The Gulf of Mexico is an economically and ecologically productive region that is particularly vulnerable to human impact due to oil drilling and intense fishing. It is a regionally and globally important body of water that connects to the Gulf Stream system via the Florida Current, and features a diverse collection of aquatic habitats. Long term climate variability within the region can impact Gulf Stream strength and oceanic heat transport, as well as the economic activity and ecological stability of the entire Northwest Atlantic. The Gulf of Mexico Regional Climatology Version 2 includes new high-resolution temperature and salinity decadal climatologies that allow researchers to more precisely assess decadal climate change in the Gulf, substantially increasing the value of the GOM RC for ocean climate studies and other applications. This climatology also includes updated data and figures for other oceanographic variables such as oxygen and nutrients.
The current version of the GOM RC was released in October, 2020 to reflect all the data from the World Ocean Database 2018 and to add higher-resolution climatologies of temperature and salinity.
Seidov, D., A.V. Mishonov, T.P. Boyer, O.K. Baranova, E. Nyadjro, S.L. Cross, A.R. Parsons, and K.W. Weathers (2020), Gulf of Mexico Regional Climatology, Regional Climatology Team, NOAA/NCEI, doi: 10.25921/4sxe-ay54
Note: If oxygen and/or nutrients were used, please also cite the corresponding Volumes 3 and/or 4 of the World Ocean Atlas 2018:
Garcia, H. E., K. Weathers, C. R. Paver, I. Smolyar, T. P. Boyer, R. A. Locarnini, M. M. Zweng, A. V. Mishonov, O. K. Baranova, D. Seidov, and J. R. Reagan, 2018. World Ocean Atlas 2018,Volume 3: Dissolved Oxygen, Apparent Oxygen Utilization, and Oxygen Saturation. A. V. Mishonov, Technical Ed.; NOAA Atlas NESDIS 83, 38 pp.,
Garcia, H. E., K. Weathers, C. R. Paver, I. Smolyar, T. P. Boyer, R. A. Locarnini, M. M. Zweng, A. V. Mishonov, O. K. Baranova, D. Seidov, and J. R. Reagan, 2018. World Ocean Atlas 2018,Volume 4: Dissolved Inorganic Nutrients (phosphate, nitrate and nitrate+nitrite, silicate). A. V. Mishonov, Technical Ed.; NOAA Atlas NESDIS 84, 35 pp.
Version 2 of the GOM RC was released in October, 2020. It includes all data from World Ocean Database 2018 (WOD18) and World Ocean Atlas 2018 (WOA18), and provides more detailed thermohaline fields and updates other oceanographic variables that were not available in the previous version. The update substantially revises and extends the original GOM RC, which was released in 2010 in the wake of the Deepwater Horizon oil spill and updated in 2011 (Boyer et al, 2011). This climatology serves as a physical oceanography baseline for NOAA Gulf of Mexico Data Atlas, and the new high-resolution temperature and salinity decadal climatologies allow researchers to more precisely assess decadal climate change in the Gulf, substantially increasing this climatology’s value for ocean climate studies and other applications.
Parameters, Climatologies, and Statistics
GOM RC version 2 parameters were computed using all the data from 1955 to 2017 available in the World Ocean Database. Version 2 includes objectively analyzed variables, and additional statistics for each variable that can be used for applied climate studies and other applications. All climatologies and statistics are calculated for each grid and standard depth unless otherwise specified.
- Objectively analyzed climatologies are the objectively interpolated mean fields for oceanographic variables at standard depth levels for the World Ocean.
- The statistical mean is the average of all unflagged interpolated values for variables. Applicable to any grid cell that contains at least one measurement for the given oceanographic variable.
- The number of observations of each variable in each grid cell of the World Ocean at each standard depth level.
- The standard deviation of the statistical mean for each variable in each grid cell at each standard depth level.
- The standard error of the mean of each variable in each grid cell at each standard depth level.
- The seasonal or monthly climatology minus the annual climatology at each grid cell at each standard depth.
- The statistical mean minus the climatological mean at each grid cell at each standard depth. This value is used as an estimate of interpolation and smoothing error.
- The number of 1° squares within the smallest radius of influence around each grid cell which contain a statistical mean.
Seasonal and annual temperature and salinity fields are based on monthly analyses on three spatial horizontal grids (1° x 1°, 0.25° x 0.25°, and 0.1° x 0.1°), which are computed by calculating the average of six decadal monthly analyses from 1955 to 2017 (the last “decade” is actually thirteen years to include all data available in WOD18). Annual and seasonal fields above 1500 m depth are calculated using the monthly fields. All monthly fields are extracted from the WOA18, where they were calculated using all data available in WOD18 for 1960—2017. Above 1500 m depth, seasonal fields are built at all depths by averaging the three months comprising each season (e.g., January, February, and March for winter) and the annual mean fields are calculated by averaging the four seasonal fields at all depths. Below 1500 m depth an annual analysis is defined as the mean of the four seasonal analyses and only annual and seasonal fields are shown (the monthly fields are not shown below 1500m depth).
