Toward Estimating Climatic Trends in SST. Part III: Systematic Biases
Toward Estimating Climatic Trends in SST. Part III: Systematic Biases
复制标题
估算海表温度的气候趋势。
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
A. Kaplan
中科院分区：
文献类型：
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作者：
Elizabeth C. Kent;A. Kaplan
提出了一种量化两种海表温度（SST）观测的系统误差的方法：桶和发动机进气测量。提出了一个简单的线性模型，其中使用桶测量的海温被空气-海洋温差的一小部分冷却或加热，而使用发动机进气测量的海温具有恒定的偏差。该模式适用于在中等风速下进行的夜间观测，允许忽略太阳辐射和上层海洋强烈垂直梯度的影响。由于所使用的所有变量都存在较大的随机误差，分析变得复杂。为了估计该模型中的系数，引入了一种新型的线性回归，其中两个变量的误差彼此相关。由于误差协方差矩阵的先验估计存在不确定性，因此对回归问题进行了贝叶斯分析，得到了模型参数后验分布的最大似然逼近。结果表明，海气温差引起的桶状海表温度变化是可以检测到的。分析表明，桶状海表温度的误差可能在海气温差的0.12°0.02°到0.16°0.02°C之间。当考虑到桶式SST的温度变化时，发现20世纪70年代中后期和80年代发动机进气SST的热偏差比以前的研究结果要小，范围在0.09°0.06°和0.18°0.05°C之间。对于20世纪90年代早期，该模型表明发动机进气SSTs可能具有0.13°0.07°C的冷偏置。
A method is developed to quantify systematic errors in two types of sea surface temperature (SST) observations: bucket and engine-intake measurements. A simple linear model is proposed where the SST measured using a bucket is cooled or warmed by a fraction of the air–sea temperature difference and the SST measured using an engine intake has a constant bias. The model is applied to collocated nighttime observations made at moderate wind speeds, allowing the effects of solar radiation and strong vertical gradients in the upper ocean to be neglected. The analysis is complicated by large random errors in all of the variables used. To estimate coefficients in this model, a novel type of linear regression, where errors in two variables are correlated with each other, is introduced. Because of the uncertainty in a priori estimates of the error covariance matrix, a Bayesian analysis of the regression problem is developed, and maximum likelihood approximations to the posterior distributions of the model parameters are obtained. Results show that the temperature change in bucket SST resulting from the air–sea temperature difference can be detected. The analysis suggests that bucket SST may be in error by a fraction from 0.12° 0.02° to 0.16° 0.02°C of the air–sea temperature difference. When this temperature change of the bucket SST is accounted for, a warm bias in engine-intake SST in the mid- to late 1970s and the 1980s was found to be smaller than that suggested by previous studies, ranging between 0.09° 0.06° and 0.18° 0.05°C. For the early 1990s the model suggests that the engine-intake SSTs may have a cold bias of 0.13° 0.07°C.