He Ruoying, McGillicuddy Dennis J, Keafer Bruce A, Anderson Donald M
Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University.
Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution.
J Geophys Res. 2008 Jul;113(C7). doi: 10.1029/2007JC004602. Epub 2008 Jul 26.
A coupled physical/biological modeling system was used to hindcast the 2005 bloom in the Gulf of Maine and investigate the relative importance of factors governing the bloom's initiation and development. The coupled system consists of a state-of-the-art, free-surface primitive equation Regional Ocean Modeling System (ROMS) tailored for the Gulf of Maine (GOM) using a multi-nested configuration, and a population dynamics model for The system was forced by realistic momentum and buoyancy fluxes, tides, river runoff, observed benthic cyst abundance, and climatological nutrient fields. Extensive comparisons were made between simulated (both physical and biological) fields and in-situ observations, revealing that the hindcast model is capable of reproducing the temporal evolution and spatial distribution of the 2005 bloom. Sensitivity experiments were then performed to distinguish the roles of three major factors hypothesized to contribute to the bloom: 1) the high abundance of cysts in western GOM sediments; 2) strong northeaster storms with prevailing downwelling-favorable winds; and 3) a large amount of fresh water input due to abundant rainfall and heavy snowmelt. Results suggested that the high abundance of cysts in western GOM was the primary factor of the 2005 bloom. Wind forcing was an important regulator, as episodic bursts of northeast winds caused onshore advection of offshore populations. These downwelling favorable winds accelerated the alongshore flow, resulting in transport of high cell concentrations into Massachusetts Bay. A large regional bloom would still have happened, however, even with normal or typical winds for that period. Anomalously high river runoff in 2005 resulted in stronger buoyant plumes/currents, which facilitated the transport of cell population to the western GOM. While affecting nearshore cell abundance in Massachusetts Bay, the buoyant plumes were confined near to the coast, and had limited impact on the gulf-wide bloom distribution.
一个物理/生物耦合建模系统被用于对2005年缅因湾的水华进行后报，并研究控制水华起始和发展的因素的相对重要性。该耦合系统由一个为缅因湾（GOM）量身定制的、采用多重嵌套配置的先进自由表面原始方程区域海洋建模系统（ROMS）和一个种群动力学模型组成。该系统由现实的动量和浮力通量、潮汐、河流径流、观测到的底栖孢囊丰度以及气候学营养场驱动。对模拟（物理和生物）场与现场观测进行了广泛比较，结果表明后报模型能够再现2005年水华的时间演变和空间分布。然后进行了敏感性实验，以区分假设对水华有贡献的三个主要因素的作用：1）缅因湾西部沉积物中孢囊的高丰度；2）伴有盛行的有利于下沉流的东北风暴；3）由于大量降雨和严重融雪导致的大量淡水输入。结果表明，缅因湾西部孢囊的高丰度是2005年水华的主要因素。风的强迫作用是一个重要的调节因素，因为东北风的间歇性爆发导致近海种群向岸平流。这些有利于下沉流的风加速了沿岸流，导致高细胞浓度的水体输送到马萨诸塞湾。然而，即使那段时期的风正常或典型，大范围的区域性水华仍然会发生。2005年异常高的河流径流导致更强的浮力羽流/水流，这促进了细胞种群向缅因湾西部的输送。虽然浮力羽流影响了马萨诸塞湾近岸的细胞丰度，但它们局限于海岸附近，对整个海湾的水华分布影响有限。
