Search for evidence of trend slow-down in the long-term TOMS/SBUV total ozone data record: the importance of instrument drift uncertainty
Search for evidence of trend slow-down in the long-term TOMS/SBUV total ozone data record: the importance of instrument drift uncertainty
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DOI：
10.5194/acp-6-4057-2006
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发表时间：
2006-09
影响因子：
6.3
通讯作者：
R. Stolarski;S. Frith
中科院分区：
文献类型：
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作者：
R. Stolarski;S. Frith
我们开发了一个合并臭氧数据集（MOD），从1978年10月到2006年6月，结合了TOMS （Nimbus 7，地球探测器）和SBUV/SBUV2 （Nimbus 7, NOAA 9/11/16）系列卫星仪器的总臭氧测量（版本8检索）。我们使用MOD数据集来寻找臭氧恢复的证据，以响应观测到的平流层中氯和溴化合物的稳定。任何时间序列分析的关键步骤是不确定性的评估。除了标准统计时间序列不确定性外，我们还评估了MOD数据集可能的仪器漂移不确定性。我们将这两种不确定性来源结合起来，并将它们应用于趋势放缓的累积残差和（CUSUM）分析。对于60°S和60°N之间的极外平均值，如果忽略仪器的不确定性，则发现趋势的明显放缓明显显著。当加上仪器的不确定度时，在2σ水平上，减速变得略微显著。北半球中纬度地区（30°~ 60°N）的趋势减缓在2σ水平上非常显著，而南半球的趋势减缓尚未达到2σ显著性标准。氯/溴化合物的变化率在两个半球是相似的，我们预计臭氧的响应在两个半球也是相似的。半球间趋势减缓的不对称性很可能反映了动力变率的影响，因此，尚未表明臭氧总量对平流层中氯和溴的趋于稳定的明显统计显著响应。
We have developed a merged ozone data set (MOD) for the period October 1978 through June 2006 combining total ozone measurements (Version 8 retrieval) from the TOMS (Nimbus 7, Earth Probe) and SBUV/SBUV2 (Nimbus 7, NOAA 9/11/16) series of satellite instruments. We use the MOD data set to search for evidence of ozone recovery in response to the observed leveling off of chlorine and bromine compounds in the stratosphere. A crucial step in any time series analysis is the evaluation of uncertainties. In addition to the standard statistical time series uncertainties, we evaluate the possible instrument drift uncertainty for the MOD data set. We combine these two sources of uncertainty and apply them to a cumulative sum of residuals (CUSUM) analysis for trend slow-down. For the extra-polar mean between 60° S and 60° N, the apparent slow-down in trend is found to be clearly significant if instrument uncertainties are ignored. When instrument uncertainties are added, the slow-down becomes marginally significant at the 2σ level. For the mid-latitudes of the northern hemisphere (30° to 60° N) the trend slow-down is highly significant at the 2σ level, while in the southern hemisphere the trend slow-down has yet to meet the 2σ significance criterion. The rate of change of chlorine/bromine compounds is similar in both hemispheres, and we expect the ozone response to be similar in both hemispheres as well. The asymmetry in the trend slow-down between hemispheres likely reflects the influence of dynamical variability, and thus a clearly statistically significant response of total ozone to the leveling off of chlorine and bromine in the stratosphere is not yet indicated.