National Centers for Environmental Prediction (NCEP) Regional Ocean Forecast System (ROFS) model output from 1997-08 (NODC Accession 0001524)

The Regional Ocean Forecast System (ROFS) has been developed jointly by the Ocean Modeling Branch of the National Weather Service's Environmental Modeling Center, the National Ocean Service's Coast Survey Development Lab, Princeton University, and Naval Oceanographic Office (NAVOCEANO). ROFS is based on a hydrodynamic, three-dimensional ocean circulation model (Princeton Ocean Model) which simulates temperature, salinity, surface elevation, and currents for a region off the U.S. East Coast from ~30 to 47N and out to 50W. The model is driven at the ocean surface boundary by heat, moisture, and momentum fluxes provided by NCEP's Eta mesoscale atmospheric forecast model. The ocean model is driven along its open (that is, southern and eastern) boundaries by climatological estimates of temperature, salinity, and transport. The spatial resolution of the model varies from approximately 20km offshore to about 10km nearshore. The coastal boundary corresponds to the location of the 10m isobath. In the vertical, an 18-layer sigma (terrain-following) coordinate system is used with at least half the layers concentrated in the upper 100m. Tidal forcing is included in the model.

At 24-hour intervals, Gulf Stream north-wall-location data and satellite altimeter data are assimilated with an OI-based algorithm from Princeton University. Gulf Stream location data are provided by NAVOCEANO and sea surface height anomalies (SSHAs) derived from satellite altimeter data are provided by the NOAA Laboratory for Satellite Altimetry. These data are input for correction of the model's sea surface height field and assimilation into the subsurface temperature and salinity fields using correlation functions statistically derived from the model itself. Gulf Stream location data for the current day and TOPEX data from the prior 10-day orbital cycle, are used in this analysis step, which provides the input fields for the second analysis step.

Sea surface temperature (SST) data from in-situ and satellite observing platforms are assimilated into the updated fields from the first data assimilation step, in a nowcast/data assimilation cycle producing initial conditions for the 48-h forecast. In-situ observations are from fixed and drifting buoys, C-MAN stations, and ships. Remotely sensed observations are MCSST retrievals from the AVHRR sensor onboard the NOAA polar orbiting satellites. Surface atmospheric forcing is obtained from 3-hourly analyses of the NCEP's Eta Data Assimilation System (EDAS).

The forecast cycle generates regional ocean forecasts out to 48 hours. Surface forcing is obtained from the 3-hourly surface fields from NCEP's Eta mesoscale atmospheric prediction model. [This abstract was obtained from the ROFS website at http://polar.wwb.noaa.gov/cofs/Description.html#OM on June 23, 2004.]

区域海洋预报系统（Regional Ocean Forecast System, ROFS）由美国国家气象局环境模拟中心海洋建模分部、美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration, NOAA）国家海洋服务局海岸勘测开发实验室、普林斯顿大学以及海军海洋学办公室（Naval Oceanographic Office, NAVOCEANO）联合开发。ROFS基于水动力三维海洋环流模型——普林斯顿海洋模型（Princeton Ocean Model）构建，可模拟美国东海岸外，北纬30°至47°、从近岸延伸至西经50°的海域的海水温度、盐度、海面高度及海流。该模型的海面边界强迫由美国国家环境预报中心（National Centers for Environmental Prediction, NCEP）的埃塔中尺度大气预报模型提供的热量、水汽与动量通量实现；其开放边界（即南部与东部边界）则通过温度、盐度和输运的气候态估算值进行强迫。模型空间分辨率从远海的约20千米向近岸逐步提升至约10千米，海岸边界对应10米等深线的位置。垂直方向采用18层σ（地形追随）坐标系，其中至少半数层级集中在表层100米范围内，且模型纳入了潮汐强迫项。

每24小时，普林斯顿大学将基于最优插值（Optimal Interpolation, OI）算法，对墨西哥湾流北壁位置数据与卫星高度计数据开展同化工作。其中，墨西哥湾流位置数据由NAVOCEANO提供，由卫星高度计数据反演得到的海面高度异常（Sea Surface Height Anomalies, SSHAs）则由NOAA卫星测高实验室提供。上述数据用于修正模型的海面高度场，并通过基于模型自身统计推导得到的相关函数，将观测数据同化至次表层温度与盐度场中。本次分析步骤使用当日的墨西哥湾流位置数据，以及前10个轨道周期的TOPEX数据，其输出场将作为第二次分析步骤的输入场。

通过现场观测与卫星观测平台获取的海表温度（Sea Surface Temperature, SST）数据，将被同化至第一次数据同化步骤得到的更新场中。该短时预报与数据同化循环会为48小时预报生成初始条件。其中，现场观测数据来自固定浮标、漂流浮标、C-MAN站以及船舶；遥感观测数据为NOAA极轨卫星搭载的先进甚高分辨率辐射计（Advanced Very High Resolution Radiometer, AVHRR）传感器反演得到的多通道海表温度（Multi-Channel Sea Surface Temperature, MCSST）产品。海面大气强迫数据取自NCEP埃塔数据同化系统（Eta Data Assimilation System, EDAS）的3小时间隔分析场。

该预报周期可生成时长达48小时的区域海洋预报产品，海面强迫数据取自NCEP埃塔中尺度大气预报模型的3小时间隔海面场。[本摘要于2004年6月23日取自ROFS官方网站http://polar.wwb.noaa.gov/cofs/Description.html#OM]