**PI:** Robert Williams, Wilford Gardner
**of:** R. Williams, Scripps Institue of Oceanography
W.Gardner, Texas A and M Univ.
**dataset:** High resolution CTD and beam attenuation data
**dates:** April 20, 1989 to June 06, 1989
**location:** N: 59.7418 S: 41.104 W: -23.022 E: -17.6433
**project/cruise:** North Atlantic Bloom Experiment/Atlantis II 119, leg 4 and 5
**ship:** R/V Atlantis II
**Methodology**
CTD and analytical procedures (Williams)
Beam attenuation (Gardner)

## Depth calculation for the CTD data files

The depth values in these CTD files have been calculated from pressure by the US JGOFS Data Management Office using the algorithm below. The latitude used in computation was the latitude recorded in the CTD data file. The CHECKVALUE was used to verify the accuracy of the computation. The stated accuracy of this algorithm is 0.1 meters. The calculated depths have been rounded to the nearest whole meter.

function DEPTH=depth(P,LAT); DEPTH Computes depth given the pressure at some latitude D=DEPTH(P,LAT) gives the depth D (m) for a pressure P (dbars) at some latitude LAT (degrees). Fofonoff and Millard (1982). UNESCO Tech Paper #44. Notes: (ETP3, MBARI) This algorithm was originally compiled by RP @ WHOI. It was copied from the UNESCO technical report. The algorithm was endorsed by SCOR Working Group 51. The equations were originally developed by Saunders and Fofonoff (1976). DSR 23: 109-111. The parameters were re-fit for the 1980 equation of state for seawater (EOS80). CHECKVALUE: D=9712.653 M FOR P=10000 DECIBARS, LAT=30 DEG CALCULATON ASSUMES STD OCEAN: T = 0 DEG C; S = 35 (IPSS-78) X = sin(LAT/57.29578); X' = X*X; GR = GRAVITY VARIATION WITH LAT: ANON (1970) BULLETIN GEODESIQUE GR = 9.780318*(1.0+(5.2788E-3+2.36E-5*X')*X') + 1.092E-6*P D = DEPTH BEFORE GRAVITY CORRECTION D = (((-1.82E-15*P+2.279E-10)*P-2.2512E-5)*P+9.72659)*P DEPTH = D/GR