BODEGA DRIFTER DATA Y. du Penhoat (ORSTOM, New Caledonia) ------------------------------------------------------------------------------- Announced availability: 1 October 1994 Last modified: 25 October 1995 Data Access BODEGA drifter data are available from the TOGA COARE International Project Office (TCIPO). Data can be accessed via anonymous FTP from tcdm.coare.ucar.edu in subdirectory pub/COARE_DATA/ocean_large_scale/BODEGA. Background Six French BODEGA drifters (SERPE-IESM, GUIDEL, 56, FRANCE TRISTAR) were deployed in August 1992 along the 165E meridian and in September 1992 along 156E. Seventeen additional BODEGA surface drifters were deployed in December 1992 and January/February 1993 from R/V Le Noroit along 156E, 4S-5N during the COARE IOP. Deployments were coordinated with a set of surface drifters that were released by Peter Niiler from the University of California, San Diego. PTT # WMO # PTT # WMO # 2675 --- 17617 ----- 2676 52891 17618 52575 2677 52892 17619 52580 2678 52889 17620 52581 2679 52890 17621 52583 2680 52893 17622 52589 2681 52894 17623 52576 2682 52895 17624 52577 2683 52586 17625 52578 2684 52571 17626 52584 2685 52572 17627 52582 2686 52573 17628 52585 2687 52574 17629 52579 2688 52587 2689 2690 52588 Sixteen of the BODEGA drifters (PTT # 2675 through 2690) transmitted to ARGOS in an "economical mode", i.e., 24 hours on, 48 hours off; the remaining drifters (PTT # 17617 through 17629) transmitted daily for two months after deployment and then switched to the economical mode. The datafile covers 27 of these drifters (drifter 2689 died during deployment and drifter 2688 had very few positions, even though the temperature sensors worked, so it was removed from the file). BODEGA drifters were equipped with a drogue sensor and with a mini-thermistor chain with five sensors at 2, 5, 8, 12, and 20 m. These sensors transmitted hourly temperature measurements (15-min sampling time). There was also a buoy hull sensor with a 2-hour sampling rate, which was less accurate. Service ARGOS provided the raw location computation that had an estimated accuracy of 300 m. The raw data were despiked by removing unacceptable high velocities in excess of 200 cm/s. Data were then interpolated to 6-hour intervals using a Krieging procedure done by the WOCE/TOGA Drifter Data Center (AOML, Miami). Calibration procedure: Thermistor sensors were calibrated by Dr. du Penhoat in lab by measuring temperature in a stable thermostated bath with the thermistor chain and a precision thermometer, before deployment. Data File Information Files are ASCII files, with one file for each individual drifter. They are named as Temp_ascii.xxxxx, with xxxxx being the drifter ID. Drifters with 176XX ID numbers transmitted data every day for the first 60 days, then switched to an economical mode. Drifters with 26xx ID transmitted on an economical mode. File Header For each individual day, the first line includes the ID number, latitude (decimal), longitude (decimal), year, month, day, starting hour (UTC), u component (cm/s), v component (cm/s) and proposed corrections for each thermistor chain sensor. These corrections were proposed to correct from small electronic drift when necessary (and possible) and were estimated by intercomparing the different sensors at night. When these corrections were too big, sensor data were removed (if correction was above >0.4). The hourly averaged temperatures for every sensor were then recorded for every hour (24 rows) of the individual day (T). On the same record, TD are temperatures using the correction proposed below. Precision of T = 0.3 deg C. The first six columns are the uncorrected T data, while the last six columns are the corrected T data with correction values that appear on the first line for each sensor ( TD(i) = T(i) + deriv(i)) for sensor nb i. write (6,'(i6,2f8.3,4i3,2f6.2,6f6.3)') c ID nb, Latitude, Longitude, c Year,month,day, starting hour c U component, V component, c (Derive(j),j=1,6) do i = 1,24 write (6,'(i4,12f6.2)') i,(SST(i,j),j=1,6),(SSTD(i,j),j=1,6) end do Data volume: 4.3 MB Data Example 2675 -0.086 165.821 92 8 13 1499.38483.73 0.000 0.000 0.000 0.000 0.000 0.000 1 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 2 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 3 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 -1.00 . . 12 29.75 29.62 29.64 29.62 29.62 29.62 29.75 29.62 29.64 29.62 29.62 29.62 13 29.75 29.61 29.62 29.61 29.61 29.61 29.75 29.61 29.62 29.61 29.61 29.61 14 29.75 29.61 29.61 29.61 29.61 29.61 29.75 29.61 29.61 29.61 29.61 29.61 15 29.75 29.59 29.60 29.60 29.60 29.60 29.75 29.59 29.60 29.60 29.60 29.60 ------------------------------------------------------------------------------- For more information, please contact: Yves du Penhoat Centre ORSTOM BP A5 Noumea New Caledonia email : dupenhoa@noumea.orstom.nc Phone: (687) 26-3243 FAX: (687) 26-4326 ------------------------------------------------------------------------------- /home/www/data/ocean_large_scale/bodega.html