Relationships among Solar Radiation, Temperature, Precipitation, and Cloud Cover in Kyushu and Okinawa

Abstract

  This study investigated the inter-relationships between weather parameters in the Kyushu–Okinawa region of Japan using the correlation coefficients derived for each pair of weather parameters. Clear and stable relationships were confirmed among precipitation, solar radiation, and cloud cover throughout the year. Precipitation tended to increase with increasing cloud availability and decreasing solar radiation. The impact of precipitation, solar radiation, and cloud cover on air temperature is more complicated and has seasonality or regionality, especially in winter. In the summer months, air temperature tended to be high when there was little precipitation, strong solar radiation, or less cloud cover, implying that solar radiation dominantly controlled air temperature on a monthly timescale. However, their impacts on air temperature turned to be opposite or unclear in winter, probably because the relative impact of the longwave energy budget increases in winter as compared to the shortwave energy budget. Some regional differences in the inter-relationships were observed among northern Kyushu, southern Kyushu, and Okinawa. While the air temperature–precipitation relationship has been of public interest, this study suggests the importance of considering cloud and solar radiation because the relationships were formed via cloud and solar radiation circumstances.