Jesse Enloe and Shawn R. Smith
World Ocean Circulation Experiment (WOCE)
Surface Meteorological Data Assembly Center
Center for Ocean-Atmospheric Prediction Studies
Florida State University
October 13, 1999
Report WOCEMET 99-13
Version 1.0
Introduction:
The data referenced in this report are bridge observations obtained from the Comprehensive Ocean Atmosphere Data Set (COADS) (Slutz et. al.). The data originated on the research vessels Takuyo (identifier: 7JWN), Hudson (identifier: CGDG), Sonne (identifier: DFCG), Le Noroit (identifier: FITA), Charles Darwin (identifier: GDLS), Chofu Maru (identifier: JCCX), Shumpu Maru (identifier: JFDG), Kaiyo (identifier: JRPG), T. Washington (identifier: KGWU), Tyro (identifier: PIBQ), Akademic A. Nesmeyanov (identifier: UBYK), Akademic Lavrentyev (identifier: UJFY), Franklin (identifier: VJJF), New Horizon (identifier: WKWB), Discoverer (identifier: WTEA), Vickers (identifier: WTEC), Malcom Baldrige (identifier: WTER), Oceanus (identifier: WXAQ), James Clarke Ross (identifier: ZDLP), and Agulhas (identifier: ZSAF). The data were provided to the Florida State University Data Assembly Center (DAC) in electronic format by and were converted to standard DAC netCDF format. The data were then processed using an automated screening program, which adds quality control flags to the data, highlighting potential problems. Finally, the Data Quality Evaluator (DQE) reviewed the data and current flags, whereby flags were added, removed, or modified according to the judgement of the DQE and other DAC personnel. Details of the WOCE quality control procedures can be found in Smith et al. (1996). The data quality control report summaries the flags for the Comprehensive Ocean Atmospheric Data Set, including those added by both the preprocessor and the DQE.
Statistical Information:
The Comprehensive Ocean Atmospheric Data Set is expected to include observations taken at irregular time intervals on all 71 WOCE cruises. Values for the following variables were collected, although some variables were not measured on different research vessels and cruises:
| Time | (TIME) |
| Latitude | (LAT) |
| Longitude | (LON) |
| Earth Relative Wind Direction | (DIR) |
| Earth Relative Wind Speed | (SPD) |
| Atmospheric Pressure | (P) |
| Air Temperature | (T) |
| Sea Temperature | (TS) |
| Dewpoint Temperature | (TD) |
| Wet Bulb Temperature | (TW) |
| Present Weather | (WX) |
| Total Cloud Amount | (TCA) |
| Low/Middle Cloud Amount | (LMCA) |
| Cloud Base Height | (ZCL) |
| Low Cloud Type | (LCT) |
| Middle Cloud Type | (MCT) |
| High Cloud Type | (HCT) |
Sixteen of the 71 WOCE cruises were missing one or more of the variables listed above. These missing variables are listed by ship and by cruise in Table 1.
Table 1: Missing Variables
| RV/CTC | TD | TW | WX | LMCA | ZCL | LCT | MCT | HCT |
|
CGDG AR_05_/01; AR_07W/02 AR_07W/03 AR_13_/05 |
X X X
|
X |
||||||
|
FITA PR_15_/18 PR_15_/19 |
X X |
|||||||
|
JCCX PR_19_/01 PR_19_/03 |
X |
X X |
||||||
|
JFDG PR_17_/04 PR_17_/19 |
X
|
X |
||||||
|
PIBQ AR_07E/01 AR_07E/02 |
X X |
|||||||
|
UBYK P__01W/00 |
X |
X |
||||||
|
UJFY PR_13N/03 |
X |
X |
||||||
|
WXAQ AR_11_/02 |
X |
X |
X |
X |
X |
|||
|
ZSAF ISS01_/01 |
X |
Details of the cruises are listed in Table 2 and include cruise dates, number of records, number of values, number of flags, and total percentage of data flagged. A total of 70,354 values were evaluated with 1,132 flags added by the preprocessor and the DQE for a total of 1.61% of the values being flagged. The coded data (WX, TCA, LMCA, ZCL, LCT, MCT, HCT) were not included in these statistics.
