WHOI IMET Mooring Subsurface Data --------------------------------- These data are from the Woods Hole Oceanographic Institution (WHOI) surface (IMET) mooring deployed in the center of the Intensive Flux Array (IFA) at 1.756S, 155.995E during the Tropical Ocean Global Atmosphere Coupled Ocean- Atmosphere Response Experiment's Intensive Observing Period (TOGA COARE IOP). The mooring was deployed by the R/V Wecoma on 21 October 1992 (04:30 UTC) and recovered by the same vessel on 4 March 1993 (00:05 UTC). The water depth at the mooring was 1744m. These data were collected by Drs. Robert A. Weller and Albert J. Plueddemann with support from the U.S. National Science Foundation (NSF) under grants OCE 91-10559 (RAW) and OCE 91-10554 (AJP). Instrumentation from the surface to 30m was provided by Weller. Instrumentation from 30m to 300m was provided by Plueddemann, except for five conductivity/temperature loggers (SeaCats) originally deployed at 45.5, 60, 76, 92 and 108m which were provided by Dr. Matthias Tomczak (Flinders University, School of Earth Sciences, Adelaide, Australia). Instrument preparation, mooring deployment, and data processing were done by the Upper Ocean Processes Group of the Woods Hole Oceanographic Institution (WHOI). If you use any of these data in a publication, please acknowledge NSF, WHOI, and Drs. Weller, Plueddemann and Tomczak. A mooring servicing occurred between 9 and 13 December which resulted in changes in instrument depth. From 9 December 1992 00:45 UTC to 13 December 05:25 UTC, the surface discus buoy was temporarily replaced with a toroid buoy. A length of wire rope inserted below the toroid increased the depth of all sub-surface instruments by 10m from their nominal deployment depths. When the discus buoy was replaced on 13 December, the 10m length of wire used with the toroid was removed and a 2.29m length of chain was permanently added below the bridle of the discus buoy. These depth changes have been accounted for in all the WHOI mooring files by interpolating measurements to their original deployment depth plus 2.29m throughout the entire deployment. For instruments attached to the buoy hull (i.e., temperatures above 4.65m and salinity at 2.0m), no interpolation was necessary and no data was available between 9 and 13 December when the discus buoy was removed from the water. Because the mooring was lowered by 10m at this time (between 9 and 13 December), no data from the water column was available shallower than 10m (the shallowest instrument, the 4.65m temperature sensor, was lowered to 14.65m). The deepest temperature (260m) and salinity (124m) measurements were interpolated to their original deployment depth. The resulting data files report depths as the depth of interpolation, not the original deployment depth. Interpolation for temperature and east and north currents were linear with depth. Interpolation for salinity was linear in temperature/salinity space where possible, linear with depth otherwise. Velocities provided below the deepest VMCM (52.5m) were measured by the ADCP. Mooring Instrumentation ----------------------- Deployment Interpolated Sensor Measurement Depth Depth ------ ----------- ---------- ------------ Brancker T-Pod Temperature 0.4 0.4 Brancker T-Pod Temperature 0.5 0.5 Brancker T-Pod Temperature 1.0 1.0 Brancker T-Pod Temperature 1.5 1.5 Brancker T-Pod Temperature 2.0 2.0 SeaCat Conductivity/Temperature 2.0 2.0 Brancker T-Pod Temperature 2.5 2.5 PMEL T-Pod Temperature 4.65 6.94 VMCM Current/Temperature 5.15 7.44 Brancker T-Pod Temperature 5.65 Failed SeaCat Conductivity/Temperature 7.48 9.77 VMCM Current/Temperature 8.9 11.19 SeaCat Conductivity/Temperature 11.52 13.81 (Conductivity Failed) VMCM Current/Temperature 12.97 15.26 SeaCat Conductivity/Temperature 15.52 17.81 VMCM Current/Temperature 17.01 19.30 SeaCat Conductivity/Temperature 19.5 21.79 ADCP Current 20.5 22.79 VMCM Current/Temperature 23.0 Failed SeaCat Conductivity/Temperature 23.5 25.79 Brancker T-Pod Temperature 27.5 29.79 VMCM Current/Temperature 31.5 33.79 SeaCat Conductivity/Temperature 31.5 33.79 Brancker T-Pod Temperature 35.5 Failed VMCM Current/Temperature 39.5 41.79 SeaCat Conductivity/Temperature 40.0 Failed SeaCat Conductivity/Temperature 45.5 47.79 VMCM Current/Temperature 52.5 54.79 SeaCat Conductivity/Temperature 52.5 54.79 SeaCat Conductivity/Temperature 60.0 Failed SeaCat Conductivity/Temperature 68.0 70.29 SeaCat Conductivity/Temperature 76.0 