sun_position

  一个相当好用的matlab函数，由美国国家可再生能源实验室科研人员设计，可以计算太阳的直射维度和方位角。只要输入时间、观测地点即可。 (This algorithm is based on numerical approximation of the exact equations. The authors of the original paper state that this algorithm should be precise at+/- 0.0003 degrees. I have compared it to NOAA solar table (http://www.srrb.noaa.gov/highlights/sunrise/azel.html) and to USNO solar table (http://aa.usno.navy.mil/data/docs/AltAz.html) and found very good correspondance (up to the precision of those tables), except for large zenith angle, where the refraction by the atmosphere is significant (difference of about 1 degree). Note that in this code the correction for refraction in the atmosphere as been implemented for a temperature of 10C (283 kelvins) and a pressure of 1010 mbar. See the subfunction un_topocentric_zenith_angle_calculation� for a possible modification to explicitely model the effect of temperature and pressure as describe in Reda & Andreas (2003). )