大理州山地日照时间的时空分布特征

Spatial and Temporal Distribution Characteristic of Sunshine Duration in Dali Mountains

基于数字高程模型(DEM)模拟计算了大理州山地日照时间的时空分布,结果显示,除了日照百分率外,坡度、坡向和地形之间的相互遮蔽对日照时间的分布有很大的影响。冬季太阳高度角较小,地形遮蔽对日照时间的影响很大,夏季相对较小。遮蔽系数4月最大,12月最小。一年中的任意时刻随着坡度的增加日照时间减少。坡向对日照时间的影响有很强的季节性:春分和秋分时期南坡与北坡日照时间相等且都为最多,夏至北坡最多,冬至南坡最多;春分至秋分期间,北坡日照时间最多,其余时间南坡日照时间最多,全年日照时间南坡最多。105°和255°坡向的坡面地形遮蔽系数常年都为0.82,不随时间变化。

This article simulated calculates the spatial and temporal distribution of mountains＇ sunshine duration in Dali based on the digital elevation model（DEM）.The results show besides the percentage of sunshine,slope,aspect and the masking of terrain have a great effect on the distribution of sunshine duration.The solar altitude is smaller in winter,the masking of terrain has a great impact on sunshine duration,but it＇s smaller relatively in summer.The ratio of masking in April is maximum and in December is minimum all year around.Any time of year with the increase in slope the sunshine duration is reduced.The aspect has a strong seasonal on the sunshine duration： the northern slope and southern slope are equal to a maximum duration of sunshine in vernal equinox and autumnal equinox,the northern slope is maximum in summer solstice and the southern slope is maximum in winter solstice.During the vernal equinox to the autumnal equinox,sunshine duration in the northern slope is maximum,the southern slope is maximum in the rest of time,but the annual sunshine duration is maximum in the southern slope.The ratio of masking terrain in 105 ° and 255 ° of slope is 0.82 all year round,and the ratio is not variable with time.