%readall5_98 % Reads the surface data file % from KNORR 1998 Lab Sea cruise % % Created by Peter Guest, pguest at nps.edu % June 23, 1998 % 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 4.2 (default "save" format) % Filename: allsfc_98.mat % Array name: all5 % File size: 2264089 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 24.4 - 44.5 (approx.) the Knorr was in the Labrador % Sea proper. This corresponds to row indices 1376-8090 in the following % data array. JD 44.5 = March 13, Noon (UTC) % Knorr IMET data: % Basic meteorological information were collected from the Knorr % "IMET" system. % "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 shortwave radiation data were based on % direct measurements after JD 28.1181. Before this time an % empirical fit based on sun angle (tuned using the later '98 % period and 1997 direct measurements) was used because no direct % data were available. Upwelling shortwave radiation is an % estimate assuming albedo = 0.1. Downwelling longwave radiation % was estimated from an empirical fit to air temperature based on % the 1997 cruise. Upwelling longwave radiation is an estimate % based on sea surface temperature which assumes surface % emissivity = 0.99. It is likely frost and liquid water affected % the downwelling shortwave measurements, but to what degree is % uncertain at this time. This would usually cause an % underestimate of downwelling shortwave radiation, but could % overestimate during low sun-angle periods. The empirical fits to % downwelling short (early cruise) and longwave (entire cruise) % radiation assume overcast conditions. I am workling on improving % these estimates using bridge-observed cloud conditions. % Turbulent fluxes: % Turbulent fluxes are based Smith's (1988) bulk method % 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 dirty and considerable despiking and other % 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. % All data, except as noted below, are now "clean and complete", % i.e. there are no obvious bad data points and all records are filled % with data (no NaN's). Salinity and conductivity values have % not been de-spiked or edited in any way. They are messy and not % calibrated. Dissolved CO2, "pco2" is garbage, ignore this variable. % Wind speed and direction are for 23 m elevation. % Multiply wind speed by 0.945 to get estimate of 10 m wind speed. % Further notes and updates: % 1 minute and raw 15 second data also available % Also MATLAB 5.0 format versions of the data are available, % although MATLAB 5.0 should be able to read this OK as is. % Total heat flux, "tothf", is positive upwards, which is the % the typical meteorological convention but not the usual % oceanographic. Oceanographers take note! % Acknowledgements: % The IMET data systems were maintained by the crew of the R/V Knorr. % In particular, I would like to thank the marine technician % during the cruise, Greg Packard. He maintained the meteorological % measurement and recording systems. My work was supported by the % Office of Naval Research, grant number N0001497WR30058 disp('reading Labrador Sea 1998 Met data - Matlab 4.0 version') load /d/ibis2/guestps/labsea98/allsfc_98 jd = all5(:,1); % Julian Day/Time at start of 5-min record 1998 lat = all5(:,2); % latitude pos = North lon = all5(:,3); % longitude neg = West ss = all5(:,4); % ship speed (scalar average) press = all5(:,5); % pressure (add 1.8) tair = all5(:,6); % air temperature (23 m) tdew = all5(:,7); % dewpoint temperature (23m) tsea = all5(:,8); % intake temp (-3m?) rh = all5(:,9); % relative humidity (wrt liquid) 23m rws = all5(:,10); % relative wind speed (scalar) ws = all5(:,11); % true wind speed (scalar) swd = all5(:,12); % downward shortwave radiation conduct = all5(:,13); % conductivity from intake salt = all5(:,14); % raw salinity from intake pco2 = all5(:,15); % CO2 from intake (garbage nothing there) wsvec = all5(:,16); % true wind speed (vector) wdvec = all5(:,17); % true wind direction (vector) rwsvec = all5(:,18); % relative wind speed (vector) rwdvec = all5(:,19); % relative wind direction (vector) ssvec = all5(:,20); % ship speed (vector) coursevec = all5(:,21); % ship course (vector) wdscal = all5(:,22); % true wind direction (rotoscalar) rwdscal = all5(:,23); % relative wind direction (rotoscalar) coursescal = all5(:,24); % ship course heading(rotoscalar) headingscal = all5(:,25); % ship position heading (rotoscalar) tau = all5(:,26); % wind stress (Newtons/m2) shf = all5(:,27); % bulk sensible heat flux (W/m2) lhf = all5(:,28); % bulk latent heat flux (W/m2) lwd = all5(:,29); % downwelling longwave radiation (W/m2) lwu = all5(:,30); % upwelling longwave radiation (W/m2) swd = all5(:,31); % downwelling shortwave radiation (W/m2) swu = all5(:,32); % upwelling longwave radiation (W/m2) tothf = all5(:,33); % total heat flux W/m2 positive upwards