Estimating energy fluxes in the North American Monsoon region using flux tower and satellite data

We present an analysis of the results measured by six flux towers in southern and central Arizona. The towers are a part of the AmeriFlux network and the longest measurements span the period from 2003 - 2010. In southern Arizona the analysis reveals a clear annual cycle in surface properties that follows the monsoon rains: a dramatic response in variables such as albedo and vegetation indices is observed. In central Arizona, there is no such obvious variation in surface properties related to the monsoon. Furthermore, the relatively long presence of the towers enables us to test the dependence of landscape response on the interannual variability of the monsoon. The results show tight coupling between the amount of precipitation, vegetation cover and albedo.

In order to observe the variations in sensible heat flux and surface evaporation on a regional scale, we used MODIS satellite data. Sensible heat flux was estimated using the MODIS Land Surface Temperature product, whereas evaporation was modeled using the Penman-Monteith model (Cleugh et al., 2007). Ultimately, the strength of land-atmosphere coupling in the NAM region will be tested by coupling the evaporation data with a regional scale atmospheric model.