Uncertainties in atmospheric surface pressure fields from global analyses
Uncertainties in atmospheric surface pressure fields from global analyses
复制标题
全球分析中大气表面压力场的不确定性
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
K. Cady
中科院分区：
文献类型：
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作者：
D. Salstein;R. Ponte;K. Cady
[1]美国国家环境预报中心（NCEP）和欧洲中期天气预报中心（ECMWF）的业务分析提供了大气表面压力等数据。这一领域对于Jason-1和GRACE（重力恢复和气候实验）等高度计和重力卫星任务的数据处理和解释特别有用。然而，定量地使用这种压力场需要知道它的不确定性。为了评估这些不确定性，我们将NCEP和ECMWF对地表压力的分析与2001-2005年期间陆地和海洋的大量地面气压观测结果进行了比较，并相互比较。每种分析与观测之间的差异非常相似，这表明两种分析一般都能很好地拟合台站观测。这种差异，包括偏差和偏差方差，在南大洋部分地区、亚洲、中非和南极洲最大。在研究期间，NCEP和ECMWF地面压力场的偏差和方差差异变化不大。不过，更重要的是，这种差异比以前在较早时期（1993-1995年）的研究发现的差异要小得多，这表明最近两种分析都有所改进。最大的差异出现在高纬度地区，特别是南极洲，以及各自的冬季半球。大部分差异发生在快速的时间尺度上，尽管有很大一部分时间尺度长于1-2个月。讨论了这些不确定性对高度计和GRACE任务的去混叠和解释海平面和重力数据的潜在影响。
[1] Operational analyses from the U.S. National Centers for Environmental Prediction (NCEP) and the European Centre for Medium-Range Weather Forecasts (ECMWF) provide, among other quantities, atmospheric surface pressure. This field is especially useful for data processing and interpretation of altimeter and gravity satellite missions like Jason-1 and GRACE (Gravity Recovery and Climate Experiment). Quantitative use of this pressure field, however, requires knowledge of its uncertainties. To assess these uncertainties, we compare NCEP and ECMWF analyses of surface pressure to an extensive set of surface barometric observations for the period 2001–2005, both land- and ocean-based, as well as to each other. Differences between each analysis and the observations are quite similar, indicating that both analyses generally fit the station observations equally well. Such differences, including both bias and variance about the bias, are largest over parts of the Southern Ocean, and over Asia, central Africa, and Antarctica. These bias and variance differences between the NCEP and ECMWF surface pressure fields change only slightly over the period of study. More importantly, though, such differences are substantially smaller than those found by previous studies for an earlier period (1993–1995), suggesting recent improvements in both analyses. The largest differences are found over high latitudes, particularly over Antarctica, and in the respective winter hemisphere. Much of the differences occur on rapid timescales, though with a significant portion at timescales longer than 1–2 months. The potential impact of such uncertainties on de-aliasing and interpreting sea level and gravity data from altimeter and GRACE missions is discussed.