Trends in atmospheric evaporative demand in Great Britain using high-resolution meteorological data
Trends in atmospheric evaporative demand in Great Britain using high-resolution meteorological data
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DOI：
10.5194/hess-21-1189-2017
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发表时间：
2017-02
影响因子：
6.3
通讯作者：
E. Robinson;E. Blyth;D. Clark;J. Finch;A. Rudd
中科院分区：
文献类型：
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作者：
E. Robinson;E. Blyth;D. Clark;J. Finch;A. Rudd
气候观测的空间尺度往往与受气候变化影响的自然环境和资源观测的空间尺度大不相同。为了利用建模帮助弥合这些尺度之间的差距，通过内插较粗分辨率的气候数据并包括当地地形的影响，创建了1961-2012年英国1公里分辨率的每日气象变量新数据集。这些变量被用来计算在相同的空间和时间分辨率的大气蒸发需求（AED）。选择了两个代表AED的函数：一个是潜在蒸散量（PET）的标准形式，另一个是水文学家使用的派生PET测量，包括冠层截留的水的影响（PETI）。计算了这些函数的时间趋势，发现PET在所有地区都在增加，在英国的总速率为0.021 ± 0.021 mm/天-1/10-1。在英国，PETI以0.019 ± 0.020 mm/天-10-1的速率增加，但这在统计学上并不显著。然而，英格兰的PETI有0.023 ± 0.023毫米/天-1/10-1的趋势。发现趋势随季节而变化，英国春季PET增加0.043 ± 0.019 mm day−1 decade−1（包括拦截校正时为0.038 ± 0.018 mm day− 1 decade−1），而其他季节没有统计学显著趋势。这些趋势在分析上归因于气候变量的趋势;总的积极趋势主要是由气温上升驱动的，尽管比湿度上升对趋势产生了负面影响。根据相对湿度重新分析显示，总体效果是相对湿度下降导致PET升高。增加向下的短波和长波辐射对PET趋势做出了总体积极的贡献，而风速降低对PET趋势做出了负面贡献。由于春季相对湿度的大幅下降和向下短波辐射的增加，春季PET的趋势尤其强劲。
Observations of climate are often available on very different spatial scales from observations of the natural environments and resources that are affected by climate change. In order to help bridge the gap between these scales using modelling, a new dataset of daily meteorological variables was created at 1 km resolution over Great Britain for the years 1961–2012, by interpolating coarser resolution climate data and including the effects of local topography. These variables were used to calculate atmospheric evaporative demand (AED) at the same spatial and temporal resolution. Two functions that represent AED were chosen: one is a standard form of potential evapotranspiration (PET) and the other is a derived PET measure used by hydrologists that includes the effect of water intercepted by the canopy (PETI). Temporal trends in these functions were calculated, with PET found to be increasing in all regions, and at an overall rate of 0.021 ± 0.021 mm day−1 decade−1 in Great Britain. PETI was found to be increasing at a rate of 0.019 ± 0.020 mm day−1 decade−1 in Great Britain, but this was not statistically significant. However, there was a trend in PETI in England of 0.023 ± 0.023 mm day−1 decade−1. The trends were found to vary by season, with spring PET increasing by 0.043 ± 0.019 mm day−1 decade−1 (0.038 ± 0.018 mm day−1 decade−1 when the interception correction is included) in Great Britain, while there is no statistically significant trend in other seasons. The trends were attributed analytically to trends in the climate variables; the overall positive trend was predominantly driven by rising air temperature, although rising specific humidity had a negative effect on the trend. Recasting the analysis in terms of relative humidity revealed that the overall effect is that falling relative humidity causes the PET to rise. Increasing downward short- and longwave radiation made an overall positive contribution to the PET trend, while decreasing wind speed made a negative contribution to the trend in PET. The trend in spring PET was particularly strong due to a strong decrease in relative humidity and increase in downward shortwave radiation in the spring.