NOAA Logo National Centers for Environmental Information

formerly the National Oceanographic Data Center (NODC)...  more on NCEI

NOAA Satellite and Information Service

You are here:HomeGTSPP › GTSPP FAQ

How does the GTSPP encode Quality Tests

The GTSPP Quality tests have been grouped according to stages. The first stage is concerned with determining that the position, the time, and the identification of a profile are sensible. The second stage is concerned with resolving impossible values for variables. The next stage examines the consistency of the incoming data with respect to references such as climatologies, followed by the stage of examining adjacent profiles in an incoming file to determine if they are similar in form. The last stage represent a visual inspection of the data as received and usually after all other tests have been completed as the final judgment of the validity of the data

The grouping of the tests suggests a logical order of implementation in that the simpler, more basic tests occur before more complicated ones. The order of presentation of tests within a stage does not imply an order in implementation. In fact, should a value be changed as a result of a test, the new value should be retested by all of the tests within the stage. Indeed, since data values can be changed, the implementation of these tests cannot take place in a strictly sequential fashion.

The tests are grouped by stages, and within Stage 1 they are presented in order of application. Tests in other stages may be applied in any order, but generally Stage 2 tests should be done before Stage 3 and so on. Each test of the Quality Control Manual is assigned an index number to base 2, which is a representation for numbers using only two digits, 0 (zero) and 1 (one) . The lists below are the test names with their index number in parentheses after each. The index number is given with every test documented in the GTSPP Quality Control Manual.

Stage 1: Location and Identification Tests
1.1 Platform Identification (1)
1.2 Impossible Date/Time (2)
1.3 Impossible Location (4)
1.4 Position on Land (8)
1.5 Impossible Speed (16)
1.6 Impossible Sounding (32)
Stage 3: Climatology Tests
3.1 Levitus Seasonal Statistics (65536)
3.2 Emery and Dewar Climatology (131072)
3.3 Asheville Climatology (262144)
3.4 Levitus Monthly Climatology (524288)
3.5 Levitus Annual Climatology (33554432)
Stage 2: Profile Tests
2.1 Global Impossible Parameter Values (64)
2.2 Regional Impossible Parameter Values (128)
2.3 Increasing Depth (256)
2.4 Profile Envelop (512)
2.5 Constant Profile (1024)
2.6 Freezing Point (2048)
2.7 Spike (4096)
2.8 Top and Bottom Spike (8192)
2.9 Gradient (16384)
2.10 Density Inversion (32768)
2.11 Bottom (8388608)
2.12 Temperature Inversion (16777216)
Stage 4: Profile Consistency Tests
4.1 Waterfall (1048576)
Stage 5: Visual Inspection
5.1 Cruise Track (2097152)
5.2 Profiles (4194304)

Attached to every profile is a hexadecimal number that indicates which tests have been employed. The hexadecimal number that describes the suite of tests employed against a profile is the sum of the index numbers, which is in decimal form, of the tests used. This hexadecimal number is constructed by converting the decimal number. As an example, if there are 10 tests, and all are employed, the Test Number is then 000003FF

Hexadecimal (also base 16, or hex) is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0– 9 to represent values zero to nine, and A, B, C, D, E, F (or alternatively a– f) to represent values ten to fifteen (A=10 through to F=15).