AVHRR warm-season cloud climatologies under various synoptic regimes across the Iberian Peninsula and the Balearic Islands

In this study we retrieved the spatial distribution of mid-afternoon clouds under various synoptic regimes across the Iberian Peninsula and the Balearic Islands for the warm/convective-season, from May to October. Accurate daily cloud masks were derived by applying a daytime over land multispectral convective cloud detection algorithm spanning 15 years (1997-2011) of Advanced Very High Resolution Radiometer (AVHRR) HRPT data. We processed a total of 2094 afternoon overpasses (between 1230 and 1720 UTC) corresponding to the NOAA-14, NOAA-16 and NOAA-18 spacecrafts, and stratified daily cloud masks as a function of: (1) the automated circulation-typing scheme of Jenkinson and Collinson and (2) the prevailing wind field at 850 hPa. The AVHRR warm-season cloud climatology with high spatial resolution (1.1-km) identified six representative areas (regions of interest; ROIs) with intensified cloud activity (hot spots). The results also revealed the typical spatial distribution of clouds for each synoptic regime across the whole region, identified the synoptic patterns and wind regimes under which high amounts of clouds occur for each ROIs, and showed that strong boundary layer winds in general increase the frequency of clouds. The regional cloud climatology presented here could be useful, e.g. to improve convective short-term forecasting by identifying active cloud areas for each atmospheric type. © 2015 Royal Meteorological Society.This research was supported by (1) the JCI-2011-10263 grant and (2) the projects CGL2011-27574-C02-02 and CGL2011-27536/HID financed by the Spanish Commission of Science and Technology and FEDER and (3) the MEDACC project (LIFE12 ENV/ES/000536). The authors would like to thank the INTA's CREPAD Program for supplying the AVHRR data (assistance provided by Angel Garcia-Sevilla and Marta Romeo-Gallego); and to Rafael Baena-Calatrava, Imanol Echave-Calvo and Fergus Reig-Gracia for the IDL programming assistance and Dr Tinghai Ou for the reanalysis data processing. The authors wish to acknowledge the two anonymous reviewers for their detailed and helpful comments to the original manuscript.Peer Reviewe