【作者】 孙昭萱；

【导师】 张强；

【作者基本信息】 兰州大学 ， 应用气象， 2010， 硕士

【摘要】 本文利用西北极端干旱区敦煌2000年9月—2001年8月陆面过程观测资料,河西走廊干旱区中部张掖地区2005年11月—2006年10月的陆面过程观测资料,黄土高原半干旱区“定西陆面过程综合观测试验站”2004年11月—2005年10月的陆面过程资料以及兰州大学半干旱气候与环境观测站2008年11月—2009年10月的陆面过程观测资料,综合分析了各个气候区的土壤温、湿度,降水量,地表反照率,地表辐射分量和能量平衡分量等物理量的年变化和日变化分布特征及其影响机制,研究了地表反照率与降水量及土壤湿度的相关关系。对四个不同气候区的陆面过程特征进行了综合的比较与对比。并得出以下几点结论：1.对于西北极端干旱区敦煌,其地表温度年较差超过42℃；地表反照率年变幅较大；净辐射夏季是冬季的4倍左右；日变化中向下和向上长波辐射的变化趋势比短波辐射滞后1小时左右。2.对于河西走廊干旱区中部,冬季土壤湿度变化对降水的响应要滞后1—2个月；地表反照率随土壤湿度的增大是减小的,两者的相关系数达到了0.7346；土壤冬季向大气输出热量而夏季转变为大气向土壤输入热量,且输入的热量要大于输出；随季节变化土壤热通量的日最大值冬季出现最晚,夏季最早。3.对于黄土高原半干旱区榆中,10cm土壤湿度最大,5—10cm以及20—40cm土壤深度范围内有逆湿存在；地表反照率与随壤湿度的增大而减小,而随降雪量的增大而增大；潜热通量秋季是冬季的6倍左右；土壤温度日波形向下传播速度约为1.5h-3h／10cm；净辐射日积分值仅占总辐射的33%,而土壤热通量还不到净辐射的1%。典型晴天时地表反照率上午大于下午；有降雨发生时地表反照率日变化比较平缓,且数值偏低；降雪天气状况下地表反照率日变化明显增大,并且波动较大。4.黄土高原半干旱区定西的土壤温度日波形向下传播速度约为2.5h—3.5h／10cm；地表反照率与土壤湿度相关系数为0.5348,而与降雪量的相关系数为0.6307；年平均日变化中地表和大气对太阳辐射加热大约需要1个小时的响应时间；潜热通量夏季是冬季的5倍多,感热通量有了两个比较明显的峰值,潜热通量、感热通量和土壤热通量的日峰值比净辐射滞后30min一1h.5.干旱区各层土壤温度年变化均比半干旱区剧烈；半干旱区土壤湿度在整体上要比干旱区大很多；全年地表反照率是敦煌最大,定西次之,张掖最小；除净辐射以外,敦煌的各辐射通量年变幅均最明显,半干旱区的相对较小；半干旱区的净辐射年变幅要比干旱区的大,定西要超出敦煌将近50%；由Bowen比可以看出定西地区比榆中偏旱。定西地区地表反照率的日变化波动不如榆中的明显；榆中地区的净辐射的日积分在总辐射中所占比例相对最大,定西地区比榆中的小16.8%左右,张掖的最小；定西地区几乎全天Bowen比均小于1。更多还原

【Abstract】 By utilizing the integrated data of land-surface processes observed in Dunhuang arid region in northwest China from Sep.2000 to Aug.2001, observed the middle of arid region in Hexi Corridor in Zhangye from Nov.2005 to Oct.2006, observed Dingxi Synthetical Experimental Observatory of Land Surface Process in the Semi-arid Region in the Loess Plateau from Nov.2004 to Oct.2005, in and observed at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) from Nov.2008 to Oct.2009, the annual and daily variation characteristics and the mechanism of influence of soil temperature, soil moisture, precipitation, surface albedo, surface radiation components and energy balance components in each climate region are systematically analyzed. As well as, the relationship between surface albedo and soil moisture, also and precipitation are researched. Then the characteristics of land surface process in the four different climate regions are compared and contrasted. The following conclusions are obtained.1. In Dunhuang the extreme arid region in northwest China, the annual range of ground surface temperature exceeds 42℃. The annual range of surface albedo is quite large. The net radiation in summer is four times more than in winter. The daily variation of upward and downward long-wave radiation lag about 1 hour hours to the net radiation.2. In the arid region in Hexi Corridor, the response of soil moisture to the precipitation in winter delays 1 or 2 months. Surface albedo increases with the soil moisture decreasing, and their correlation coefficient reaches 0.7346. The soil heat flux is exported from soil to the air in winter while imported from air to the soil in summer. The import is lager than export. The diurnal maximum of soil heat moisture is the latest in winter and earliest in summer.3. In Yuzhong the semi-arid region in the Loess Plateau, the 10cm soil moisture is the biggest. There is a moisture inversion layer between 5 and 10 cm below the ground, as well as between 20 and 40cm. The surface albedo decreases with soil moisture increasing, while increasing with snow precipitation increasing. The latent heat flux in autumn is about 6 times as large as in winter. The downward transfer velocity of soil temperature daily waveform is about 1.5h-3h/10cm. The daily integral of net radiation is only 33%of global radiation, and the soil heat flux do not reach 1%of net radiation. The surface albedo in the morning is bigger than in the afternoon in the typical sunny day. The surface albedo varies gently when it rains, and its value is small. The surface albedo increases significantly when it snows, and the fluctuation is big.4. In Dingxi the semi-arid region in the Loess Plateau, the downward transfer velocity of soil temperature daily waveform is about 2.5h-3.5h/10cm. The correlation coefficient of surface albedo with soil moisture is 0.5338. While the correlation coefficient with snow precipitation is 0.6645. It takes 1 hour for solar radiation to heat the surface and atmosphere. Latent heat flux in summer is five times more than in winter. There are two obvious peak value of sensible heat flux. The daily peak values of latent heat flux, sensible heat flux, and soil heat flux lag 30 minutes-1 hour to the net radiation.5. The annual variation of soil temperature in the arid region is stronger than in the semi-arid region. On the whole, the soil moisture in semi-arid region is much greater than in arid region. The mean surface albedo of Dunhuang is the largest, and the smallest of Zhangye. The annual range of radiation components in Dunhuang is the most obvious, except the net radiation, and they are quite small in semi-arid regions. The annual range of net radiation in semi-arid region is lager than in arid region, and the one in Dingxi exceeds 50%more than in Dunhuang. It’s drier in Yuzhong than in Dingxi by the Bowen ratio. The daily fluctuation of surface albedo is less obvious in Dingxi than in Yuzhong. The daily integral of net radiation of global radiation in Yuzhong is smallest, while it’s 16.8%more than in Dingxi, and it’s smallest in Zhangye. The Bowen ratio is less than 1 all day in Dingxi.更多还原