Changes in cloud amount over South America

TESTANI, NADIA; ROBLEDO, FEDERICO; DÍAZ, LEANDRO B.

Conferencia; 13th meeting of the International Conference on Southern Hemisphere Meteorology and Oceanography; 2022

American Meteorological Society

Cloudiness is a key element of the climate system and has a large influence on agricultural production. Although large-scale patterns of cloud change have been observed in the last decades, there are few studies that explore the particularities of these changes in South America (SA). In this research cloudiness over SA is studied using satellite-based observations, primarily from the International Satellite Cloud Climatology Project, ISCCP, in order to describe regional cloud climatology and changes.We use the visible/IR detected cloud amount product of the ISCCP-H data set, with monthly mean global coverage from July 1983 to June 2017 on a 1⁰ X 1⁰ grid. Clouds are classified as low (cloud top pressure≥680 hPa), middle (440 hPa≤cloud top pressure ≤ 680 hPa) and high (cloud top pressure≤440 hPa). Long-term annual and seasonal trends in monthly mean cloud amount over South America are examined. This analysis is extended to low, middle and high cloud amounts. The study reveals that the South America mean month total cloud amount is characterised by seasonal variability and shows a statistically significant decrease over the 1983-2017 period in most regions, with the major decrease in low clouds.Finally, ISCCP-H cloud amount series were compared against individual cloud cover observations over northeast Argentina meteorological stations from the National Weather Service. The results of this comparison will be shown in the conference.