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Synoptic-scale controls of fog and low-cloud variability in the Namib Desert

Andersen, Hendrik; Cermak, Jan; Fuchs, Julia; Knippertz, Peter; Gaetani, Marco; Quinting, Julian; Sippel, Sebastian; Vogt, Roland

Abstract (englisch):
Fog is a defining characteristic of the climate of the Namib Desert, and its water and nutrient input are important for local ecosystems. In part due to sparse observation data, the local mechanisms that lead to fog occurrence in the Namib are not yet fully understood, and to date, potential synoptic-scale controls have not been investigated. In this study, a recently established 14-year data set of satellite observations of fog and low clouds in the central Namib is analyzed in conjunction with reanalysis data in order to identify synoptic-scale patterns associated with fog and low-cloud variability in the central Namib during two seasons with different spatial fog occurrence patterns. It is found that during both seasons, mean sea level pressure and geopotential height at 500 hPa differ markedly between fog/low-cloud and clear days, with patterns indicating the presence of synoptic-scale disturbances on fog and low-cloud days. These regularly occurring disturbances increase the probability of fog and low-cloud occurrence in the central Namib in two main ways: (1) an anomalously dry free troposphere in the coastal region of the Namib leads to stronger longwave cooling of the marine boundary layer, increasing low-cloud cover, especially over the ocean where the anomaly is strongest; (2) local wind systems are modulated, leading to an onshore anomaly of marine boundary-layer air masses. ... mehr

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Verlagsausgabe §
DOI: 10.5445/IR/1000117856
Veröffentlicht am 25.03.2020
Originalveröffentlichung
DOI: 10.5194/acp-20-3415-2020
Scopus
Zitationen: 1
Web of Science
Zitationen: 1
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Meteorologie und Klimaforschung - Forschungsbereich Troposphäre (IMK-TRO)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2020
Sprache Englisch
Identifikator ISSN: 1680-7324
KITopen-ID: 1000117856
HGF-Programm 12.01.02 (POF III, LK 01)
Proc.res.f.multisc.predictab.of weather
Erschienen in Atmospheric chemistry and physics
Band 20
Heft 6
Seiten 3415–3438
Bemerkung zur Veröffentlichung Gefördert durch den KIT-Publikationsfonds
Vorab online veröffentlicht am 24.03.2020
Nachgewiesen in Scopus
Web of Science
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