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Northwest Atlantic Regional Climatology Version 2

The Northwest Atlantic (NWA) is a resource rich coastal zone with abundant fisheries and other material resources. The region includes The Gulf Stream and North Atlantic Current System, key features that facilitate northward heat transport and Meridional Overturning Circulation in the Atlantic Ocean. The NWA Regional Climatology (RC) version 2 replaces the previous version of the NWA RC published in 2016. The updated high-resolution temperature and salinity climatologies allow researchers to assess decadal ocean climate change more precisely in the critically important NWA region. The updates substantially increase the value of the NWA RC for ocean climate studies and other applications.

Northwest Atlantic

Access Methods

These decadal climatologies were generated from regional data in the World Ocean Database. The datasets used are described in WOD 2018.

Citations

  • Seidov, D., Mishonov, A.V., Baranova, O.K., Boyer, T.P., Nyadjro, E., Bouchard, C., Cross, S.L., 2022: Northwest Atlantic Regional Climatology version 2 (NCEI Accession 0242042). NOAA National Centers for Environmental Information. Dataset.
  • Seidov, D., Mishonov, A.V., Baranova, O.K., Boyer, T.P., Nyadjro, E., Bouchard, C., Cross, S.L., 2022: Northwest Atlantic Regional Ocean Climatology version 2. NOAA Atlas NESDIS 88, Silver Spring, MD, 75 pp. doi: https://doi.org/10.25923/c6fz-fp67 |  PDF

Parameters

The NWA Regional Climatology was created to assess long-term climatological tendencies in this important region of the Atlantic Ocean. The set is comprised of objectively analyzed temperature and salinity fields, and additional parameters, including:

  • Simple statistical means
  • Data distributions
  • Standard deviations
  • Standard errors of the mean
  • Observed minus analyzed
  • Seasonal minus annual distributions for both temperature and salinity

Analysis Methods

Seasonal and annual fields are based on complete monthly analyses of all three horizontal grids (1°x1°, a 1/4°x1/4°, and 1/10°x1/10°), which are computed by averaging six decadal monthly analyses from 1955 to 2017. Seasonal fields at all depths above 1500 meters are computed from the average of the three months comprising each season (e.g., January, February, and March for winter), while annual mean fields are computed by averaging the four seasonal fields at all depths. The annual analysis of measurements below 1500 meters is the mean of the four seasonal analyses, and only shows annual and seasonal fields (the monthly fields are not shown).

Using High Resolution Fields

The high-resolution monthly temperature and salinity data coverage on the 1/10°x1/10° 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 1/10°x1/10° may show too strong eddy-like irregularities in some regions due to interpolation and plotting artifacts combined. 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 is much more 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., 2018) describe a method employed to stabilize the water column anywhere in the world ocean by minimally altering climatological temperature and salinity profiles. All analyses shown in the NWA regional climatology were performed using this stabilizing method.

Other parameters from WOD18 that are included in the WOA18, such as oxygen, nutrients, etc., were not additionally processed in the NWA RC version 2. They are provided in WOA18 on the 1°x1° grid only. Parameters with this resolution would not provide any additional value to the high-resolution temperature and salinity NWA RC and therefore were not included. The one-degree resolution fields of all parameters other than temperature and salinity can be directly extracted from the WOA18.

Temporal Resolution

All data from the WOD18 for the NWA domain were used to calculate six decadal climatologies
within the following time periods: 1955–1964, 1965–1974, 1975–1984, 1985–1994, 1995–2004, and 2005–2017 (the last “decade” was extended three years from 2014–2017 to include all data ingested in the WOA18). The all averaged decades climatology was calculated by averaging the six individual decades listed above (see World Ocean Database 2018).

Each decadal climatology consists of:

Annual Fields

Computed as 12-months averages
Seasonal Fields
Winter (Jan.-Mar.), Spring (Apr.-Jun.), Summer (Jul.-Sep.), Fall (Oct.-Dec.) computed as 3-months averages
Monthly Fields
Grids above 1500 m

Spatial Resolution

Annual, Seasonal and Monthly Fields
1°x1°, 1/4°x1/4°, and 1/10°x1/10° latitude/longitude grids
Monthly Fields
Grids above 1500 m

Vertical Resolution

Annual and Seasonal Fields
0 to 5500 m depth on 102 standard levels
Monthly Fields
0 to 1500 m on 57 standard levels

Standard depth levels in the NWA regional climatology are the same as in the WOA18 (see Table 3 in the WOA18 documentation).

