OCS Study 

MMS 95-0027 

Louisiana/Texas Shelf 

Physical Oceanography Program : 

Eddy Circulation Study 

Annual Report : Year 2 

U .S. Department of the Interior 

bw 

Minerals Management Service 

Gulf of Mexico OCS Region 
OCS Study 

MMS 95-0027 

Louisiana/Texas Shelf 

Physical Oceanography 

Eddy Circulation Study 

Annual Report : Year 2 

Author 

Science Applications International Corporation 

Prepared under MMS Contract 

14-35-0001-30633 

by 

Science Applications International Corporation 

615 Oberlin Road, Suite 300 

Raleigh, North Carolina 27605 

Published by 

Program : 

U.S . Department of the Interior 

Minerals Management Service New Orleans 

Gulf of Mexico OCS Region May 1995 
111 

DISCLAIMER 

This report was prepared under contract between the Minerals 

Management Service (MMS) and Science Applications International 

Corporation (SAIL) . This report has been technically reviewed by 

the MMS and approved for publication . Approval does not signify 

that the contents necessarily reflect the views and policies of the 

Service, nor does mention of trade names or commercial products 

constitute endorsement or recommendation for use . It is, however, 

exempt from review and compliance with MMS editorial standards . 

REPORT AVAILABILITY 

Extra copies of the report may be obtained from the Public 

Information Unit (Mail Stop 5034) at the following address : 

U .S . Department of the Interior 

Minerals Management Service 

Gulf of Mexico OCS Region 

Public Information Unit (MS 5034) 

1201 Elmwood Park Boulevard 

New Orleans, Louisiana 70123-2394 

Telephone Number : 1-800-200-GULF 

(504) 736-2519 

CITATION 

Suggested citation : 

Science Applications International Corporation . 1995 . Louisiana/ 

Texas Shelf Physical Oceanography Program : Eddy Circulation 

Study, Annual Report : Year 2 . OCS Study MMS 95-0027 . U .S . 

Department of the Interior, Minerals Management Service, Gulf 

of Mexico OCS Region, New Orleans, La . 63 pp . 
v 

TABLE OF CONTENTS 

Section Title Paae 

List of Figures . . . . . . . . . . . . . . . . . . . . . . vii 

List of Tables . . . . . . . . . . . . . . . . . . . . . . , xi 

I . INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 1 

II . OVERVIEW AND CHRONOLOGY OF INDIVIDUAL TASKS . . . . . . 3 

2 .1 Task C-l : Drifting Buoys Provided to Other 

Contractors . . . . . . . . . . . . . . . . . . . 3 

2 .2 Task C-2 : Drifting Buoys in Loop Current Eddies 3 

2 .3 Task C-3 : Drifting Buoys in Other Meso-Scale 

Features . . . . . . . . . . . . . . . . . . . . . 5 

2 .4 Task C-4 : Returned Buoys . . . . . . . . . . . . . 6 

2 .5 Task C-5 : Buoy Quality Control . . . . . . . . . . 6 

2 .6 Task C-6 : Aerial Surveys . . . . . . . . . . . . . 6 

2 .7 Task C-7 : Altimetry . . . . . . . . . . . . . . . 7 

2 .8 Task C-8 : Ships-of-Opportunity . . . . . . . . . . 9 

2 .9 Task C-9 : Data Quality Control . . . . . . . . . . 9 

2 .10 Task C-10 : Analyses and Reports . . . . . . . . . 10 

2 .11 Task C-11 : Information Transfer . . . . . . . . . 10 

2 .12 Task C-12 : Government Furnished Equipment /Capital 

Equipment . . . . . . . . . . . . . . . . . . . . 11 

III . DETAILS OF DATA COLLECTION AND ANALYSIS . . . . . . . . 13 

3 .1 Aerial Surveys and Drifting Buoy Deployments . . . 13 

3 .1 .1 Slope Surveys . . . . . . . . . . . . . . 13 

3 .1 .2 Loop Current Eddies . . . . . . . . . . . 26 

3 .1 .3 Squirts and Jets Surveys . . . . . . . . . 26 

3 .2 Task C-7 : Altimetry . . . . . . . . . . . . . . . 38 

3 .3 Data Quality Control . . . . . . . . . . . . . . . 48 

3 .3 .1 Hydrographic Profile Data . . . . . . . . 54 

3 .3 .2 Lagrangian Data . . . . . . . . . . . . . 60 

IV . REFERENCES . . . . . . . . . . . . . . . . . . . . . . 63 
V11 

LIST OF FIGURES 

Figure Caption Paae 

3 .1-1 Plan for Year 2 Slope Surveys . . . . . . . . . . . 15 

3 .1-2 Station plot for surveys F08SLOPE and 

F09SEDDY . . . . . . . . . . . . . . . . . . . . . 16 

3 .1-3 Flight tracks used during special photo 

mission along ERS-1 ground tracks . . . . . . . . . 17 

3 .1-4 Depth of 20°C isotherm from F08SLOPE and 

F09SEDDY AXBT data . . . . . . . . . . . . . . . . 18 

3 .1-5 Depth of 15°C isotherm from F08SLOPE and 

F09SEDDY AXBT data . . . . . . . . . . . . . . . . 19 

3 .1-6 Depth of 8°C isotherm from F08SLOPE and 

F09SEDDY AXBT data . . . . . . . . . . . . . . . . 20 

3 .1-7 East-west 800 m section at approximately 

27°05'N from F08SLOPE and F09SEDDY AXBT data . . . 21 

3 .1-8 Station plot for surveys FlOSLOPE and 

F1ILEDDY . . . . . . . . . . . . . . . . . . . . . 22 

3 .1-9 Depth of 20°C isotherm from FlOSLOPE and 

F1ILEDDY AXBT data . . . . . . . . . . . . . . . . 23 

3 .1-10 Depth of 15°C isotherm from FlOSLOPE and 

F1ILEDDY AXBT data . . . . . . . . . . . . . . . . 24 

3 .1-11 Depth of 8°C isotherm from F10SLOPE and 

F1ILEDDY AXBT data . . . . . . . . . . . . . . . . 25 

3 .1-12 East-west 800 m section at approximately 

26°05'N from F10SLOPE and F1ILEDDY AXBT data . . . 27 

3 .1-13 Station plot for survey F12SLOPE . . . . . . . . . 28 

3 .1-14 Depth of 20°C isotherm from F12SLOPE AXBT data . . 29 

3 .1-15 Depth of 15°C isotherm from F12SLOPE AXBT data . . 30 

3 .1-16 Depth of 8°C isotherm from F12SLOPE AXBT data . . . 31 
viii 

LIST OF FIGURES (continued) 

Figure Caption Pacre 

3 .1-17 East-west 800 m section at approximately 

26°22'N from F12SLOPE AXBT data . . . . . . . . . 32 

3 .1-18 Station plot of FlOSLOPE and F1ILEDDY in 

opcplot format . . . . . . . . . . . . . . . . . . 33 

3 .1-19 Depth of the 15°C isotherm only from survey 

F1ILEDDY AX BT data . . . . . . . . . . . . . . . . 34 

3 .1-20 Plot of Drifter 2448 during period August 1-7, 

1993 and the depth of the 15°C isotherm from 

FlOSLOPE and F1ILEDDY AXBT data . . . . . . . . . 35 

3 .1-21 Station plot for survey F14LEDDY . . . . . . . . . 36 

3 .1-22 Depth of the 20°C isotherm from F14LEDDY AXBT data 37 

3 .1-23 Station plot for surveys F13SQURT and F14LEDDY . . 39 

3 .1-24 Depth of the 20°C isotherm from F13SQURT and 

F14LEDDY AXBT data . . . . . . . . . . . . . . . . 40 

3 .1-25 Depth of the 15°C isotherm from F13SQURT and 

F14LEDDY AXBT data . . . . . . . . . . . . . . . . 41 

3 .1-26 Depth of the 8°C isotherm from F13SQURT and 

F14LEDDY AXBT data . . . . . . . . . . . . . . . . 42 

3 .1-27 East-west 800 m section at approximately 

27°00'N from F13SQURT and F14LEDDY AXBT data . . . 43 

3 .1-28 Station plot for F13SQURT AXCP survey . . . . . . 44 

3 .1-29 Currents above the 15°C isotherm from 

F13SQURT AXCP data and tracks of drifters 

7842 and 7843 . . . . . . . . . . . . . . . . . . 45 

3 .2-1 Dynamic height anomalies in the Gulf of 

Mexico from TOPEX and ERS-1 altimeter data 

relative to the corrected Rapp mean surface . . . 47 
1X 

LIST OF FIGURES (continued) 

Figure Caption Page 

3 .2-2 Dynamic heights across central Gulf of Mexico 

from TOPEX and ERS-1 altimeter data and 

hydrographic data along track of R/V GYRE 

cruise 92G13 . . . . . . . . . . . . . . . . . . . 49 

3 .2-3 Sea surface height anomaly in the Gulf of 

Mexico from TOPEX Cycle 7 and ERS-1 data . . . . . 50 

3 .2-4 Current velocities derived from TOPEX and ERS1 altimetry data and positions of drifter 

2447 . . . . . . . . . . . . . . . . . . . . . . . 51 

3 .2-5 Current velocities derived from TOPEX and ERS1 altimetry data and positions of drifter 

7835 . - - - - - - ~ - - - - - - - . . . . . . . . 52 

3 .2-6 Dynamic height anomalies in the Gulf of Mexico 

from GEOSAT ERC 48 data relative to the 

corrected Rapp mean surface . . . . . . . . . . . 53 

3 .3-1 Schematic diagram of AXBT/XBT QA/QC 

procedures . . . . . . . . . . . . . . . . . . . . 55 

3 .3-2 Plot of (a) raw AXBT and (b) QA/QC'ed data 

from survey F12SLOPE station 6 showing data 

dropouts corrected by interpolation . . . . . . . 56 

3 .3-3 AXCP data file format from F13SQURT station 21 . . 58 

3 .3-4 Plot of AXCP data from F13SQURT station 21 

after QA/QC . . . . . . . . . . . . . . . . . . . 59 

3 .3-5 Track of Drifter 7838 during December 9-15, 

1993 in opcplot format . . . . . . . . . . . . . . 61 
X1 

LIST OF TABLES 

Table Title Page 

2 .1-1 LATEX Drifter Inventory - Year 2 . . . . . . . . . 4 

2 .6-1 Aerial Survey Dates and Probe Usage . . . . . . . 8 
1 

I . INTRODUCTION 

This document describes progress of Science Applications 

International Corporation (SAIL) and its subcontractors in 

accomplishing the principal objectives of the Gulf of Mexico Eddy 

Circulation Study (Minerals Management Service (MMS) Contract 14-

35-0001-30633) during the second field year, May l, 1993 through 

April 30, 1994 . The study is also known as the C component of the 

Louisiana/Texas Shelf Physical Oceanography Program (LATEX 

Program) . Briefly stated, the study objectives are : 

" monitoring and characterizing three classes of mesoscale 

circulation patterns important in the open sea and slope 

waters of the northwestern Gulf of Mexico (Tasks C-2, C-3, C6, C-7) ; 

" providing efficient, centralized logistics support, including 

Service ARGOS liaison for drifting buoys, air deployed 

expendable bathythermograph (AXBT) and current profiler (AXCP) 

probes, and expendable bathythermograph (XBT) probes for a 

ship-of-opportunity program (Tasks C-1 through C-6 and C-8) ; 

" disseminating information collected during this study to other 

investigators on a regular basis (Tasks C-9 through C-11) . 