Table 2: Statistical Cruise Information
|
RV/CTC |
Dates |
Number of Records |
Number of Values |
Number of Flags |
Percentage Flagged |
|
CGDG AR_05_/01; AR_07W/02 AR_07W/03 AR_10_/07 AR_07W/04 AR_13_/02; AR_07W/05; AR_13_/04 AR_13_/05 A__01W/00 |
04/25/91 - 05/23/91 05/27/91 - 06/04/91 05/28/92 - 06/13/92 04/07/93 - 05/12/93 06/19/93 - 06/28/93 11/05/93 - 12/16/93 05/25/94 - 06/12/94 10/13/94 - 11/09/94 04/20/95 - 05/16/95 06/09/95 - 07/04/95 |
88 20 40 72 32 79 45 91 60 63 |
792 180 360 720 320 790 450 910 600 630 |
12 0 0 6 8 0 1 4 2 1 |
1.52 0.00 0.00 0.83 2.50 0.00 0.22 0.44 0.33 0.16 |
|
DFCG IR_04_/01 |
12/23/90 - 01/19/91 |
95 |
950 |
17 |
1.79 |
|
FITA PR_15_/17 PR_15_/18 PR_15_/19 PR_15_/20 PR_15_/21 PR_15_/22 PR_15_/23 AR_04_/05; |
02/01/91 - 03/03/91 03/11/91 - 04/06/91 07/18/91 - 08/13/91 01/02/92 - 02/16/92 02/21/92 - 03/17/92 08/06/92 - 08/31/92 09/05/92 - 10/02/92 09/09/95 - 10/11/95 |
139 83 70 224 185 177 173 239 |
1,390 747 630 2,240 1,850 1,770 1,730 2,390 |
10 6 7 7 7 10 13 21 |
0.72 0.80 1.11 0.31 0.38 0.56 0.75 1.51 |
|
GDLS AR_10_/03 AR_11_/08 AR_10_/08 |
05/09/92 - 06/07/92 10/01/92 - 10/20/92 04/23/93 - 05/24/93 |
113 59 125 |
1,130 590 1,250 |
9 3 24 |
0.80 0.51 1.92 |
|
JCCX PR_19_/01 PR_19_/02 PR_19_/03 PR_19_/05 |
11/13/90 - 11/16/90 11/18/90 - 11/21/90 11/07/91 - 11/08/91 11/08/92 - 11/18/92 |
25 29 12 75 |
250 290 108 750 |
3 0 0 14 |
1.20 0.00 0.00 1.87 |
|
JFDG PR_17_/04 PR_17_/17 PR_17_/19 |
10/14/91 - 10/16/91 10/01/94 - 10/05/94 07/01/95 - 07/05/95 |
22 37 34 |
198 370 340 |
0 0 0 |
0.00 0.00 0.00 |
|
JRPG PR_24_/02 PR_23_/03 |
10/06/92 - 10/19/92 12/13/92 - 12/23/92 |
15 56 |
150 560 |
0 9 |
0.00 1.61 |
|
KGWU P__17C/00 P__17S/00 P__16C/00 |
06/03/91 - 07/11/91 07/17/91 - 08/25/91 09/01/91 - 10/01/91 |
132 120 85 |
1,320 1,200 850 |
1 10 10 |
0.08 0.83 1.18 |
|
PIBQ AR_07E/01 AR_07E/02 |
07/03/90 - 08/02/90 04/13/91 - 04/30/91 |
64 31 |
576 279 |
5 3 |
0.87 1.08 |
|
UBYK P__01W/00 |
08/31/93 - 09/03/93 |
11 |
88 |
3 |
3.41 |
|
UJFY PR_13N/03 |
05/13/93 - 06/08/93 |
75 |
600 |
0 |
0.00 |
|
VJJF IR_04_/03 IR_02_/01 ISSO3_/01 IR_06_/04 |
08/28/94 - 09/03/94 11/20/94 - 12/01/94 04/01/95 - 04/22/95 09/20/95 - 10/09/95 |
23 22 66 66 |
230 220 660 660 |
0 7 3 2 |
0.00 3.18 0.45 0.30 |
|
WKWB PRS03_/04 |
11/17/94 - 12/04/94 |
29 |
290 |
1 |
0.34 |
|
WTEA PR_16_/01 P__16N/01 P__16N/02 PR_16_/03 PR_16_/05 PR_16_/09 PR_16_/10 PR_16_/14 PR_16_/16 |
11/28/90 - 12/06/90 02/28/91 - 02/28/91 03/07/91 - 04/06/91 11/01/91 - 11/13/91 10/14/92 - 11/18/92 09/18/93 - 10/15/93 01/27/94 - 01/29/94 02/06/95 - 05/02/95 08/05/95 - 08/26/95 |
74 8 241 231 209 168 19 189 156 |
740 80 2,410 2,310 2,090 1,680 190 1,890 1,560 |
19 0 28 36 43 40 0 15 6 |
2.57 0.00 1.16 1.56 2.06 2.38 0.00 0.79 0.38 |
|
WTER PR_16_/02 PR_16_/04 PR_16_/06 PR_16_/07 AR_21_/02 PR_16_/11 PR_16_/15 PR_16_/12 PR_16_/13 IR_04_/05 |
03/23/91 - 04/19/91 02/23/92 - 03/26/92 02/21/93 - 03/18/93 04/18/93 - 05/14/93 08/22/93 - 10/03/93 04/16/94 - 05/09/94 05/17/94 - 06/17/94 08/04/94 - 08/25/94 08/30/94 - 09/25/94 08/24/95 - 09/25/95 |
205 255 208 221 259 229 284 215 247 238 |
2,050 2,550 2,080 2,210 2,590 2,290 2,840 2,150 2,470 1,380 |
13 34 74 66 14 75 106 138 91 0 |
0.63 1.33 3.56 2.99 0.54 3.28 3.73 6.42 3.68 0.00 |
