Drifting buoy sea‐surface temperature (SST) records have been used to characterize the diurnal variability of ocean temperature at a depth of order 20 cm. We use measurements covering the period 1986–2012 from the International Comprehensive Ocean‐Atmosphere Data Set (ICOADS) version 2.5, which is a collection of marine surface observations that includes individual SST records from drifting buoys. Appropriately transformed, this dataset is well suited for estimation of the diurnal cycle, since many drifting buoys have high temporal coverage (many reports per day), and are globally distributed. For each drifter for each day, we compute the local‐time daily SST variation relative to the local‐time daily mean SST. Climatological estimates of subdaily SST variability are found by averaging across various strata of the data: in 10° latitudinal bands as well as globally; and stratified with respect to season, wind speed and cloud cover. A parameterization of the diurnal variability is fitted as a function of the variables used to stratify the data, and the coefficients for this fit are also provided with the data. Results are consistent with expectations based on the previous work: the diurnal temperature cycle peaks in early afternoon (circa 2 pm local time); there is an increase in amplitude and a decrease in seasonality towards the equator. Generally, the ocean at this depth cools on windy days and warms on calm days, so that a component of subdaily variability is the SST tendency on slower timescales. By not ‘closing’ the diurnal cycle when stratified by environmental conditions, this dataset differs from previously published diurnal‐cycle parameterizations. This thorough characterization of the SST diurnal cycle will assist in interpreting SST observations made at different local times of day for climatological purposes, and in testing and constraining models of the diurnal‐cycle and air‐sea interaction at high temporal resolution.

中文翻译：

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从浮标数据看海表温度的气候日变化

漂流浮标的海表温度（SST）记录已用于表征20 cm深度的海洋温度的日变化。我们使用国际综合海洋大气数据集（ICOADS）2.5版涵盖1986-2012年的测量数据，该数据集是海洋表面观测的集合，其中包括来自浮标的单个SST记录。经过适当转换后，此数据集非常适合于估算昼夜周期，因为许多漂流浮标的时间覆盖率很高（每天有很多报告），并且分布在全球各地。对于每天的每个流浪者，我们都计算相对于本地每日平均SST的本地每日SST的变化。次日SST变异性的气候学估计值是通过对各个数据层进行平均得出的：在10°纬度带以及全球范围内；并根据季节，风速和云层进行了分层。日变化的参数化根据用于对数据进行分层的变量进行拟合，并且该拟合的系数也随数据一起提供。结果与先前的工作预期相符：昼夜温度周期在下午初（当地时间下午2点左右）达到峰值；赤道的振幅增加，季节性的减少。通常，此深度处的海洋在大风天变冷，而在平静天变暖，因此，次日变化的一个组成部分是在较慢的时间尺度上的海温趋势。通过在环境条件分层时不“关闭”昼夜周期，此数据集与先前发布的昼夜周期参数设置不同。