By Todd B. Johnson and Andy Nunn

The LMG data acquisition systems continuously log data from a suite of instrumentation throughout the cruise. This document describes the format of that data and its location on the distribution CDs. It also contains important information which may affect how this data is processed such as instrument failures or other known problems with acquisition.

The data collected during this cruise is distributed on a CD-ROM written in ISO9660 level-1 format. This data format has very strict requirements on filenames and organization. However, it is readable by virtually every computing platform.

All of the data has been archived with the Unix "tar" command and/or compressed using Unix "gzip" compression. Tar files have a ".tar" extension and Gzipped files have a ".gz" extension. Tools are available on all platforms for uncompressing and de-archiving these formats. On Macintosh, Stuffit Expander with DropStuff will open a tar archive and uncompress gzipped and Unix compressed files. For Windows9X, WinZip, a shareware utility included on this CD (remember, it is shareware) will open these files.

In some cases to adhere to the ISO9660 format the .tar extension was removed. When we tarred the files then gzip the tar archive the name of the file became File.tar.gz. This name does not follow the 8.3 naming convention of the ISO9660 format. So the file was renamed without .tar making the file name File.gz. On Windows and Mac Platforms Winzip and Stuffit Expander handles this just fine. When they expand the File.gz the expanded file becomes File.tar, which both software packages can handle. On Unix platform gunzip expands File.gz but it does not append the .tar extension. So you may not recognize the file as a tar archive, but OS does recognize it as a tar archive. If you use the file command it will return saying it is a tar file. The below tar command will un-archive the file just fine.

It is often useful to know exactly how an archive was produced when expanding its contents. Tar files were created using the following commands:

To create a list of the files in the archive:

To extract the files from the archive:

G-zipped files will have a ".gz" extension on the filename. These files can be decompressed after de-archiving, using:

/Adcp/

The ADCP DAS data files are named pingdata.xxx (xxx representing a file number). Note that these extensions do NOT represent Julian day numbers. Please refer to the file’s creation date. The ADCP DAS computer creates a new pingdata file when the current one reaches a size of 320K. The ping files logged on Gentoo, the Linux processing computer, however are created new each day.

Some ADCP data is also transmitted to RVDAS. East and North vectors for ship’s speed relative to the reference layer and ship’s heading are archived in the navigational data section of RVDAS.

/Cal/

The tar files in the Cal directory contain images of calibration sheets for each of the following systems: Sound Velocity Probe(SVP_CALS.TAR), Meteorological System(MET_CALS.TAR), Underway System(UW_CALS.TAR), and CTD(CTD_CALS.TAR).

CTD diagrams can be found in the ctd Cal directory for voltage and frequency sensors.

/CTD/

The ctd data was collected and processed on a windows 98 computer, using Seasave Win32 – Version 5.25a and SBE Data Processing – Version 5.21.

This directory contains the original .con, .dat, .bl, and .hdr files files produced for each CTD cast.

Each processed cast is represented here by a set of ten files. Note that cast 1 was split into a separate data set for the up and down segments. Also, the DO2 sensor was only added onto to the instrument package for the 4^th cast. In addition to the standard files listed below, an additional round of post processing was done to produce rg302EEE.cnv and .asc files containing non-bin averaged data and an ascii conversion of that data.

/MAP/

PostScript cruise track plots have been produced for this cruise, in three sizes. It has also been converted to a jpeg format. The cruise track file track.txt is also included and contains the latitude and longitude in 10-minute intervals.

/ICE_IMAGE/

This directory contains .jpg files of Terrascan ice imagery sent to the ship from Palmer station before and during the cruise.

/Isobars/

This directory contains GIF image files. These file are an analysis of mean sea level pressure from the National Center for Environmental Prediction's Medium Range Forecast Model. They are updated every 6 hours. Naming the convention is as follows yyjjj.hh.gif where yy is the year, jjj is the day number, and hh is the hour.

/Report/

Copies of this report in MS Word, HTML, and text formats.

/QC_PLOTS/

Postscript files of data stored each day on RVDAS for quality control analysis during the cruise. There are 3 types of files, named metXXX.ps, navXXX.ps, and oceanXXX.ps, where XXX is represents the Julian day. Met files are a summary of the data from the meteorological instruments, Nav files are a summary of navigational data, and Ocean files are a summary of the underway seawater and bathymetry data.

/Science/ and /Moor2003/

These directories contain additional data provided by the PI to supplement the standard distribution data set.

/JGOF/

Additionally, 3 separate QC plots are generated daily by the ET using the JGOFS data set. These plots include TSG and Bathymetry data, meteorological data, and navigation data. The files are called ocean<julian_day>.ps, met<julian_day>.ps, and nav<julian_day>.ps respectively.

/rvdas/

RVDAS (Research Vessel Data Acquisition System) was developed at Lamont-Doherty Earth Observatory of Columbia University and has been used on the R/V Maurice Ewing for several years. It was adapted for use on the Nathaniel B. Palmer and her sister ship, the R/V Laurence M. Gould.

Below you will find detailed information on the data included. Be sure to read the "Significant Acquisition Events" section below for important information about data acquisition during this cruise.

RVDAS data is divided into two broad categories, Underway and Navigation. The groups are abbreviated "uw" and "nav". Thus, these two tar files, lmguw.tar and lmgnav.tar exist under the top-level rvdas directory. The instruments are broken down as shown. Each data file is g-zipped to save space on the distribution. Not all data types are collected everyday or on every cruise.

RVDAS data files are named following the convention: LMG[FileID].dDDD.

• The FileID is a 4-character code representing the system being logged, for example: lmet (for meteorology)
• DDD is the Julian day of the data collection

Data is received by the RVDAS system via RS-232 serial connections. The data files that comprise the rvdas data set are described below. A time tag is added to each line of data received and the data is written to disk.

Where, YY: two-digit year, DDD: Julian Day, HH: 2 digit hours, MM: 2 digit minutes SS.SSS: seconds. All times are UTC.

The delimiters used to separate fields in the raw data files are usually spaces and commas, but other delimiters are used (::, =, @) and occasionally there is no delimiter. Care should be taken when reprocessing the data that the fields separations are clearly understood. An example data

99+099:00:18:19.775 hf,305.2,lf,304.3

02+314:23:59:50.067 01.2 047 028 01.3 063 042 0988.8 001.7 084 -000.2192 0000.9358 0025.5875

02+310:23:57:30.200 8542 -1.2580 34.1740 -1.2030 3.435 0.349 27.361205

02+319:23:59:13.748 2002319.99851 7154.27 26.49 1033.6 325.79 6.74 329.3 53.76 0 Equil

00+348:01:59:52.128 1539.40

00+019:23:59:59.099 $PUHAW,UVH,-1.48,-0.51,250.6