Monitoring mesoscale features has been accomplished by a series of 

seven aerial surveys with AXBTs and AXCPs to examine the 

instantaneous hydrographic and velocity structures of selected 

features . Continuous monitoring of features has been done using 

air-deployed, satellite-tracked drifting buoys (Clearwater 

Instrumentation, Inc ., model LSD2) . Satellite altimetry has been 

used to provide an historical perspective of conditions in the Gulf 

of Mexico from early 1985 through 1990 . 

Aerial surveys (including photography) and drifting buoy 

deployments were executed by an experienced subcontractor, AeroMarine Surveys, Inc ., under the direct supervision of an SAIC 

scientist . Eddy characterization will be accomplished by careful 

analysis of the data collected in this study along with selected 

data elements from the other two field components of the program 

and through synthesis of knowledge gained during this study with 

what is already known . 

SAIC provided centralized storage and shipping of drifting buoys 

and air and ship launched expendable probes from a facility in 

Plano, Texas, operated by Specialty Devices, Inc . The operator of 

the facility is responsible for checkout of the satellite uplink 
2 

transmitter in each drifting buoy procured under this program . 

SAIC has made all necessary Service ARGOS arrangements and fee 

payments for drifting buoys, and provides ongoing liaison with 

Service ARGOS and the National Oceanic and Atmospheric 

Administration (NOAA) Office of Global Programs . 

Dissemination of quality controlled data and analyzed results has 

taken place through regular posting on the GULF .MEX bulletin board 

service of OMNET"' and through regular interaction among the 

investigators on this project . Drifter data have been provided 

periodically to Dr . Robert Leben, a LATEX C Principal Investigator 

at Colorado Center for Astrodynamics Research (CCAR) at the 

University of Colorado, for assimilation with ERS-1 and TOPEX 

altimeter data . Drifter data and AXBT/AXCP data have also been 

provided to Dr . Douglas Biggs at Texas A&M University (TAMU) and 

Dr . Giulietta Fargion (TAMU, Galveston) with whom joint papers have 

been presented at the 1994 Spring AGU Meeting in Baltimore, 

Maryland . 

Chapter II presents an overview and chronology of events 

accomplished under each task of the contract . Chapter III 

documents progress during the second field year under Tasks C-2, C3, C-6, C-7, C-8, and C-9 in data collection and archiving, results 

of quality control exercises, data shared with other investigators, 

analytical methods employed, and standard computer graphics . 
3 

II . OVERVIEW AND CHRONOLOGY OF INDIVIDUAL TASKS 

2 .1 Task C-1 : Drifting Buoys Provided to Other Contractors 

Seventeen drifters "drogued at the surface" were ordered for 

subsequent distribution : 16 to Texas A&M University (TAMU), prime 

contractor for the Louisiana/Texas Shelf Circulation and Transport 

Processes (LATEX A) Study; and one to Louisiana State University 

(LSU), prime contractor for the Mississippi River Plume Hydrography 

(LATEX B) Study . The chosen configuration was a Clearwater 

Instrumentation, Inc ., World Ocean Circulation Experiment (WOCE) 

type drifter with a 6xl m holey sock drogue and approximate 3 m 

tether such that the bottom of the drogue was at 9 m . 

Under this task Specialty Devices, Inc . of Plano, Texas maintained 

a central logistics facility and performed a variety of logistics 

tasks involving shipping and receiving drifters for this Task and 

Tasks C-2 and C-3, aerial expendable stores for Task C-6, and 

expendable stores and equipment for Task C-8 . 

The original 17 surface configured drifters were received at the 

central logistics facility in two shipments on April 14, 1992, and 

May 29, 1992 during Year 1 . By the end of Year 1 all but three of 

the drifters (two for LATEX A and one for LATEX B) had been 

shipped . Two of these drifters were shipped to LATEX A on July 28, 

1993 . The drifter allocated to LATEX B was shipped on March 17, 

1994 and deployed on April 15, 1994 . Four drifters provided to 

LATEX A during Year 1 were deployed on May 2, 1993 . 

The Specialty Devices, Inc . facility also accommodated the 

remaining eight (out of 20) air-deployed drifters delivered in Year 

2 . The air deployed drifters were received on May 5, 1993 and were 

shipped to various locations during the year as directed by the 

Program Manager . Table 2 .1-1 shows the disposition of drifters 

during Year 2 . 

2 .2 Task C-2 : Drifting Buoys in Loop Current Eddies 

The drifter configuration for this task was a Clearwater 

Instrumentation, Inc ., WOCE type drifter with a 12x1 m holey sock 

drogue and approximate 88 m tether such that the bottom of the 

drogue was at 100 m . During Year 1 one drifter was air-deployed in 

October 1992 and failed immediately . A replacement drifter 

deployed two weeks later, from R/V GYRE during a transit of the 

Gulf of Mexico, operated for 169 days and stopped transmitting just 

before the end of Year l . 
Table 2 .1-1 . LATEX Drifter Inventory - Year 2 

SHIPPED YEAR END TOTAL 

PTT ID DEPTH RCVD TO DEPLOY STATUS DAYS 

02498 100m 04/22/92 GYRE 06/02/93 off 0 

02499 100m 04/22/92 GYRE 10/30/92 off 135 

02450 200m 04/22/92 Galveston 12/12/93 on 138 

06935 6m 05/29/92 TAMU 05/02/93 off 53 

06937 6m 05/29/92 TAMU 05/02/93 off 43 

06938 6m 05/29/92 TAMU 05/02/93 off 171 

06939 6m 05/29/92 TAMU 05/02/93 off 0 

06941 6m 05/29/92 LSU 04/15/99 on 15 

07835 50m 05/29/92 Galveston 01/09/93 off 59 

07838 100m 05/05/93 Galveston 12/09/93 off 119 

07842 50m 05/05/93 Lafayette 12/22/93 off 245 

07843 50m 05/05/93 Lafayette 12/22/93 on 128 

07844 50m 05/05/93 Lafayette 12/22/93 off 152 

07845 50m 05/05/93 Lafayette 12/22/93 on 128 

Drifters remaining for d eployment in Year 3 

02445 200m 04/22/92 Biggs 

07841 200m 05/05/92 Bigqs 

Plus eight ordered from Horizon Mari ne for De livery in Year 3 . 

LATEX A : 

REMARKS/PERFORMANCE 

Eddy W 

Eddy U 

GulfCet deploy in small cyclone 

Exit GOM 6/93 ; OFF 6/29/93 

GulfCet deploy in Eddy X 

Cyclone 

Cyclone 

Cyclone 

Cyclone : no fixes,l-2 xmits/day 

Transferred to Dr . Doug Biggs/TAMU for 

ship deployment in Loop Current Eddies 

07833 50m 05/29/92 TAMU 

07839 50m 05/29/92 TAMU Remaining air-deployable drifters 

07839 100m 05/05/92 TAMU transferred to TAMU for ship launch 

07840 100m 05/05/92 TAMU 

03589 6m 09/21/92 TAMU 

06936 6m 05/29/92 TAMU 

06940 6m 05/29/92 TAMU 
5 

Subsequently, during Year l, it became apparent that the airdeployable version of this drifter was experiencing a large number 

of failures which were related to the parachute deployment system . 

Additionally there appeared to be other problems with the surface 

drifters where the drifters did not transmit as long as expected . 

All of the difficulties were outlined in the Year 1 Report (SAIC 

1994) . A decision was made during the later part of Year 1 not to 

deploy any drifters from aircraft until the problem was resolved . 

Discussions were undertaken with Clearwater Instruments, Inc . to 

determine the source of the problem and effect a solution . During 

the discussions it was decided to repackage five drifters in our 

possession and these were returned to Clearwater for rework . Eight 

drifters intended for delivery in Year 2 were also to be packaged 

in this new configuration . 

A decision was also made that the drifters would be deployed from 

ships if this could be done . Thus, drifters 2448 and 7838 were 

deployed in Eddy W (June 2, 1993) and Eddy X (December 9, 1993), 

respectively . The deployment of drifter 2448 was made from R/V 

GYRE during a transit of the Gulf of Mexico and deployment of 

drifter 7838 was made from R/V PELICAN during a "Distribution and 

Abundance of Marine Mammals in the North-Central and Western Gulf 

of Mexico" (GulfCet) Program cruise . 

2 .3 Task C-3 : Drifting Buoys in Other Meso-Scale Features 

Two different air-deployable configurations of the Clearwater 

Instrumentation, Inc ., WOCE type drifter were chosen : one set of 

four with the bottom of the drogue at 200 m for deployment in slope 

eddies, and one set of 10 with the bottom of the drogue at 50 m for 

deployment in squirts . Except for drogue tether length, these 

drifters were identical to the Loop Current eddy drifters . 

Following deployment of four repackaged drifters (see Section 2 .2 

above) in November 1993, when one drifter failed immediately and 

two others provided only intermittent fixes, a decision was made to 

provide the four remaining Clearwater drifters to LATEX A for 

conversion to the surface configuration . Two additional drifters 

were earmarked for deployment by ship in the Loop Current as 

opportunity arose . These six units were shipped on April 14, 1994 

to TAMU . 

After reprogramming funds originally budgeted for buoy 

refurbishment, eight drifters were ordered from Horizon Marine, 

Inc . These drifters were packaged in a configuration approximating 
6 

the dimensions of an A-size sonobuoy (0 .9144 m (36 in) by 0 .124 m 

(4 .875 in) diameter) such that they could be launched from the same 

aircraft used for the aerial surveys, rather than from a leased air 

freighter . The drifters were configured with holey sock drogues 

and tethers to place the bottom of the drogue at 50 m (4), 100 m 

(2), or 200 m (2) . 

2 .4 Task C-4 : Returned Buoys 

No buoys were recovered after deployment and returned to the 

manufacturer for refurbishment during Year 1 or Year 2 . Funds from 

this task were reprogrammed to allow purchase of Horizon Marine air 

deployable drifters for use in Year 3 . 

