The Iberian Peninsula Thermal Low

Kurzfassung

Statistics of the thermal low above the Iberian Peninsula are presented for the period between 1979 and 1993, based on gridded data from the European Centre for Medium-Range Weather Forecasts reanalysis project. The sample of days with a thermal low above the Iberian Peninsula was selected objectively using criteria applied to mean-sea-level pressure and 925 hPa geopotential fields. The synoptic- and regional-scale horizontal structure is characterized by the climatology of the 500 hPa geopotential and mean-sea-level pressure distributions. The diurnal evolution of the mean-sea-level pressure is portrayed by mean fields at 00, 06, 12 and 18 U TC. The climatological vertical structure of the thermal low is shown by relation to meridional and zonal cross-sections passing through the thermal low's centre. The diurnal evolution of the divergence, relative vorticity, potential temperature and vertical velocity is investigated. Statistics are presented also for the monthly frequency, geographical location, vertical extent and intensity of the Iberian thermal low