Dataset: broadscale_summary
Deployment: AL9901

Broadscale physical and nutrient kriged data, five year summary.
Principal Investigator: 
Dr David Mountain (National Oceanic and Atmospheric Administration, NOAA)
BCO-DMO Data Manager: 
Nancy Copley (Woods Hole Oceanographic Institution, WHOI BCO-DMO)
Current State: 
Final no updates expected
Version Date: 

Modeling study performed at WHOI using Broadscale cruise data. Thumbnail images of the broad-scale data, processed using kriging techniques, are displayed here. Clicking on the thumbnail image will open a new browser window displaying the original, large image. Matlab data files are also accessible on these pages by clicking on the appropriate link. Matlab data files are of kriged values for Georges Bank with 2385 grid points. Note that on some browsers it will be necessary to hold down the "shift key" before clicking on the link in order to download the data to a file. Otherwise the data are loaded into your browser. Unless your browser knows what to do with Matlab binary data, it is best to download the whole file.

Thumbnail images were created from the original Matlab generated images using the mogrify utility in a single batch operation prior to serving. The thumbnail image page, however, is created each time it is viewed so that the most recent images are incorporated in the served data.

These maps were created using EasyKrig 3.0 (D. Chu, WHOI, 2004, by Nancy Copley, WHOI. All data were treated anisotropically, i.e., the variable of interest changes more rapidly in one direction than in another, essentially stretching the effect. In this case the x:y ratio was 2:1 and the rotation was 45 degrees for alignment with the Bank. These parameters were chosen based upon known circulation and geography of Georges Bank. When plotting the station locations as circles on the maps, only those stations containing data are shown. Some datasets are quite sparse, e.g. ammonia at 50-100m.

Nutrients: nitrates & nitrites (NO3/NO2), ammonia (NH4), silica (SiOH4), phosphates (PO4) (Townsend et al, U. Maine):
Data are available for 1997-1999, for January through June except:
1997: no January or June data
1998: no January data

The same colorbar range was used for the nutrient maps (nitrates/nitrites, ammonia, phosphates, silicates) as D. Townsend used in his plots, located on the GLOBEC website at:,

Chlorophyll-a values for 1995-1996 (February through July 1995 and January through June 1996) are from the ctd_hydrography; the 1997-1999 data are from D. Townsend's nutrient data. The color range is given as both 0-6 and 0-10 in order to make both large and small scale variations more clearly visible.

Nutrient and chl-a data were averaged from 3 depth strata: 0-15m, 15-50m, and 50-100m. There were usually one or two bottle samples in each range.

Biovolume data from bongo net displacement volumes is from D. Mountain, Jack Green and Joe Kane, NMFS:,

Temperature, fluorometry, salinity and density stratification values were kriged from data provided by D. Mountain at under ctd_hydrography.

The density stratification was calculated by first finding the density of each station and depth for which there was a temperature and salinity using a Matlab mfile function called sw_dens.m. Then the mean density was calculated for the depth strata 0-15 meters and for 50-100 m. If the maximum depth of a station was less than 50 m, the mean of 25-50m was used as the deep value. The difference is the stratification index.

More information about this dataset deployment