Objectives

Higher spatial resolutions – here the 1/10°x1/10° grid – provide major advantages in 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, the significantly shorter radius of influence in the objective analysis procedure makes the structure of the gridded fields much more well sustained, especially in regions with sharp gradients of the essential oceanographic parameter (temperature and salinity). Residual effects of quasi-stationary meanders and transient mesoscale eddies on climatological fields are clearly seen at 1/10°x1/10° resolution. They are better preserved in high-resolution climatological fields, which make them more valuable for ocean modeling and other applications.

Units

Temperature
°C
Salinity
Unitless on the Practical Salinity Scale-1978.

Bathymetry

For all three grid resolutions, mean depth values at the center of a grid square with the respective resolution were extracted from the ETOPO2 World Ocean bathymetry.

Method

The methods of calculating mean climatological fields are described in 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. 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° radius of influence 1/4° radius of influence 1/10° radius of influence
1 892 km 321 km 253 km
2 669 km 267 km 198 km
3 446 km 214 km 154 km

Most of the procedures used for generating NCEI regional climatologies are similar to those used for WOA18, e.g., (Locarnini et al., 2018; Zweng et al., 2018). Several recently published studies of long-term ocean climate change are based on SWNARC (Seidov et al., 2015; Seidov et al., 2017; Seidov et al., 2018).

Longitude
80.0°W—40.0°W
Latitude
32.0°N— 65.0°N

Related Publications

  • Boyer, T., S. Levitus, H. Garcia, R.A. Locarnini, C. Stephens, and 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., 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
  • Boyer, T.P., O.K. Baranova, M. Biddle, D.R. Johnson, A.V. Mishonov, C. Paver, D. Seidov and M. Zweng (2015). Arctic Ocean Regional Climatology (NCEI Accession 0115771). [indicate subset used]. NOAA National Centers for Environmental Information. Dataset. doi:10.7289/V5QC01J0.
  • 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, 173 pp., U.S. Gov. Printing Office, Rockville, MD. ftp://ftp.library.noaa.gov/noaa_documents.lib/NOAA_professional_paper/NOAA_paper_13.pdf
  • 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, M. Biddle, T.P. Boyer, D.R. Johnson, A.V. Mishonov, C. Paver, Christopher, and M. Zweng (2013). Greenland-Iceland-Norwegian Seas Regional Climatology (NCEI Accession 0112824). [indicate subset used]. NOAA National Centers for Environmental Information. Dataset. doi: 10.7289/V5GT5K30.
  • Seidov, D., J.I. Antonov, K.M. Arzayus, O.K. Baranova, M. Biddle, T.P. Boyer, D.R. Johnson, A.V. Mishonov, C. Paver and M.M. Zweng (2015). Oceanography north of 60°N from World Ocean Database, Progress in Oceanography, 132, 153-173, doi:10.1016/j.pocean.2014.02.003.
  • 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, 99(10), 2129-2138, doi:10.1175/BAMS-D-17-0205.1
  • Seidov, D., A. Mishonov, J. Reagan, and R. Parsons (2019a). Eddy-Resolving In Situ Ocean Climatologies of Temperature and Salinity in the Northwest Atlantic Ocean. Journal of Geophysical Research: Oceans, 124(1), 41-58. doi:10.1029/2018JC014548
  • Seidov, D., A. Mishonov, J. Reagan, and R. Parsons (2019b). Resilience of the Gulf Stream path on decadal and longer timescales. Scientific Reports, 9, 11549. doi:10.1038/s41598-019-48011-9
  • Seidov, D., A. Mishonov, and R. Parsons, 2021: Recent warming and decadal variability of Gulf of Maine and Slope Water. Limnology and Oceanography, 66, 3472-3488. doi: 10.1002/lno.11892
  • 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