Documentation for the SHEBA partial "column model" data organization 7 Jan 02 MGM The following was developed as means of identifying particular events during the SHEBA drift, and assembling in one place data necessary for driving and verifying ice/ocean models. It does not include cloud or precipitation data. A graphical overview of the drift and oceanograpic profiler data (T/S and ADP velocities) is given in the 33 page pdf document ocean_summary.pdf Matlab functions and data file names are case sensitive, and this can lead to problems with cdrom formats and file transfer, so the directory is stored as a "tar" archive file. unpack with %mrc tar xvf tar_lowercolumn (includes this file as events/README_lowercolumn) The simplest way to use this data compilation is through the matlab function: assemble_data.m in the 'events' directory. However, there is considerably more information available than is returned by assemble_data. These data are embedded in the subdirectories, as listed below. Time: the convention adopted for time is decimal days of 1997 UT where 1200UT on 1 Jan 98 is 366.500 example: From p. 28 of the ocean_summary document, the period 597 to 602 (20-25 Aug 1998) is one of especially fast drift. In the events directory >> DATA=assemble_data(597,602); Save data structure? n y WOULD SAVE AS ASDATA597_602.mat >> DATA met: [1x1 struct] spo: [1x1 struct] nav: [1x1 struct] ice: [1x1 struct] ocean: [1x1 struct] >> DATA.met MET TOWER DATA STRUCTURE t120: [120x1 double] time vector, hourly centered W: [120x2 double] complex in direction of wind vector [2.5m 10 m] pres: [120x1 double] temp: [120x2 double] [2.5m 10m] LWd: [120x1 double] longwave downwelling LWu: [120x1 double] longwave upwelling SWd: [120x1 double] shortwave downwelling SWu: [120x1 double] shortwave upwelling ustar: [120x3 double] [flux bulk2.5m bulk10m] hfs: [120x3 double] sensible heat flux same desc as ustar hsl: [120x3 double] latent heat flux same desc as ustar >> DATA.spo SPO TOWERS DATA STRUCTURE t120: [120x1 double] time vector, hourly centered W: [120x2 double] [2m 10m] pres: [120x1 double] temp: [120x2 double] [2m 10m] LWd: [120x1 double] SWd: [120x1 double] >> DATA.nav NAVIGATION, BATHYMETRY DATA tvp: [241x6 double] [time (half hr) uE vN lat long okflag] okflag=1 if there were enough fixes for the complex demodulation 0 for linear interplolation Vice: [241x1 double] complex ice velocity, no inertial component fcor: [241x1 double] Coriolis parameter s^{-1} zbot: [241x1 double] bottom elevation >> DATA.ice ICE, INTERFACE DATA tprof: [...] times of ice profiles zprof: [1x50 double] measurement elevation wrt to initial ice surface Tprof: [5x50 double] ice temperature profiles bot_el: [5x1 double] bot elevation wrt initial ice surface dTdz: [5x1 double] estimate of gradT from temperature in the lower 50 cm of the ice column sal: [2.7000 1.3000] mean and std deviation of ice salinities for multiyear ice cores at depths > 150 cm from Melnikov's samples mastdraft: [6x2 double] estimate of ice draft at turbulence mast site us0_logz0: [8x3 double] estimate of LOCAL u*0, z0 at ice/ocean interface >> DATA.ocean Prof: [1x1 struct] Trb: [1x3 struct] TSmast: [1x3 struct] ADP: [1x1 struct] >> DATA.ocean.Prof OCEAN PROFILER TEMPERATURE, SALINITY t: [25x1 double] T: [151x25 double] avg T profiles, every 3 hr S: [151x25 double] avg S Tst: [151x25 double] T std dev at each level Sst: [151x25 double] S std dev Tn: [25x1 double] no. of T profiles in each avg Sn: [25x1 double] no. of S profiles z: [1x151 double] vertical coordinate (from surface) >> DATA.ocean.Trb TURBULENCE CLUSTER DATA >> DATA.ocean.Trb(1) [3 or 4 element array of data structures] cluster: 1 t: [8x1 double] time T: [8x1 double] mean T, 3 hr avg S: [8x1 double] mean S U: [8x1 complex] mean velocity, real east, imag north depth: [8x1 double] cluster