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土壤湿度是生态系统的关键参数,实时、有效地监测土壤湿度有助于增强对区域气候与环境变化的理解。利用温度植被干旱指数法(TVDI)反演羌塘高原2000-2014年夏季土壤湿度,以2014年为例分析该年夏季土壤湿度空间分布并探讨2000-2014年土壤湿度的动态特征。结果表明:(1)2014年羌塘高原夏季土壤湿度空间分布表现为东南部偏湿润、西北部偏干旱。从东到西土壤湿度逐渐降低,南北干湿状况交替分布。土壤湿度干旱、偏干、正常、偏湿、湿润面积比分别为3.84%、27.17%、37.64%、29.63%、1.72%。(2)2000-2014年羌塘高原北部和中部地区夏季土壤湿度呈现显著变干的趋势,而南部大部分地区土壤湿度变化趋势不显著。15年间土壤干旱和湿润面积比例最小且波动小,偏干、正常、偏湿土壤面积均出现不同程度的波动。(3)降水量是影响TVDI的重要因子且具有一定的滞后性,而气温影响相对较小。
Soil moisture is a key parameter of the ecosystem. Monitoring soil moisture in real time and effectively helps to improve understanding of regional climate and environmental changes. The soil moisture of summer 2000-2014 in the Qiangtang Plateau was retrieved by TVDI. The spatial distribution of soil moisture in summer of this year was analyzed with 2014 as an example to study the dynamic characteristics of soil moisture from 2000 to 2014. The results showed as follows: (1) In summer, the spatial distribution of summer soil moisture in the Qiangtang Plateau in 2014 showed a partial humidification in the southeast and a partial drought in the northwest. From the east to the west, the soil humidity gradually decreased and the north-south wet-dry conditions were alternately distributed. Soil moisture was dry, dry, normal, wet, wet area ratio was 3.84%, 27.17%, 37.64%, 29.63%, 1.72%. (2) In the northern and middle Qiangtang Plateau, the soil moisture in summer showed a trend of significant drying in 2000-2014, while the trend of soil moisture in most of southern China was not significant. In the 15 years, the proportion of soil arid and wet area was the smallest and the fluctuation was small, dry, normal and wet soil area fluctuated in varying degrees. (3) Precipitation is an important factor affecting TVDI and has a certain degree of lag, while the impact of temperature is relatively small.