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 August 6, 2001 WOCEMET deleted the line designator PRS01_/02. The quality control information for this data has been left in this report, but please note that the line designator PRS01_/02 has been removed.
WOCEMET deleted the line designators PR_05_/05 and PRS01_/05. The quality control information for this data has been left in this report, but please note that the line designators PR_05_/05 and PRS01_/05 have been removed.
WOCEMET deleted the line designator PRS01_/07. The quality control information for this data has been left in this report, but please note that the line designator PRS01_/07 has been removed.
WOCEMET deleted the line designator PRS01_/08. The quality control information for this data has been left in this report, but please note that the line designator PRS01_/08 has been removed.
WOCEMET deleted the line designator PRS01_/09. The quality control information for this data has been left in this report, but please note that the line designator PRS01_/09 has been removed.
|Platform Relative Wind Direction||(PL_WDIR)|
|Platform Relative Wind Speed||(PL_WSPD)|
Details of the cruises including dates, number of records, number of values, number of flags, and percentage flagged are listed in Table 1. A total of 721048 values are evaluated with 7133 flags added by the preprocessor and Data Quality Evaluator for a total of 0.99 percent of the values being flagged.
|CTC||Cruise Dates||Number of Records||Number of Values||Number of Flags||Percentage Flagged|
|3 Feb 92 - 14 Feb 92||8020||64160||5998||9.35|
|12 May 93 - 31 May 93||13438||107504||116||0.11|
|PR_06_/10||7 Feb 94 - 19 Feb 94||8858||70864||22||0.03|
|10 May 94 - 23 May 94||10080||80640||6||0.01|
|7 Feb 95 - 23 Feb 95||11593||92744||303||0.33|
|PR_06_/14||9 May 95 - 25 May 95||12157||97256||284||0.29|
|25 Aug 95 - 13 Sep 95||13731||109848||394||0.36|
|20 Feb 96 - 8 Mar 96||12254||98032||10||0.01|
The SAIL AWS data from the John P. Tully are in excellent condition with only 0.99 percent of the data being flagged for errors. Table 2 provides the numbers and percentage of flags for each variable. A thorough discussion of the flags follows.
|Variable||B||F||J||K||S||Total Number of Flags||Percentage of Variable Flagged|
|Total number of Flags||16||1075||5847||78||117||7133|
|Percentage of All Values Flagged||0.00*||0.15||0.81||0.01||0.02||0.99|
Value Out of Realistic Range ("B" flags):
A few "B" Flags were administered to Platform Course and Platform Speed by the preprocessor. The flags identify values that are in excess of 15 meters per second for Platform Speed and in excesss of 359 degrees for Platform course. It is unlikely for a research vessel to travel at a speed of 15 meters per second, and compass values of more than 359 degrees are in error. Therefore, these data should be recognized as unrealistic and NOT BE USED.
Unrelealistic Platform Velocity ("F" flags):
Some latitude and longitude variables were flagged with the "F" flag. These flags indicate that the platform speed computed between sequential ship positions by the preprocessor exceeds a realistic speed for a research vessel (15 meters per second). These latitude and longitude positions should be used with caution.
Erroneous Data ("J" flags):
"J" flags were assigned to Platform Course, Platform Speed, Platform Relative Wind Direction, Platform Relative Wind Speed, and Pressure. Most (99.3 percent) of the "J" flags were applied to pressure on one cruise (3 Feb 92 - 14 Feb 92). Visual inspection revealed the pressure data to hold at a constant value for about 9 percent of the cruise. Figure 1a, a graph of the pressure data from 00:00 UTC 12 Feb 92 to 00:00 UTC 13 Feb 92, shows a period of constant pressure data. Since it is physically unrealistic to have pressure exactly constant a whole day, "J" flags were applied to pressure variables, indicating erroneous data. Clearly, some kind of instrument error occurred but we could not confirm our suspicion. Regardless, the flagged data are erroneous and should NOT BE USED.
Figure 1: SAIL data for 12 Feb 1992. Pressure a) with "J" flags marking all of the data as erroneous. Platform Course b) and Platform Speed c) with "K" flags marking the suspect data.
Spike in the Data ("S" flags):
The Data Quality Evaluator applied "S" flags to various parameters. The flags indicate areas in the data that are drastically out of the current data trend. Spikes are common to electronic data and may be associated with power surges that briefly disrupt the electronic integrity of the AWS systems.
With the exception of the pressure data from 3 Feb 92 to 14 Feb 92, the John P. Tully SAIL AWS data are of excellent quality and should be very reliable for the user.
da Silva, A. M., C. C. Young and S. Levitus, 1994: Atlas of Surface Marine Data 1994, Volume 1: Algorithms and Procedures. NOAA Atlas Series. In preparation.
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 32301