Assessing the contribution of solar proxies to cloud cover, as differentiated by height and season

Cloud formation is due to a combination between water uptake and aerosol distribution and characteristics. Globally, the state of the terrestrial atmosphere is influenced by solar activity and galactic cosmic rays through the global electric circuit. This paper investigates the possible link between cloud cover and solar proxies, namely sunspot number (SSN), solar/plasma wind speed (PWS), and the associated interplanetary electric and magnetic fields (IEF, IMF), respectively, for two solar cycles. The seasonal variation on possible links is also investigated. Each solar driver may influence the atmospheric electricity, thus cloud formation and cloud cover. The study uses the first long-term cloud database, as provided by the International Satellite Cloud Climatology Project (ISCCP), since these data had sufficient time for validation and are ready to use as such. Solar proxies were taken from NASA’s OMNIWeb database, from measurements with instruments onboard several spacecraft with geocentric orbits. Cloud types were individually considered, and global distribution of cloud cover was analyzed. The study reveals that the cloud cover response to changes in various solar indicator depends on local conditions, and varies with season. E.g., high clouds cover exhibited anticorrelation with IEF in January on large areas, while low cloud cover was moderately positively correlated with PWS on extended regions in July.