78.29 SeaCat Conductivity/Temperature 84.0 86.29 SeaCat Conductivity/Temperature 92.0 94.29 SeaCat Conductivity/Temperature 100.0 102.29 SeaCat Conductivity/Temperature 108.0 110.29 Brancker T-Pod Temperature 116.0 118.29 SeaCat Conductivity/Temperature 124.0 126.29 Brancker T-Pod Temperature 132.0 134.29 Brancker T-Pod Temperature 148.0 150.29 Brancker T-Pod Temperature 164.0 166.29 Brancker T-Pod Temperature 180.0 182.29 Brancker T-Pod Temperature 196.0 198.29 Brancker T-Pod Temperature 212.0 214.29 Brancker T-Pod Temperature 228.0 230.29 Brancker T-Pod Temperature 244.0 Failed Brancker T-Pod Temperature 260.0 260.00 Data Files ---------- Each file is uniformly spaced in time. Bad values or missing data are indicated by the value 9.96921e+36 Salinity Filename: togaSalinity.epic Sample interval: 900 seconds Number of samples: 12846 Start: 21 October 1992 04:31:53 UTC End: 3 March 1993 23:46:53 UTC Number of depths: 15 Depth range: 2.0 - 124.0m Units: PSU Temperature Filename: togaTemperature.epic Sample interval: 900 seconds Number of samples: 12846 Start: 21 October 1992 04:31:53 UTC End: 3 March 1993 23:46:53 UTC Number of depths: 41 Depth range: 0.45 - 260.0m Units: degrees C Velocity Filename: togaVelocity.epic Sample interval: 900 seconds Number of samples: 12846 Start: 21 October 1992 04:31:53 UTC End: 3 March 1993 23:46:53 UTC Number of depths: 25 Depth range: 7.44 - 340.5m Units: cm/s Calibration ----------- The following is documentation for calibrations applied to the original data. Data supplied in the archive files (togaSalinity.epic, togaTemperature.epic and togaVelocity.epic) have had the corrections described here already applied. DO NOT apply these corrections again. Salinity A time-dependent drift was detected in the 2.0m and 9.77m salinity measurements. Correction constants are provided below. A = 1.023E-02 B = 7.054E-05 C = -2.247E-08 A = 6.721E-03 B = 2.478E-04 C = -1.898E-06 The corrections took the form: days = days since start of deployment offset = A + B * days + C * (days * days) [PSU] The computed offset was subtracted from the original salinity measurements. Velocity Magnetic variation correction of +7.67 degrees has been applied to currents We gratefully acknowledge Eric Antonissen's (OSU,USA) intercomparison of the shipboard ADCP and the moored VMCMs and ADCP. Based on this intercomparison and additional analyses, directional errors were discovered in each VMCM and the ADCP compass. Rotational correction constants are provided below. 7.44m VMCM: A = 5.4784 B = -43.6205 C = -1.5389 11.19m VMCM: A = -1.6658 B = -304.3457 C = -0.4148 15.26m VMCM: A = 4.0246 B = -65.7481 C = -0.8506 19.30m VMCM: A = -5.2206 B = -333.9808 C = 0.8737 33.79m VMCM: A = 8.0419 B = -62.5923 C = -0.4753 41.79m VMCM: A = 6.6423 B = 299.8813 C = -6.7539 54.79m VMCM: A = -6.4865 B = 287.5624 C = -5.8766 Each VMCM was rotated by the angle theta as follows: theta = -1 * [A * sin(compass_direction + B) + C] [degrees] where a positive theta rotates east of north. The ADCP rotational correction constants are as follows: ADCP: A = -5.6058 B = -241.2480 C = 6.0464 where the rotation correction angle, theta, for the ADCP is equal to: theta = -1 * [A * sin(current_direction + B) + C] [degrees] ADCP velocities have NOT been corrected for soundspeed variations from the reference value of 1536 m/s. This will be a small correction (<1%) given the in-situ sound speed near 1540 m/s at the transducers. The bin depths have NOT been corrected for soundspeed variations from the reference value of 1475 m/s. The true bin depths will be approximately 1540/1475=4.4% larger than the nominal values. Contacts -------- If you have any questions regarding these data, please contact: Dr. Robert Weller Woods Hole Oceanographic Institution Woods Hole, MA 02543 (508) 289 - 2508 rweller@whoi.edu Dr. Albert Plueddemann Woods Hole Oceanographic Institution Woods Hole, MA 02543 (508) 289 - 2789 aplueddemann@whoi.edu Dr. Steven Anderson Woods Hole Oceanographic Institution Woods Hole, MA 02543 (508) 289 - 2876 sanderson@whoi.edu Mr. Mark Baumgartner Woods Hole Oceanographic Institution Woods Hole, MA 02543 (508) 289 - 2677 mbaumgartner@whoi.edu References ---------- Plueddemann, A.J., R.P. Trask, W.M. Ostrom, R.A. Weller, B.S. Way, S.P. Anderson, N. Bogue, J. Shillingford and S. Hill, 1993: TOGA COARE mooring deployment, check-out, and recovery cruises. Woods Hole Oceanographic Institution Technical Report WHOI-93-30, 54 pp.