2 .5 Task C-5 : Buoy Quality Control 

Each of the drifters received by Specialty Devices, Inc ., was 

turned ON, on receipt and again prior to shipment, and checked with 

a Telonics TSUR-B Satellite Uplink Receiver/Analyzer System to 

verify correct operation of the ARGOS platform terminal transmitter 

(PTT) . Each unit's operation was also verified through receipt of 

the signal through Service ARGOS . No unit failed these 

predeployment tests . 

2 .6 Task C-6 : Aerial Surveys 

Five types of aerial survey were proposed to accomplish the 

objectives of the LATEX C program : Slope Surveys, Slope Eddy 

Surveys, Loop Current Eddy Surveys, Squirts and Jets Surveys, and 

Squirts and Jets Locator Surveys . These survey types are described 

below : 

Slope Survey - made over two days with 32 AXBTs on a regular 

hydrographic grid of five or six lines covering a portion of 

the upper slope between the 200 m and 2000 m isobaths . Three 

surveys were planned during each program year . The area 

covered in Year 2 was between 92°00'W and 94°36'W . 

Slope Eddy Location Survey - made with 16 AXBTs and five AXCPs 

on an as required basis if a slope eddy was discovered during 

a Slope Survey . Each survey was to be followed by aerial 

deployment of a drifter with a drogue at 200 m . 
Loop Current Eddy Survey - made with 16 AXBTs on an as 

required basis whenever the center of a Loop Current eddy was 

determined to have reached 90°W after separating from the Loop 

Current . Each survey was to be followed by aerial deployment 

of a drifter with a drogue at 100 m. 

Squirts and Jets Survey - made over two days with 32 AXBTs and 

nine AXCPs whenever a 'squirt' was detected in satellite 

imagery . This survey was to be followed by a Squirts and Jets 

Location Survey (16 AXBTs) and deployment of two drifters with 

drogues at 50 m . A sequence of two of these survey sets, 

separated by about one week, was planned in Year 2 . 

Squirts and Jets Location Survey - made in one day with 16 

AXBTs to determine the best locations in a 'squirt' for 

subsequent deployment of two drifters with drogues at 50 m . 

Seven aerial surveys were actually conducted during Year 2 : three 

Slope Surveys, one Slope Eddy Survey, two Loop Current Eddy 

Surveys, and a modified Squirts and Jets Survey/Squirts and Jets 

Location Survey . Additionally two days in May 1993 were devoted 

exclusively to aerial photography along selected ERS-1 ground 

tracks . Table 2 .6-1 shows the surveys in sequence along with the 

types of probes used in each survey and the number of probes in 

each survey which returned valid data . 

During Year 2 reduced size AXBTs ('A/3', 0 .30 m (10 .98 in) vice 

0 .9144 m (36 in) long and lighter in weight than standard 'A' 

size) were ordered from Hermes Electronics of Canada . The remaining 

full size ('A' size) Sparton AXBTs were used for Loop Current Eddy 

surveys . Use of the 'A/3' AXBTs allowed more probes to be carried 

and added to flexibility in flight scheduling . Reliability of 'A' 

size AXBTs was 100 .00, of 'A/3' size AXBTs was 93 .50 and of AXCPs 

('A' size) was 90 .50 . 

All surveys during Year 2 were conducted from the Paul Fournet Air 

Services facility at Lafayette Regional Airport in Lafayette, 

Louisiana . The support provided by this fixed base operator 

continued to be exceptional and included shipping and receiving 

activities before each survey and storage of materials, at no cost 

to the program . 

2 .7 Task C-7 : Altimetrv 

The goal of this task, which is being carried out by Drs . George 

Born and Robert Leben at CCAR, is to use all publicly available 

U .S . Navy Geodetic Satellite (GEOSAT) data to provide an altimeter 

climatology consisting of the following elements : 
Table 2 .6-1 . Aerial Survey Dates and Probe Usage 

Survey Type Dates ACT AXCP Drifters Remarks 

used good used good 

F08 Slope 5/15-16/93 36 34 - - 

F08 Slope 5/14,5/17/93 - - - - Photo runs (352 

frames) 

F09 Slope Eddy 5/18-19/92 15 14 5 4 3819 NRL/SSC Drifter, 

did not operate 

F10 Slope 8/3-4/93 36 35 - - 

F11 LCE 8/5/93 16 16 - - 2448 Eddy W 

F12 Slope 10/28- 44 40 

11/1/93 

F13 Squirt 12/16-21/93 62 57 16 15 7842, 7843 7845 failed 

7844, 7845 immediately 

7842 & 7844 

provided only 

sporadic positions 

F14 LCE 12/23/93 16 16 - - 7838 Eddy X from R/V 

PELICAN 

Total 225 T212 21 19 

Percent good 94 .2 90 .5 
9 

charts of the mean sea surface and mean slope ; 

charts of sea surface topographic variability and slope 

variability for each year and season ; 

charts of sea surface topography anomalies for each exact 

repeat cycle (ERC) ; 

charts of eddy paths, eddy size and shape, eddy decay and Loop 

Current penetration derived from the above ; and 

wave height and wind speed analyses . 

Work on the mean sea surface and mean slope was completed during 

Year 2 using 31-~ years of GEOS 3, three months of Seasat and 22 

cycles (approximately one year) of GEOSAT Exact Repeat Mission 

(ERM) altimeter data and bathymetric data . A method has been 

developed for correcting the selected reference mean surface for 

short wavelength geoid errors which allows accurate referencing of 

both historical and current repeat track altimeter data . The 

accuracy of this mean surface has been validated by comparisons of 

altimetry derived products with surveys and drifting buoys . 

2 .8 Task C-8 : Ships-of-Opportunity 

Support of the Ships-of-Opportunity (SOOP) program during Year 2 

involved distribution of seven cases of T-7 XBT probes, in case 

lots, to investigators designated by the MMS Contracting Officer's 

Technical Representative (COTR) . Four cases were provided to the 

GulfCet Program (Dr . Giulietta Fargion) and three cases to the TAMU 

Ship of Opportunity Program (Dr . Doug Biggs) . 

Data from these programs has been shared among the various 

Principal Investigators . In each instance where probes have been 

provided, they have been used to augment other sources of data and 

so do not represent a separate 'contiguous' data set . A side 

benefit from these programs was deployment of drifters in Loop 

Current eddies . 

2 .9 Task C-9 : Data 4uality Control 

The goals of this task are to eliminate spurious or doubtful values 

in the data sets and to correct, where possible, values affected by 

identifiable and quantifiable sources of bias . Data collected or 

processed comprise three basic data types : 
10 

Hydrographic Profile Data (XBTs/AXBTs/AXCPs), 

Lagrangian Data (Drifting Buoys), and 

Remotely Sensed Data (Altimetry) . 

Hydrographic profile data from AXBTs, AXCPs and drifter data are 

processed by SAIC, while quality control of altimetry data is 

performed by CCAR . Data from XBTs distributed under the SOOP 

Program are processed by the individual programs or investigators 

receiving the probes . 

Initial quality control of AXBTs and AXCPs occurred in the field 

and involved aural evaluation when the probe was dropped, to ensure 

'normal' operation, and substantial effort to provide duplicate 

copies of the raw data on nine-track analog tape and on digital 

audio cassette tape . Overall data return from AXBTs was 94 .20, as 

the result of 13 data losses in 225 drops . As noted in Section 

2 .6, two types of AXBT were used : 'A' size with reliability of 

100 .0° and 'A/3' size with reliability of 93 .50 . Similarly, data 

return from AXCPs was 90 .50, based on two instrument failures in 21 

drops . Final quality assurance/quality control (QA/QC) of these 

data is described in Section 3 .9 . 

2 .10 Task C-10 : Analyses and Reports 

The Annual Report : Year 1 (SAIL 1994) was prepared and submitted 

during Year 2 . Work on updated drifter track analysis programs was 

initiated . Selected plots were generated with the opcplot plotting 

program (Brown 1994) . 

2 .11 Task C-11 : Information Transfer 

This task has included posting to the GULF .MEX Electronic Bulletin 

Board on OMNET of the following types of messages : 

drifter tracks on a weekly basis, whenever a drifter was 

operational, 

cruise plans and reports before and after each set of surveys, 

inflection points from AXBTs after each aerial survey, and 

program schedule changes . 
11 

2 .12 Task C-12 : Government Furnished Equipment/Capital Equipment 

There has been no activity under this task, which is designated for 

the refurbishment and return to MMS of government owned property at 

the end of the project . 
13 

III . DETAILS OF DATA COLLECTION AND ANALYSIS 

3 .1 Aerial Surveys and Drifting Buoy Deployments 

Throughout the following discussion reference is made to scheduled 

activities even in the case of clearly event driven activities like 

Loop Current Eddy Surveys . The schedule was developed initially as 

a means of cost estimating and as a means of keeping the scientific 

community informed of forthcoming events in case cooperative 

ventures could be developed . The schedule was continually refined 

and updated based on occurrence of various events and on 

recommendations of the LATEX Science Advisory Panel or individual 

members of the panel . 

Each survey event was identified in the schedule, and in the 

following discussions, by a designator which noted it as an 

aircraft based survey (F), a two digit sequence number, and a five 

character nickname . Thus the first survey conducted in Year 1 was 

identified as FOlSLOPE . This same identification scheme was used 

for all data files . 

The plan for each survey flight originally included aerial 

photography of the sea surface using a 70 mm format camera and 

black and white film, with emphasis on oceanic fronts . After the 

first series of 63 photographs, taken during the first Slope Survey 

in Year l, were evaluated and found to be inadequate because they 

were taken at low altitude, discussions were initiated among MMS, 

SAIC, Aero-Marine Surveys and the Principal Investigator receiving 

the photographs to define more fully the exact requirements for the 

photographic component of the program . It was decided that the 

stated altitude requirement (3,000 m) for useful photographs was 

incompatible with safety requirements imposed by dropping 

expendable probes from an aircraft and that photography would be 

limited to occasions when the altitude requirement could be met 

without compromising the main part of the program . An opportunity 

to provide a substantial number of photographs was developed during 

the last months of Year 1 and was carried out successfully during 

F08SLOPE in May 1993 . 

3 .1 .1 Slope Surveys 

Three Slope Surveys were scheduled during Year 2 at times to 

coincide approximately with the quarterly hydrographic surveys made 

on the shelf by TAMU in the LATEX A study . The 'missing' Slope 

Survey was staggered over the three years of field work so that no 

one season would be consistently unsampled . The three planned 
14 

surveys were conducted as scheduled in early May, early August and 

early November 1993 . The original grid planned for Year 2 and the 

grid actually used are shown in Figure 3 .1-1 . Modifications to the 

original grid were made based on flight experience during Year l . 

