both surplus and deficient) can be very well understood from the seasonal dynamics of the LE couplings. 1. INTRODUCTION Spatiotemporal variations of land surface parameters are transformed in to atmosphere through numerous interconnected land surface-atmosphere pathways. The paths may be either through terrestrial or atmospheric components. The terrestrial component deals with the exchange of surface energy fluxes from land surface to the atmosphere, which is sensitive to the changes of the land surface status and meteorological pattern. The latent heat flux (LE), the most dominant terrestrial parameter is the indicator of precipitation responds well to the moisture availability at the land surface to exert control on the properties of the atmospheric boundary layer to cause rainfall. The meteorological component which deals with the development of the atmospheric boundary layer leading to cloud formation and then precipitation is highly sensitive to the exchange of surface energy fluxes such as evapotranspiration (latent heat flux) or sensible heat flux. All these components are strongly coupled to each other and hence, the predictability in the climate system can be determined through the interaction of these parameters through “Coupling hot spots”, where both terrestrial and meteorological components are strongly linked with each other. The sensitivity of surface fluxes to soil moisture, evaporative fraction, surface temperature and air temperature are indicated by either positive or negative correlation (Koster et al., 2004; Guo et al., 2006, Choudhury and Ghosh, 2014). With the availability of remote sensing sensors at various optical, thermal to microwave spectral ranges, estimation of the above parameters are possible to understand their spatiotemporal changes and hence, the resulting hydrological pattern.