Abstract:The Yellow Sea, as a typical semi-enclosed shelf shallow sea, is subject to the combined influence of monsoon climates and complex sea-land interactions.Its western coastal zone, characterized by complex multi-scale weather processes and significant socio-economic importance, necessitates focused analysis to improve meteorological prediction and support regional resilience. This study focuses on three basic marine meteorological elements of the Western Coastal Yellow Sea, including air temperature (AT), sea-level pressure (SLP), and sea surface temperature (SST). Based on 5 buoy stations and contemporaneous ERA5 data covering the period from March 2023 to February 2024, we analyze the multi-scale variation characteristics and response mechanisms of the three elements, conduct a comparative analysis between the in-situ data and ERA5 data, and evaluate the applicability of ERA5 data in the shallow waters of the western Yellow Sea. The analysis results indicate that 1) There is a significant interdependence among the three variables: AT and SST show a strong positive correlation (r≈0.9), while AT inversely correlates with SLP (r≈-0.8), and SST demonstrates a moderate negative relationship with atmospheric pressure (r≈-0.55); 2) Both AT and SST exhibit unimodal diurnal variations, and they reach the peak in summer- autumn, decrease in winter-spring. However, SST shows smaller diurnal and seasonal thermal amplitudes than AT, and the valley values of SST also lag behind that of AT by 1 hour in diurnal minima and 1 month in seasonal minima. In contrast, SLP exhibits double-peak and double-valley diurnal variations, and it reaches the peak in autumn and winter, decreases in spring and summer; 3）The sea-air temperature gradient (SST-AT) exhibits a regular diurnal cycle, expanding at night and peaking at 06:00, then shrinking during the day and reaching a trough at 16:00. On an annual scale, SST exceeds AT from August to February of the following year, accounting for approximately 58%; 4) In terms of responses to typical weather processes, key elements exhibited distinct response patterns: During the sea fog event in June, warm-moist advection over a cold sea surface drove the SST-AT to -3.31 ℃, forming the thermodynamic conditions for advective cooling fog; Under the influence of the Jiang-Huai cyclone in August, the elements responded in a clear sequence: AT > SLP > SST, while the recovery periods are similar between AT and SLP but longer for SST; Throughout the cold wave event in November, AT showed a “cliff-like” decrease of 14.95 ℃ within 40 hours, while SST decreased by only 2.41 ℃, highlighting the ocean''s significant thermal inertia. 5) Compared to in situ observations, ERA5 fails to resolve SST diurnal variability, exhibits systematic biases (-0.19 ℃ AT, -0.26 hPa SLP , -0.14 ℃ SST). This study is based on data from March 2023 to February 2024, which has certain limitations in temporal coverage. Future work will focus on analyzing longer-term time-series data to enhance statistical robustness. Besides, we will further quantify the threshold of SST-AT for sea fog/low cloud formation, to provide more representative insights into Yellow Sea air-sea interaction mechanisms and their climatic implications.