A global survey of the instantaneous linkages between cloud vertical structure and large-scale climate

Abstract

The instantaneous linkages between cloud vertical structure and various large-scale meteorological parameters are investigated using 5 years of data from the CloudSat/CALIPSO instruments. The linkages are systemically explored and quantified at all vertical levels and throughout the global ocean in both the long-term mean and on month-to-month timescales. A number of novel large-scale meteorological parameters are used in the analysis, including tropopause temperatures, upper tropospheric stability, and storm track activity. The results provide a baseline for evaluating physical parameterizations of clouds in GCMs and a reference for interpreting the signatures of large-scale atmospheric phenomena in cloud vertical structure. In the long-term mean, upper tropospheric cloud incidence throughout the globe increases with (1) decreasing tropopause temperature (at a rate of ∼2–4% K−1), (2) decreasing upper tropospheric stability (∼5–10% per K km−1), and (3) increasing large-scale vertical motion (∼1–4% per 10 hPa d−1). In contrast, lower tropospheric cloud incidence increases with (1) increasing lower tropospheric stability (10% per K km−1) and descending motion (1% per 10 hPa d−1) in regions of subtropical regime but (2) decreasing lower tropospheric stability (4% per K km−1) and ascending motion (2% per 10 hPa d−1) over the Arctic region. Variations in static stability and vertical motion account for ∼20–35% of the month-to-month variance in upper tropospheric cloudiness but less than 10% of the variance in lower tropospheric clouds. Upper tropospheric cloud incidence in the storm track regions is strongly linked to the variance of large-scale vertical motion and thus the amplitude of baroclinic waves.