Data for: Global Diurnal Sea Surface Temperature Variability and the Role of Ocean-Atmosphere Interactions

Diurnal variations in sea surface temperature (SST) influence the atmospheric boundary layer and the hydrological cycle. Using a decade of satellite data, we identify global patterns of diurnal SST variability, capturing both warming and cooling phases. We highlight diurnal cooling as a distinct and previously underrecognized phenomenon, accounting for over 38% of observed cases. By focusing on extreme cooling and warming events, defined as diurnal SST changes exceeding ± 3.16° C from the mean, we explore the spatial distribution, seasonality, and mechanisms driving transitions between three SST states: diurnal warming, a balanced state, and diurnal cooling. These states correspond to distinct upper-ocean mixing regimes: minimal, neutral, and strong, each shaped by atmospheric forcing, including wind stress, cloud cover, and precipitation. In the tropics and mid-latitudes, extreme warming events dominate, occurring primarily during the transition and summer seasons under calm winds, clear skies, and little to no rain. In contrast, high-latitude regions are characterized by frequent diurnal cooling during winter, with passing storms emerging as key modulators of SST variability. Storms that occur during the day typically trigger strong cooling, while those passing at night can occasionally result in warming. By integrating seasonal context and focusing on extreme events, this study provides new insights into the atmospheric drivers of diurnal SST variability, an important step in constructing and tuning models that capture diurnal layer dynamics. These findings have implications for understanding energy budgets, air–sea interactions, and feedbacks in the coupled climate system.

海表面温度（sea surface temperature, SST）的日变化会对大气边界层与水文循环产生显著影响。本研究依托十年卫星观测数据，识别出全球海表温度日变化变率的空间分布模式，同时涵盖了增暖与降温两个相位。研究重点揭示了日降温现象：这是一种独特且此前未被充分认知的现象，其占全部观测案例的比例超过38%。本研究聚焦于日SST变化量相较于平均值超出±3.16℃的极端增暖与极端降温事件，探究了三种SST状态间转换的空间分布、季节特征与驱动机制，这三种状态分别为日增暖态、平衡态与日降温态。上述三种状态对应不同的上层海洋混合模态：弱混合、中性混合与强混合，其形成均受包括风应力、云量与降水在内的大气强迫作用调控。在热带与中纬度区域，极端增暖事件占据主导，多发生于季节转换期与夏季，此时风速平缓、天空晴朗且几乎无降水。与之形成鲜明对比的是，高纬度地区冬季则频繁出现海表温度日降温现象，过境风暴被证实是调控SST变化的关键因子。日间发生的过境风暴通常会引发强烈的海温降温，而夜间过境的风暴则偶尔会导致海温增暖。本研究结合季节背景并聚焦极端事件，为海表温度日变化变率的大气驱动机制提供了全新认知，这是构建与调优能够刻画日层动力学的气候模型的重要一环。上述研究结果对于理解耦合气候系统中的能量收支、海气相互作用以及反馈机制具有重要意义。