冷空氣影響期間海水水溫和溶解氧特征分析及預報

何彩芬+金靚+徐彬+倪永森+何成芳

摘要 研究旨在建立冷空氣影響期間海水水溫和溶解氧的預報方程，以期為海水養殖戶做好防災減災氣象服務。通過分析近5年寧波西滬港0.5、2.5 m深海水水溫、溶解氧在11月至翌年3月的日逐時平均變化特征以及較強冷空氣影響期間的變化特征，采用數理統計方法建立相應的預報方程。結果表明，溶解氧、水溫的日均變化與氣溫的變化具有較好的相似性，前兩者的變化幅度較氣溫平緩，日極值出現時間較氣溫平均滯后1～3 h。較強冷空氣影響期間，水溫的降溫時間和最低值出現時間較氣溫有1～3 d的滯后性，其降幅與相對濕度、冷空氣強度和過程極大風速有關，而最低值滯后時間與相對濕度和冷空氣強度有關。水溫與氣溫、相對濕度成正相關，與極大風速成負相關。伴有低溫陰雨的冷空氣過程易導致2.5 m溶解氧的下降，其降幅與同期氣溫的降幅、水汽壓的增幅及前期氣壓的降幅有關。溶解氧與氣溫及本站氣壓成線性相關，與水汽壓呈二次多項式相關。建立0.5、2.5 m深平均、最低水溫預報方程以及2.5 m深平均、最低溶解氧濃度的預報方程，方程均通過α=0.01的顯著性檢驗。0.5、2.5 m水溫預報最大誤差在1 ℃以內，平均誤差在0.3 ℃以內。2.5 m的平均、最低溶解氧最大誤差分別為0.40、0.97 mg/kg，平均誤差分別為0.10、0.25 mg/kg。

關鍵詞 冷空氣；海水養殖；水溫；溶解氧；特征分析；預報方程

中圖分類號 P731 文獻標識碼 A 文章編號 1007-5739（2017）22-0144-05

Abstract The aim of this study was to establish the forecast equation of sea-water temperature and dissolved oxygen during the cold air affecting period，so as to provide better meteorological services of disaster prevention and reduction for the mariculture households. The diurnal variation characteristics of the 0.5 m-depth and 2.5 m-depth sea water temperature，and dissolved oxygen in Xihu Port of Ningbo City from November to next March in recent 5 years，as well as that during the cold air affecting periods were analyzed. By using mathematical statistics methods，the corresponding forecast equations were established. The results showed that the diurnal variation of dissolved oxygen and water temperature were similar to the change of air temperature. The variation ranges of the former two indexes were gentler than that of air temperature. The time of diurnal extremums of dissolved oxygen and water temperature lagged by 1-3 h on average，compared with that of air temperature. During the cold air affecting periods，the time of the water temperature decline and the minimum value lagged by 1-3 days，compared with that of air temperature，while the decline degree was related to the relative humidity，cold air intensity and the maximum wind speed.The lag time of minimum value appearing was related to the relative humidity and cold air intensity.Water temperature was positively correlated with air temperature and relative humidity，and negatively correlated with maximum wind speed.Cold air process accompanied by low temperature and rain was easy to cause the decrease of 2.5 m dissolved oxygen，and its decline was correlated to the temperature decline and the vapor pressure increase in the same time period，as well as the decline of atmospheric pressure in the early stage.Dissolved oxygen was linearly correlated with air temperature and local air pressure，and had quadratic polynomial relationship with water vapor pressure. On the basis of correlation analysis and stepwise regression analysis，the forecast equations of the 0.5 m/2.5 m mean water temperature and the minimum water temperature，as well as the 2.5 m mean dissolved oxygen concentration and the minimum dissolved oxygen concentration were established，which passed the test of significance by α=0.01. The maximum error of 0.5 m/2.5 m water temperature prediction was less than 1 ℃，and the average error was less than 0.3 ℃.The maximum error of the 2.5 m average and minimum dissolved oxygen was 0.40 mg/kg and 0.97 mg/kg respectively，and the average error was 0.10 mg/kg and 0.25 mg/kg respectively.endprint

Key words cold air；mariculture；water temperature；dissolved oxygen；characteristic analysis；forecast equation

寧波市位于我國海岸線中段，擁有漫長的海岸線，其間港灣曲折，島嶼星羅棋布。……