基于多套再分析资料的全球蒸发量时空变化特征及其成因研究

发布时间：2017-12-31 07:44

本文关键词：基于多套再分析资料的全球蒸发量时空变化特征及其成因研究　出处：《兰州大学》2016年博士论文　论文类型：学位论文

【摘要】：蒸发是全球能量和水循环的关键环节,也是决定各地区天气与气候状况的重要因子。蒸发作为地球系统水分消耗的主要方式,对气候变化的响应十分敏感,是地球系统中最活跃的因子之一。但是由于缺少蒸发量的实况观测数据,并且气候模式对水循环的模拟水平也非常有限,目前对于全球蒸发量时空变化的趋势、幅度和区域分布等依然不能给出明确结论。再分析资料的不断发展为解决上述问题提供了新的途径。本论文基于目前使用较为广泛的多套再分析资料,研究了全球蒸发量的时空变化特征和成因,同时对比分析了各套资料的异同点,探讨了各套资料在不同时段、不同地区的适用性。主要结论概括如下:(1)全球蒸发量的空间分布具有明显的海陆、经向分布差异,并且同纬度陆地上高海拔地区蒸发量小于低海拔地区。整体而言,MERRA与NCEP-R2资料能够同时较好地反映出全球蒸发量的时空变化特征,具有很好的代表性;此外,CFSR与ERA-40资料也可以较好地刻画出陆地蒸发量的变化特点,而ERA-Interim、NCEP-R1、OAFlux、HOAPS等资料比较适用于对海洋蒸发量的研究。各套资料陆地与海洋平均蒸发量在1958~1978年基本都呈现显著的线性减少趋势,而在1979~2011年时间段内大多是线性增加的,其中海洋地区更加显著。(2)中国地区实际蒸散发整体上呈现自东南沿海向西北内陆地区递减的形势,只是五套再分析资料在西北至青藏高原西北部和东南沿海等地区差别较大。实际蒸散发的逐年变化也不完全相同,其中NCEP-R2与JRA-55比较一致,均有显著地线性增加趋势,MERRA与ERA-Interim更为接近,而NCEP-R1偏差较大。年内实际蒸散发约有43%集中在夏季,季节变化明显。中国不同地区实际蒸散发和蒸发皿蒸发的关系有明显差异,互补理论多适用于非湿润地区,而正比假设理论多适用于偏湿润地区,即在水分控制条件下存在互补关系,在能量控制条件下存在正比关系。(3)1979~2013年全球陆地实际蒸散发的变化具有非常明显的区域性特征,其中在气候较为湿润的地区实际蒸散发有明显的线性增加趋势,而在相对干旱的地区实际蒸散发的增加趋势则主要集中在21世纪。极端干旱区、干旱区、半干旱区、半湿润干旱区和半干旱湿润区等实际蒸散发的变化主要与降水量有关,而半湿润区、湿润区和极寒区实际蒸散发的增加是气候变暖背景下降水量与潜在蒸散发变化共同作用的结果,只是潜在蒸散发的作用要相对更大。从能量和水分循环的角度,NCEP-R2与Budyko模型估算结果最为一致,可信度最高,MERRA次之,ERA-Interim和JRA-55误差相对较大,尤其是在极端湿润区不确定性较高。(4)1979~2001年热带海洋蒸发量呈现显著地线性增加趋势,其中以1991~1998年增加幅度最大,之后则基本保持稳定,近几年有逐渐下降的趋势。根据1979~2013年六套再分析资料热带海洋蒸发量MV-EOF分解结果,第一模态主要与气候变化有关,而第二模态、第三模态和第四模态都与ENSO循环紧密相关。从海表温度(SST)异常的角度研究热带海洋蒸发量变化的成因大致有两种途径,其一是当SST异常偏高时,海平面气压(SLP)会异常偏低,这将有利于水汽的辐合,进而增加当地大气水汽含量,对蒸发过程有抑制作用;另外一种途径是SST异常偏高会直接造成当地地表气温(SAT)偏高,进而促使大气持水能力增强,有利于蒸发量增加。
[Abstract]:Evaporation is the key link in the global energy and water cycle, an important factor is decided on the weather and climate conditions in different regions. The main way of evaporation of the earth system of water consumption, in response to climate change is very sensitive, is one of the most active factor in the earth system. But due to the lack of observation data of evaporation, and climate model simulation of the horizontal water cycle is also very limited, the current trend for evaporation of temporal and spatial changes of global and regional distribution range, still can not give a clear conclusion. The continuous development of reanalysis data provides a new way to solve the above problems. This paper is widely used at present several sets of reanalysis data based on research the temporal and spatial variation characteristics and causes of global evaporation, and comparative analysis of the data sets of the similarities and differences, discusses the set of data in different time, suitable for different regions . the main results are as follows: (1) global evaporation are found in the spatial distribution of land and sea, meridional distribution differences, and the same amount of evaporation in high altitude area on land is less than that of the low altitude latitude. Overall, the MERRA and NCEP-R2 data can reflect the spatial and temporal variation characteristics of global evaporation, representative very good; in addition, the CFSR and ERA-40 data can depict the changes of evaporation and land ERA-Interim, NCEP-R1, OAFlux, HOAPS and other materials is suitable for the research of ocean evaporation. Each set of data of land and sea average evaporation in 1958~1978 years showed