Abstract: By analyzing and comparing climatological calculation methods of global solar radiation at home and abroad, an optimal calculation formula was identified and then used in Inner Mongolia. In accordance with monthly global solar radiation and percentage of sunshine at 24 solar radiation observation stations in Inner Mongolia and its surrounding areas, experiential coefficients in the formula were fitted in terms of least square method. An interpolation method of IDW was then used to extend these coefficients to 108 weather stations. Finally, a global solar radiation calculation model was established for Inner Mongolia. The calculating results from this model show that the annual global solar radiation is in a decreasing trend from 1978 to 2010, while it is not significant and the decreasing rates in different regions differ obviously. The highest value of global solar radiation occurs in May, then follows in June and July, and the lowest value is in December. The monthly variation presents a single peak. The spatial distributions of monthly global solar radiation are consistent with that of annual global solar radiation, and both increase gradually from northeast to southwest of Inner Mongolia. The annual global solar radiation ranges from 4633 MJ·m^-2 to 6616 MJ·m^-2. The grade of solar energy resources in Inner Mongolia is abundance grade or above it. The grades of solar energy resources fall in categories of the best abundance grade and better abundance grade in most areas of Inner Mongolia, so it has great potential for development and utilization of solar energy resources.

Key words: font-family: "Times New Roman", mso-ansi-language: EN-US, mso-fareast-language: ZH-CN, mso-bidi-language: AR-SA, Global solar radiation')">mso-fareast-font-family: 宋体">Global solar radiation, Climatological calculation, Least square method