Statistical distributions of water content and sizes for clouds above Europe

Abstract

Abstract. The statistics of quantities involved in the synthesis of cloud scenes have been investigated from an original data base. Frequency distributions of ice and water content (IWC), horizontal and vertical sizes (L and H), and top temperatures (T) of clouds above Europe have been derived for nine types of clouds (As, Cb, Ci, Cg, LwCg, OrCg, Cs, Ns, Sc). It appears that the cumulated frequency plots can be well ®tted with log-normal or Weibull pro®les, and that for IWC and T cloud types can be split into two or three classes according to slopes in logarithmic coordinates. Crosscorrelation coecients between IWC, L, H and T have been also derived. Implications for the physics of the cloud build-up processes are brie¯y outlined. Critical analysis and comparison of other published results are proposed.

Humidity observations in the Arctic troposphere over Ny-Ålesund, Svalbard based on 14 years of radiosonde data

“…A method to get more detailed information on the vertical extent of these layers was described by . Using a statistical approach described by Berton (2000) to analyse ice-supersaturation layers, they showed that the thickness of ice-supersaturation layers over Lindenberg followed a Weibull distribution with different slopes for shallow and thicker layers. They also determined that the transition between the two regimes occurred around 1 km thickness.…”

“…The slope of the line in this part is 0.9. For visible cirrus, the corresponding shape parameter is around 1 (Berton, 2000;Spichtinger et al, 2003). Layers less thick than 2 km probably contain data from true ice-supersaturation layers and perhaps sub-visible cirrus.…”