SandyDuck '97 Experiment: AJB Wave and Current Data

Please contact Stephen Henderson steveh@phys.ocean.dal.ca or shenders@coas.oregonstate.edu if you transfer any of these data. DATA LINK ... ********************************************************************* INFORMATION REGARDING DALHOUSIE UDATS SANDYDUCK DATA ********************************************************************* This file contains information about the 'udats' (ie. non-acoustic) data collected by the Dalhousie group during the Sandyduck experiment of 1997. Five instrument-bearing frames (labeled a, b, c, d and f) were deployed. The positions of these frames were: X(m) Y(m) Z(m) Latitude Longitude a = 185.2 996.9 -1.2 36 11.19960' 75 45.07104' b = 234.7 995.6 -2.83 36 11.20726' 75 45.03939' c = 269.6 995.6 -2.95 36 11.21314' 75 45.01726' d = 310.0 996.4 -2.84 36 11.22035' 75 44.99182' f = 184.3 885.1 -1.1 36 11.14200' 75 45.04839' where X, Y, and Z respectivly indicate cross-shore, longshore, and elevation, positions with horizontal positions given in the FRF coordinate system (m), and elevation given in m relative to NGVD. The following variables were measured at 2Hz ('fast_data') at each of the five frames: t=time (yearday) p=water pressure (m) u=cross-shore water velocity (m/s) v=longshore water velocity (m/s) Pressure was measured using Viatran pressure transducers. Velocities were measured using Marsh-McBirney current meters. p,u and v measurements are recorded in subdirectories of the directory 'fast_data'. Data are saved in the binary 'DSF' format (see "DSF_nan_standards"). The easiest way to load both fast and slow data (see below) is to use the matlab routines provided in the directory "programs". Each of these routines starts with documentation. The matlab routine "load_fast"), contained in the directory 'programs', can be used to load the 2Hz puv data. If you are in matlab, and in the directory `programs', you can get help by typing, for example, `help load_fast'. Minutely averages ('slow_data') of p, u and v are recorded in DSF-format files in the directory "slow_data", along with the following additional variables: atmp = atmospheric pressure (mb) h = distance downwards to sea bed from zero NGVD (m) n = sea level elevation relative to NGVD, (so h+n=total water depth) (m) temp = water temperature (deg.C) varp = minutely water pressure variance (m^2) varu = minutely variance of cross-shore velocity ((m/s)^2) varv = minutely variance of longshore water velocity ((m/s)^2) The matlab routines "load_slow") and "get_one_inst") in the directory 'programs' can be used to load the minutely data. All times in 2Hz and minutely files are in yearday. The matlab routines 'date2day' and 'day2date' in the directory 'programs' can be used to convert between time in yearday and time in year,month,day,hour,minute,second. Most bad data has been replaced with nan's (matlab not-a-number's). I am aware of the following exceptions: All t, all data, frame=f: spikes present in time series, indicating bad data. Suspiciously regular oscillations also found. Result is that all f data is suspect although much of the data seems reasonable (I've avoided using this data. Use at own risk). t<244, data=u,v, frame=b,c: biofouling leads to reduction in gains (fixed by cleaning instruments). 264.2<t<266.6, data=p, frame=f: gain too low due to sand blocking pressure tube, fixed by cleaning. 267.3<t<270.9, data=p, frame=f: gain too low due to sand blocking pressure tube, fixed by cleaning. 280<t<287.4, data=u,v, frame=f: f gain becomes too low (biofouling), fixed by cleaning. 286.58<t<287.55, data=u,v,frame=c: measured (u,v) rotated because current meter rotated. 301.1<t, data=p, frame=b: gain too low due to sand blocking pressure tube. If anyone finds any further problems please report them to steveh@phys.ocean.dal.ca and shenders@coas.oregonstate.edu Questions can also be sent to these addresses.