During Year 1 LATEX A deployed two inverted echo sounders along 

92°W as shown in Figure 3 .1-1 and AXBT drops were made at each 

station during Year 1 . No further AXBT drops were made at LATEX A 

Mooring Station 43, the inverted echo sounder at 25°32 .5'N 

91°59 .9'W, after the instrument was reported to be unrecoverable . 

Slope Survey 4 (F08SLOPE and F09SEDDY) 

The fourth Slope Survey (F08SLOPE) was conducted May 15-16, 1993 as 

shown in Figure 3 .1-2 . The survey was flown in two legs . It was 

preceded by a special photographic mission on May 14 along portions 

of an ERS-1 ground track (398), and followed on May 17 by an 

additional photographic mission along and parallel to ERS-1 ground 

track 441 as shown in Figure 3 .1-3 . A Slope Eddy Survey was 

undertaken on May 18 and consisted of two parallel north-south 

lines between the western edge of F08SLOPE and the Texas shelf 

break as shown in Figure 3 .1-2 . 

Figures 3 .1-4, 3 .1-5 and 3 .1-6 plot the depths of the 20°C, 15°C, 

and 8°C isotherms, respectively, from the combined data set and 

show a large anticyclone in the western half of the survey and 

possibly a smaller anticyclone in the northeastern corner . Figure 

3 .1-7 shows the thermal structure in the upper 800 m along an eastwest section through the anticyclone . The original estimate was 

that the anticyclone observable in the western portion of this 

survey was Eddy V ; however, later analysis indicated the feature 

observed was not Eddy V, which was believed to have dissipated in 

early spring (Year 1) . The anticyclone was probably a remnant of 

an old Loop Current eddy . 

A drifter provided by Naval Research Laboratory-Stennis Space 

Center was deployed following an AXCP pattern at 27°00'N 95°00'W in 

the anticyclone, but failed to operate . 

Slope Survey 5 (F10SLOPE) 

The fifth Slope Survey (FlOSLOPE) was conducted August 3-4, 1993 as 

shown in Figure 3 .1-8 . A Loop Current Eddy survey (F1ILEDDY), 

completed on August 5, 1993, is plotted also in Figure 3 .1-8 to 

show its relation to FlOSLOPE . F1ILEDDY is discussed below . 

Figures 3 .1-9, 3 .1-10, and 3 .1-11 show the depths of the 20°C, 15°C, 
15 

98 W 

30 N 

97 W 96 u 95 W 94 W 93 W 92 W 91 W 90 W 89 U 

~Lafayefte~ 

30 N 

. 

. 

29 N 29 N 

.~ . : . 

8 N v _ ._ . . 

. ,- ,. 

._ 

.. __ .~ .y 

..i~. 

.: . . _ 

. ._, - 

` 

8 N 

0 ~`' r 0 

r' 0 0 0 0 

O . .~ . 4`~ '~- 

~ r ~ °` ~ 1 27 N ,. 0 0 0 , ; ~ 1 

~ f'J 

26 N `~ F~~-1 . . 26 N 

r 

O 

25 N ,o ~ F ~ 25 N 

F 0 

N 

24 N '~J ~ ' 24 N 

98 u 97 u 96 u 95 w 94 w 93 w 92 w 91 u 90 u 69 u 

Figure 3 .1-1 . Plan for Year 2 Slope Surveys . Original AXBT 

stations are shown as small dots, actual AXBT 

stations as open diamonds, and IES 43 as an open 

square . 
16 

AXBT 

98 W 

1 N 

FLIGHTS 8 & 

97 W 96 

9 -- 

W 

LATEX C 

95 W 94 

5/i2/93 TO 5/18/93 

W 93 W 92 W 91 W 90 W 

3 1 

Louisiana 

3 N 

30 N 30 N 

Texas b " 

29 N _ ~ 29 N 

Gulf of Mexico 

0 

28 N 28 N 

_ ---t-X . , 

-9-x-,. -_ .~t7x''-?24 x ' 31 x 

- 

101 x- 109 x x x ` x x x 

vy ' x x x x x x x 

27 N 

x x x x x x x 

27 N 

x x x x x x x 

x x _, x x x 3 6 x 

114 x 

r30 x - -_ . 

177 x g x j( x 

_ ` 

26 N ; c, 

. , . 

> 26 N 

N 

2 5 N 25 N 

9 8 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 

- Eddy Circulation Study - 

Figure 3 .1-2 . Station plot for surveys F08SLOPE and F09SEDDY . 
17 

LAKE CHARLES 

a LqFAYETTE 

o NEW ORLEANS 

o HOUSTON o HOUMA 

a CORPUS CHRISTI 

o HARLINGEN 

Figure 3 .1-3 . Flight tracks used during special photo mission 

along ERS-1 ground tracks . Eastern set shows track 

on May 14, 1994, including excursion over Flower 

Garden Banks . Western set shows track on May 17, 

1994 . Origin of flights was Lafayette, Louisiana . 
18 

AXBT FLIGHTS 8 & 9 -- LATEX C 5/12/93 TO 5/18/93 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 

31 N 

Louisiana 

31 N 

30 N 30 N 

Texas 

29 N 29 N 

Gulf of Mexico 0 

28 N 

- 

28 N 

,_ 

0 ( l 

27 N 27 N 

I ~~ v m ~ ~; +Q . ``{ ~ ~~ 5 ` l 

26 N 

1 

26 N 

S 

25 N 25 N 

98 W 97 W 96 W 95 W 94 u 93 W 92 W 91 W 90 W 

DEPTH OF 20 .00 (DEG C) TEMPERATURE SURFACE 

- Eddy Circulation Study - 

Figure 3 .1-4 . Depth of the 20°C isotherm from F08SLOPE and 

F09SEDDY AXBT data . 
19 

31 

AXBT 

98 W 

N 

FLIGHTS 

97 W 

S & 9 -- LATEX 

96 W 95 W 

C 5/12/93 TO 5/18/93 

94 W 93 W 92 W 91 W 90 W 

Louisiana CC 

31 N 

30 N 

, 

~ 

~ ~ 

30 N 

Texa s b ``'~ t1 

29 N ~ ~ 29 N 

o Gulf of Mexico 

V 

28 N 

-v - 

28 N 

. . o 

27 N 

% 

~ 

I 

\ T 

it'~ 

~ 

~r~ ~ 

l 

5 

- C ~ 27 

r . ~, ~ ~ ! 

.u ( _ 

A 

26 N ' i T ` 26 N 

S 

` 

F 

mod' 

25 N 

98 W 97 W 96 W 95 W 

25 N 

94 W 93 W 92 W 91 W 90 W 

DEPTH OF 15 .08 (OEG Cl TEMPERATURE SURFACE 

- Eddy Circulation Study - 

Figure 3 .1-5 . Depth of the 15°C isotherm from F08SLOPE and 

F09SEDDY AXBT data . 
20 

AXBT 

98 W 

FLIGHTS 8 & 9 -- LATEX C 5/12/93 TO 5/18/93 

97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 U 

31 N 

Louisiana 

31 N 

3eN ~ 

T ~ ~d ` 'e 

30 N 

exas C/ 

29 N ~ ~ 29 N 

Gulf of Mexico 

0 

28 N ~ ' - 28 N 

2 7 N 

" ,e .e 

C 

. 

0 

2 7 N 

26 N ~.% 26 N 

1 

N 

25 N 25 N 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 9 0 W 

DEPTH OF 8 .00 (DEG CI TEMPERATURE SURFACE 

- Eddy Circulation Study - 

Figure 3 .1-6 . Depth of the 8°C isotherm from F08SLOPE and 

F09SEDDY AXBT data . 
21 

STATION 

N m (~ C 

p ~ N N f7 

0 -21 

G0

/----15 15 ---- 200 \ 7 S 

V) ~ 1 5 --~ 

w 

w ~(p 1m lit 

400 

z 70 

a 

w 

0 

600 

800 

0 40 80 120 160 200 240 280 320 360 400 

DISTANCE (KM) 

AXBT FLIGHTS 8 & 9 -- LATEX C 

5/12/93 TO 5/18/93 

STATIONS 34 TO 103 

TEMPERATURE (DEG Cl 

MIN = 5 .83 MAX = 25 .32 

- Eddy Circulation Study - 

Figure 3 .1-7 . East-west 800 m section at approximately 27°05'N 

from F08SLOPE and F09SEDDY AX BT data . 
22 

31 

AXBT 

98 W 

N 

FLIGHTS 10 & 11 

97 W 96 u 

--LATEX C 

95 W 94 W 93 W 92 W 

8/ 3/93 TO 8/ 5/93 

91 W 90 W 89 W 

LOIIISIam O 

31 W 

Texas 

. 

30 N 30 N 

C~ 

29 N Gulf of Mexico ~ 29 N 

s 

28 N ~ {O1 28 N 

lx 9x 17x 24x 31x x 

d x x x x x x 

lry x x x x x x 

27 N x x x x x x 27 N 

x x x x x 

x .. x x x - 

x ' ., x 

__ 

x x Iz6 x x x x x x x x109 

26 N 

x x 

x 26 N 

F 0 

108 

DO 

25 N 25 N 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

Eddy Circulation Study 

Figure 3 .1-8 . Station plot for surveys FlOSLOPE and F1IZEDDY . 
23 

AXBT 

98 W 

31 N 

FLIGHTS 18 & 11 

97 W 96 W 

--LATEX C 

95 W 94 W 93 

8/ 3/93 TO 8/ 5/93 

W 92 W 91 W 90 W 89 W 

LL ouisiana ' 

31 N 

30 N - 

Texas 

30 N 

V 

29 N - ~ ~ Gulf of Mexico 29 N 

e 

28 N ~ 28 N 

d ~ 

27 N 

B , 

A ~ ,60 : 

27 N 

26 N v~ 

m 26 N 

N SCE 

25 N

. . v . . . ~ i i i i 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 

25 N 

W 

DEPTH OF 20 .08 fDEG Cl TEMPERATURE SURFACE 

Eddy Circulation Study 

Figure 3 .1-9 . Depth of the 20°C isotherm from F10SLOPE and 

F1ILEDDY AXBT data . 
24 

AXBT FLIGHTS 10 & 11 

98 W 97 W 96 W 

31 N 

--LATEX C 8/ 3/93 TO 8/ 5/93 

95 W 94 W 93 W 92 W 91 W 90 W 89 W 

L .OII1SIaI13 /~ 

31 N 

30 N 

Texas 

30 N 

C) 

29 N Gulf of Me.)dco 29 N 

Y W~° 

d 

0 

28 N ~ 28 N 

27 N O ,m V 

i e 

27 N 

w 

26 N J BB ~ 26 N 

F ' - 

o 

N ODZIP 

25 N 25 N 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

DEPTH OF 15 .08 (DEG C) TEMPERATURE SURFACE 

Eddy Circulation Study 

Figure 3 .1-10 . Depth of the 15°C isotherm from FlOSLOPE and 

F1ILEDDY AXBT data . 
25 

AXBT 

98 W 

FLIGHTS 1m & 11--LATEX C 8/ 3/93 TO 8/ 5/93 

97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

31 N 31 N 

I .OWSiiUId D _0 

30 N Texas 30 N 

29 N - Gulf of Mexico - " ~ 

V 

29 N 

28 N ~ 28 N 

d % ~ Q 

27 N `/ 

m

m . O 

] ~ ,so° ^ ~ , Q v ~o 27 N 

26 N 

O 

26 N 

F 

N d o 

25 N 25 N 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

DEPTH OF 8 .00 (DEG Cl TEMPERATURE SURFACE 

Eddy Circulation Study 

Figure 3 .1-11 . Depth of the 8°C isotherm from FlOSLOPE and 

F1ILEDDY AXBT data . 
26 

and 8°C isotherms, respectively, from the combined data sets . 