depth (subtract ice draft for distance from interface) ustar: [8x1 double] square root of Reynolds stress q: [8x1 double] (++)^1/2 wT: [8x1 double] , heat flux/rho*cp wS: [8x1 double] use caution, this is estimated by lagging the SBE04 conductivity measurements, as correlated with microC measurements For Site 2, after March, there were two clusters, but 3 are shown. The third cluster refers to the data using the microC sensor, but should not be used without confirming from the original data >> DATA.ocean.ADP DOPPLER PROFILER DATA (SEE NOTES BELOW) day: [1x0 double] lat: [1x0 double] ADP navigation data long: [1x0 double] posok: [1x0 double] position quality flag maghd: [1x0 double] magok: [1x0 double] magdec: [1x0 double] Uice: [1x0 double] complex ice velocity viceok: [1x0 double] Urel: [205x0 double] complex velocity in each ADP bin, measured relative to ice dep: [205x1 double] bin depths If unfamiliar with matlab data structures, to plot ice velocity, for example, one would simply type >> vice=DATA.nav.tvp(:,2:3); >> t98=DATA.nav.tvp(:,1)-365; >> plot(t98,vice);grid on; >> legend('U(east)','V(north)') >> title('Ice Velocity from Complex Demodulation of GPS positions') >> xlabel('Day of 1998');ylabel('m s^{-1}') to include velocity without the inertial component, add >> hold on >> plot(t98,[real(DATA.nav.Vice) imag(DATA.nav.Vice)],'--','linewidth',2) ************************************************************************ ************************************************************************ The data are arranged in matlab binary files (.mat suffix, V 5) and often presented as matlab data structures. For more detailed descriptions, refer to the metafiles at CODIAC. In the "data" directory, there are 7 subdirectories: met ice sheba_gpsdata turb_mast profiler ADP bathymetry 1. met this directory contains matlab data files from both the Sheba Project Office (sbo) and meteorological tower (met). all times are for 1-hr averages CENTERED on the given time hourly.mat matlab version of the met tower data compilation from CODIAC HDR 1x41 4246 cell array => identifies the columns y 8112x41 2660736 double array => 41 column data matrix wind_hr.mat => spo wind at 2, 10 m, complex vector in the direction of surface wind, plus times in days of 19120 (366=1 Jan 98) W10 8601x1 137616 double array (complex) W2 8619x1 137904 double array (complex) time10 8601x1 68808 double array time2 8619x1 68952 double array temp_hr.mat => temperature at 2 and 10 m plus time vectors other_met_hr.mat => other data from the SPO towers (not met tower) RH 8619x2 137904 double array => rel humid at 2 levels dlw 8619x1 68952 double array => downwelling longwave dsw 8619x1 68952 double array => downwelling shortwave pres 8619x1 68952 double array => surface air pressure tday 8619x1 68952 double array => time in days of 19120 2. ice These data are partial compilations from the CRREL cdrom there are 3 matlab data files ICE_DRAFT.mat => used to determine distance of turbulence clusters from interface idraft1 134x1 double array => ice draft at the turbulence mast hole, 1st site idraft2 175x1 double array => ice draft at the turbulence mast hole, 2nd site tdraft1 134x1 double array => times in days of 19120 tdraft2 175x1 double array PITT_GAUGES.mat => 4 element array of data structures with data from site Pittsburgh >> A(1) gauge: 53 site: 'Pittsburgh' date: {1x71 cell} t120: [71x1 double] => time in days of 19120 sn: [71x1 double] => snow measure itop: [71x1 double] => ice top elevation, rel to initial placement ibot: [71x1 double] => ice bot elevation, rel to initial top pd: [71x1 double] => ?? all NaNs PTherm.mat => thermistor string temperatures at Pittsburgh >> PTherm => data structure t120: [1x339 double] z: [1x50 double] T: [339x50 double] (3) sheba_gpsdata PHASORS_ALL.mat => complex demodulation