Using High Resolution Fields
The high-resolution monthly temperature and salinity data coverage on the 0.1° x 0.1° grid have more gaps than seasonal and annual fields computed from the monthly fields. In general, all high-resolution analyzed fields should be reviewed carefully before using them in critical mission applications, particularly high-resolution monthly fields. Users should review the data distribution and statistical mean arrays before deciding whether to use the high-resolution analyzed temperature and salinity fields or their climatological means. Moreover, the monthly maps of objectively analyzed data on 0.1° x 0.1° may show too strong eddy-like irregularities in some regions due to interpolation and plotting combined (Seidov et al., 2019). Although these cases are rare, it’s important to carefully review fields with such occurrences before using analyzed variables in research or applications.
Temperature and Salinity
Temperature and salinity climatologies are calculated separately, because there are significantly more in situ temperature data than salinity data. Because of this disparity, there are not always concurrent temperature and salinity measurements.
As a result, instabilities in the vertical density field can occur when density is calculated from standard level climatologies of temperature and salinity. Appendices A and B in (Locarnini et al., 208) describe a method employed to stabilize the water column anywhere in the world ocean by minimally altering climatological temperature and salinity profiles. However, such instabilities are not common in the GOM domain.
The entire Gulf of Mexico, the Northern Caribbean Sea, a small part of the western Atlantic Ocean along the US coast and a small part of the Pacific Ocean along the Mexican coast.
- Longitude: 98.0° W to 75.0° W
- Latitude: 18.0° N to 35.0° N
All temperature and salinity data from the WOD18 for the GOM domain were used to calculate six decadal temperature and salinity climatologies within the following time periods: 1955-1964; 1965—1974; 1975—1984; 1985—1994; 1995—2004; 2005—2017. The averaged climatology for 1955—2017 (“all data” climatology) was calculated by averaging six individual decades listed above (see World Ocean Database 2018 Introduction). For all other parameters (dissolved oxygen, percent oxygen saturation, etc.), the climatologies were extracted from WOA18, where they were calculated for using all data from 1960 to 2017 and are referred to as “all decades” Climatologies. Each decadal climatology consists of:
- Computed as 12-months averages from surface to 5500m depth
- Winter (Jan.-Mar.), Spring (Apr.-Jun.), Summer (Jul.-Sep.), Fall (Oct.-Dec.)
- Monthly fields:
- From surface to 1500 m depth only
Spatial Resolution for Temperature and Salinity
- Annual, Seasonal, and Monthly Fields:
- Available on 1°x1°, 0.25°x0.25°, and 0.1°x0.1° latitude/longitude grids
Spatial Resolution for Other Variables
Resolution for dissolved oxygen, percent oxygen saturation, apparent oxygen utilization, silicate, phosphate, and nitrate.
- Annual, Seasonal, and Monthly Fields:
- Available on a 1°x1° latitude/longitude grid.
- Annual and Seasonal Fields:
- 0 to 5500 m depth on 102 standard levels
- Monthly Fields:
- Surface to 1500 m depth on 57 standard depth levels
Higher spatial resolutions of temperature and salinity – here the 0.1°x0.1° grid – provide major advantages in the areas where they are feasible and supported by data availability. The quality control on a higher-resolution grid reveals more outliers than an analysis on coarser grids. More importantly, with the significantly shorter radius of influence in the objective analysis procedure, the structure of the gridded fields is far better sustained, especially in regions with sharp gradients of the essential oceanographic parameter (temperature and salinity). The residual effect of quasi-stationary meanders and transient mesoscale eddies on climatological fields is clearly seen at 0.1°x0.1° spatial resolution. They are better preserved in high-resolution climatological fields, which make them even more valuable for ocean modeling and other applications. The GOM RC version 2 includes all the data from the most recent release of WOD18 and WOA18, which provides additional seventeen years of data coverage to the first version of this climatology released in 2010.
- Unitless on the Practical Salinity Scale-1978
- Dissolved Oxygen:
- Percent Oxygen Saturation:
- Apparent Oxygen Utilization, Silicate, Phosphate, and Nitrate:
All data for the period from 1955 to 2017 (for temperature and salinity) and 1960 to 2017 (for all other parameters) from WOD18 and WOA18 were used to generate the GOM mean and decadal climatologies. Temperature and salinity were compiled on the regular grids with three spatial resolutions (1° x 1°, 0.25° x 0.25°, and 0.1° x 0.1°) using the objective analysis technique similarly to WOA18. All other variables were extracted from WOA18 on the 1°x1° spatial resolution grid (see above). The description of employed datasets can be found in Boyer et al., 2018.
For all three spatial grid resolutions, mean depth values at the center of a grid square with the respective resolution were extracted from the ETOPO2 World Ocean bathymetry.
