Long-range operational military forecasts for Afghanistan

Abstract

We have investigated statistically significant signals in Afghanistan associated with two global scale climate variations, El NinÌ o-La NinÌ a (ENLN) and the North Atlantic Oscillation (NAO). The results of primary interest were in seasonal 850hPa temperatures and precipitation rates (PR), as these variables affect many military operations. Our primary data sets were National Centers for Environmental Prediction (NCEP) reanalysis fields and indices of ENLN and NAO activity. Our methods involved a two-step process. We first performed composite analyses of past events in an effort to identify statistically significant (SS) relationships between climate variations and 850hPa temperatures and PRs for Afghanistan. If SS was identified, we then used a forecast of ENLN or NAO conditions to produce a probabilistic forecast of potential occurrence of the particular variable, with a two-week lead time. We identified statistically significant results in all four seasons for both ENLN and NAO. The NAO has a larger impact on 850hPa temperatures while ENLN has a larger impact on PRs. The ENLN impacts on PRs are associated with anomalous advection of moisture out of the Arabian Sea or out of central Asia. The NAO impacts on 850hPa temperatures are associated with variations in storm tracks over southwest Asia. We generated initial probabilistic forecasts of PRs and 850hPa temperatures for Afghanistan for all four seasons. These serve as first steps in providing in-depth climatological planning products to military commanders and bridging the gap between civilian and military climatological products.