Intraseasonal Variability of the Saharan Heat Low and Its Link with Midlatitudes

摘要: Abstract The Saharan heat low (SHL) is thought to be a key feature of the West African monsoon, and its variations during summer season have not yet been systematically assessed. To characterize intraseasonal SHL, real complex empirical orthogonal function analyses were applied 850-hPa potential temperature field over northern Africa Mediterranean, using NCEP–Department Energy (DOE) Atmospheric Model Intercomparison Project (AMIP-II) reanalysis results. A robust quasi-propagative mode was highlighted North Mediterranean. This consists two phases. west phase corresponds maximum coast Morocco–Mauritania, propagating southwestward, minimum between Libya Sicily, southeastward. east opposite structure, which propagates as in phase. lag-composite analysis revealed that this SHL preceded by large-scale, midlatitude, intrase...