Figure 3 .1-12 shows an east-west section through the survey area . 

Slope Survey 6 (F12SLOPE) 

The sixth Slope Survey (F12SLOPE) was completed in two legs between 

October 28 and November l, 1993, as shown in Figure 3 .1-13 . Figure 

3 .1-14, 3 .1-15, and 3 .1-16 show the depths of the 20°C, 15°C, and 

8°C isotherms, respectively . Two probable cyclones and an 

anticyclone are observable in the data . Figure 3 .1-17 shows an 

east-west section through the survey area . 

3 .1 .2 Loop Current Eddies 

Two Loop Current Eddy Surveys were planned during Year 2, in April 

and October 1993, based on an estimated nine month eddy shedding 

period for Loop Current eddies and the expectation that an eddy 

would have been shed early in 1992 just prior to Year l . The two 

surveys were actually conducted in August 1993 and December 1993 . 

Eddy W (F1ILEDDY) 

A survey of Eddy W (F1ILEDDY) was completed on August 5, 1993 

following a Slope Survey (FlOSLOPE) . The plan for the Loop Current 

Eddy survey was drawn to augment data collected during FlOSLOPE and 

thus provide a fuller view of Eddy W . Figure 3 .1-18 shows the 

station locations for both FlOSLOPE and F1ILEDDY . Figure 3 .1-19 

shows the depth of the 15°C isotherm determined solely from 

F1ILEDDY data . Figure 3 .1-20 shows the path of Drifter 2448, which 

was deployed in Eddy W on June 2, 1993 from R/V GYRE, combined with 

the station locations for FlOSLOPE and F1ILEDDY . 

Eddy X (F14LEDDY) 

A survey of Eddy X (F14LEDDY) was undertaken December 23, 1993 

following F13SQURT as shown in Figure 3 .1-21 . No drifter was 

deployed following the survey since drifter 7838 had been deployed 

in the eddy on December 9, 1993 from R/V PELICAN . Figure 3 .1-22 

shows the depth of the 20°C isotherm determined from this survey . 

3 .1 .3 Squirts and Jets Surveys 

The first double Squirts and Jets survey was conducted in Year 1 

and is documented in SAIC (1994) . A second double survey 

(F13SQURT) was completed in Year 2 and is described below . 
27 

STATION 

.O «1 v 111 (7 N 9 O` (7 O r r ~ B .- 

r N M r r r r r r r r "- 

Kl 

15 ~\ 

~ e 200 S 20 

cn 7S 

Lij -~ 

w 

1 5 

1 m'\ 7 0 

57 400 

78 

~-~ 1 e 

w 

0 

600 

800 

0 50 100 150 200 258 300 350 400 450 580 

DISTANCE (KM) 

AXBT FLIGHTS 10 & 11 -- LATEX C 

8/ 3/93 TO 8/ 5/93 

STATIONS 7 TO 109 

TEMPERATURE IDEG C) 

MIN = 5 .95 MAX = 30 .41 

Eddy Circulation Study - 

Figure 3 .1-12 . East-west 800 m section at approximately 26°05'N 

from FlOSLOPE and F1ILEDDY AXBT data . 
28 

31 

F12SLOPE 

98 W 97 

N 

AXBT'S 

W 96 

-- LATEX C 

W 95 W 94 W 93 W 92 W 

1/28/93 TO 11/ 1/93 

91 W 90 W 89 W 

Louisiana 

31 N 

Texas 

30 N (` I 

v 

~ Q ~ 

~ 

30 N 

0j C , 

29 N Gulf of Mejzco ~ ~ 29 N 

Yv 

0 

28 N ~ 28 N 

37x 24x 3Ix 

x lox 18x x x 

x 3x x x x x 

27 N - 

x x x x x 

- 27 N 

x x x x x 

x x x x x 36x 

x x 

- 

x 23x 30x 

44x ', 8x 16x 

26 N 26 N 

; . . 

ti o oh d o 

25 N 25 N 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

Eddy Circulation Study 

Figure 3 .1-13 . Station plot for survey F12SLOPE . 
29 

31 

F12SLOPE 

98 W 97 

N 

AXBT'S 

W 96 

-- LATEX C 1/28/93 TO 11/ 1/93 

W 95 W 94 W 93 U 92 W 91 W 90 W 89 W 

Louisiana 

31 N 

30 N Texas 

n ~ 

U 

30 N 

~~`l ' 

l/ 

29 N Gulf of Mexico 29 " 

a 

28 N ~ 28 N 

v-y 

27 N 

g ~0 

27 N 

26 N r 26 N 

o 

0 N 

25 N 25 N 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

DEPT H OF 20 .00 (DEG C) TEMPERATURE SURFACE 

Eddy Circulation Study 

Figure 3 .1-14 . Depth of the 20°C isotherm from F12SLOPE AXBT data . 
30 

31 

F12SLOPE 

98 W 97 

AXBT"S 

W 96 

-- LATEX C 

W 95 W 94 W 93 W 92 W 

10/28/93 TO 11/ 1/93 

91 W 90 W 89 W 

N 31 

Louisiana 

N 

30 N 

Texas ~ ~ Q I t 30 N 

29 N Gulf of Mexico ~ 29 N 

v 

u 

28 N ~ 28 N 

d 

27 N 

is 

27 N 

26 N 

. . 

~ 26 N 

E 

0 0 

N 

OH O 

25 N 25 N 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

DEPT H OF 15 .08 IDEG C1 TEMPERATURE SURFACE 

Eddy Circulation Study 

Figure 3 .1-15 . Depth of the 15°C isotherm from F12SLOPE AXBT data . 
31 

F12SLOPE 

98 W 97 

31 N 

AXBT'S -- LATEX C 

W 96 W 95 W 94 W 93 W 92 W 

18/28/93 TO 11/ 1/93 

91 W 90 W 89 W 

1 

Louisiana 

3 N 

30 N - 

Texas 

30 N 

29 N Gulf ofMeazco 29 N 

O 

28 N ~ 28 N 

27 N 

d 

~ ~bee~~ a 

" \~ .J~ a 

27 N 

26 N 

V 

n- 26 N 

F 

0 

O O 

ri0 

25 N 25 N 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

DEPTH OF 5 .00 (OEG C) TEMPERATURE SURFACE 

Eddy Circulation Study 

Figure 3 .1-16 . Depth of the 8°C isotherm from F12SLOPE AXBT data . 
32 

STATION 

m 

v f~ r N ('1 ('7 

-~ 2m 

8-~20 

200 /S 15 

_ \~S 15~ 

w 

w 

400 

1e \ 

10----1 0 

W 

O 

600 

i800 

8 58 100 150 200 250 300 350 

DISTANCE (KM) 

F12SLOPE AXBT'S --LATEX C 

10/28/93 TO 11/ 1/93 

STATIONS 36 TO 43 

TEMPERATURE IDEG CI 

MIN -- 5 .97 MAX = 27 .64 

Eddy Circulation Study - 

Figure 3 .1-17 . East-west 800 m section at approximately 26°22`N 

from F12SLOPE AXBT data . 
33 

LAKE CHARLES 

0 

o NEW ORLEANS 

o HOUSTON 

o HOUMA 

GALVESTON 

87 CORPUS CHRISTI o 

0 0 0 0 0 0 

o' o 0 0 0 0 0 

0 0 0 0 0 0 

0 0 0 0 0 

0 0 0 0 

o HARLINGEN 

0 0 0 0 ° o 0 0 0 0 0 

0 0 0 

0 

Figure 3 .1-18 . Station plot of FlOSLOPE and F1ILEDDY in opcplot 

format . 
34 

31 

F11LEDDY AXBT'S -- LATEX C 

98 W 97 W 96 W 95 W 

N 

8/ 5/93 TO 8/ 5/93 

94 W 93 W 92 W 91 W 90 W 89 W 

L°"'S`a`ia D 

31 N 

30 N 

Texas 

'Z ~ ,. se N 

o 

29 N Gulf of Mexico - ~ ~ 29 " 

v 

28 N ~ 28 N 

a 

27 N ~ 

27 N 

m m . e' 

0 

26 N 26 N 

F 

N 

~- 

25 N 25 N 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

DEPTH OF 15 .08 (OEG C) TEMPERATURE SURFACE 

Eddy Circulation Study 

Figure 3 .1-19 . Depth of the 15°C isotherm only from survey 

F1ILEDDY AXBT data . 
35 

31 

98 W 

N 

97 W 96 W 95 W 

8/ 1/93 TO 8/ 7/93 

94 W 93 W 92 W 91 W 90 W 89 W 

IAUisiana 

31 N 

3e N Texas 

~ 

R - /~ CI I b 

~J ~ 

30 N 

Q~ tJ 

29 N Gulf of Mexico 29 N 

s 

28 N 

v . ._. ... ..._ _ .. ._.. ... 

28 N 

v 

d ~ 

-v l e 

r -. ... 

._ ... . D ... .. .. . _. . 

i 

. . 

2 7 N e 

. 

