Russo Aniello, Maccaferri Simona, Djakovac Tamara, Precali Robert, Degobbis Danilo, Deserti Marco, Paschini Elio, Lyons Daniel M
Department of Marine Sciences, Polytechnic University of Marche, 60131 Ancona, Italy.
Sci Total Environ. 2005 Dec 15;353(1-3):24-38. doi: 10.1016/j.scitotenv.2005.09.058. Epub 2005 Nov 17.
Mucilage events (formation of very large organic aggregates and gelatinous surface layers) have been documented several times during the past two centuries in the northern Adriatic Sea (NA), while their frequency has significantly increased since 1988. In this work, meteorological and oceanographic conditions in the NA during the period June 1999-July 2002 are described and their relation to the outbreak and fate of the mucilage phenomenon was investigated. Salinity and temperature data were collected during approximately monthly cruises along three transects in the NA. Relevant meteorological situations (air temperature, rainfall, wind) were selected from large-scale ECMWF analyses and from the Local Analysis and Prediction System (LAPS; Emilia Romagna Meteorological Service), while sea conditions (waves) were analysed by means of the Wave Adriatic Model (WAM). Data for air temperature, rainfall, and wind from several meteorological stations in the region were used. Average seasonal cycles of sea temperature and salinity simulated with statistical models, based on historical data collected in the NA since 1972, were used to determine thermal and haline anomalies. The monthly anomaly variability of maximum and minimum air temperatures, rainfall amount and number of rainy days did not appear to be relevant for the mucilage phenomenon outbreak. In contrast, both vertical and horizontal thermohaline gradients in the region were more developed during late spring and summer of 2000 and particularly of 2002, when the mucilage events were of greatest extent in space and time, compared to 2001 (short-lived event) and 1999 (no event). These more pronounced gradients were due to a combination of several unusual conditions: sharp heating of the sea surface in May-June, domination of eastwards transport of freshened waters formed in the Po Delta area, and intrusion of very high salinity intermediate waters originating in the eastern Mediterranean. Moreover, in winter of both 2000 and 2002 very dense and cold water formed and remained in the bottom layer until spring, contributing to increase the stratification degree of the water column. The duration of the mucilage events and their spatial distribution in the region depend strongly on meteorological changes. Recurrent anticyclonic conditions, characterized by low wind and calm sea, favour extended events in time (up 2 months in 2002). In contrast, highly perturbed weather, particularly due to strong "bora" wind, can be determined in sharp decay of the event (e.g. in July 2000).
在过去两个世纪里，亚得里亚海北部（NA）已多次记录到黏液事件（形成非常大的有机聚集体和凝胶状表层），而自1988年以来其发生频率显著增加。在这项工作中，描述了1999年6月至2002年7月期间NA的气象和海洋学状况，并研究了它们与黏液现象的爆发及演变的关系。沿着NA的三条断面大约每月进行一次巡航，收集盐度和温度数据。从欧洲中期天气预报中心（ECMWF）的大规模分析以及本地分析与预测系统（LAPS；艾米利亚 - 罗马涅气象服务局）中选取相关气象情况（气温、降雨量、风速），同时借助亚得里亚海浪模型（WAM）分析海况（海浪）。使用了该地区几个气象站的气温、降雨量和风速数据。基于自1972年以来在NA收集的历史数据，用统计模型模拟的海温与盐度的平均季节周期，用于确定热异常和盐度异常。最高和最低气温、降雨量以及降雨天数的月异常变化似乎与黏液现象的爆发无关。相比之下，与2001年（短暂事件）和1999年（无事件）相比，在2000年尤其是2002年的春末和夏季，该地区的垂直和水平热盐梯度更为明显，当时黏液事件在空间和时间上的影响范围最大。这些更显著的梯度是由几种异常情况共同作用造成的：5月至6月海面急剧升温、波河三角洲地区形成的淡水向东输送占主导地位以及源自东地中海的高盐度中层水入侵。此外，在2000年和2002年的冬季都形成了非常密集且寒冷的水体，并一直留在底层直至春季，这导致水柱分层程度增加。黏液事件的持续时间及其在该地区的空间分布在很大程度上取决于气象变化。以低风速和平静海面为特征的反复出现的反气旋状况有利于事件在时间上的持续（2002年长达2个月）。相反，高度扰动的天气，特别是由于强烈的“布拉风”，会导致事件急剧衰减（例如在2000年7月）。
