海北高寒草甸地区太阳总辐射、植被反射辐射的有关特征

祁连山海北高寒草甸地区,有较强的太阳总辐射及地表反射辐射.通过2000年观测结果表明,在植物生长期的4～10月,太阳总辐射和地表反辐射总量分别达422.049MJ·m^-2和93.556MJ·m^-2.二者有明显的日变化规律,瞬时最高值出现于北京时间13～14h左右,日瞬时最大值分别可达1200W·m^-2和220W·m^-2以上.植物生长期间太阳总辐射变化受太阳高度角及其当地气候环境的影响,太阳高度角高或气候干燥时太阳总辐射值大,而地表反辅射依太阳总辐射的变化而变化,二者均在月最高,5月次高.植物生长后期,气候湿润,太阳总辐射和地表反射辐射均较低.地表反射率不论在日间还是植物生长的季节间,均表现一"U"型变化过程,其中日间在中午前后最低,最低可达0.19,季节变化以6～月最低,约为0.21,当然受土壤潮湿程度及地表性质等影响,其它时间也可降到0.21.就整个植物生长期内来看,祁连山海北高寒草甸地区地表反射率平均约为0.23.

The Study of Reflective Radiation and Surface Albedo of Alpine Meadow Vegetation

The Sun total radiation (Eg) and surface reflective radiation (Er) were higher in Haibei alpine meadow area of Qilian mountain. The Eg and Er were 4227.049 MJ·m^-2, 973.556 MJ·m^-2 respectively, during plant growing season (from April to October) by the analysis of observed data in 2000. The Eg and Er had obvious diurnal change pattern. The instant maximum of Eg and Er appeared about from 13:00 to 14:00, and were more than 1200 W·m^-2 and 220 W·m^-2, respectively. The change of Eg was influenced not only by suns altitude but also by weather and climate in seasonal change during plant growing period. The Eg was higher if suns altitude was more and climate was dry, whereas the change of Er was followed by change of Eg. The Eg and Er reached the maximum in July, then in May. The Eg and Er were lower because of wet climate during the later plant growing period. The soil surface albedo (A) showed as a "U" type change not only in a day but in seasonal change during plant growing period. The minimum of the soil surface albedo was 0.19, appeared at noon about in a day. The minimum of the soil surface albedo was about 0.21, appeared from May to June during the process of seasonal change, and it will decreased to 0.21, too, in other seasons if soil moisture was different. The average soil surface albedo was about 0.23 in Haibei alpine meadow area of Qilian mountain druing whole plant growing period.