Does evapotranspiration influence the strength of the North American monsoon? — Multitemporal satellite analysis of evapotranspiration and its effects

Abstract

We test the hypothesis that strength of North American monsoon is influenced by surface processes such as evapotranspiration and sensible heat flux. In order to estimate evapotranspiration, three different satellite remote sensing-based methods are used: We use the Penman-Monteith approach developed by Cleugh et al. (2007) [2] and the revised Penman-Monteith approach developed by Mu et al. (2007) [5]. Furthermore, we use a simple latent heat residual method. All three methods use MODIS data as input datasets. The results obtained by the three methods are compared against flux tower measurements. Sensible heat flux is estimated using satellite measurements of land surface temperature and balloon sounding measurements of air temperature. Evapotranspiration shows a sharp peak during the monsoon season and this feature is captured by all three methods. This lends credence to the hypothesis that increased latent heat flux results in more monsoonal precipitation.