Title: METADATA FOR ADCP DATA SETS FROM FIXED VESSEL COLUMBIA RIVER LMER PROJECT Contact:David Jay Center for Coastal and Land Margin Research Oregon Graduate Institute of Science and Technology PO Box 91000 Portland, OR 97291-1000 USA email: djay@ese.ogi.edu Principle Investigators (Institution) and research area: Antonio Baptista (Oregon Graduate Inst. of Science and Technology), hydrodynamics David Jay (Oregon Graduate Inst. of Science and Technology), geophysics Preliminary ADCP data sets are located on this website, and "post-processed" data sets and plots are later made available at: http://www.ccalmr.ogi.edu/~orton/lmer-cretm/ When visiting that site, be sure to consult the README.TXT file for guidance. To get the PASSWORD for the post-processed data server, email Philip Orton at: orton@ccalmr.ogi.edu. The post-processed data sets are different in that they have had additional quality control, are converted into matrix form, are referenced to depth AND height above the bed, and contain velocities rotated to along- and across-channel directions. Plots are available with data referenced to height above the bed. DATA DESCRIPTION: Sampling took place during one 28-35 day cruise per year in 1990, 1991, 1992, 1995, and 1996; two-week "seasonal" cruises in May, July, and October 1997, and February 1998; and two-week comparison cruises on the Columbia River and the Fraser River in British Columbia, Canada, in June and July 1999. ADCP data was also collected from a roving vessel during these cruises. For these data, please link to Oregon Graduate Institute webpage given above. The Acoustic Doppler Current Profiler (ADCP) acquires a fine-scale record of horizontal current flow through the water column. Data document the temporal change in degree of riverine versus marine influence and, thus, are important in understanding the transport of material in estuarine turbidity maxima (ETM) over time. These data are used to evaluate the hydrographic influences (e.g. tides, river flow) on the ETM and are used in conjunction with other data sets to model particle dynamics, biological production, and geochemical processing of organic material. A 1.2 MHz Narrow-Band ADCP (NB-ADCP) was mounted on an anchored vessel during time series in 1995 and 1996. Raw data were averaged 1 minute, and were then low-passed to 15 minute intervals. In 1997, data were averaged every 5 minutes and low-passed to 15 minute intervals. On the Fraser 1999 cruise, a Workhorse BroadBand ADCP (BB-ADCP) was used, with higher temporal resolution. Vertical bin size of all data was 1 m, but since the ship moved vertically with the tide, these depths are NOT fixed relative to MLLW and may need to be adjusted vertically. The first depth bin is usually around 6m below the water surface for NB-ADCP data, and 4.5 m for BB-ADCP data. Ship's position was determined using GPS or dGPS (after 1995). Current direction was resolved with a vessel gyrocompass. The link to the vessel gyrocompass was not functional in 1995, however, and current speed was converted to velocity under the assumption that current was perfectly reversing and oriented in either the flood (ship's heading = 315) or ebb (ship's heading = 135) direction. Although u and v velocity vectors are given for the 1995 data set, it is strongly recommended that one use total speed (sqrt(u^2 = v^2)) instead. VARIABLES: Header line: Last two digits of year Month of year Day of month Hour (Pacific Standard Time) of measurement Minute of measurement Latitude (see note below) Longitude (see note below) Water column depth in m (see note below) Apparent bottom speed in east-west direction (mm / sec) Apparent bottom speed in north-south direction (mm / sec) Ship's heading used in model (see below) Tidal height (always zero here since depths are relative to surface) Ebb/Flood tide (1995 data set) Data lines: Depth (m) of profiled layer Current speed in the u (east-west) dimension (mm / sec) Current speed in the v (north-south) dimension (mm / sec) Current speed in the w (vertical) dimension (mm / sec) Error velocity estimate (mm / sec) (see below) Notes and caveats on the data: *** positive values of the u velocity variable indicate flood tide due to the approximate e-w orientation of the estuary *** positive velocity values indicate east, north, and upward flowing currents *** depth is given from the transducers which are approximately 3 m below the water surface. *** error velocity is obtained from the ADCP as a measure of instrument error. It represents the difference in the vertical velocity as estimated by the two pairs of opposite beams on the ADCP. *** velocity values of 19999.0 indicate non-applicable data bins (out of range) *** zero values for latitude and longitude may be present when readings were not taken or navigation was malfunctioning. All coordinates should be identical for time series measurements since the boat only moved several to tens of meters on its anchor line. File format: comma-delineated ASCII with header line; maximum number of records = 32,000+; number of data columns = 14 -------------------------------------------------------------------------------------------------