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首页> 外文会议>International Space Science Institute workshop on the Earth's cryosphere and sea level change >Precipitation Changes in High Southern Latitudes from Global Reanalyses: A Cautionary Tale
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Precipitation Changes in High Southern Latitudes from Global Reanalyses: A Cautionary Tale

机译：来自全球Reanalyses的高南部纬度的降水变化：一个警示的故事

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The temporal consistency of the moisture fields (precipitation, evaporation and total precipitable water) from five global reanalyses is examined over Antarctica and the Southern Ocean during 1989-2009. This concern is important given that (1) global reanalyses are known to be prone to inhomogeneities and artificial trends caused by changes in the observing system, and (2) the period of study has seen a dramatic increase in the volume of satellite observations available for data assimilation. In particular, the study aims to determine whether the recent reanalyses are suitable for investigating changes in Antarctic surface mass balance. The datasets investigated consist of NCEP-2, JRA-25, ERA-Interim, MERRA and CFSR. Strong evidence of spurious changes is found in NCEP-2, JRA-25, MERRA and CFSR, although the magnitude, spatial patterns and timing of these artifacts vary between the reanalyses. MERRA exhibits a jump in Antarctic precipitation-minus-evaporation (P-E) and in Southern Ocean precipitation in the late 1990s. This jump is related to the introduction of sounding radiances from the Advanced Microwave Sounding Unit (AMSU). The impact of AMSU is also discernible, albeit less pronounced, in CFSR data. It is shown that ERA-Interim likely provides the most realistic depiction of the interannual variability and overall change in Antarctic P-E since 1989. We conclude that the presence of spurious changes is not a solved problem in recent global reanalyses. Caution should continue to be exercised when using these datasets for trend analyses in general, particularly in high southern latitudes.
机译：在1989 - 2009年期间，在南极和南海洋中检查了来自五个全球性Reanalyses的水分田（沉淀，蒸发和总沉淀水）的时间一致性。鉴于（1）已知全球性Reanalyses易患被观察系统的变化造成的全球性排序和人工趋势，并且（2）研究的卫星观察量的急剧增加数据同化。特别是，该研究旨在确定最近的Reanalyses是否适合于研究南极表面质量平衡的变化。调查的数据集由NCEP-2，JRA-25，ERA临时，Merra和CFSR组成。在NCEP-2，JRA-25，Merra和CFSR中发现了杂散变化的强大证据，尽管这些伪影的幅度，空间模式和时序在Reanalyses之间变化。 Merra在20世纪90年代后期展示了南极沉淀 - 减去蒸发（P-E）和南海降水。这次跳跃与从先进的微波探测单元（AMSU）引入探测辐射。在CFSR数据中，AMSU对AMSU的影响也是明显的，尽管较少。结果表明，自1989年以来，ERA-Anstim可能提供了南极P-E的年间变异性和整体变化的最逼真的描述。我们得出结论，虚假变化的存在不是最近的全球性Reanalyses的解决问题。在使用这些数据集通常在趋势分析中，应继续行使谨慎，特别是在高南部纬度。

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