Labrador Sea Deep Convection Experiment:

- The 1997 cruise of the R/V Knorr -

Meteorology Results

The R/V Knorr in "warm" weather conditions. (Christopher Griner©WHOI)

Overview

After a lackadaisical start, the winter of 1997 turned into a blockbuster season for forcing deep convection in the Labrador Sea. During the period February 8 to March 13, 1997, several hardy souls on board the R/V Knorr documented some of the largest surface ocean cooling ever observed directly. For virtually the entire cruise period, cold, dry, continental air masses streamed over the Labrador Sea from the north and west. The strong contrast between these air masses and the relatively warm, moist surface of the ice-free Labrador Sea, along with strong winds, resulted in extreme loss of heat from the ocean. The surface cooling destabilized the ocean mixed layer, which grew from approximately 400 to 1500 meters in some locations during just one month. The atmosphere also experienced deep convection, in one case extending from the surface to almost 5 km elevation. Near-continuous snow showers had an important affect on ocean buoyancy, counteracting the cooling and evaporation by approximately 20%.

The analyses of these atmospheric forcing features is ongoing. Several researchers have formed an e-mail working group to organize atmospheric studies of the Labrador Seas. Click here for more details on the working group.

This site shows some of the preliminary in situ Knorr results of the Labrador Sea Deep Convection Experiment meteorology research program . Here you can find links to some plots of surface meteorology variables and descriptions of available data sets.

Who performed the meteorological measurements?

During the 1997 Knorr cruise, meteorological measurements were performed by:

We also operated equipment supplied by the Environmental Technical Laboratory/NOAA, Boulder Colorado, The University of Washington, Department of Atmospheric Science, Seattle, Washington, and The Woods Hole Oceanographic Institution, Woods Hole, Massachussets as part of our collaboration with the FASTEX project.

Click here for a detailed list of all the 1997 Knorr meteorological measurements

Plots

Following are links to some plots of meteorological parameters and other quantities measured during the cruise. These may be freely copied, but please acknowledge the original author(s) if the plots are used in any publication or presentation. Make sure other people who receive anything here are also aware of this request.

Available Meteorological Data from the Knorr

All the data shown on these plots (and more) are available from a public ftp site. Also available are MATLAB programs used to read the data sets and create the above plots. For details on data quality and ftp address information, send an e-mail to Peter Guest or call him at 1-831-656-2451.
  1. Comprehensive surface meteorology - five minute averages of
    • Knorr location
    • Surface true and relative wind vector, air temperature, humidity, pressure
    • Sea surface temperature
    • Bulk estimates of the turbulent fluxes of sensible heat, latent heat (evaporation) and momentum (wind stress)
    • Direct measurements of downwelling longwave and shortwave radiation
    • Estimates of upwelling radiation
    • Total heat flux
    • Detailed description of surface data set
  2. Rawinsonde soundings - upper air profiles of
  3. Daily Precipitation Estimates
  4. Hourly Eyeball Weather Observations
    • Visibility
    • Clouds
    • Precipitation
    • Waves and swell
    • Ice type

Other Links

Acknowledgements

I thank all the crew of the R/V Knorr and all the scientists and technicians who helped make this such a successful cruise. Keith Jones and Dick Lind provided valuable equipment and software support. Peter Guest's Labrador Sea deep convection studies and the preparation of these web sites were sponsored by the Office of Naval Research grant number N0001497WR30058.

Last update: 5/3/99

Please send all comments and suggestions to the author, Peter Guest