|
WXAQ AR_11_/02 |
06/19/91 - 07/04/91 |
8 |
72 |
0 |
0.00 |
|
ZDLP SR_01_/04 |
11/20/93 - 12/18/93 |
64 |
640 |
14 |
2.19 |
|
ZSAF ISS01_/01 |
04/05/91 - 05/07/91 |
186 |
1,674 |
81 |
4.84 |
Summary:
The overall quality of the bridge data for the COADS proves to be excellent, though the quality varies by ship and by cruise. The distribution of flags for each variable is detailed in Table 3.
Table 3: Number of Flags and Percentage Flagged for Each Variable
Variable |
B |
D |
F |
G |
L |
S |
T |
Total Number of Flags |
Percentage of Variable Flagged |
|
TIME LAT LON DIR SPD P T TS TD TW WX TCA LMCA ZCL LCT MCT HCT |
55
6
|
7
6 13
|
57 57
|
20 4 17 16
|
1 1
|
166 145 5 13 10 8 16 7 5
|
497
|
497 225 202 60 33 14 32 38 13 18 0 0 0 0 0 0 0 |
6.99 3.16 2.84 0.84 0.46 0.20 0.45 0.53 0.18 0.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
|
Total Number of Flags |
61 |
26 |
114 |
57 |
2 |
375 |
497 |
1,132 |
|
Percentage of All Values Flagged |
0.09 |
0.04 |
0.16 |
0.08 |
0.00* |
0.53 |
0.70 |
1.61 |
| *Percentage < 0.01 |
Time Duplicate Problem:
Almost seven percent of the time stamps were flagged with the T flag by the preprocessor, indicating time duplication. If there are two values for any given variables that share the same time stamp they will both be displayed at that time by the visual data assessment tool (VIDAT). In many cases, this problem caused spikes in the data. Often times if a spike occurred the DQE determined which value was real and flagged the other value as a spike (S). Though the time duplicate spike occurred throughout the data, it was most common in the position data. The user may wish to avoid using meteorological data at times flagged as duplicates.
Other Problems:
Latitude and Longitude received F flags indicating unrealistic platform velocity as determined by the position data. Both variables also received an L flag, denoting a position over land. Erroneous position reports are not uncommon to bridge data.
A total of 26 D flags were assigned by the preprocessor to T, TW, and TD for failing the T>TW>TD test. In the free atmosphere, the value of the temperature is always greater than or equal to the wet-bulb temperature, which in turn is always greater than or equal to the dewpoint temperature (Smith et al. 1996).
The G flag designates data that have values four standard deviations or greater from the COADS climatological means (da Silva et al. 1994).
The B flag assigned by the preprocessor designates a wind direction outside the 0 to 360 degree bounds. A value of 362 degrees refers to variable wind and 361 degrees refers to calm wind in COADS data. All of these values were flagged with the B flag by the preprocessor, but can be considered as reliable data values.
References:
Smith, S.R., C. Harvey, and D.M. Legler, 1996: Handbook of Quality Control Procedures
da Silva, A.M., C.C. Young and S. Levitus, 1994: Atlas of Surface Marine Data 1994, Volume 1:
Slutz, R.J., S.J. Lubker, J.D. Hiscox, S.D. Woodruff, R.L. Jenne, D.H. Joseph, P.M. Seurer and
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 32306-2840
Algorithms and Procedures. NOAA Atlas Series.
J.D. Elms, 1985: COADS - Comprehensive Ocean Atmosphere Data Set,
CIRES/ERL/NCAR/NCDC, Boulder, Colorado.