Cloud Cover over the South Pole from Visual Observations, Satellite Retrievals, and Surface-Based Infrared Radiation Measurements

• DOI: 10.1175/jcli4005.1
• Publication Date: 2007-02-09T23:01:56Z
• Authors: Michael S. Town; Von P. Walden; Stephen G. Warren
• Keywords: Longwave; Downwelling; Outgoing longwave radiation; Cloud forcing; Cloud top; Cloud fraction; Advanced very-high-resolution radiometer

Abstract Estimates of cloud cover over the South Pole are presented from five different data sources: routine visual observations (1957–2004; Cvis), surface-based spectral infrared (IR) (2001; CPAERI), broadband IR (1994–2003; Cpyr), Extended Advanced Very High Resolution Radiometer (AVHRR) Polar Pathfinder (APP-x) dataset (1994–99; CAPP-x), and International Satellite Cloud Climatology Project (ISCCP) CISCCP). The seasonal cycle is found to range 45%–50% during short summer a relatively constant 55%–65% winter. Relationships between Cpyr 2-m temperature, 10-m wind speed direction, longwave radiation investigated. It shown that clouds warm surface in all seasons, 0.5–1 K 3–4 annual radiative forcing 18 W m−2 for downwelling 10 net radiation. datasets intercompared time periods which they overlap. nighttime bias Cvis worse than previously suspected, by approximately −20%; CISCCP shows some skill polar day, while CAPP-x at night. masks satellite reviewed here not yet accurate enough reliably derive or properties East Antarctic Plateau. best source terms combination accuracy length record determined be Cpyr. use further tests retrievals models recommended.