30 September 2003
Title:  Arctic Nutrient Database  
File:  Arctic_Nutrient_Db_v3g.mdb
Data Version: 3g, 29 Sep 2003


Authors: 
Glenn Cota 
Center for Coastal Physical Oceanography
768 W 52nd St Crittenton Hall 
Old Dominion University
Norfolk VA 23508
Phone: 757.683.5835
Fax: 757.683.5550
Email: cota@ccpo.odu.edu
Web: www.ccpo.odu.edu/~orca

Larry Pomeroy
University of Georgia
Institute of Ecology
Athens GA 30602-2202
Phone: 706.542.3415
Fax: 706.542.6040
Email: lpomeroy@ecology.uga.edu
Web:

Data Set Overview: www.ccpo.odu.edu/~orca/sbi.htm

Data Format: 
Microsoft Access 2002 Database 
	Four linked tables: country, cruise, station, and profile.

	Country: Country Code (CC) and Country Name.
	Cruise: Country Code and Cruise code/name.
	Station: Station information, Quality Control Flags, and other (see below).
	Profile: profile sample data (see below).

	The tables are linked by Country Code to Cruise to Station.

Data Remarks:  
This is the intermediate version of the Cota - Pomeroy Arctic Nutrient Database.  
It will be revised and updated as additional and new data is acquired.  
Standard disclaimers of data quality apply.  



Station Table parameter and units:

QC: Quality Control flags codes, see below for types and code definitions.
Cruise:  Unique cruise ID for database table link
Station:  Unique station number for database table link
OSN:  Original Station Number or code from the cruise, or an alternate listing.
Latitude, Longitude: Decimal degree, positive north and east
YYYY, MM, DD: Year, month, and day
Time: Decimal hours (GMT)
Julian Day: Julian day
sounding:  Sounding depth included with original data (m)
predicted sounding: Sounding depth interpolated from IBCAO data (m)
Mlz: Modified layer depth (m), or 1.11 for an undetermined mlz.
O2_Mlz:  O2 Modified layer depth (m)
Max_z:  Maximum profile sample depth (m)
Prod_Integ_1%:  Integrated Production to the 1% light level (g C/m^2/yr)
Prod_Integ_0_1%:  Integrated Production to the 0.1% light level (g C/m^2/yr)
transparency:  Water transparency or Secchi depth (m)
water color:  Water color, NODC WOD98 code appendix 2C


Profile Table parameters and units:

Station:  Unique station number for database table link
z:  Sample depth (m)
T:  Temperature (C)
Sal:  Salinity (psu) and (ppt)
O2:  Dissolved Oxygen (ml/l)
O2_Solublty: O2 saturation (ml/l)
XS_O2: Saturation state (ml/l)
PO4:  Phosphate (mM)
SiO3:  Silicate (mM)
NO2:  Nitrite (mM)
NO3:  Nitrate (mM)
NO2+NO3: (mM)
NH4:  Ammonia (mM)
Chl:  Chlorophyll (mg/m^3)
phaeo:  Phaeophytin (mg/m^3)
POC:  Particulate Organic Carbon ()
Prod:  Production (g C/m^2/yr)
NO3/PO4:  N/P ratio
NO3/SiO3:  N/Si ratio 
NO:  see analyses section below
PO:  see analyses section below
NO/PO:  ratio
N*(N_star):  (uM/kg)
N**(Ndbl_star):  (uM/kg)



Nutrient/Oxygen Data Analyses: Variables, Equations, and Units

Definitions and Notes:

Missing sounding depths from the input data were filled in with interpolated depths from IBCAO data.  These predicted soundings in the “sounding” depth column are tagged with a .9.  If the deepest profile depth was greater than but within 10% of the predicted depth the profile depth was used with a .9 tag.  If less than 10% of the predicted depth the sounding field was left blank.  A zero in the predicted sounding field indicates an above water elevation was found in the IBCAO data or four surrounding points could not be found in the data for an interpolation.  

Modified Layer depth (Mlz) values of 1.11 are filling blank spaces until depths can be determined.  These are also tagged with a “c” in the QC field.

Constant column (cc) and winter (w) stations have their deepest profile depth as their Mlz.

In most cases, station profiles with three or less profile samples were removed from the database.

QC Flags: (Station Table)

c - stations are flagged stations to "checked" later for various reasons.
cc - stations are "constant column" stations showing no vertical stratification.
co - chlorophyll only stations
e - stations are "estuarine" stations which have a salinity of ~<= 10 psu throughout the profile not just in the first few meters, could be problematic in river plumes and in melt-water lenses of marginal ice zones
s - stations are "shallow" stations which the soundings are <= 50 m.  
w – winter profile type stations in spring, (no positive XS_O2, but not a cc).

Variables: (Profile Table)

[NO3] = nitrate (mM)

[NO2] = nitirite (mM)

[NH4] = ammonium (mM)

[PO4] = phosphate (mM)

[SiO3] = silicate (mM) or Si(OH)4 silicic acid

[O2] = dissolved oxygen (conversion: ml/l *44.66 = umol/kg) 
(refs: Carpenter 65 & others)


Layer Definitions:

MLz = Modified Layer depth (m), User defined phys/chem/bio upper layer.

SLz = Surface Layer depth (m), (depths: 0 <= MLz)

LLz = Lower Layer depth (m), (depths > MLz to sounding or last depth sampled)

O2_Mlz = O2 Modified Layer depth (m), Interpolated depth of O2 saturation.


Derived Products:

NO3/PO4 = N/P ratio (dimensionless)

NO3/SiO3 = N/Si ratio (dimensionless)

NO ("no") = 9[NO3] + O2 (Broecker 1974)

PO ("po") = 135[PO4] + O2 (Broecker 1974)

NO/PO ("no/po ratio") = (dimensionless)

N* ("N-star")= (NO3 - 16PO4 + 2.9) * 0.87 (uM/kg) (Gruber and Sarmiento 1997)

N** ("N-double star") = ((NO3+NO2+NH4) - 16PO4 + 2.9) * 0.87 (uM/kg) (Codispoti pers. comm.)

O2_Solublty = O2 saturation (see Oxygen computations section below)

XS_O2 = O2 observed - O2_Solublty (see Oxygen computations section below)


Secondary Product Computations:
Depth Interval = depth j - depth i (always starts at ocean surface z = 0)

Oxygen computations:
O2 saturation = lnC0* = Ao + A1Ts + A2Ts2 +A3Ts3 + A4Ts4 + A5Ts5 + S(B0 + B1Ts + B2Ts2 + B3Ts3) + C0S2  (umol kg-1). (Garcia and Gordon 1992)   
Conversion factor=divide by 1.02=umol/kg (Millero 1996)
XS_O2 (saturation state) = (O2 observed - O2@saturation) * 44.66 = (uM/l) (Carpenter 1965)