Cloud-top temperature inversion derived from long-term radiosonde measurements at the ARM TWP and NSA sites

Abstract

A temperature inversion layer often occurs above a cloud layer due to longwave cooling in the upper cloud levels; however, few previous studies have been conducted on the climatologic statistics of cloud-top temperature inversion features. By using a high-quality continuous radiosonde dataset from 2002/05 to 2014/05 at the Atmospheric Radiation Measurement (ARM) Tropical Western Pacific (TWP) site at the islands of Manus and North Slope of Alaska (NSA) site near Barrow, Alaska, this study investigated the long-term characteristics of cloud-top temperature inversion over the single- and double-layer clouds (SLC and DLC, respectively) in these two different geographic locations and climate regimes. Cloud tops extended much higher vertically at the TWP than at the NSA due to their different local atmospheric environments. Because of the radiative energy interactions between the two layers of clouds, a thinner temperature inversion depth was presented by the DLC lower clouds than by the DLC higher clouds at the TWP site. However, much weaker temperature inversions were detected above the DLC higher clouds than the DLC lower clouds which were often bounded by a ubiquitous surface radiative cooling-induced inversion at the NSA site. A close temperature inversion was observed between the morning and evening at both sites. A thinner temperature inversion depth was displayed in the summer and autumn melt seasons when weak surface radiative cooling occurred at the NSA, whereas a smooth seasonal temperature inversion occurred at the TWP. The climatologic results of this study are expected to provide a better understanding of the complex interactions between clouds and temperature inversion, especially their unique climatic features in the tropics and Arctic.