27 N 

. _ 

ti2448 

26 N ~~ ~ ~ 0~ ~ `~ "" ` f `~ s 

49 26 N 

25 N 25 N 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

Eddy Circulation Study 

Figure 3 .1-20 . Plot of Drifter 2448 during period August 1-7, 1993 

and the depth of the 15°C isotherm from FlOSLOPE 

and F1ILEDDY AXBT data . 
36 

31 

F14LEDDY AXBT'S 

98 W 97 W 96 

N 

-- LATEX 

u 95 W 

C 12/23/93 TO 12/23/93 

94 W 93 W 92 W 91 W 90 W 89 W 

Louisiana O 

31 N 

30 N Texas 

3 0 N 

a 

29 N GulfofMexico 29 " 

s 0 

28 N ~ 28 N 

2x 

d x 

4 x 

27 N - 16x x x x -x -x x x9 - 27 N 

x 

x 

26 N o 8x 26 N 

N 

25 N

. i 25 N 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

Eddy Circulation Study 

Figure 3 .1-21 . Station plot for survey F14LEDDY . 
37 

31 

F14LEDDY AXBT'S 

98 W 97 W 96 

N 

-- LATEX 

W 95 W 

C 

94 W 93 W 

12/23/93 TO 12/23/93 

92 W 91 W 90 W 89 W 

Louisiana 

~ 

31 N 

30 N 

Texas 

8 Z~ 

~ ' t 30 N 

(Z) 

29 N G ulf of Mexico 29 " 

e 

28 N ~ 28 N 

wSf g0 _ , 

27 N 16x x~X9 27 N 

Sx ' 

s o 

26 N o 8x o 26 N 

w 

O 

N 

25 N 25 N 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

Eddy Circulation Study 

Figure 3 .1-22 . Depth of the 20°C isotherm from F14LEDDY AXBT data . 
38 

Modified Squirts and Jets Survey (F13SQURT) 

F13SQURT was undertaken December 16-21, 1993 in possible cyclone 

between Eddy X and another possible large anticyclone at about 

26°30'N 94°00'W, A 63-station AXBT survey was first completed 

December 16-18, 1993 as shown in Figure 3 .1-23, along with survey 

F14LEDDY . Figures 3 .1-24, 3 .1-25, and 3 .1-26 show the depths of 

the 20°C, 15°C, and 8°C isotherms determined from F13SQURT and 

F14LEDDY AXBT data . Figure 3 .1-27 shows an 800 m deep, east-west 

section along 27°00'N from the combined surveys . Four drifters 

(7842, 7843, 7844, and 7845) were deployed on December 19, 1993 in 

the cyclone confirmed by the AXBT data . A 16-station AXCP survey 

was completed on December 21, 1993 through the drifter deployment 

area as shown in Figure 3 .1-28 . Figure 3 .1-29 shows the first two 

days of two drifter tracks (7842 and 7843) and the currents above 

the 15°C isotherm as determined from the AXCP data . 

3 .2 Task C-7 : Altimetrv 

The goal of this task is to produce an altimeter derived 

climatology from the GEOSAT Geodetic and ERM altimeter data sets . 

Over four years of altimeter data were collected from these 

combined missions, spanning the time period from April 1985 through 

December 1989, during which six major and at least two minor Loop 

Current eddies were directly observed . 

To produce the final report climatology, CCAR has generated a 

gridded archive using the existing NOAA geophysical data record 

(GDR) GEM-T2 GEOSAT ERM data set available on compact disk read 

only memory (CD-ROM) . This archive includes the 62 cycles of data 

that were obtained before the GEOSAT tape recorder failed in 

September 1989 and the line of sight data stream collected over the 

Gulf of Mexico by The Johns Hopkins University Applied Physics 

Laboratory until the ultimate failure of the satellite in January 

1990 . 

A significantly improved version of the GEOSAT ERM data is in 

preparation for release in late spring or early summer 1995 by the 

National Oceanographic Data Center (NODC) . This release will 

include new 10-cm orbits computed by the Goddard Space Flight 

Center, a more accurate ocean tide model derived from 

TOPEX/Poseidon altimeter data and a more reliable ionosphere 

correction from the IRI-90 model . If time permits, this data set 

can be used to compute the GEOSAT ERM topographic analyses for the 

program . Regridding of the altimeter data for collinear processing 
39 

AXBT 

98 W 

31 N 

FLIGHTS 13 8 14 -- LATEX 12/16/93 TO 12/23/93 

97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

I'°"'s'ana D 

31 N 

30 N Texas 

Q~ R It 30 N 

1~/ V 

29 N Gulf of Mexico ~ , 29 N 

" v0 

28 N - 

- 

----_ 

---~( ",~~-- 

"\. 102 

I lo 19 3'~ 6 

28 N 

x x ,5 rt 4 x 55a 

p x x x 29rc x x 

27 N 

O 

104x 

x x a x x x n -' `- 

~ \' x x x x x a (16x ;~~~ ~~ x x x x109 27 N 

x x x x a x K S , , _ _ j\i~~ 

~~' X X X X X UJ ~ -~5C ~ y 

,,JJ ~X X X X X 

~ 

26 N 

1 ~ Jf~~X~ X X X 

x x x x 63x 

168 26 N 

25 N 25 N 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

Eddy Circulation Study - 

Figure 3 .1-23 Station plot for surveys F13SQURT and F14LEDDY . 

AXBT stations are indicated by x and AXCP stations 

by o . 
40 

AXBT FLIGHTS 13 & 14 

98 W 97 W 96 W 

-- LATEX C 12/16/93 TO 12/23/93 

95 W 94 W 93 W 92 W 91 W 90 W 89 W 

31 N 31 N 

Louisiana 

30 N 

Texas 

30 N 

29 N Gulf of Mexico 29 N 

a 

28 N ~ 28 N 

m 

27 N O. ~ R 27 N 

26 N R 26 N 

N ~O~ 

n 0 

25 N 25 N 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

DEPTH OF 20 .88 (DEG Cl TEMPERATURE SURFACE 

- Eddy Circulation Study 

Figure 3 .1-24 . Depth of the 20°C isotherm from F13SQURT and 

F14LEDDY AXBT data . 
41 

AXBT 

98 W 

31 N 

FLIGHTS 13 & 14-- LATEX C 12/16/93 TO 12/23/93 

97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

IAUIS 1111a O 

31 N 

30 N Texas 

30 N 

29 N ~ ~ Gulf of Mexico 29 N 

0 

28 N ~ 28 N 

27 N 

. ~ . mm D . 

~ 

60 

27 N 

26 N 26 N 

F 0 0 

O 

DO 

2 

25 N 25 N 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

DEPTH OF 15 .88 (DEG Cl TEMPERATURE SURFACE 

Eddy Circulation Study 

Figure 3 .1-25 . Depth of the 15°C isotherm from F13SQURT and 

F14LEDDY AXBT data . 
42 

1 

AXBT 

98 W 

N 

FLIGHTS 13 & 14-- LATEX C 12/16/93 TO 12/23/93 

97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

3 31 N 

Louisiana O 

b 

30 N Texas 30 N 

29 N - Gulf ofMexico " ~ 29 N 

O 

28 N ~ 28 N 

570.0' 

27 N . Oe 

yI(_ l/ 

\~ 

27 N 

~m m 

26 N 

~~`l1 ' \~ ` I Y ~\ 

26 N 

F 0 0 

Off` 

25 N 25 N 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

DEPTH OF 8 .00 (DEG Cl TEMPERATURE SURFACE 

Eddy Circulation Study 

Figure 3 .1-26 . Depth of the 8°C isotherm from F13SQURT and 

F14LEDDY AXBT data . 
43 

STATION 

(7 N m P P .-

Q r N f'] R O t[1 r 

200 

cn 

w 

w 

400 

z 

a 

w 

a 

600 

Boo 

m 

(") 

rN 

m P 

r r r B 

50 140 150 200 250 300 358 

DISTANCE (KM) 

AXBT FLIGHTS 13 & 14 -- LATEX C 

12/16/93 TO 12/23/93 

STATIONS 4 TO 109 

TEMPERATURE (DEG C) 

MIN = 5 .52 MAX = 24 .55 

400 450 500 

Eddy Circulation Study - 

Figure 3 .1-27 . East-west 800 m section at approximately 27°00'N 

from F13SQURT and F14LEDDY AXBT data . 
44 

31 

F13SQUIRT AXBT'S -- LATEX 

98 W 97 W 96 W 95 W 

N 

C 

94 W 93 W 92 W 

12/21/93 TO 12/21/93 

91 W 90 W 89 W 

1 

Louisiana 

3 N 

Texas 

30 N ~ ~ Q _ I t 30 N 

29 N v Gulf of Mexico 29 N 

s -V 

.- 

28 N 28 N 

-- v 

119x 129'x137 x155 

x 

/ 

121x x 139 x157 

1z~ 

.. 

27 N x149 

.\ 

27 N 

123x x141 x159 ~=f` )'~~ ` 

_ . ._ :, 

125x `- : x143 :~ .s< . ~° 

. 

26 N 26 N 

l 

J .t 

25 N ~ / 25 N 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

Eddy Circulation Study 

Figure 3 .1-28 . Station plot for F13SQURT AXCP survey . 
45 

31 

DRIFTERS : 07842 

98 W 97 W 96 

N 

07843 

W 95 W 

12/22/93 TO 12/25/93 

94 W 93 W 92 W 91 W 90 W 89 W 

$0 cm/s Louisiana 

b 

31 N 

30 N 

Texas 111~ e I ti 30 N 

29 N Gulf of Mexico 

29 N 

v 

28 N ~ J am / 

--'- 

_ 

--_-- ~. . . "

--200M 

"-- 

S N 

27 N ~ y ~ l ,-J .~?,~~` \ ( /` ~ 27 N 

`+1 i L?~' 

7gq2 

may/ 

` ~

.t ~~N 

26 N ~ 

l.s 

~ 26 N J 7843 

25 N

I 

I 25 N 

98 W 97 W 96 W 95 W 94 W 93 W 92 W 91 W 90 W 89 W 

Eddy Circulation Study 

Figure 3 .1-29 . Currents above the 15°C isotherm from F13SQURT AXCP 

data and tracks of drifters 7842 and 7843 . 
46 

can be performed quickly when the new CDs are available, using the 

software developed for the NOAA altimeter data format, which is not 

planned to be changed substantially in the new release (J . 

Lillibridge, NOAA/NODC, personal communication) . 

Research efforts at CCAR during Year 2 have focused on validating 

techniques which will be used to produce the GEOSAT derived 

altimetric data sets . Validation has been performed using TOPEX 

and ERS-1 data over the Gulf of Mexico by comparisons with LATEX 

hydrographic surveys and satellite-tracked drifting buoy 

observations . These comparisons have shown that it is now possible 

to accurately reference all past, present and future altimetric 

observations over the Gulf of Mexico to the same mean surface, 

allowing consistent comparisons and estimates of Loop Current eddy 

center paths, translation speeds and dynamic height anomalies . A 

byproduct of this validation effort has been production of a TOPEX 

and ERS-1 Gulf of Mexico climatology spanning the time period from 

April 1992 to December 1993, and near real-time altimetry products 

from TOPEX/Poseidon which are continually updated as those data 

become available . These products have been made available to LATEX 

Principal Investigators and can also be viewed on the World Wide 

Web (http ://shaman .colorado .edu/gom .html) . 

