敦煌戈壁秋初太阳分光辐射及其反照率特征

CHARACTERISTICS OF SOLAR SPECTRAL RADIATION AND ALBEDO DURING EARLY AUTUMN IN DUNHUANG GOBI

利用2010年9～10月实地观测资料,分析了敦煌戈壁地区秋初地表太阳总辐射和分光辐射及其地表反照率特征,并对比分析了不同天气条件下的辐射及反照率日变化特征,结果表明:由于季节转换,受天文因素太阳南撤的影响,地表总辐射及分光辐射强度整体变化呈下降趋势。晴天时,辐射通量日变化规则,全天呈对称分布,中午时达到最大值。阴天时,总辐射及分光辐射日变化明显受到云量的影响,辐射强度明显减小,变化呈现出无规则的锯齿型。地表对太阳总辐射及分光辐射的平均反照率变化不大,波动较小,30d变化趋势近似成直线。地表对总辐射及分光辐射加权平均反照率的平均值分别为:总辐射0.24,紫外辐射0.10,可见光辐射0.23,近红外辐射0.26。晴天时,地表对太阳总辐射、可见光辐射及近红外辐射反照率均有明显的日变化特征,早晚大,中午小。但对紫外辐射的反照率变化不明显。阴天与晴天时变化基本一致,阴天时全天平均地表反照率与晴天时基本相同。

Using the field observational data from September to October, 2010, the land surface global radiation and solar spectral radiation and their albedo characteristics during early autumn in Dunhuang Gobi were analyzed. The diurnal variation characteristics of radiation and their albedo under different types of synoptic conditions were also discussed. The results show that the land surface global radiation and solar spectral radiation intensity, by the reason of season transition and moving southward of the sun, show a downward trend on a whole. In the clear day, the diurnal variations of radiation flux showed a regular trend and symmetrical distribution. The radiation flux inten- sity appeared the maximum value at noon. However, it was dissimilar in the cloudy day. Diurnal variations of land surface global radiation and solar spectral radiation were affected by the cloud. Radiation intensity distinctly de- clined. The diurnal variations of radiation flux showed an irregular trend and serration type. The daily variations of the average albcdo value of surface global radiation and solar spectral radiation showed a flat fluctuation. The trend of the average albedo changing approximated a straight-line. The average value of weighted average value of the al- bedo of surface global, solar ultraviolet, visible and near infrared radiation is 0.24, 0.10, 0.23 and 0.26, respec- tively. The albedo of the land surface global, visible and near infrared radiation showed a distinctly diurnal varia- tion feature. From dawn to dusk, they were bigger at noon than at dawn and dusk. The surface ultraviolet radiation albedo variation was not distinct as the others. The characteristics of the albedo diurnal variation in cloud day were consistent with the clear day. The average surface albedo value was also in accordance with the clear day.