Changes in Cloud Cover, Precipitation, and Summer Temperature from 1982 to 2009

From a surface energy balance perspective, the summer mean daily maximum temperature change can be affected by changes in solar heating that is associated with cloud cover change, and changes in surface evaporative cooling due to different precipitation and land surface wetness, but little is known about regional cloud cover and precipitation feedbacks to decadal temperature trends. The relationship between summer mean daily maximum temperature, total cloud cover and precipitation over the northern continents was investigated using observation-based products of temperature and precipitation, and satellite-derived cloud cover and radiation products. A partial least squares regression approach was used to separate the local influences of cloud cover and precipitation on summer mean daily maximum temperature variations. Results show that summer mean daily maximum temperature variance is largely explained by changes in cloud cover and precipitation. Cloud cover effect dominates at the high and middle latitudes and precipitation is a more dominant factor in the middle latitudes. The results indicate that cloud cover is either the major indicator of the summer mean daily maximum temperature changes (the effect) or the important local factor influencing the changes (the cause).