The mean climatological field calculation methods are described in the following publications: Temperature: Locarnini et al., 2018, Salinity: Zweng et al., 2018. Additional details on high-resolution climatological calculations can be found in Boyer et al., 2005 and Seidov et al, 2016, 2019. The updated table from Boyer et al., 2005, including the 1/10° grid resolution, provides radii of influence for the analysis procedure as:
|Pass||1-deg radius of influence||1/4-deg radius of influence||1/10th deg radius of influence|
Data Distribution formats
- Comma Separated Values (CSV), which gives latitudes and longitudes of the center of a grid box and the value at each depth in that grid box (XYZ triplets)
- ArcMap shape-file
Most of the procedures used to generate the NCEI regional ocean climatologies are similar to those used for the WOA18, e.g., (Locarnini et al., 2018; Zweng et al., 2018). There are several recent published studies of long-term ocean climate change based on WOD data analyses for different regional climatologies (Seidov et al., 2016; 2017; 2018; 2019)
Boyer, T., S. Levitus, H. Garcia, R.A. Locarnini, C. Stephens, J. Antonov, 2005. Objective analyses of annual, seasonal, and monthly temperature and salinity for the world ocean on a 0.25 degree grid. International Journal of Climatology, 25(7), 931-945.
Boyer, T.P., Biddle, M., Hamilton, M., Mishonov, A.V., Paver, C. R., Seidov, D., Zweng, M., 2011. Gulf of Mexico Regional Climatology, NOAA/NODC, dataset doi 10.7289/V5C53HSW.
Boyer, T. P., O. K. Baranova, C. Coleman, H. E., Garcia, A. Grodsky, R. A. Locarnini, A. V. Mishonov, C. R. Paver, J. R. Reagan, D. Seidov, I. V. Smolyar, K. Weathers, M. M. Zweng, 2018: World Ocean Database 2018. A. V. Mishonov, Technical Ed.; NOAA Atlas NESDIS 87, 209 pp. https://www.ncei.noaa.gov/sites/default/files/2020-04/wod_intro_0.pdf
Garcia, H. E., K. Weathers, C. R. Paver, I. Smolyar, T. P. Boyer, R. A. Locarnini, M. M. Zweng, A. V. Mishonov, O. K. Baranova, D. Seidov, and J. R. Reagan, 2018. World Ocean Atlas 2018, Volume 3: Dissolved Oxygen, Apparent Oxygen Utilization, and Oxygen Saturation. A. V. Mishonov, Technical Ed.; NOAA Atlas NESDIS 83, 38 pp. https://www.ncei.noaa.gov/sites/default/files/2020-04/woa18_vol3.pdf
Garcia, H. E., K. Weathers, C. R. Paver, I. Smolyar, T. P. Boyer, R. A. Locarnini, M. M. Zweng, A. V. Mishonov, O. K. Baranova, D. Seidov, and J. R. Reagan, 2018. World Ocean Atlas 2018, Volume 4: Dissolved Inorganic Nutrients (phosphate, nitrate and nitrate+nitrite, silicate). A. V. Mishonov, Technical Ed.; NOAA Atlas NESDIS 84, 35 pp.
Levitus, S., 1982: Climatological Atlas of the World Ocean, NOAA Professional Paper 13, U.S. Gov. Printing Office, Rockville, M.D., 190 pp.
Locarnini, R. A., A. V. Mishonov, O. K. Baranova, T. P. Boyer, M. M. Zweng, H. E. Garcia, J.R. Reagan, D. Seidov, K. Weathers, C. R. Paver, I. Smolyar, 2018: World Ocean Atlas 2018, Volume 1: Temperature. A. V. Mishonov, Technical Ed.; NOAA Atlas NESDIS 81, 40 pp. https://www.ncei.noaa.gov/sites/default/files/2020-04/woa18_vol1.pdf
Seidov, D., O. K. Baranova, T. Boyer, S. L. Cross, A. V. Mishonov, and A. R. Parsons, 2016: Northwest Atlantic Regional Ocean Climatology, in NOAA Atlas NESDIS 80, edited, p. 56, NOAA/NESDIS, Washington, DC, doi:10.7289/V5/ATLAS-NESDIS 80; https://repository.library.noaa.gov/view/noaa/12209.
Seidov, D., A. Mishonov, J. Reagan, and R. Parsons, 2017: Multidecadal variability and climate shift in the North Atlantic Ocean, Geophys. Res. Let., 44(10), 4985-4993, doi:10.1002/2017GL073644.
Seidov, D., A. Mishonov, J. Reagan, O. Baranova, S. Cross, and R. Parsons, 2018: Regional climatology of the Northwest Atlantic Ocean high-resolution mapping of ocean structure and change, Bulletin of the American Meteorological Society, 9(10), doi:10.1175/BAMS-D-17-0205.1.
Seidov, D., Mishonov, A., Reagan, J., Parsons, R., 2019: Eddy-Resolving In Situ Ocean Climatologies of Temperature and Salinity in the Northwest Atlantic Ocean. Journal of Geophysical Research: Oceans, 124, 41-58, doi:10.1029/2018JC014548
Zweng, M. M, J. R. Reagan, D. Seidov, T. P. Boyer, R. Locarnini, H. E. Garcia, A. V. Mishonov, O. K. Baranova, K. Weathers, C. R. Paver, I. Smolyar, 2018: World Ocean Atlas 2018, Volume 2: Salinity. A. V. Mishonov, Technical Ed., NOAA Atlas NESDIS 82, 39 pp. https://www.ncei.noaa.gov/sites/default/files/2020-04/woa18_vol2.pdf