
METADATA FOR LMG SHIPBOARD ADCP NB150

#DATA_DATES: 2021/10/07 18:48:00 --- to --- 2021/10/22 16:32:00
#LAT_RANGE: 65.02 S --- to --- 59.79 S
#LON_RANGE: 70.05 W --- to --- 61.48 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 2110
#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        : SVP data gap 283.4805 to the end of the cruise. 
    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
          2021/10/07  18:48:48   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          : 2022-01-26
     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 292.85 to 294.36
             Calculation done at Wed Jan 26 21:42:36 2022
              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: 147 points
          edited:   89 points, 2.0 min speed, 2.5 max dev
                      median     mean      std
          amplitude   0.9840   0.9806   0.0262
          phase       0.0624  -0.1233   1.1976
          
     WATER TRACK METHOD          : yes
           ADCP watertrack calibration
           Time range 281.23 to 292.91
             Calculation done at Wed Jan 26 21:42:37 2022
             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:  29 out of  33
             amp   = 0.9931  + 0.0009 (t - 282.6)
             phase =   0.29  + 0.0982 (t - 282.6)
                      median     mean      std
          amplitude   0.9910   0.9931   0.0122
          phase       0.0770   0.2927   0.6662
          nav - pc    2.0000   3.2414   3.4605
          var         0.0040   0.0061   0.0058
          min var     0.0040   0.0052   0.0053
          delta-u    -1.7100  -0.1093   4.6386
          delta-v    -0.4600   0.5666   4.0960
          
     FINAL SELECTION             : AMPLITUDE= 0.987        PHASE= 0.16
     COMMENTS                    : Because the nb150 velocities did not match the os38nb velocities,
                                 : an historical value of 0.987 was chosen instead of the water
                                 : track calibration of 0.984. , and an historical valued of 0.16 was chosed instead
                                 : of the bottom track calibration of 0.06.  With the historical amp and phase,
                                 : the nb150 and the os38nb velocities are more closely matched.

     AGREEMENT WITH PREVIOUS 
       CRUISES                   : OK
     SOUND SPEED CORRECTIONS     : yes
     COMMENTS                    : In August 2000, a sound velocity probe (SVP)
                                   was installed in the transducer well.
                                   When available, SVP data are used to correct
                                   sound speed at the transducer. Because the SVP was not
                                   working properly for most of the cruise and only 3 days of
                                   SVP data are available, a linear least
                                   squares regression of sound speed from the SVP
                                   versus transducer temperature from the ADCP
                                   is computed.  ss_corrected = b + m * tr_temp
                                   b = 1549.60              m = 3.97

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

