%readallsfc % Reads the combined surface data file % from KNORR 1997 Lab Sea cruise % % Created by Peter Guest, pguest at nps.navy.mil % Dec 31, 1997 % For sample plots of this data, surf the web at % http://www.met.nps.navy.mil/~guestps/labsea/ % % % WARNING: % It is strongly recommended that you contact Peter Guest before % using this data set so that you may be kept updated on any new % information. These data are preliminary. % % % Data File Description % % Format: MATLAB (default "save" format) % Filename: allsfc.mat % Array name: all_5 % File size: 2580506 Bytes % % % Notes on Data Collection and Processing % % The records (rows) represent concurrent 5 minute averages of the % quantities listed below. Each record is identified in space and % time. This data set includes travel periods; During the period % Julian day/time 39-72 (approx.) the Knorr was in the Labrador % Sea proper. JD 63.5 = March 4, Noon (UTC) % Knorr IMET data: % Basic meteorological information were collected from the Knorr % "IMET" system. Quantities were sampled every 1 second and and % stored 15 second averages. During the period JD 63 - 69.7 % the ship wind sensor was inoperational and wind speed % and direction were based on hourly visual estimates, % interpolated to 5-minute values. Relative (wrt ship) wind % speed and direction (scalar and vector) are no good during this % period and are set to NaN. % "Scalar" directions are determined using what I call a "rotoscalar % technique". I vector average unit vectors of different directions % to get the "average direction". Note that this is different % from a vector-averaged wind direction. % Long and Shortwave Radiation: % The downwelling radiation data were based on direct % measurements. Upwelling longwave radiation is an estimate % assumming surface emissivity = 0.98. Upwelling shortwave % radiation is an estimate assuming albedo = 0.1 % Turbulent fluxes: % Bulk turbulent fluxes are based on Smith (1988) with surface % humidity set to 98% surface temperature saturation value. % Data quality and corrections: % Quantities were plotted and checked for % problems such as spikes and obviously bad values. % The data were quite clean "as is" and virtually % no editing was performed. There were no corrections for flow % distortion effects or thermal, moisture or radiation % contamination from the ship. Errors due to these effects % could be substantial, depending on the paramter. Contact Peter % for estimates of errors for various quantities. % The pressure appeared to be have a bias that was not corrected; % add 1.8 hPa to pressure value for best estimate. % Wind speed and direction are for 23 m elevation except for period % JD 63 - 69.7 when values are nominally for 10 meter elevation. % Multiply wind speed from other periods by 0.945 to get estimate % of 10 m wind speed. % "rwdvec" values are not correct; use "rwdscal" % instead for relative wind direction. % Further notes and updates: % Corrected data for JD 63 added 12/30/97 % 15 second data also available % Acknowledgements: % IMET data systems maintained by the crew of the R/V Knorr. % IMET data recorded and hourly observations performed by % Karl Bumke (PI), Klaus Uhlig, Uwe Karger and Hauke Berndt % Institut for Meereskunde, University of Kiel, Germany. % Radiation instruments provided by the Naval Postgraduate School. % This work was supported by the Office of Naval Research, % grant number N0001497WR30058. load /d/ibis2/guestps/labsea/ftp/allsfc %change path for your system jd = all_5(:,1); % Julian Day/Time at start of 5-min period 1997 lat = all_5(:,2); % latitude pos = North lon = all_5(:,3); % longitude neg = West ss = all_5(:,4); % ship speed (scalar average) press = all_5(:,5); % pressure (add 1.8) tair = all_5(:,6); % air temperature (23 m) tdew = all_5(:,7); % dewpoint temperature (23m) tsea = all_5(:,8); % intake temp (-3m?) rh = all_5(:,9); % relative humidity (wrt liquid) 23m rws = all_5(:,10); % relative wind speed (scalar) ws = all_5(:,11); % true wind speed (scalar) wsvec = all_5(:,12); % true wind speed (vector) wdvec = all_5(:,13); % true wind direction (vector) rwsvec = all_5(:,14); % relative wind speed (vector) rwdvec = all_5(:,15); % relative wind direction (vector) ssvec = all_5(:,16); % ship speed (vector) coursevec = all_5(:,17); % ship course (vector) wdscal = all_5(:,18); % true wind direction (rotoscalar) rwdscal = all_5(:,19); % relative wind direction (rotoscalar) coursescal = all_5(:,20); % ship course heading(rotoscalar) headingscal = all_5(:,21); % ship position heading (rotoscalar) shf = all_5(:,22); % bulk sensible heat flux (W/m2) lhf = all_5(:,23); % bulk latent heat flux (W/m2) tau = all_5(:,24); % wind stress (Newtons/m2) lwd = all_5(:,25); % downwelling longwave radiation (W/m2) lwu = all_5(:,26); % upwelling longwave radiation (W/m2) swd = all_5(:,27); % downwelling shortwave radiation (W/m2) swu = all_5(:,28); % upwelling longwave radiation (W/m2)