README FILE FOR 2021 BERING STRAIT CTD DATA             Version 25th May 2022
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This is an archive of CTD data from the 2021 Bering Strait mooring cruise.

The cruise was funded by the NSF-Arctic Observing Network grant:
- PLR-1758565 (PIs: Woogate and Peralta-Ferriz). 

The data are from a ~ 10 day cruise 
- on the US vessel Norseman II 
- from 7th-17th July 2021 
- sailing from and to Nome, Alaska, USA 
- to the Bering Strait and southern Chukchi Sea.
The cruise was also to service oceanographic moorings in the strait and those
data are archived separately. 

A total of 276 casts were taken and are included in this archive.
Water samples were taken for trace metals during this cruise using a separate
pumping system (lead: Laramie Jensen). 
Stations were taken in US waters near mooring locations and on sections
in the Bering Strait and southern Chukchi Sea.  See cruise report for
map, station locations, calibration, and processing details. 

The data are taken using an SBE911p system, recording 
- pressure 
- temperature (dual system)
- conductivity (dual system)
- oxygen (dual system)
- fluorescence
- turbidity.

For an overview of previous and on-going Bering Strait mooring work,
please see http://psc.apl.washington.edu/BeringStrait.html.

For details of the measurements and their interpretation, please see:
   Woodgate, R.A., K.M.Stafford and F.G.Prahl (2015) A synthesis of
   year-round interdisciplinary mooring measurements in the Bering
   Strait (1990-2014) and the RUSALCA years (2004-2011), Oceanography
   28(3):46-67, doi:10.5670/oceanog.2015.57

Please cite that reference for the data. 

For queries, please contact:
   Rebecca Woodgate   woodgate@uw.edu   (206) 221-3268
   Polar Science Center, Applied Physics Lab, University of Washington
   1013 NE 40th, Seattle, WA  98105-6698   USA

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Meta data
=========

1) Platform: SBE911p CTD system on board the RV Norseman II

2) Project title: Bering Strait

3) Data collection dates: 7th-17th July 2021

4) PI:   Rebecca Woodgate (woodgate@uw.edu)

5) Data collection method:
     Hydrographic casts (no water samples)

6) Data calibration method:
     Instrument calibrated by manufacturers prior to deployment.
        Pressure calibrated June 2019
        Temperature calibrated January 2021
        Conductivity calibrated February 2021
        Oxygen calibrated February 2021
        Fluorescence / Turbidity calibrated  March 2010
     All times are given in GMT.
     All positions and times are from ship's Bridge NMEA.
     For SBEs, calibration and processing details are in file header.

7) Instrumentation used:
     Sea-Bird SBE911p system sampling at 24Hz with
         two SBE3F temperature sensors
         two SBE4C conductivity sensors
         two SBE43 Oxygen sensors
         one Wetlabs FLNTURT fluorescence/turbidity sensor
         one Benthos altimeter (data only intermittently reliable)
         two SBE pumps

8) Quality control procedures:
     Basic quality control provided by Rebecca Woodgate.
     CTD processing by SBE software as described in cruise report and file headers. 
     Fluorescence/turbidity sensor cleaned prior to each cast. 

9) Data format:
     Bstrait21nnn.hex data - as collected
     Bstrait21nnn.XMLCON - calibration coefficients
     Bstrait21nnnA00B15AdvOx34CTML7m4m18p5mndpDMF17.cnv
                         - processed data (at native time resolution)
     Bstrait19nnnA00B15AdvOx34CTML7m4m18p5mndpDMF17BADCS010.cnv
                         - processed data averaged to 1m bins from downcast
     nnn gives cast number
     Time (GMT), Latitude and longitude are recorded in the data files	
      
10) Data collection problems:
	Altimeter data - the Benthos altimeter only returned believable data for some 
       casts. Thus water depths should be taken from the event log in the cruise report.
     For casts up to and including 9, the system was deployed without the TSduct, leading
	  to mismatch in conductivity versus temperature measurements.  Subsequent casts 
       were deployed with the TS duct installed, and thus these first 9 casts (primarily
       calibration casts for near bottom instrumentation) have not been specially processed.
     Cast 10 was deployed (as an experiment) without the pump being turned on
     Cast 25 was relowered after the main cast (as another experiment).  Full cast is
       retained in this archive as 025orig, but cast trimmed to original lower and raise
       only is included as 025. 
	Cast 114 was aborted as CTD came out of the water during soak.  Recast as 115.
	Cast 172 gave erroneous downcast readings likely due to blocked vent plugs.
        Recast as 173
	Cast 222 is suspected to have hit bottom.  Oxygen data on up cast are suspect.
	Vent plug issues are suspected on casts 42, 62, 63, 117, 
     Many casts struggle with sharpness of thermocoline giving erroneous signals in 
        salinity.  These issues appear to be resolved in the aligning process.
     Many casts struggle with sharpness of thermocoline giving erroneous signals in 
        oxygen.  These issues are somewhat but not entirely resolved in the aligning process.
  
     Salinity (from conductivity) senors show an offset of 0.006psu, varying during
       the cruise.  As no water samples were taken we cannot ascertain which sensor 
       is correct.  See cruise report for more details. 

11) Other related data sets:
       This data set is a part of a suite of measurements made in the
       Bering Strait almost continuously since 1990.  Mooring data have
       already been archived via the SBI project, managed by JOSS/EOS,
       and at NODC.
       For details see
        http://psc.apl.washington.edu/BeringStrait.html
        http://www.eol.ucar.edu/projects/sbi/
        http://sbi.utk.edu/
        http://www.nodc.noaa.gov
       Since 2000, CTD sections have been run in the Bering Strait on
       the mooring cruises.  These data are also accessible via the http
       links above.

12) Conditions for use or citation:
       Data freely available
       Please, as a courtesy, contact the PIs before using these data and cite as
           Woodgate, R.A., K.M.Stafford and F.G.Prahl (2015) A synthesis of
             year-round interdisciplinary mooring measurements in the Bering
             Strait (1990-2014) and the RUSALCA years (2004-2011), Oceanography
             28(3):46-67, doi:10.5670/oceanog.2015.57

13) Data qualifications or warnings:
       See also Data collection problems.
       SBE data: Standard Sea-Bird limitations apply
           - pressure 0.015% of FSR (6800m), i.e., ~ 1m (calibration suggests 0.6m)
           - temperature 0.001degC
           - Conductivity 0.0003S/m
               Combined errors equivalent to salinity error of ~0.008psu

14) Grant numbers:
      Work funded by:
      - National Science Foundation (NSF) Arctic Observing Network (AON)
      program, grant PLR-1758565 (PI: Woodgate and Peralta-Ferriz)

15) Sample repository locations:
        National Ocean Data Center/National Centers for Environmental
          Information (http://www.nodc.noaa.gov)
        University of Washington (http://psc.apl.washington.edu/HLD)

16) Please use the following citation for these data:
   Woodgate, R.A., K.M.Stafford and F.G.Prahl (2015) A synthesis of
       year-round interdisciplinary mooring measurements in the Bering
       Strait (1990-2014) and the RUSALCA years (2004-2011), 
       Oceanography, 28(3):46-67, doi:10.5670/oceanog.2015.57

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FILE LISTING
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Total number of files:  1114 including 3 subdirectories.
Total number of casts: 276  (also cast 0 and two versions of 25 = 278 file sets)

Size (b)   Name
---------  ----
= Metadata file (1 file)
     9356 Bering_Strait_CTD_July2021_NSFAON_ReadMe_versMay2022.txt

= Cruise report (1 file)
 18440418 BeringStrait2021CruiseReport_Norseman2_24thMay2022withEventLog.pdf

.. and the 3 subdirectories: 

== One subdirectory of SBE .hex and .XMLcon calibration files (556 files)
./BeringStraitCTD_hexandXMLCON:
Bstrait21nnn.hex and BSTRAIT21nnn.XMLCON where nnn is cast number, e.g.,
 287553  Bstrait21001.hex
   9958  BSTRAIT21001.XMLCON

== One subdirectory of processed data at native time resolution (278 files)
./BeringStraitCTD_processed:
Bstrait21nnnA00B15AdvOx34CTML7m4m18p5mndpDMF17.cnv where nnn is cast number, e.g.,
 997465 Bstrait21001A00B15AdvOx34CTML7m4m18p5mndpDMF17.cnv

== One subdirectory of processed data averaged to 1m bins from the down cast (278 files)
./BeringStraitCTD_Binaveraged:
Bstrait21nnnA00B15AdvOx34CTML7m4m18p5mndpDMF17BADCS010.cnv where nnn is cast number, e.g.,
 `4906 Bstrait21001A00B15AdvOx34CTML7m4m18p5mndpDMF17BADCS010.cnv


+++++++++ END OF FILE LISTING ++++++++++++++++++++++++++++++ 