Production of a "climatological" mean reference surface which can 

be used to accurately reference sea surface topography from the 

GEOSAT time period has been completed . A mean slope has also been 

computed from this reference surface . The altimetric mean 

reference surface selected is a gridded mean surface (Basic and 

Rapp 1992) which is referred to as the Rapp mean, and is based on 

a combination of 3;,~ years of GEOS 3, three months of Seasat and 22 

cycles (approximately one year) of GEOSAT ERM altimeter data and 

bathymetric data . This mean surface estimate over the Gulf of 

Mexico is one of the most accurate available because of the high 

spatial resolution of the GEOS-3 data and the use of bathymetric 

data to improve accuracy at short length scales, and so was 

selected over a mean surface computed from only GEOSAT along-track 

data . A method has been developed for correcting the Rapp mean 

surface for short wavelength geoid errors, allowing accurate 

referencing of both historical and current repeat track altimeter 

data . The accuracy of this mean surface has been validated by 

comparisons of altimetry derived products with surveys and drifting 

buoys . 

Optimally interpolated altimeter data coincident with the October 

28-31, 1992 R/V GYRE Cruise 92G-13 are shown in Figure 3 .2-1 . 

Station locations are shown as filled circles along the cruise 

transect . Two warm-core rings, Eddies U and V, that were crossed 

by the survey line are clearly seen in the altimetry . The centers 
47 

Gulf of Mexico Dynamic Height Anomaly 

w.r.t . Corrected Rapp Mean 

TOPEX Cycle 4.5 to 5 .5 - Oct 27 to Nov. 6, 1992 

Including ERS-1 35 Day Repeat 

centered on midpoint of Topex Cycle 

95°W 90°W 85°W 80°W 

30°N 

25°N 

20°N 

v ,`` `_ -- 

--- 

__ 

u 

19 . ~ _ - a Station 32 ~ ::-:7~ - 

,Sta tion 1 

--- o 

- 

CD O - O _ 

v 

_ 

--' 

.= 

~ - 

~j 

AIV, 

R/V Gyr e Cruise 92G-13 

- October 28 - 31, 1992 

30°N 

25°N 

20°N 

95°W 90°W 85°W 80°W 

Figure 3 .2-1 . Dynamic height anomalies in the Gulf of Mexico from 

TOPEX and ERS-1 altimeter data relative to the 

corrected Rapp mean surface . Track of R/V GYRE 

Cruise 92G13 is indicated by dotted line . 
48 

of Eddies U and V are located near 90°W, 24°N and 94°W, 26°N, 

respectively, in Figure 3 .2-1 . Comparison with hydrography (Figure 

3 .2-2) shows agreement to 6 .5 cm rms at all stations along the 

survey line . Differences at stations (16-32) west of 90°W, from 

near the center of Eddy U through Eddy V, had an rms value of only 

3 .1 cm . The excellent agreement west of 90°W supports the 

hypothesis that the mean circulation is quite weak in the deep 

western Gulf of Mexico and has been well approximated by the Rapp 

mean surface and correction . 

Satellite-tracked drifting buoys have also been used to verify the 

accuracy of the altimetric mean reference surface . The 

trajectories of LATEX C Buoys 2447 and 2449, coincident with TOPEX 

cycle 7 (Figure 3 .2-3), closely trace the sea surface height 

contours of Eddies U and V determined from combined TOPEX and ERS-1 

analysis for this cycle . The qualitative agreement between the two 

data products is excellent . Quantitative validation is also 

possible by comparison of drifter velocities with altimetric 

derived geostrophic velocities at locations and times described by 

drifter trajectories . Geostrophic velocity anomalies are computed 

by differentiation of the altimeter derived sea surface height 

relative to the corrected mean reference surface . Simple linear 

interpolation is used to estimate the surface height field at times 

between successive analyses . Central finite differences are used 

to compute both the altimeter and buoy derived velocities . 

Comparison of these velocity estimates for the trajectories of 

buoys 2447 and 7835 (Figures 3 .2-4 and 3 .2-5, respectively) show 

that the altimetric analysis techniques and mean reference surface 

can be used to accurately describe the circulation in the western 

Gulf of Mexico . Analyses based on the tools validated with the 

TOPEX and ERS-1 data will be performed with the sea surface 

topography maps created from GEOSAT data (Figure 3 .2-6) . 

3 .3 Data Quality Control 

This section addresses data quality control performed after the 

data have been collected and reviewed in the field . The procedures 

described are largely interactive steps undertaken on an ENCORE 

Series 91 Dual Processor machine running under UMAX V, a variant of 

AT&T UNIX V Release 4 optimized for parallel processing, in an XWindows environment . The processing steps were largely developed 

over more than a decade using FORTRAN 77 and NCAR graphics and 

analysis routines . These routines are completely linked to a 

relational data base management system tailored in-house to support 

physical oceanographic work . 
49 

Shipboard vs . Altimetric Derived Dynamic Height 

180 

+ RN Gyre Cruise 92-G 13, Oct 28-31, 1992 

170 )K Topex and ERS-1 OI Altimetry 

160 -

150 -

-140-

_r_ X ~¬ 

z 130 , \ 

U 

.cz 120 3fE )fE 

Eddy V ~ ~ Eddy U 110 

i 

100 

90 -

835 

' 

30 25 20 15 10 5 0 

Station 

Figure 3 .2-2 . Dynamic heights across central Gulf of Mexico from 

TOPEX and ERS-1 altimeter data and hydrographic 

data along track of R/V GYRE cruise 92G13 . Cruise 

track is shown in Figure 3 .2-1 . 
50 

Gulf of Mexico - Sea Surface Height Anomaly 

w.r .t . Along Track Corrected Rapp Mean Surface 

TOPER Cycle 7 - Nov 21 to Dec 1, 1992 

Including ERS-1 35 Day Repeat centered on midpoint of UP Cycle 

98°W 96°W 94°W 92°W 90°W 88°W 86°W 84°W 82°W 80°W 

30°N ~ v 30°N 

28°N ° - o 28 N . 

-- - 

26°N ° 

` V 

26 N 

=ip ~, 

24°N "-- >>` ' ° - . - o - / \ 24 N 

22°N ~-0 , - 22°N 

20°N ° _ . . ---- - - 20 N 

--- 

18°N 18°N 

98°W 96°W 94°W 92°W 90°W 88°W 86°W 84°W 82°W 80°W 

Figure 3 .2-3 . Sea surface height anomaly in the Gulf of Mexico 

from TOPER Cycle 7 and ERS-1 data . Contemporaneous 

tracks of drifters 2447 (left, in Eddy V) and 2449 

(right, in Eddy U) are shown by heavy lines . 
51 

Latex C Buoy: b02447 

96°W 92°W 88°W 84°W 80°W 

UP and ERS-1 

28 ° N 2 8°N VS . 

Buoy 

24'N * Derived Velocities 24 N 

° ~ ° Buoy 20 N 

woo 

20 N Altimeter 

96°W 92°W 88°W 84°W 80°W 

1 .0 - i ~ 

0 .5 - . i , _ 

v 

0.0 

1 

V 

1 0 

,. _ _ . 

- . 

1 .0 

u 

U _

. . . _ _ . ... . . ._.... . _ __ ._ .. . I~ .._ 

0 .0 - 

-0.5 - 

.- 

I 

- 1 . 0 

1 .5 

1 .0 _ . 

v, _ V . . _._.. . .._ ._. _. _ . 0.5 

o . o 

280 300 320 340 360 380 400 

Days past January l, 1992 

Figure 3 .2-4 . Current velocities derived from TOPEX and ERS-1 

altimetry data and positions of drifter 2447 . 
52 

Latex C Buoy: b07835 

96°W 92°W 88°W 84°W 80°W 

28°N 

24°N 

UP and ERS-1 

28°N v s . 

Buoy 

Derived Velocities 

20°N 20°N 

Buoy 

Altimeter 

380 400 420 440 460 480 500 520 

Days past January 1, 1992 

Figure 3 .2-5 . Current velocities derived from TOPEX and ERS-1 

altimetry data and positions of drifter 7835 . 
53 

Gulf of Mexico Dynamic Height Anomaly 

w.r.t . Corrected Rapp Mean 

GEOSAT Cycle 48 - Jan 15 to Jan 31, 1989 

Tilt and Bias Least Absolute Deviation Detrending 

Standard Corrections 

950W 90°W 850W 80°W 

30°N 

25°N 

20°N 

o o ° --: 

- ^ 11 ---- - ----- - C 

o --_- -- - - 20 - 'd` 

-- - -_ 

-20 

O - 

O O `'~', 

s 

o~ 

-- -: ^ o 

- ~ ~ - 

95°W 90°W 85°W 

30°N 

25°N 

20°N 

80°W 

Figure 3 .2-6 . Dynamic height anomalies in the Gulf of Mexico from 

GEOSAT ERC 48 data relative to the corrected Rapp 

mean surface . 
54 

3 .3 .1 Hydrographic Profile Data 

Detailed interactive computer procedures for QA/QC of profile data 

are online and are an integral part of entering data into the SAIC 

Physical Oceanographic Data Base Management System (PODBMS) . These 

procedures provide specific checks at key junction points to insure 

a high-quality data product as diagrammed in Figure 3 .3-1 . The 

following summarizes the processing steps for XBT/AXBT and AXCP 

profile data : 

XBT/ACT Processing Procedures 

Two hundred twenty five AXBTs were processed in Year 2 . The data 

were recorded on both nine-track analog tape and on DAT cassettes 

from separate channels of the receiver in the aircraft . These data 

were then processed after the flight through a Sippican Mkl2 

Oceanographic Data Acquisition System which converts the data to an 

ASCII file containing a header with information about the drop and 

depth temperature pairs at approximately 0 .15 m increments to a 

maximum depth of 760 m. The depth is computed from the fall time 

of the thermistor probe through the water column . The coefficients 

of the drop equation have been determined experimentally during the 

development of the probes . Calibration of the thermistor is 

accomplished during manufacture and is not duplicated in the field . 

The AXBT data are received from AeroMarine Surveys on 31-t" IBM PC 

compatible diskettes . 

XBT/AXBT data are transferred into the PODBMS and a unique 

identifier (ID) is assigned to the data . The survey sequence 

number is part of the individual data file name, for example, 

file AB$01010 .EDF is the AXBT deployed at station 10 in the 

first survey (FOlSLOPE) . Section 3 .1 described the formation 

of the IDs used in this program . The data are then checked 

for spikes, large data gaps and total number of points through 

an interactive digital processing routine . The corrected data 

are archived to tape (nine-track, EXABYTE, or 1-4" cassette) 

and stored in a climate controlled environment . 

Vertical temperature profiles are then checked individually, 

using an interactive graphics editor, for accuracy and 

smoothness . The routine allows the user to clip bad/noisy 

casts and to apply a spline to noisy or gappy data (a common 

problem of AXBT data, see Figure 3 .3-2) in an attempt to 

smooth the data or supply missing data . The smoothing can be 

applied to an entire cast or to only a portion of the cast . 

