Abstract:

Semi-Lagrangian particle tracking is conducted to examine the ability of surface drifters to reproduce Eulerian velocity structure functions in the northern Gulf of Mexico for a generic winter (January, February, March) and summer (July, August, September). Near-surface drifters are tracked by the Lagrangian TRANSport model (LTRANS) with a 30-minute averaged Eulerian velocity field produced by Regional Ocean Modeling System (ROMS) at 0.5 km resolution in summer and winter, and 0.5 km resolution in winter only. Forcing for the models used a set of climatological datasets. The atmospheric forcing is climatological, with a QuikSCAT-based daily product of scatterometer wind stresses (Risien and Chelton 2008), Common Ocean Reference Experiment (CORE; Large and Yeager 2009) monthly heat-flux atmospheric forcing, and Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data (HOAPS; Andersson et al. 2010) monthly freshwater atmospheric forcing. No tidal forcing is used, and a daily river forcing is applied based on daily river volume flux data from the USGS for the year 2010. This dataset supports the publication: Pearson, J., Fox-Kemper, B., Barkan, R., Choi, J., Bracco, A., & McWilliams, J. C. (2019). Impacts of Convergence on Structure Functions from Surface Drifters in the Gulf of Mexico. Journal of Physical Oceanography, 49(3), 675–690. doi:10.1175/jpo-d-18-0029.1.

Suggested Citation:

Choi, Jun and Annalisa Bracco. 2020. Clustered and gridded particle trajectories from the surface velocity field of a Regional Oceanic Modeling System (ROMS) simulation of the northern Gulf of Mexico for a generic winter and summer. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-rfyb-k993

Publications:

Pearson, J., Fox-Kemper, B., Barkan, R., Choi, J., Bracco, A., & McWilliams, J. C. (2019). Impacts of Convergence on Structure Functions from Surface Drifters in the Gulf of Mexico. Journal of Physical Oceanography, 49(3), 675–690. doi:10.1175/jpo-d-18-0029.1

Purpose:

To characterize the impact of using surface drifters to estimate Eulerian statistics in the northern Gulf of Mexico based on season, launch location, and deployment pattern.

Data Parameters and Units:

Variables: Particle Number (integer), Longitude (degrees), Latitude (degrees). The filenames: *_*_*.txt corresponds to Type_Grid_Season.txt * Particle#: Particle index * Type R indicate particles in a regular grid. * Type C indicate particles in a clover shape. It consists of 2 clovers. * Type S indicates particles in S-shape. It consists of 2 S-shapes. * Grid: ROMS grid resolutions of both 500m and 150m. * Season: Summer and Winter indicate Jul 20 - Sep 20 and Jan 20 - March 20 respectively. * Time interval is one hour for all cases.

Methods:

Two types of deployments are considered: gridded and clustered. For the 150m resolution winter runs, only two sets of clustered drifters were released, centered within the model domain following the S-shape of the Grand LAgrangian Experiment (GLAD) of 2012 and clover shape of the LAgrangian Submesoscale ExpeRiment (LASER) of 2016 for a total of four deployments. These clusters include 90 and 300 particles, respectively. For the 500m resolution winter and summer runs, both types of deployments were conducted. The gridded release includes 28,870 particles with an initial separation distance of 0.02 degree on a regular grid. In addition, drifter clusters were released to mimic GLAD and LASER not just in terms of release pattern, but also release location and season, for a total of eight deployments. One of each S and clover shape cluster was deployed at the centered locations of (88.13˚ W, 28.8˚N) and (87.68˚ W, 29.05˚N) corresponding to the GLAD S1 and LASER P1 deployments respectively for each season. Type R particles were deployed at (-91.9 ˚W, 28.2 ˚N) Note that S1 and P1 are the only two launches mimicked from the campaigns, and all trajectories for both resolutions are sampled hourly for analysis.

Provenance and Historical References:

Andersson, A., K. Fennig, C. Klepp, S. Bakan, H. Graßl, and J. Schulz, 2010: The Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data–HOAPS-3. Earth Syst. Sci. Data, 2, 215–234, https://doi.org/10.5194/essd-2-215-2010. Large, W., and S. Yeager, 2009: The global climatology of an interannually varying air–sea flux data set. Climate Dyn., 33, 341–364, https://doi.org/10.1007/s00382-008-0441-3. Risien, C. M., and D. B. Chelton, 2008: A global climatology of surface wind and wind stress fields from eight years of QuikSCAT scatterometer data. J. Phys. Oceanogr., 38, 2379–2413, https://doi.org/10.1175/2008JPO3881.1.

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