Cloudiness decrease over Northeastern Argentina based on two lines of evidence: Surface Observations and Satellite-Derived Data

NADIA TESTANI; FEDERICO ARIEL ROBLEDO; LEANDRO DIAZ

Kigali

Conferencia; World Climate Research Programme (WCRP) Open Science Conference; 2023

World Climate Research Programme (WCRP)

Clouds cover roughly two thirds of the globe and are a key element of the climate system as they play an important role in the Earth’s energy balance and hydrological cycle, both at global and local scales. Moreover, clouds can have a large influence on, for example, agricultural production. Although it was observed a slow but steady decrease in global total cloud cover (TCC) with most of the decrease emanating from mid-latitude regions, there have been few studies that explore the particularities of TCC changes in South America (SA) and, particularly, none in its densely populated, highly productive sub-region of South-Eastern South America (SESA). As the impacts of climate change are generally experienced at local and regional scales and so climate information on those spatial scales is considered to be more impact- and risk-relevant climate change information, the objective of the present study is to present the climatology and the observed long term changes of TCC in Northeastern Argentina (NEA), a SESA sub-region with high economic and demographic significance as it concentrates most of the agricultural production and the population of the country. Analyses are performed on the basis of two independent lines of evidence: TCC ground based (GB) observations and satellite based estimations of the International Satellite Cloud Climatology Project (ISCCP) over their common period: December 1983 to November 2016 -the Satellite Period-, and only on the basis of GB TCC observations over a longer period: March 1961 to February 2021 -the Ground Based Period-. Relying on two lines of independent evidence allows us to build more robust information for the Satellite Period and thereby to improve the confidence in our findings. We found that TCC has a distinguishable annual cycle and a large spatial variability over NEA, coherent in both satellite and GB datasets. To ensure consistency of our results, we compared the two datasets used in the study and we observed that although the ISCCP Cloud Amount (CA) overestimates the GB TCC in one okta in nearly half of the analyzed cases, both datasets show a similar temporal variability. Furthermore, an annual and seasonal decrease of NEA mean TCC over the Satellite Period (GB Period) is detectable in both datasets (the GB dataset) with a great spatial variability. Overall, our results provide evidence for consistently decreasing cloudiness over NEA in the last six decades based on ground-based and satellite information.