Changes in Global Cloud Cover Based on Remote Sensing Data from 2003 to 2012

As is well known, clouds impact the radiative budget, climate change, hydrological processes, and the global carbon, nitrogen and sulfur cycles. To understand the wide-ranging effects of clouds, it is necessary to assess changes in cloud cover at high spatial and temporal resolution. In this study, we calculate global cloud cover during the day and at night using cloud products estimated from Moderate Resolution Imaging Spectroradiometer (MODIS) data. Results indicate that the global mean cloud cover from 2003 to 2012 was 66%. Moreover, global cloud cover increased over this recent decade. Specifically, cloud cover over land areas (especially North America, Antarctica, and Europe) decreased (slope =–0.001, R2 = 0.5254), whereas cloud cover over ocean areas (especially the Indian and Pacific Oceans) increased (slope = 0.0011, R2 = 0.4955). Cloud cover is relatively high between the latitudes of 36°S and 68°S compared to other regions, and cloud cover is lowest over Oceania and Antarctica. The highest rates of increase occurred over Southeast Asia and Oceania, whereas the highest rates of decrease occurred over Antarctica and North America. The global distribution of cloud cover regulates global temperature change, and the trends of these two variables over the 10-year period examined in this study (2003–2012) oppose one another in some regions. These findings are very important for studies of global climate change.