
METADATA FOR LMG SHIPBOARD ADCP OS38NB

#DATA_DATES: 2019/02/17 09:13:00 --- to --- 2019/03/20 15:31:00
#LAT_RANGE: 65.08 S --- to --- 52.78 S
#LON_RANGE: 67.97 W --- to --- 60.55 W  
#DEPTH_RANGE:   ( see "DEPTH RANGE" under "ADCP INSTRUMENT CONFIGURATION" below )
#SAC_CRUISE_ID: 
#PLATFORM_NAME: R/V Laurence M. Gould
#PRINCIPAL_INVESTIGATOR_NAME: Dr. Teresa K. Chereskin
#PI_INSTITUTION: Scripps Institution of Oceanography
#PI_COUNTRY: USA                                      
#PROJECT: Southern Ocean Current Observations from the U.S. Antarctic Research Vessels
#CRUISE_NAME: LMG 1902 
#PORTS: Punta Arenas to Palmer Station, to Punta Arenas
#GEOGRAPHIC_REGION: Southern Ocean
#PROCESSED_BY: Scripps Institution of Oceanography
#NAVIGATION: GPS
#QUALITY_NAV: good
#GENERAL_INFORMATION: 
CRUISE NOTES
    CHIEF SCIENTIST ON SHIP      : 
    INSTITUTE                    : 
    COUNTRY                      : 
    SIGNIFICANT DATA GAPS        : 
    SPECIAL SHIP TRACK PATTERNS  :
    COMMENTS                     :    
       Two data sets are available for this cruise:  nb150, and
       narrowband pings for the os38.

ADCP INSTRUMENTATION
  MANUFACTURER                : RD Instruments (RDI)
  HARDWARE MODEL              : Ocean Surveyer 38
  SERIAL NUMBERS              :
  FIRMWARE VERSION            :
  TRANSMIT FREQUENCY          : 38kHz narrowband
  ACOUSTIC BEAM WIDTH         :
  TRANSDUCER BEAM ANGLE       : 30 degrees
  COMMENTS                    : phased array

ADCP INSTALLATION
  METHOD/DESCRIPTION OF THE
    ATTACHMENT TO THE HULL    :
  LOCATION/DEPTH ON HULL      : nominally at 6 m
  REPEATABLE ATTACHMENT       : 
  DATE OF MOST RECENT ATTACH. :
  ACOUSTIC WINDOW             : yes, Z-Lux
  COMMENTS                    :

ADCP INSTRUMENT CONFIGURATION     
  DEPTH RANGE                 : 46 m --- to --- 1462 m
  BIN LENGTH                  : 24 m
  NUMBER OF BINS              : 60
  TRANSMIT PULSE LENGTH       : 24 m
  BLANKING INTERVAL           : 16 m 
  ENSEMBLE AVERAGING INTERVAL : 300 s
  SOUND SPEED CALCULATION     : FUNCTION OF TEMP AT TRANSDUCER
  BOTTOM TRACKING             : yes
  DIRECT COMMANDS             :
  COMMENTS                    : BOTTOM TRACKING - Typically, bottom tracking is ON when in shallow water,
                                        such as the Patagonian Shelf or the Bransfield Strait.
          
           Configuration History File 
          Columns are as follows: 
           B : CODAS logical block number  
          BT : bottom track mode (on or off)  
          SI : sampling interval or averaging period for ensemble (sec)
          NB : number of bins
          BL : bin length (m)
          PL : pulse length (m)
          TD : transducer depth (m)
          BK : blanking length (m)
          TR : top reference bin (m)
          BR : bottom reference bin (m)
          HO : heading offset applied by DAS (deg)
          HB : heading bias (deg)
          CRPH : compensation for roll-pitch-heading, 1:on, 0:off)
          
          yy/mm/dd  hh:mm:ss   B    BT    SI  NB   BL PL TD BK   TR BR       HO     HB CRPH
          2019/02/17  09:13:18   0    on   300  60   24 24  6 16    2 20   120.00   0.00 0001  

ADCP DATA ACQUISITION SYSTEM
  SOFTWARE DEVELOPERS         : E.Firing,J.Hummon
  SOFTWARE VERSIONS           : UHDAS
  DATA LOGGER, MAKE/MODEL     : Linux
  ADCP/LOGGER COMMUNICATION   : 
  CLOCK                       :
  COMMENTS                    : 