Bad casts are deleted from the PODBMS . 
55 

CTD / XBT QA 

PROCEDURES 

Transcribed 9-Track HP-85 Tapes or Tape or 

IBM- IBM-Compatible Disks Compatible Disks 

Arrive (CTD) Arrive (CTD or XBT) 

Data Loaded on 

Encore Computer 

Unique Cruise ID 

Assigned Discard Cast 

Cruise Track Map NO 

is Generated 

YES Are 

Raw Data Profile Data 

Plots Generated Usable? 

Spikes YES Data Smoothing 

or Routines 

Gaps? 

Data Uploaded into 

Hydrographic Data 

Base(RIM) 

Sections and Surface 

Tracks Plotted 

Special YES Special 

Requests? Analysis 

NO 

Archive to Tape and Submit to 

Client and NODC 

Figure 3 .3-1 . Schematic diagram of AXBT/XBT QA/QC procedures . 
56 

(3) Raw data 

TEMPERATURE OEG C 

- 10 0 10 28 3m 

0 

_ 288 

w 

w 

400 - 

z Fa 

w 

° 600 - 

Boo 

STATION 6 18/31/93 12 .1 

F12SLOPE AXBT"S -- LATEX C 

26 36 .0 N 94 42 .8 W 

TEMPERATURE DEG C 

(b) Clean data 0 10 20 30 

0 

200 

w 

w 

37 

z 

4P0 

0 

600 

STATION 6 10/31/93 12 .1 

F12SLOPE AXBT'S -- LATEX C 

26 36 .0 N 94 42 . 0 W 

Figure 3 .3-2 . Plot of (a) raw AXBT data and (b) QA/QC'ed data 

from survey F12SLOPE station 6 showing data 

dropouts corrected by interpolation . 
57 

One-meter increment data are used to produce vertical sections 

along and across isobaths (see Figure 3 .1-7) or along major 

survey axes and horizontal contour maps of selected 

temperature surfaces (see Figure 3 .1-4) or temperature at a 

selected depth . Surface tracks are also generated for each 

survey . 

AXCP Processing Procedure 

Twenty one AXCPs were processed during Year 2 . Data acquisition 

for these probes was essentially similar to data acquisition for 

the AXBTs . Processing of these data was completed by AeroMarine 

Surveys, Inc ., at their facility in Gales Ferry, Connecticut, using 

a Sippican Mk 10 XCP Digital Data Acquisition System which converts 

the data to an ASCII file containing a header with information 

about the drop, and depth, temperature, and velocity information at 

approximately 2 .7 m increments to a maximum depth of 1500 m . 

Figure 3 .3-3 shows the header and first five data lines generated 

by the Mk 10 system . Computations of depth and temperature are 

made in the same manner as for AXBTs . 

Computation of velocity components from AXCP data uses a set of 

five 'standard' coefficients or five coefficients unique to each 

probe . Data processing procedures by SAIC after receipt of the 

AXCP data on 31-~" diskettes are described below . 

Current Profiler data are transferred into the PODBMS from 

computer diskettes and the data set is assigned a unique ID as 

described above . The data are checked for spikes, large data 

gaps and the total number of points through an interactive 

digital processing routine . The corrected data are then 

archived to tape and stored in a climate controlled 

environment . 

Individual 'u' and 'v' components and temperature profiles are 

plotted and edited in a manner similar to XBT/AXBT data as 

shown in Figure 3 .3-4 . The three data components can be 

clipped or smoothed individually, depending on the quality of 

the data . Once again, the bad casts are deleted from the 

PODBMS . 

Ten-meter increment data are used to produce both vertical and 

horizontal contour sections . Cruise tracks and surface tracks 

are also generated for each flight . In addition, temperature 

data from adjacent AXBT stations can be merged with the AXCP 

data to provide a more detailed analysis of the vertical 

thermal structure of the water column . 
58 

(d) MK10 Post Processing Application 

Version V1 .0 August, 1989 

- 

Sippican, Inc 

Probe Hea der Information - -- ----------------------------- ------ - 

Filename : C :\MK10\ XCP$83 .PR0 

SIN : 9999 Depth(m) : 1500 

Gcca : 1846 .02 Latitude : 27,12 .O,N 

Gcora : 915 .66 Longitude : 093,40 .O,w 

Gefa : 24831 .35 Cruise . LATEX C 13 

Gevfa : 497 .01 Ship : N900AM 

Gcvfa . 493 .07 Speed : 140 knots 

Fh . .2674441 Heading : 360 degrees 

Fz . - .405899 Memo : sn . 93041012 

F1trSz : 22 Date : 12-21-1993 

StepSz : 11 Time : 15 :20 :01 

Depth(m) Temp(C) U V Area Rotf Fefb Fccb Velerr 

7 .59 18 .36 126 .32 -31 .88 369 15 .32 1354 2203 174 .53 

10 .42 22 .92 11 .88 -61 .88 578 16 .64 1544 2249 1 .66 

13 .16 22 .93 12 .83 -57 .04 576 17 .14 1580 2250 1 .22 

15 .87 22 .95 14 .47 -56 .04 576 17 .32 1537 2249 1 .04 

18 .58 22 .91 10 .85 -58 .70 579 17 .37 1404 2248 1 .24 

(b) 

Figure 3 .3-3 . AXCP data file format from F13SQURT station 21 . (a) 

Text from post-processing routine and (b) PC screen 

output . 
59 

TEMPERATURE (DEG Cl 

5 10 15 20 25 

DIRECTION (DEG) 

90 180 270 360 

I I I I I 

SPEED (CM/S) 

0 20 40 60 80 

0 - 

- ------------ 

-- 

200 - 

cr) 

L'i 

400 - 

LIJ C) 600 - 

TT SS ~D 

800 ' I 

STATION 121 12/21/93 15 .3 

F13SQUIRT AXBT'S -- LATEX C 

27 12 .0 N 93 40 .0 W 

Figure 3 .3-4 . Plot of AXCP data from F13QURT station 21 after 

QA/QC . 
60 

An NODC format tape is produced for data submission within 

three months of data receipt, and again at the end of the 

program . 

3 .3 .2 Laqranqian Data 

LATEX drifter data are received daily from the Service ARGOS U .S . 

Global Processing Center (USGPC) over the Internet . Drifter data 

for the shelf drifters deployed in LATEX A are also delivered daily 

to the LATEX A Data Office on Internet . The drifter data are also 

available through a dialup service (TYMNET) to the USGPC computer, 

and are thus available essentially in real time for use in the 

field to verify correct operation . These data include all 

transmissions received from each drifter and each position of the 

drifter determined by Service ARGOS . The files are edited to 

separate the position data for processing in the PODBMS, while the 

transmissions from the drifters are reviewed to evaluate 

qualitatively battery condition, drogue presence, and sea water 

temperature . 

Interactive procedures remove all duplicate positions, verify the 

validity of each position fix, sort the data into a time-ordered 

sequence and archive the data into the PODBMS . Once loaded into 

the system, a final visual check is made on the data by plotting 

the individual buoy trajectories on a high-resolution map of the 

study area, which contains detailed bathymetry and coastline, and 

looking for spurious changes in the buoy's movement (see Figure 

3 .1-20, for example) . The data are also written in opcplot (Brown 

1994) format for placement on the GULF .MEX electronic bulletin 

board as shown in Figure 3 .3-5 . 
61 

(a) Data file 

07838,9312092225,-90 .6370,27 .4010,D 

344,9312102219,-90 .3670,27 .2940,B 

346,9312121420,-89 .9810,26 .8950,B 

347,9312131358,-89 .8680,26 .6280,B 

348,9312142129,-89 .8560,26 .2670,B 

349,9312151458,-89 .9030,26 .0290,B 

(b) Graphic 

OLAf1YETTE / 

o~[u Ofte~~~s 

GILYESiOY "' 

b[ WS [NO ISTI 

a~a 

yr 7~~ 

7~6 

~I1 

3~8 O x~lllYLfY 

719 

Figure 3 .3-5 . Track of Drifter 7838 during December 9-15, 1993 in 

opcplot format . (a) Portion of data file . (b) 

Graphic from opcplot . 
63 

IV . REFERENCES 

Basic, T . and R .H . Rapp . 1992 . 

Anomalies and Sea Surface 

Geosat Altimeter Data, and 

No . 416, Dep . of Geodetic 

State University, Columbus . 

Oceanwide Prediction of Gravity 

Heights Using Geos-3, Seasat and 

ETOP05U Bathymetric Data . Report 

Science and Surveying, The Ohio 

Brown, M .L . 1994 . OPCPLOT : Oceanographic charting software for the 

world's seas, May 1994 . OCS Report MMS 93-0020 . U .S . 

Department of the Interior, Minerals Management Service, Gulf 

of Mexico OCS Region, New Orleans, La . 61 pp . 

Science Applications International Corporation . 1994 . Louisiana/ 

Texas Shelf Physical Oceanography Program : Eddy Circulation 

Study, Annual Report : Year l . OCS Study MINIS 94-0027 . U .S . 

Department of the Interior, Minerals Management Service, Gulf 

of Mexico OCS Region, New Orleans, La . 53 pp . 
ST, NT P OFT,y ~'y~ The Department of the Interior Mission 

p As the Nation's principal conservation agency, the Department of the Interior has responsibility for 

a most of our nationally owned public lands and natural resources. This includes fostering sound 

use of our land and water resources; protecting our fish, wildlife, and biological diversity; 

preserving the environmental and cultural values of our national parks and historical places; 

9RCH 9 ~e and providing for the enjoyment of life through outdoor recreation . The Department assesses our 

energy and mineral resources and works to ensure that their development is in the best interests 

of all our people by encouraging stewardship and citizen participation in their care. The 

Department also has a major responsibility for American Indian reservation communities and for 

people who live in island territories under U.S . administration . 

The Minerals Management Service Mission 

<~``+~ 

or 

~`wa As a bureau of the Department of the Interior, the Minerals Management Service's (MMS) primary 

responsibilities are to manage the mineral resources located on the Nation's Outer Continental Shelf 

(OCS), collect revenue from the Federal OCS and onshore Federal and Indian lands, and distribute 

s ~ 

s r 

those revenues. 

Moreover, in working to meet its responsibilities, the Offshore Minerals Management Program 

administers the OCS competitive leasing program and oversees the safe and environmentally sound 

exploration and production of our Nation's offshore natural gas, oil and other mineral resources. 

The MMS Royalty Management Program meets its responsibilities by ensuring the efficient, timely 

and accurate collection and disbursement of revenue from mineral leasing and production due to 

Indian tribes and allottees, States and the U.S . Treasury . 

The MMS strives to fulfill its responsibilities through the general guiding principles of : (1) being 

responsive to the public's concerns and interests by maintaining a dialogue with all potentially 

affected parties and (2) carrying out its programs with an emphasis on working to enhance the 

quality of life for all Americans by lending MMS assistance and expertise to economic development 

and environmental protection .