A high-resolution (10 km × 10 km) multiscale ocean modeling system was developed for short-term (1 - 2 weeks) ocean state hindcasting/forecasting in the Bay of Bengal (BOB) region. This paper is Part I of a two-p...A high-resolution (10 km × 10 km) multiscale ocean modeling system was developed for short-term (1 - 2 weeks) ocean state hindcasting/forecasting in the Bay of Bengal (BOB) region. This paper is Part I of a two-part series of studies. The Regional Ocean Modeling System (ROMS) was implemented and initialized with Levitus 1/4° climatological fields for short-term forecasting. The results from these climatology-based model simulations for three representative months (February, June and October) in three different seasons (winter, summer and autumn) are discussed herein. This high-resolution model implementation simulates most of the observed dominant circulation features. The multiscale features during February include an anticyclonic basin-scalegyre with a strong western boundary current (WBC) in the western basin, the formation of several shallow mesoscale eddies in the head of the Bay and a cyclonic sub-basin-scale Myanmar Gyre in the northeast. During June, no well-defined boundary current is simulated along the Indian coast;instead, alternating cyclonic and anticyclonic eddies appear along the east coast with cross-basin eastward flow to support a deep cyclonic Andaman Gyre. In October, a basin-scale cyclonic gyre with a continuous well-defined East India Coastal Current (EICC), weak inflow from the Malacca Strait to the Andaman Sea and advection of BOB water into the Arabian Sea via the Palk Strait are simulated well by the model. A number of mesoscale eddies appear on the eastern half of the basin during October. Physical pattern of simulated eddies and transports across selected sections are validated against available drifter climatology, ARGO data and previous observations. Application of this system to synoptic short-term predictions for October 2008 will be presented in Part II.展开更多
A high-resolution (10 km × 10 km) multiscale ocean modeling system was developed for the Bay of Bengal (BOB) region for short-term ocean hindcasts/forecasts. A physical validation of this system that was based on...A high-resolution (10 km × 10 km) multiscale ocean modeling system was developed for the Bay of Bengal (BOB) region for short-term ocean hindcasts/forecasts. A physical validation of this system that was based on climatological initialization and short-term simulations was presented in Part I of this series of studies. Realistic structures for prevalent eddies, fronts and gyres were reasonably reproduced and validated for three individual months (February, June and October). In this study, we present an application and synoptic validation of the system for October 2008 in a hindcast mode. The system is based on the Regional Ocean Modeling System (ROMS), which assimilates satellite and in-situ measurements within the background climatology using an objective analysis to produce the synoptic initial condition for the model and/or to produce an estimation of the current ocean state. A meteorological forecast is then input into this synoptic three-dimensional ocean model to produce the ocean hindcast/forecast. The high-density Array for Real-time Geotropic Oceanography (ARGO) observations, and the Tropical Rain Measuring Mission (TRMM) satellite’s microwave imager (TMI) passes during the beginning of the month of October 2008, provided a unique opportunity for the system to assimilate these in-situ observations at initialization. Then, the ARGO and TMI observations during the later part of October 2008 were used for the statistical validation of the system’s fidelity. The validation shows that the hindcast/forecast system can reasonably predict the ocean currents, temperature and salinity. The forecast error increases as the forecast time window increases, although the system has a reasonable predictability for up to seven to ten days. The assimilation of both in-situ ARGO and satellite data at initialization produced better hindcasts/forecasts.展开更多
文摘A high-resolution (10 km × 10 km) multiscale ocean modeling system was developed for short-term (1 - 2 weeks) ocean state hindcasting/forecasting in the Bay of Bengal (BOB) region. This paper is Part I of a two-part series of studies. The Regional Ocean Modeling System (ROMS) was implemented and initialized with Levitus 1/4° climatological fields for short-term forecasting. The results from these climatology-based model simulations for three representative months (February, June and October) in three different seasons (winter, summer and autumn) are discussed herein. This high-resolution model implementation simulates most of the observed dominant circulation features. The multiscale features during February include an anticyclonic basin-scalegyre with a strong western boundary current (WBC) in the western basin, the formation of several shallow mesoscale eddies in the head of the Bay and a cyclonic sub-basin-scale Myanmar Gyre in the northeast. During June, no well-defined boundary current is simulated along the Indian coast;instead, alternating cyclonic and anticyclonic eddies appear along the east coast with cross-basin eastward flow to support a deep cyclonic Andaman Gyre. In October, a basin-scale cyclonic gyre with a continuous well-defined East India Coastal Current (EICC), weak inflow from the Malacca Strait to the Andaman Sea and advection of BOB water into the Arabian Sea via the Palk Strait are simulated well by the model. A number of mesoscale eddies appear on the eastern half of the basin during October. Physical pattern of simulated eddies and transports across selected sections are validated against available drifter climatology, ARGO data and previous observations. Application of this system to synoptic short-term predictions for October 2008 will be presented in Part II.
文摘A high-resolution (10 km × 10 km) multiscale ocean modeling system was developed for the Bay of Bengal (BOB) region for short-term ocean hindcasts/forecasts. A physical validation of this system that was based on climatological initialization and short-term simulations was presented in Part I of this series of studies. Realistic structures for prevalent eddies, fronts and gyres were reasonably reproduced and validated for three individual months (February, June and October). In this study, we present an application and synoptic validation of the system for October 2008 in a hindcast mode. The system is based on the Regional Ocean Modeling System (ROMS), which assimilates satellite and in-situ measurements within the background climatology using an objective analysis to produce the synoptic initial condition for the model and/or to produce an estimation of the current ocean state. A meteorological forecast is then input into this synoptic three-dimensional ocean model to produce the ocean hindcast/forecast. The high-density Array for Real-time Geotropic Oceanography (ARGO) observations, and the Tropical Rain Measuring Mission (TRMM) satellite’s microwave imager (TMI) passes during the beginning of the month of October 2008, provided a unique opportunity for the system to assimilate these in-situ observations at initialization. Then, the ARGO and TMI observations during the later part of October 2008 were used for the statistical validation of the system’s fidelity. The validation shows that the hindcast/forecast system can reasonably predict the ocean currents, temperature and salinity. The forecast error increases as the forecast time window increases, although the system has a reasonable predictability for up to seven to ten days. The assimilation of both in-situ ARGO and satellite data at initialization produced better hindcasts/forecasts.
