| 基于组网观测的那曲土壤湿度不同时间尺度的变化特征 |
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| 引用本文： | 李博,张淼,唐世浩,董立新.基于组网观测的那曲土壤湿度不同时间尺度的变化特征[J].气象学报,2018,76(6):1040-1052. |
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| 作者姓名： | 李博 张淼 唐世浩 董立新 |
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| 作者单位： | 1.国家卫星气象中心, 北京, 100081 |
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| 基金项目： | 第三次青藏高原大气科学试验——边界层与对流层观测（GYHY201406001）、国家重点研发计划项目（2016YFA0600101）、国家自然科学基金项目（41605028）。 |
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| 摘 要： | 利用第三次青藏高原大气科学试验的土壤湿度观测数据，分析了那曲多空间尺度组网观测的28个站2、5、10、20和30 cm 5个不同深度土壤湿度的季节变化和日变化特征，并对比讨论了土壤湿度站点间的差异。分析表明，各层土壤湿度均存在显著的季节变化。冬春季节，20 cm以上土壤湿度随深度变浅而减小。夏秋季节土壤湿度随深度增加而减小，并分别在7月上、中旬和9月出现两个峰值。10月以后进入土壤湿度衰减期。土壤温度和土壤湿度存在协同变化关系。在一定的温度范围内，土壤发生冻结-融化过程，引起土壤湿度变化。在太阳辐射加热下，土壤表层水分蒸发，进而影响土壤温度。不同观测站间土壤湿度差异较大，夏秋季离散性大于冬春季。不同季节土壤湿度的日变化存在差异。春季10 cm以上土壤湿度日变化明显，08-10时（北京时）达到最低，19-20时达到最高。夏季土壤湿度日变化较为平缓。秋季2 cm深度土壤湿度日变化明显。线性拟合结果表明，1、4、10月土壤湿度和土壤温度为正相关关系。但是在夏季，土壤湿度与土壤温度为负相关。站点间土壤湿度变化的离散性表明，多测站才能全面体现青藏高原某区域的陆面状态。文中结果为青藏高原地区土壤湿度卫星参数验证和数值模式参数化提供了多角度的观测依据。
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| 关 键 词： | 土壤湿度 土壤温度 季节变化 冻融 日变化 |
| 收稿时间： | 2018/3/8 0:00:00 |
| 修稿时间： | 2018/9/20 0:00:00 |
Variations of soil moisture over Nagqu at different time scales based on network observations |
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| LI Bo,ZHANG Miao,TANG Shihao and DONG Lixin.Variations of soil moisture over Nagqu at different time scales based on network observations[J].Acta Meteorologica Sinica,2018,76(6):1040-1052. |
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| Authors: | LI Bo ZHANG Miao TANG Shihao and DONG Lixin |
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| Institution: | 1.National Satellite Meteorological Center, Beijing 100081, China2.Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites, China Meteorological Administration, Beijing 100081, China |
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| Abstract: | Based on the soil observations under the support of the Third Tibetan Plateau project, the seasonal and diurnal variations of soil moisture measured at 2, 5, 10, 20 and 30 cm depths at 28 stations in Nagqu are analyzed. The results show that in the winter and spring, the soil moisture decreased from 20 cm depth upward; in the summer and autumn, the soil moisture decreased with the increase of depth. Two peaks of soil moisture occurred in early-to-mid-July and from early September to early October, respectively, followed by a decreasing period. Soil temperature and soil moisture changes were closely related to each other. Freezing-thawing process occurred within a certain range of soil temperature, causing changes in soil moisture. Soil temperature was affected by soil surface evaporation. The discreteness of soil moisture observed at different stations was larger in the summer and autumn than in the spring and winter. The diurnal variation of soil moisture above 10 cm depth in the spring was obvious, and the minimum and maximum values appeared at 08:00 to 10:00 and 19:00 to 20:00 BT, respectively. The diurnal variation of soil moisture was relatively weak in the summer and became obvious at 2 cm depth in the autumn. The linear fit results show that soil moisture and soil temperature were positively correlated in January, April and October, and negatively correlated in July. The soil moisture discreteness among the sites indicates that observations from only a few observational sites cannot reflect the comprehensive status of land surface in the Tibetan Plateau. The current study provides a basis for the validation of satellite observations and numerical model parameterizations of soil moisture in the Tibetan Plateau. |
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| Keywords: | Soil moisture Soil temperature Seasonal variation Freeze thawing Diurnal variation |
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