SHIP HEADING                      
  INSTRUMENT MAKE/MODEL       : gyrocompass
  SYNCHRO OR STEPPER          : 
  SYNCHRO RATIO               :
  COMPENSATION APPLIED        : yes
  GPS ATTITUDE SYSTEM         : yes - Seapath330, GPS
    LOCATION OF ANTENNAS      : main mast
    RIGID ATTACHMENT          : yes
    LOGGING RATE              : 1 Hz

ANCILLARY MEASUREMENTS            
  SURFACE TEMP AND SALINITY   : thermosalinograph, when available
  PITCH/ROLL MEASUREMENTS     : yes
  HYDRO CAST MEASUREMENTS     : 
  BIOMASS DETERMINATION       :
    DATE OF LAST CALIBRATION  :
    CALIBRATION COEFFICIENTS  :
    BEAM-AVERAGED AGC AVAILABLE?: < NO > < YES >
    CALIBRATION NET TOWS?     :   < NO > < YES >
  COMMENTS                    :

ADCP DATA PROCESSING/EDITING
     PERSONNEL IN CHARGE         : Processer 1, T.Chereskin Group
     SOUND SPEED CORRECTIONS     : not needed for phased array
     DATE OF PROCESSING          : July 2 2019
     ADDED TO NODC DB            : 
     NOTABLE SCATTERING LAYERS   :
     COMMENTS                    : Single pings are QC'd then averaged to 300 s ensembles, using the
                                 : University of Hawaii ADCP processing software. The final calibrated
                                 : CODAS database is inspected manually and has further editing applied to
                                 : remove suspect data and to edit out the bottom.
     COMMENTS                    : The os38 temperature probe at the transducer is noisy. Temperature
                                   is centered around a reasonable temperature,  although there are
                                   periods during the cruise when it is ok.
     
NAVIGATION
    TRANSIT                      :
       MAKE/MODEL                :
       LOGGED WITH ADCP DATA     :
       COMMENTS                  :
    GPS                          :
       MAKE/MODEL                :
       SELECTIVE AVAILABILITY    : 
       P-CODE                    : 
       DIFFERENTIAL              :
       SAMPLE INTERVAL           : 1 Hz
       LOCATION OF ANTENNA
         RELATIVE TO TRANSDUCER  :
       TIME OBTAINED RELATIVE TO
         START/END OF ENSEMBLE   : end
       AVERAGING/EDITING APPLIED : yes
       LOGGED WITH ADCP DATA     : yes
       LOGGED INDEPENDENTLY      : yes
       COMMENTS                  :
    OTHER                        : 

CALIBRATION 
     GYROCOMPASS CORRECTION      : yes, using Seapath330
     BOTTOM TRACK METHOD         : yes
          ADCP bottomtrack calibration
          Time range  47.38 to  78.65
             Calculation done at Tue Jul  2 19:39:22 2019
              step: 1
              min_depth:  80   max_depth: 1800
              min_speed:  2.0 m/s   max_sig:  2.5 std devs
              max_gap:  0.10 minutes   tol_dt: 0.02 (fraction)
          unedited: 4798 points
          edited:   2171 points, 2.0 min speed, 2.5 max dev
                      median     mean      std
          amplitude   1.0057   1.0064   0.0041
          phase       1.0798   1.1281   0.3779
          
     WATER TRACK METHOD          : used to monitor the phased array for amplitude bias
           ADCP watertrack calibration
           Time range  50.48 to  77.48
             Calculation done at Tue Jul  2 19:39:22 2019
             delta-u min = -100.00, max = 100.00
             delta-v min = -100.00, max = 100.00
             clip_amp = 0.04,  clip_ph =  3.0
             clip_dt =   60,  clip_var = 0.050
          Number of edited points:  39 out of  86
             amp   = 1.0054  + 0.0006 (t -  65.0)
             phase =   0.91  + -0.0003 (t -  65.0)
                      median     mean      std
          amplitude   1.0070   1.0054   0.0215
          phase       0.8430   0.9136   1.2594
          nav - pc    2.0000   1.3333  11.4784
          var         0.0110   0.0125   0.0083
          min var     0.0100   0.0101   0.0064
          delta-u    -0.2200  -0.4397   3.8746
          delta-v     1.1100   0.8228   3.8576
          
