John P. Tully Sequential ASCII Interface Loop (SAIL)
Data Quality Control Report


Daniel M. Gilmore and Shawn Smith
World Ocean Circulation Experiment(WOCE)

Surface Meteorological Data Assembly Center
Center for Ocean Atmospheric Prediction Studies
The Florida State University

August 6, 2001

Report WOCEMET 97-9

Version 4.0


Members of the WOCE Hydrographic Project Office (WHPO) and WOCEMET met at the 13th Data Products Committee (DPC) meeting in College Station, TX to discuss reconciliation of the WOCE cruise line designators. This was done in anticipation of the future release of version 3 of the WOCE global data set, and resulted in changes to several WOCE cruise line designations.

On March 15, 2001, WOCEMET combined the WOCE designator for the cruises, P__15N/01 and P__15N/02 to the updated from, P__15N/01.

On August 6, 2001 WOCEMET deleted the line designator PRS01_/06. The quality control information for this data has been left in this report for the user, but please note that the line designator PRS01_/06 has been removed.


The data referenced in this report were collected from the research vessel John P. Tully (Call sign: CG2958; Data Provider: Institute of Ocean Science, Canada; P.I.: H. Freeland) SAIL System for 2 WOCE cruises covering 4 hydrographic lines. These data were received in electronic format and converted to the standard FSU format. Then they were preprocessed using an automated data checking program. Next a visual inspection was completed by a Data Quality Evaluator who reviewed, modified and added appropriate quality control (QC) flags to the data. Details of the WOCE QC can be found in Smith et al (1996). The data quality control report summarizes the flags for the John P. Tully SAIL data, including those added by both the preprocessor and the analyst.

Statistical Information:

The data referenced in this report were expected to include observations taken every 2 minutes by the John P. Tully SAIL System. The details of the cruise, including start and end date, number of values, records, and flags, and percentage flagged are outlined in Table 1.

Time (TIME), latitude (LAT), longitude (LON), platform heading (PL_HD), platform speed (PL_SPD), earth relative wind direction (DIR), earth relative wind speed (SPD), sea temperature (TS), and atmospheric pressure (P) were analyzed.

Table 1: Statistical Cruise Information
CTC Dates Number of Records Number of Values Number of Flags Percentage Flagged
09/06/94 - 10/08/94 22738 204642 44780 21.88
P__15N/02 10/13/94 - 11/11/94 20136 181224 42773 23.60

A total of 385866 values were checked, with 87553 flags added by the prescreener and analyst, resulting in 22.69 percent of the data being flagged. The distribution of flags for each variable sorted by flag type is detailed in table 2.

A:Major Problems:
There is only 1 major problem in this data set: the wind data, both DIR and SPD are completly erroneous. Throughout all the files, both of these variables have a signature of the ship's movement in them. This problem was encountered in other data sets such as the Thompson(WTEA) and the Knorr(KCEJ). It was determined that this problem was a result of a mis-calculation of the data where all the available information was not being used. This resulted in a signature of the ship's movement in the DIR and SPD data, with the problem being worse at high ship speeds. The problem with the WTEA and KCEJ was resolved by recalculating the winds with all of the available parameters: PL_WSPD, PL_WDIR, PL_HD, PL_SPD, and PL_CRS. However, the CG2958 does not include all of these parameters, so there is no way to recalculate the earth relative winds. Thus, all the data was flagged with "J" or "K" flags; the "K" flags being applied when ship speeds were lower, thus the observed wind speeds are closer to the true wind speed.
Table 2:Number of Flags and Percentage Flagged for Each Variable
Variable G H J K S Total Number of Flags  Percentage of Variable Flagged
TIME             0 0.00
LAT           2 2 0.00
LON           2 2 0.00
PL_HD             0 0.00
PL_SPD             0 0.00
DIR       42872     42872 100.00
SPD       31648 11224   42872 100.00
TS         103 150 253 0.59
P 1547 2 3       1552 3.62
Total Number of Flags Used 1547 2 3 74520 11327 154 87553 22.69
Percentage of Flags Used 0.33 0.00* 0.00* 15.80 2.40 0.03 22.69  

G: Data point greater than 4 standard deviations from climatology
H: Data shows a discontinuity
I: Data has an interesting feature
J: Data is erroneous
K: Data is suspect, use caution
S: Data shows a spike

 B: Minor Problems:

Final Note:

Depending on which variables the user is considering using, these data are either in good shape or poor shape. The wind data, DIR and SPD, are unusable in their current condition. The TS and P data on the other hand are in outstanding condition. The user should have no problem with these variables.


Smith, S.R., C. Harvey, and D.M. Legler, 1996: Handbook of Quality Control Procedures and Methods for Surface Meteorology Data. WOCE Report No. 141/96, Report WOCEMET 96-1, Center for Ocean Atmospheric Prediction Studies, Florida State University, Tallahassee, FL 32310.