Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Parameters
• Instruments
• Deployments
• Project Information
• Program Information
• Funding

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, http://globec.whoi.edu/software/kriging/easy_krig/easy_krig.html) 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: http://globec.whoi.edu/jg/info/globec/gb/nut_phyto%7Bdir=globec.whoi.edu/jg/dir/globec/gb/,data=grampus.umeoce.maine.edu/jg/serv/globec/nut_phyto.html0%7D?

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:http://globec.whoi.edu/jg/serv/globec/gb/broadscale/bongovols.html0%7Bdir=globec.whoi.edu/jg/dir/globec/gb/broadscale/,info=globec.whoi.edu/jg/info/globec/gb/broadscale/bongovols%7D

Temperature, fluorometry, salinity and density stratification values were kriged from data provided by D. Mountain at http://globec.whoi.edu/jg/dir/globec/gb/broadscale/ 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.

See cruise reports for information on original data used to create the kriged maps.

NOTE: There appears to be a decrease in the sensitivity of the fluorometer beginning in
June 1997 (It may have begun earlier but the data is too variable to tell).
It appeared to remain about the same until January of 1999 where it declined again
and became only about 1/3 - 1/4 the sensitivity of what it was in 95 and 96.
There does not appear to be a further change during 1999 although again it is hard
to tell. (E.D.,8/05)

VARIABLE STRUCTURE

There are two structures: "para" and "data", where structure "para" contains all parameters including "load data", "variogram", "kriging", and "display", and structure "data" contains the input ("in")and output data ("out") structures.

3. Example
To plot the kriging map using your own program, load the output file saved
from easy_krig3.0 and then type:

>>pcolor(data.out.krig.Xg,data.out.krig.Yg,data.out.krig.Cg);
>>colorbar;shading interp

to plot a kriging image, or

>>pcolor(data.out.krig.Xg,data.out.krig.Yg,data.out.krig.Eg);
>>colorbar;shading interp

to plot the kriging variance image. The structured variable "data.out.krig.Xg" means "out" is a substructure under "data", "krig" is a substructure of "out", and "Xg" is a member (2d array) of the substructure "krig". All substructures and members of the primary structures "data" and "para" are listed and explained above (note that only part of those parameters may be useful to the users).

Last modified: May 18, 2005

The U.S. GLOBEC Georges Bank Program is a large multi- disciplinary multi-year oceanographic effort. The proximate goal is to understand the population dynamics of key species on the Bank - Cod, Haddock, and two species of zooplankton (Calanus finmarchicus and Pseudocalanus) - in terms of their coupling to the physical environment and in terms of their predators and prey. The ultimate goal is to be able to predict changes in the distribution and abundance of these species as a result of changes in their physical and biotic environment as well as to anticipate how their populations might respond to climate change.

The effort is substantial, requiring broad-scale surveys of the entire Bank, and process studies which focus both on the links between the target species and their physical environment, and the determination of fundamental aspects of these species' life history (birth rates, growth rates, death rates, etc).

Equally important are the modelling efforts that are ongoing which seek to provide realistic predictions of the flow field and which utilize the life history information to produce an integrated view of the dynamics of the populations.

The U.S. GLOBEC Georges Bank Executive Committee (EXCO) provides program leadership and effective communication with the funding agencies.

U.S. GLOBEC (GLOBal ocean ECosystems dynamics) is a research program organized by oceanographers and fisheries scientists to address the question of how global climate change may affect the abundance and production of animals in the sea.

The U.S. GLOBEC Program currently had major research efforts underway in the Georges Bank / Northwest Atlantic Region, and the Northeast Pacific (with components in the California Current and in the Coastal Gulf of Alaska). U.S. GLOBEC was a major contributor to International GLOBEC efforts in the Southern Ocean and Western Antarctic Peninsula (WAP).