phasors calculated every 3 hrs from ocean city GPS with gaps filled by met gps where available see function fetch_tvp.m for extracting EN velocity and position data from these files (4)turb_mast there are Site1_3hr.mat and Site2_3hr.mat data containing data structure arrays Site1_3hr: B 1x4 4862784 struct array >> B(1) id: [1 285 450 0.1250 4] => cluster ts te avg_time min_15realization t: [391x1 double] dmn: [391x6 double] => mean quantities [T S u v depth theta] u and v are east and north components (true), where compass headings have been corrected using the Canadian Geomagnetic Reference Field Model depth is from the pressure gauge adjusted for atmospheric pres theta rotation angle about the horizontal, mainly a diagnostic dmnsd: [391x6 double] => sample std dev from 15 min realizations nsam: [391x1 double] => no. of 15 min realization in each avg dtrb: [391x9 double] => turbulence quantitities dtrbsd: [391x9 double] => sample std dev from 15 min realizations spc: [391x30x6 double] => log10(weighted (slope) spectral densities), averaged in evenly spaced logarithmic wavenumber bins (see kb): T S u v w err, where here u is the downstream, v is cross-stream, w is vertical spcst: [391x30x6 double] std dev, used for error estimates kb: [1x30 double] log10(wavenumbers) (5) profiler The mon_clean.mat files contain data structures with all of the casts from TS1M, despiked and otherwise cleaned up. See fix_month.m and message_profiler.m routines Example: >> load nov_clean >> whos Name Size Bytes Class A 1x1 1881764 struct array >> A td: [1x773 double] yr: [1x773 double] T: [151x773 double] S: [151x773 double] z: [1x151 double] in November there were 773 profiles (these are all downcasts) from 0 to 150m the upper few bins bins have been filled with the first value unaffected by the startup transients and hydrohole water COR_ALL3hr. mat includes for each 3 hr block in the project the average T/S for each cluster and average profiles The T/S values have been corrected via the cross calibrations detailed in sheba_matdata/TSonly Note that the in COR_ALL3hr cluster T/S values are NOT taken from the turb_mast data (4 above) but rather from a separate analysis of all the SBE sensor data regardless of whether all current meters are turning >> load COR_ALL3hr >> whos B 1x4 614912 struct array P 1x1 121207432 struct array Cluster data: >> B(3) [refers to cluster 3, note that for Site 2 this is the same as cluster 2 except that the microC sensor is used instead of SBE04 t: [2672x1 double] day of 19120 d: [2672x1 double] cluster depth T: [2672x1 double] temperature, after cross calibration Tst: [2672x1 double] T std dev nT: [2672x1 double] number of samples in each average, 0 means no data S: [2672x1 double] salinity, after cross calibration Sst: [2672x1 double] S std dev nS: [2672x1 double] number of samples in each average Profile 3 hr data >> P t: [2672x1 double] day of 19120 T: [151x2672 double] T profiles S: [151x2672 double] S profiles Tst: [151x2672 double] T std dev Sst: [151x2672 double] S std dev Tn: [2672x1 double] number of profiles in the 3 hr avg Sn: [2672x1 double] number of profiles in the 3 hr avg z: [1x151 double] vertical coord (6) ADP contains the original low frequency doppler profiler data from Scripps, see matlab function fetch_ADPsubset.m for extracting a time series of velocities. It will also provide a complex demod estimate of ice velocity where the scripps gps data are missing Please use care in interpretation of the ADP data: (a) read Chris Halle's notes (codiac); and (b) still be cautious of excessive shear in the upper part of the mixed layer (sometimes as far down as bins 6-8 (12-16 m)) (7) bathymetry see README for descriptions of the two bathymetries (ETOPO5 or IBCAO beta) covering the SHEBA drift. There are substantial differences along the SHEBA track