significant linear decreasing trend. However, in 1979~2011 years time mostly increase linearly, while the ocean area is more significant. (2) Chinese area showing the overall actual evapotranspiration decreases from the southeast coast to the northwest inland region shape Potential, only five sets of reanalysis data differences in the northwest to the northwest of the Tibetan Plateau and southeast coastal areas. Actual evaporation changes year by year distributed is not exactly the same, where NCEP-R2 and JRA-55 are consistent, increased significantly with MERRA linear, ERA-Interim is more close to that of NCEP-R1 years on the actual large deviations. The evapotranspiration of about 43% concentrated in the summer, seasonal changes. The relationship between different regions Chinese actual evapotranspiration and pan evaporation are significantly different, complementary theory is suitable for the non humid regions, and is more applicable to the hypothesis of partial wet area, that there is a complementary relationship in the water control condition, there is positive relation the energy control conditions. (3) the Global Land Evapotranspiration changes 1979~2013 has very obvious regional characteristics, the climate is more humid regions in actual evapotranspiration has obvious line Of increasing trend, while in the relatively arid regions of actual evapotranspiration increased is mainly concentrated in the arid region in twenty-first Century. In extreme arid area, semi-arid area, arid area, changes of semi humid and semi humid areas such as drought of actual evapotranspiration is mainly related to precipitation, and semi humid, wet and very cold the actual evapotranspiration increased climate warming decreased water interaction and potential evaporation changes from the results, only the potential evapotranspiration effect is relatively greater. From the angle of the energy and water cycle, NCEP-R2 and Budyko model estimation results most, the credibility of the highest, followed by MERRA, ERA-Interim and JRA-55, the error is relatively large in particular, the uncertainty in the extreme high humid area. (4) 1979~2001 in the tropical ocean evaporation showed a significant linear increase trend, the largest increase in 1991~1998, then the stable, There is a gradual downward trend in recent years. According to 1979~2013 six year reanalysis data of tropical ocean evaporation MV-EOF decomposition results, the first mode is mainly related to climate change, while the second mode, third mode and the fourth mode are closely related with ENSO. From the sea surface temperature (SST) causes abnormal changes of the tropical ocean evaporation there are basically two ways, one is when the SST is abnormally high, the sea level pressure (SLP) will be extremely low, which facilitates vapor convergence, thus increasing the water vapor content in the atmosphere is inhibited by the local evaporation process; the other way is abnormally high SST will be the direct result of local surface high temperature (SAT), so as to enhance the water holding capacity of the atmosphere, conducive to increased evaporation.

【学位授予单位】：兰州大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P426.2

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