     FINAL SELECTION             : AMPLITUDE= 1.000        PHASE= 1.08
                                   The default amplitude correction for a Teledyne RDI phased array is 1.0,
                                   and that is the value used here.  In general, an amplitude correction
                                   based on in situ sound speed is not needed for a phased array.  Some
                                   phased array instruments, however, do show an amplitude bias and require
                                   correction, although the reasons are not well understood (Jules Hummon,
                                   personal communication).  We monitor the LMG OS38 for amplitude bias
                                   using the watertrack calibration whenever appropriate data are
                                   collected.

     AGREEMENT WITH PREVIOUS 
       CRUISES                   : OK
     SOUND SPEED CORRECTIONS     : not needed for phased array
     COMMENTS                    :
                                 
NAVIGATION CALCULATION             
     NAVIGATION USED             : GPS
     REFERENCE LAYER DEPTH RANGE : 2 thru 20, PG_MIN = 50
     FILTERING METHOD FOR 
       SMOOTHING REFERENCE LAYER 
       VELOCITY (FORM/WIDTH)     : Blackman window function of width T(half hour): 
           w(t) = 0.42 - 0.5 * cos(2 * pi *t / T) + 0.08 * cos(4 * pi * t / T).
     FINALIZED SHIP VEL/POSITIONS 
       STORED IN DATABASE        : YES 
     COMMENTS                    : An off set of dx=3 and dy=23 was applied to the navigation in order to
                                   translate the GPS positions to the transducer location.  This
                                   improves the u and v velocities when the ship is turning.

QUALITY ASSESSMENT
     ON-STATION VS. UNDERWAY     :
     VECTOR, CONTOUR, STICK PLOTS: YES, OK
     COMMENTS     


 REFERENCES (DATA REPORTS,ETC.) : 

         Lenn, Y.-D., T. K. Chereskin, J. Sprintall, and  E. Firing, 2007.
         Mean Jets, Mesoscale Variability and Eddy Momentum Fluxes in the
         Surface Layer of the Antarctic Circumpolar Current in Drake Passage,
         J. Mar. Res, 65, 27-58.

         Chereskin, T. K., and  G. A. Tarling, 2007.
         Interannual to diurnal variability  in the near-surface scattering
         layer in Drake Passage, ICES J. Mar. Sci.,
         doi: 10.1093/icesjms/fsm138.

         Lenn, Y.-D., T. K. Chereskin, and J. Sprintall, 2008.
         Improving estimates of the Antarctic Circumpolar Current streamlines
         in Drake Passage, J. Phys. Oceanogr., 38, 1000-1010.

         Lenn, Y.-D. and T. K. Chereskin, 2009.
         Observations of Ekman Currents in the Southern Ocean,
         J. Phys. Oceanogr., 39, 768-779.

         Savidge, D. K. and J. A. Amft, 2009.
         Circulation on the West Antarctic Peninsula derived from 6 years of 
         shipboard ADCP transects, Deep-Sea Res. I, 56, 1633-1655, 
         doi:10.1016/j.dsr.2009.05.011

         Lenn, Y.-D., T. K. Chereskin, J. Sprintall and J. McLean, 2011.
         Near-surface eddy heat and momentum fluxes in the Antarctic Circumpolar
         Current in Drake Passage,  J. Phys. Oceanogr., 41, 1385-1407, 
         doi: 10.1175/JPO-D-10-05017.1.

         Firing, Y. L., Chereskin, T. K.,  and M. R. Mazloff, 2011.
         Vertical structure and transport of the Antarctic Circumpolar
         Current in Drake Passage from direct velocity observations,
         J. Geophys. Res., 116, C08015, doi:10.1029/2011JC006999.

         Gutierrez-Villanueva, M. O., Chereskin, T. K., and Sprintall, J. 2020.
         Upper-ocean eddy heat flux across the Antarctic Circumpolar Current in
         Drake Passage from observations: time-mean and seasonal variability,
         J. Phys. Oceanogr., 50(9), 2507-2527.
         http://dx.doi.org/10.1175/JPO-D-19-0266.1

