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首页> 外文期刊>Agricultural and Forest Meteorology >Spatio-temporal patterns of evapotranspiration based on upscaling eddy covariance measurements in the dryland of the North China Plain
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Spatio-temporal patterns of evapotranspiration based on upscaling eddy covariance measurements in the dryland of the North China Plain

机译：基于北方平原旱地升高的涡流协方差测量的蒸发时空模式

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摘要

Accurate evapotranspiration (ET) estimation is important for understanding hydrological cycle and water resources management in the cropland. Based on eight flux sites within the North China Plain (NCP) and the surrounding area, which were integrated together for the first time, we applied support vector regression method to develop ET dataset for the cropland in NCP from 1982 to 2015 with 1/12 degrees spatial resolution and eight-day temporal interval. The mean annual ET over cropland within NCP was 575 mm yr(-1) with a non-significant increasing trend. In wheat season, the seasonal ET increased significantly at the rate of 1.28 mm yr(-2) with a mean value of 238 mm yr(-1); in maize season, the mean value of seasonal ET was 221 mm yr(-1) with a decreasing trend of -0.95 mm yr(-2). The comparatively high mean annual ET values occurred primarily in the well irrigated area near the Taihang Mountains, irrigation districts along the Yellow River and the humid region. The attribution analysis which combined multiple regression with the first difference method revealed that human activities dominated ET trend at annual scale as well as in wheat season, with relative contributions of 52% and 56%, respectively. While in maize season, ET trend was mostly controlled by climate change with relative contribution of 77%. Among the climate factors, in wheat season, the significantly increasing air temperature was the principal climatic cause of ET increase which was partly offset by the significantly decreasing wind speed; while in maize season, the significant ET decline was primarily resulted from the significantly decreasing net radiation and wind speed. Compared with our ET dataset, the four widely used global or national ET datasets significantly underestimated ET in wheat season, especially in the extensively irrigated areas, suggesting that local observations are crucial for regional studies.
机译：准确的蒸散（ET）估算对于了解农田的水文循环和水资源管理是重要的。基于华北平原（NCP）和周边地区的八个助焊站点，我们首次集成在一起，我们申请了支持向量回归方法，从1982年到2015年为NCP的农田为2015年开发ET数据集程度空间分辨率和八日的时间间隔。 NCP内的平均年度ET在NCP内为575毫米（-1），具有非显着提高趋势。在小麦季节，季节性ET以1.28mm YR（-2）的速率显着增加，平均值为238mm YR（-1）;在玉米季节中，季节性ET的平均值为221毫米（-1），趋势降低-0.95mm YR（-2）。相对高的平均年度ET值主要发生在太行山附近的灌溉区域，沿着黄河灌区和潮湿地区。与第一差异方法组合多元回归的归因分析显示，人类活动以年度规模以及小麦季节为主，分别为52％和56％。在玉米季节，ET趋势主要受气候变化控制，相对贡献为77％。在小麦季节的气候因素中，空气温度显着增加是ET增加的主要气候原因，这部分抵消了风速显着降低;在玉米季节，重要的ET下降主要是由于净辐射和风速显着降低。与我们的ET数据集相比，这四个广泛使用的全球或国家ET数据集明显低估了小麦季节，特别是在广泛的灌溉区域，表明当地观察对于区域性研究至关重要。

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