Le Noroit Quality Control Report

Christopher Harvey

Tropical Ocean Global Atmosphere (TOGA)
Coupled Ocean Atmosphere Response Experiment (COARE)

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

September 15, 1995

Report COAREMET 95-16

Version 1.0

Introduction:

The general surface meteorological data referenced in this report were
collected from the research vessel Le Noroit (call sign FITA; data
acquired from the ORSTOM Noumea) for TOGA COARE during the Intensive
Observing Period (IOP).  All data were converted to a standard format
and were then preprocessed using an automated data quality checking
program.  The data were then visually inspected by a data quality
analyst who reviewed, modified, and added appropriate quality control
(QC) flags to the data.  This report summarizes the flags for the Le
Noroit data sets, including both flags added by the preprocessor and
the analyst.

Statistical Information:

The data from the Le Noroit during the IOP were expected to include
standard observations every three hours from a cruise which began on
December 2, 1992 and lasted for 89 days.  Time (TIME), latitude (LAT),
longitude (LON), wind direction (DIR), wind speed (SPD), atmospheric
pressure (P), temperature (T), wet-bulb temperature (TW), and sea
surface temperature (TS) were quality controlled.  A total of 5,319
values were reviewed and checked and 151 flags were added resulting in
2.8389 percent of the data being flagged.  Table 1 details the
distribution of flags and includes the percentages flagged for each
variable sorted by flag type.

Summary:

As can be seen from the statistical information, the data from the Le
Noroit are considered to be in good condition.  The most outstanding
reason for flags was the high number of wind speed values that were
flagged for being greater than four standard deviations from the da
Silva climatological mean.  The climatological mean lies between five
and ten meters per second while the values flagged range from 15 to 30
m/s.  The nature of these higher wind speed values is still unclear.
Other problems, such as spikes in the data, unrealistic Table 1:
Frequency of Flags Assigned for Each Variable and Flag Type


                           > 4 S.D. From                                          Percent of
            Unrealistic    Climatological      Spike in  Time       Total Number  Variable Records
Variable    Movement	        Mean           Data      Duplicate  of Flags      Flagged
						
TIME                                                        2          2             0.3384
LAT            3                                                       3             0.5076
LON            3                                                       3             0.5076
DIR                                              1                     1             0.1692
SPD                            139                                   139            23.5195
P                                                2                     2             0.3384
T                                                                      0              0
TW                                                                     0              0
TS                                               1                     1             0.1692
Total          6               139               4         2         151
						
Percent of
Total Data
Flagged     0.1128           2.6133            0.0752    0.0376     2.8389

ship movement, and time duplicates, were minor.

Final Notes:

The data from the Le Noroit appear to be in good condition and the
analyst does not foresee any problems in using the data.  However, the
wind speed data should be used with some caution.

Reference:

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.