2015年7月珠江口逆温现象的观测与分析

根据珠江口2015年7月6日至17日航次的CTD（conductivity， temperature， and depth）观测结果，分析得到：珠江口附近海域存在海水的垂向逆温现象，逆温差平均值为0.42 oC，上界深度在1 m-6 m间，下界深度在3 m-10 m间，逆温层平均厚度约为4 m。根据时空分布差异的不同，逆温现象可区分为以下三种情况：（1）在狮子洋、太平水道和蕉门水道的出口汇集处，存在温、盐差异的不同水体的交互过程中，由于潮汐和径流的作用所形成的水平流场差异导致了垂向温度的逆转现象。（2）在珠江口西侧的盐度锋面区域附近，第一航段观测期间锋面内侧低盐水团的温度低于锋面外侧高盐水团约2 oC，此时可观测到逆温现象；但在同一区域的第二航段观测期间由于河口内表层水温的上升，导致了逆温现象消失。该区域盐度锋面附近的两个水团在锋面位置附近发生叠置，冲淡水覆盖于海水之上，两个水团的温、盐差异是温度逆转现象的主因。（3）香港西南侧的上升流区域与盐度锋面的相互作用导致了该区域逆温现象的产生。

Analysis of temperature inversion in the Zhujiang River Estuary in July 2015

This study investigates the temperature inversion phenomenon in the Zhujiang (Pearl) River Estuary (ZRE) using hydrological data collected in a summer cruise during July 6-17, 2015. The results suggest that temperature inversion occurred primarily near the salinity front, with an average temperature difference (ΔT) of 0.42℃ between the inversion layer and the underlying water. The inversion layer was approximately 4 m thick on average, with an upper boundary at a depth of 1-6 m and a lower boundary at a depth of 3-10 m. Different mechanisms and dynamic processes were responsible for temperature inversion in different parts of the study area. (1) At the salinity front in the west of the ZRE, the measurements collected by CTD (conductivity, temperature, and depth) showed that the low-salinity water mass on the inner side of the front was approximately 2℃ cooler than the high-salinity water mass on the outer side. Temperature inversion occurred when the cooler low-salinity water overlapped the warmer high-salinity water near the front due to the driving force of the background flow. (2) Inversion layers occurred at the mouth of the Taiping waterway as a result of varying horizontal flow between two different water masses under the effects of tides and runoff. (3) To the southwest of Hong Kong, temperature inversion occurred due to the interaction of upwelling and the salinity front.