
METADATA FOR LMG SHIPBOARD ADCP NB150

#DATA_DATES: 2019/12/03 01:23:00 --- to --- 2019/12/19 08:42:00
#LAT_RANGE: 64.88 S --- to --- 52.77 S
#LON_RANGE: 67.98 W --- to --- 60.61 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 1911
#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                : RDI
     HARDWARE MODEL              : VM-150
     SERIAL NUMBERS              : transducer SN 536; chassis SN 631
     FIRMWARE VERSION            : 17.12 (but reported as 17.10)
    <the following 5 fields are specific to a given hardware model>
     TRANSMIT FREQUENCY          : 153.6 kHz
     TRANSDUCER CONFIGURATION    : JANUS CONCAVE
     ACOUSTIC BEAM WIDTH         :
     TRANSDUCER BEAM ANGLE       : 30 deg.
     COMMENTS                    :

ADCP INSTALLATION
  METHOD/DESCRIPTION OF THE
       ATTACHMENT TO THE HULL    : The NB150 transducer is installed in the forward,
                                   starboard well, accessed from the bow thruster room.
                                   The sonar well is approx. 28x28x25 inches (lxwxh).
                                   The acoustic window installed at the bottom of the well is
                                   17x17x2 inches and made of polyurethane.
                                   The ADCP transducer is bolted to a steel mounting
                                   plate that is secured to 4 tabs, one welded to each
                                   wall of the well. Eight bolts are used to secure
                                   the transducer to the plate, and eight bolts are used
                                   to secure the plate to the tabs (2 per tab). All 4
                                   sonar wells on the LMG are in a submerged pod whose 
                                   streamlined shape deflects ice and bubbles. The orientation
                                   of the transducer is beam 3 points 45 degrees to the starboard
                                   side of forward.
     LOCATION/DEPTH ON HULL      : nominally at 6 m
     REPEATABLE ATTACHMENT       : The ADCP mounting fixture allows a small amount of
                                   variation in transducer orientation relative to the ship.
                                   Once the bolts are secure, the orientation does not change.
                                   The maximum variation between installations is estimated at 2
                                   degrees. There is a procedure in place to produce a repeatable
                                   installation. When it is followed, the procedure produces
                                   an installation repeatable to better than 1 degree.
     DATE OF MOST RECENT ATTACH. : August 1999 (Note: LMG shipyard periods are normally during the
                                   months June-August. While we do not always know whether the
                                   transducer installation changed during a shipyard period, August
                                   1999 was the initial installation on the LMG.)
     ACOUSTIC WINDOW             : YES, polyurethane.
     COMMENTS                    : The transducer is mounted in a well behind a polyurethane
                                   window. The well is filled with an antifreeze solution.
                                   Higher glycol concentration results in higher sound speed.
                                   Prior to 2005/5/15: 30%  ethylene glycol/70% fresh water
                                   After 2005/5/15:    10% propylene glycol/90% fresh water
                                   After 2009/9:       12% propylene glycol/88% fresh water
                                   After 2012/9:      unk% propylene glycol/unk% fresh water
                                   After 2014/06/01:    unk% propylene glycol/unk% fresh water
                                   After 2017/07/01:    unk% propylene glycol/unk% fresh water
                                   After 2019/10/01:    unk% propylene glycol/unk% fresh water

ADCP INSTRUMENT CONFIGURATION     
     DEPTH RANGE                 : 22 m --- to --- 414 m 
     BIN LENGTH                  : 8 m
     NUMBER OF BINS              : 50
     TRANSMIT PULSE LENGTH       : 8 m
     BLANKING INTERVAL           : 8 m
     ENSEMBLE AVERAGING INTERVAL : 300 s
     SOUND SPEED CALCULATION     : 
     BOTTOM TRACKING             : in shallow water, see comments.
     DIRECT COMMANDS             :
     COMMENTS                    : BOTTOM TRACKING - Typically, bottom tracking is ON when in shallow water,
					such as the Patagonian Shelf or the Bransfield Strait.   
					Using UHDAS software for the nb150,  the output from  
                                        CODAS lst_conf.cnt (below) in does not differentiate whether
				   	bottom tracking is ON or OFF.  
          
           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
          2019/12/03  01:23:02   0    on   300  50    8  8  6  8    2 20    45.00   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     : yes
     DATE OF PROCESSING          : May 13 2020
     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.

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 336.06 to 352.36
             Calculation done at Wed May 13 19:25:18 2020
              step: 1
              min_depth:  20   max_depth: 800
              min_speed:  2.0 m/s   max_sig:  2.5 std devs
              max_gap:  0.10 minutes   tol_dt: 0.02 (fraction)
          unedited: 1614 points
          edited:   910 points, 2.0 min speed, 2.5 max dev
                      median     mean      std
          amplitude   0.9885   0.9881   0.0051
          phase       0.1501   0.1522   0.2535
          
     WATER TRACK METHOD          : yes
           ADCP watertrack calibration
           Time range 337.80 to 349.68
             Calculation done at Wed May 13 19:25:18 2020
             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:  23 out of  25
             amp   = 0.9841  + 0.0001 (t - 341.2)
             phase =   0.08  + 0.0475 (t - 341.2)
                      median     mean      std
          amplitude   0.9840   0.9841   0.0089
          phase       0.1660   0.0794   0.9104
          nav - pc    1.0000   1.6087   4.1750
          var         0.0060   0.0063   0.0039
          min var     0.0050   0.0060   0.0037
          delta-u    -2.4600  -1.0378   3.8155
          delta-v    -0.0300  -0.0065   3.5047
          
     FINAL SELECTION             : AMPLITUDE= 0.987        PHASE= 0.15
     COMMENTS                    : Because the nb150 velocities did not match the os38nb velocities,
                                 : a historical value of 0.987 was chosen instead of the water
                                 : track calibration of 0.984.  Using a final amplitude of 0.987,
                                 : the nb150 and the os38nb velocities are more closely matched.

     AGREEMENT WITH PREVIOUS 
       CRUISES                   : OK
     SOUND SPEED CORRECTIONS     : yes
     COMMENTS                    : After the shipyard period in June 2014, the antifreeze mixture in the
                                   transducer wells was changed. Sound velocities determined from a sound
                                   velocity probe (SVP) in the NB150 well were very high (above 1700 m/s
                                   during lg1409), and the SVP time series recorded over multiple cruises
                                   indicated that the antifreeze concentration was changing from the first
                                   post-shipyard cruise, lg1406. Our prior method of fitting a linear
                                   relation between sound velocity and temperature no longer gave good
                                   results because temperature was no longer the main factor determining
                                   the sound velocity. Instead, we use the SVP directly to estimate the
                                   sound speed at the transducer for each 5-min ensemble. The sound velocity (SV)
                                   recorded from the probe at a sampling rate of about 1 Hz was averaged to 1-minute 
                                   intervals.  SV was then interpolated to the 5-min ensemble times. The results
                                   compared well to a ratio method, where the NB150 forward velocity was
                                   regressed against the OS38 forward velocity (the OS does not need a
                                   sound speed correction). The OS38/NB150 ratio provides a scale factor
                                   correction to the original sound speed used (seawater) and can be
                                   compared to the ratio of SV/seawater. The two methods track each other
                                   reasonably well, showing the same patterns versus time and temperature
                                   and a similar range of SV values.

NAVIGATION CALCULATION             
     NAVIGATION USED             : GPS
     REFERENCE LAYER DEPTH RANGE : 4 to 12, 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                    : 
     COMMENTS                    : An offset 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

