| 摘要: |
| 蒸散发是陆面水循环的关键环节，在高寒、干旱生态环境中表现更加复杂。由于青海湖地区蒸发皿实测值存在数值偏大、长期观测器皿不统一的问题，本文采用Penman-Monteith (P-M)模型研究了青海湖地区天峻、刚察气象站潜在蒸散发的时空变化特征及影响因子。结果表明：（1）1967—2010年青海湖地区潜在蒸散发呈下降趋势，天峻站的平均下降速率为0.807 mm∙a−1，刚察站为0.499 mm∙a−1。（2）青海湖地区存在“蒸发悖论”现象，潜在蒸散发的主要影响因子存在地域差异：天峻为风速主导；刚察则由气温和风速共同主导。（3）与蒸发皿实测值的潜在机理相比，P-M模型更强调水汽输送条件的影响作用；在能量供给条件上，P-M模型与气温关系更密切，而蒸发皿实测值与日照百分率相关性更高。 |
| 关键词: Penman-Monteith模型 潜在蒸散发 因子分析 青海湖地区 |
| DOI：10.7515/JEE222058 |
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| 基金项目:国家自然科学基金项目（42071124）；黄土与第四纪地质国家重点实验室开放基金（SKLLQG1809）；中央高校基础科研基金（XZY012019008） |
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| Analysis of potential evapotranspiration trends and its factors in Qinghai Lake area |
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TIAN Lu, GUO Wei, NI Xiangnan, LI Xiaoting
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School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an 710049, China
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| Abstract: |
| Background, aim, and scope Evapotranspiration plays a critical role in regulating feedback within the climate system and holds significant potential for vegetation dynamics, water conservation, and soil conservation, particularly in arid regions. The Qinghai Lake area, situated in the northeast of the Qinghai-Tibet Plateau, exemplifies a cold and semi-arid climate, making it an ideal context to explore the impacts of evapotranspiration. Furthermore, understanding the hydrologic balance is of utmost importance for scientific research in this region. However, since around 2004, the reliability of evaporation pan records in the area has been compromised owing to the introduction of a new measuring instrument, rendering these inconsistent measurements unsuitable for conducting long-term analyses. Materials and methods As an alternative, potential evapotranspiration, which is calculated based on climatic factors using specific models, has been employed to study the evapotranspiration mechanism. In line with this approach, the present study utilized the Penman-Monteith (P-M) model to examine the temporal characteristics of potential evapotranspiration at the Tianjun and Gangcha stations within the Qinghai Lake area from 1967 to 2010. This study quantified its responses to climatic factors and compared the underlying mechanisms of variation with data obtained from the evaporation pan. Results The potential evapotranspiration in the Qinghai Lake area exhibited a decreasing trend, with Tianjun station decreasing at a rate of 0.807 mm·a−1 and Gangcha station decreasing at a rate of 0.499 mm·a−1 from 1967 to 2010. Notably, Tianjun station experienced a sudden change in 1981, whereas Gangcha station had two mutation points in 1983 and 1986, with the 1983 mutation being more pronounced. Additionally, the monthly evapotranspiration at Tianjun station surpassed that at Gangcha station, primarily due to higher net radiation from May to Sep. and higher wind speed and vapor pressure deficit throughout the rest of the year. Discussion It was found that the potential evapotranspiration at the Tianjun station was mainly influenced by water vapour transport, as evidenced by the higher standardised coefficients for wind speed and actual water vapour pressure than the other climatic factors, and that the sunshine and radiation in the Tianjun area were strong enough to provide sufficient heat supply for evaporative transport conditions. In contrast, the standardised coefficients for the temperature factor, representing energy supply conditions, and the wind speed factor, representing water vapour transport conditions, are both much higher than the other factors for the Gangcha station, indicating that the potential evapotranspiration at Gangcha station is regulated by a combination of energy supply and water vapour transport conditions. Conclusions The potential evapotranspiration in the Qinghai Lake area exhibited a downward trend from 1967 to 2010, with variations characterized by significant fluctuations before 1981 and more gradual changes thereafter. The main influencing factors of potential evapotranspiration differed between the two stations, with wind speed playing a leading role at Tianjun station, while temperature and wind speed were equally important at Gangcha station. Furthermore, compared to the underlying mechanisms observed in the evaporation pan data, the P-M model emphasized the influence of water vapor transport on evapotranspiration and showed a stronger association with air temperature as an energy supply, whereas values from the evaporation pan were more closely related to the sunshine percentage. Recommendations and perspectives This study provides valuable insights into the factors determining evapotranspiration and highlights the differential impacts of measurement methods and models. |
| Key words: Penman-Monteith model potential evapotranspiration factor analysis Qinghai Lake area |
