Abstract:

The 49 simulations forming the ensemble have been performed using the HYbrid Coordinate Ocean Model (HYCOM's web page can be found at http://www.hycom.org). The ensemble members differ in their initial conditions, which are perturbed to specifically isolate the uncertain signature of a cyclonic frontal eddy along the northern edge of the Loop Current. The Loop Current is the dominant dynamical feature in the Gulf of Mexico, and frontal eddies are known to affect the Loop Current pathway, and to play a role in the shedding of anticyclonic Loop Current Eddies. The data uploaded contain the daily model state for each member and cover the period May 1 to June 30, 2010.

Suggested Citation:

Matthieu Le Hénaff. 2017. Ensemble of HYCOM simulations of the Gulf of Mexico to study uncertainties stemming from uncertain initial conditions using the Polynomial Chaos approach. Distributed by: Gulf of Mexico Research Initiative Information and Data Cooperative (GRIIDC), Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N77H1GNF

Publications:

Iskandarani, M., Le Hénaff, M., Thacker, W. C., Srinivasan, A., & Knio, O. M. (2016). Quantifying uncertainty in Gulf of Mexico forecasts stemming from uncertain initial conditions. Journal of Geophysical Research: Oceans, 121(7), 4819–4832. doi:10.1002/2015jc011573

Wang, S., Li, G., Iskandarani, M., Le Hénaff, M., & Knio, O. M. (2018). Verifying and assessing the performance of the perturbation strategy in polynomial chaos ensemble forecasts of the circulation in the Gulf of Mexico. Ocean Modelling, 131, 59–70. doi:10.1016/j.ocemod.2018.09.002

Purpose:

The ensemble of HYCOM simulations of the Gulf of Mexico was generated to quantify uncertainties stemming from uncertain initial conditions using the Polynomial Chaos approach.

Data Parameters and Units:

The configuration of HYCOM adopted here is similar to the experiment 20.1 used operationally by the US Navy for ocean prediction during the period 2003–2010 (see https://hycom.org/data/goml0pt04/expt-20pt1 for more details). The model has a 1/25° (~4 km) horizontal resolution and 20 vertical levels. The computational domain is open along portions of its southern, eastern and northern boundaries, where values are provided by a lower-resolution (1/12◦ vs. 1/25◦) simulation of HYCOM configured for the Atlantic Ocean. The model is forced at the surface by three hourly outputs from the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMP), which has a 27-km resolution. For the present study, model simulations are run for 2 months, from May 1 to June 29, 2010. Each model output is the daily averaged, centered at 12 noon, of the date corresponding to the file name (e.g. archm.2010_121_12.cdf is the file corresponding to the 121st day of the year 2010). Each file includes the coordinates of the grid in terms of latitude, longitude, as well as the following 2D and 3D variables: - 2D variables: Montgomery potential (non-dimensional), sea surface height (meter), zonal and meridional barotropic currents (m/s). - 3D variables: temperature (deg C), salinity (psu), zonal and meridional currents (m/s), layer thickness (meter). The HYCOM model uses a hybrid vertical grid, with some layers being isopycnal and defined by their potential density referenced to the surface. However, the model outputs only provide layer thicknesses (in meter). The depth of a layer can be estimated by summing the layer thicknesses from the surface down to the corresponding layer. The files are in NetCDF format.

Individual Files: