NB.  This document is subject to updates when data become available and issues
become known or resolved.

Filenaming convention
=====================
<buoy_id>_QC_buoy_YYYYJJJ-yyyyjjj.txt

where buoy_id is L4 or E1
YYYY is the start year
JJJ is the start julian day
yyyy is the end year
jjj is the end julian day


Data description
================
The data contained in the QC files has been essentially cleaned up from the 30
second acquisition bursts measured by each buoy.  Generally for each instrument
(WQM - in water bio-geochemical measurements; CDM - in water CDOM fluorescence;
NLF - in water nitrate measurements; MPB - meteorological parameters; HSE -
hyperspectral irradiance; PHL - SeapHet pH) it is an average of 30 - 60 individual measurements. 
The main instrument is the WQM (temperature, salinity, oxygen, chlorophyll,
suspended particulate matter) and all data are merged to these measurements.

The header in each file gives the data type:

Year Jd  Time    Dyear         Lat      Lon     nw  nc  nn  nm np  SST   SST_sd  Sal   Sal_sd   Oxy  Oxy_sd  Chl  Chl_sd  SPM   SPM_sd    CDM    CDM_sd  Nit  Nit_sd Prs       Prs_sd Ta      Ta_sd   Hum      Hum_sd   U      U_sd    V      V_sd  PAR  pH1   pH2

Year - year
Jd   - Serial (Julian) day of year
Dyear - decimal year
Lat - latitude measured in degrees and decimal minutes i.e. 50.026 is 50 degrees
2.6 minutes
Lon - Longitude measured in degrees and decimal minutes
nw - number of WQM measurements in averaging
nc - number of CDM measuremnets in averaging
nm - number of meteorological measurements in averaging
np - number of PAR measurements in averaging
SST - sea surface temperature (at depth of 1.5 m) in degC
SST_sd - SST standard deviation over period of measurements
Sal - salinity at depth of 1.5 m in PSU
Sal_sd - salinity standard deviation
Oxy - Oxygen concentration in uM / kg
Oxy_sd - oxygen concencentration standard deviation
Chl - chlorophyll concentration mg/m3
Chl_sd - chlorophyll concentration standard deviation
SPM - suspended particulate matter concentration (Nephelitic Turbidity Unit)
SPM_sd - SPM standard deviation
CDM - CDOM fluorescence (Quinine Sulphate fluorescence Units - QSU)
CDM_sd - CDOM standard deviation
Nit - Nitrate concentration (uM) - this has been calibrated against in situ
measurements and corrections applied
Nit_sd - Nitrate concentration standard deviation
Prs - Atmospheric pressure (mb)
Prs_sd - Atmospheric pressure standard deviation
Ta - Air temperature (deg C) - about 4 m above sea surface
Ta_sd -  Air temperature standard deviation
Hum - Relative Humidity (%) - about 4 m above sea surface
Hum_sd - Relative Humidity (%) standard deviation
U - zonal (W/E) wind speed (m/s)
U_sd - zonal wind speed standard deviation
V - meridional (S/N) wind speed (m/s)
V_sd - meridional wind speed standard deviation
PAR - Photosynthetically Active Radiation (W/m2) - calculated from hyperspectral
irradiance sensor - hyperspectral data is available on request
pH1 - pH measured using SeapHet (2014 onwards): external channel **USE THIS ONE**
pH2 - pH measured using SeapHet (2014 onwards): internal channel

Buoy specific information and data quality issues
=================================================
L4
==
Dates of deployment
===================
2009 076 - 347: deployment at L4.  Storms hit the buoy around day 317 and crippled some of the systems before she was finally brought in around day 347.  During that period the data are reliable but intermittant.
2010 100 - 343 - deployment at L4.  The buoys were then switched around with the
E1 buoy being deployed at L4
2010 344 - 2011 061: deployment at L4 using the E1 buoy hull and instruments.
2011 061 - 2011 286: deployment at L4 using L4 buoy hull.  Power issues cut
deployment short.

Update: dates of deployment for each year are now in the filenaming convention

Known issues
============
During 2011 there were several periods of bio-fouling which are difficult to
interpret or form a definitive data for start points.  The occurrences are
obvious from the data and are shown as sharp and unrealistic peaks in the
chlorophyll, CDOM and turbidity sensors.  The temperature and salinity are
unaffected by this.

Instument details
=================
HSE - Satlantic hyperspectral downwelling irradiance - unit 0298: calibrated 13/12/2007
CDM - WetLabs ECO CDOM fluorometer - S/N FLCDS-1302: calibrated 11/2/2009
StorX unit 052
NLF - Satlantic ISUS nitrate sensor - S/N 0167: calibrated 3/12/2007 - baseline correction checked in August 2008 found to be OK - although need for correction against in situ data in the field
GPS, MPB - AirMar PB100 met head 3772 - unsure when calibrated - although sometime before 17/12/2007; does both GPS and met data.
WQM - Wetlabs WQM sensor - S/N 0032 for 2008 data; S/N ***** for 2009 data - calibrated 11/2/2009

NB. The instruments for the period 2010 344 - 2011 061 used the E1 buoy setup
 - see below.

E1
==
Dates of deployment
===================
2008 - some useable data before instruments dropped off the rig
2009 218 - 319: 100 days in the field before power systems failed.  Problem
early on the in deployment with power and data communications (227 - 264)
2010 160 - 201: large storm on St. Swithin's day crippled power, just as a large
bloom was occurring.
2011 076 - 318: power issues affected acquisitions later on.  Bio-fouling an
issue during June and September.  Need to look at the bio-optical data carefully before
using.

Update: dates of deployment for each year are now in the filenaming convention

Instument details
=================
HSE - Satlantic hyperspectral downwelling irradiance - unit 0297: calibrated 13/12/2007
CDM - WetLabs ECO CDOM fluorometer - S/N FLCDS-: calibrated 11/2/2009
StorX unit
NLF - Satlantic ISUS nitrate sensor - S/N 
GPS, MPB - AirMar PB100 met head; does both GPS and met data.
WQM - Wetlabs WQM sensor - S/N 

All enquiries to Tim Smyth.  All data should be used with care and if any
publications arise, please contact:

tjsm@pml.ac.uk

============
Tim Smyth
1/9/2014