automated validation for summary of the day temperature data

September 23, 2003 National Climatic Data Center

AUTOMATED VALIDATION FOR

SUMMARY OF THE DAY TEMPERATURE DATA

Authors: William E. Angel, Michael L. Urzen,

Stephen A. Del Greco, and Matthew W. Bodosky

Special Thanks to Arthur G. DeCotiis


COMMON ACROYMNS

ASOS – Automated Surface Observing SystemAWOS – Automated Weather Observing SystemCOOP – Cooperative Observers NetworkGEA – Graphical Edit AnalysisGMT – Generic Mapping ToolsNEWAE – NEW Areal EditTEMPVAL – Automated Temperature Validation

System


COOPERATIVE DATA – WHAT IS IT?

COOP OBSERVERAM, PM, MID READERS


~8500 Stations


NWS

NCDC

SIMPLIFIED COOPERATIVE DATA FLOW

COOP Forms

Data Entry

Monthly QC

Archive

Publication

Internet

COOP Observer


COOPERATIVE DATA PROCESSING (TEMPVAL Plug In)

RecordsTranscription

Auto Aerial Edit

(NEWAE)

InteractiveValidation

(GEA)Last Look

TEMPVAL


PRE-TEMPVAL OPERATIONAL OVERVIEW

Validation Based on Cooperative NeighborsApproximately 70% Automated, 30% ManualRules Based – AutomatedUnresolved Data – Manual Review by Validator

Compared Daily Departures From Station Monthly Mean Temperature3-Sigma Mean Value


PRE-TEMPVAL OPERATIONAL OVERVIEW

Looked For Shifter SignatureObservation Day Versus Calendar DayCommon With AM Readers

Detected FlatlinersRepeating Same Temperature 3 Or More Days In A Row


WHY TEMPVAL?Improve Validation Accuracy

Change in Methodology– Use of Grid Fields Instead of COOP Neighbors

High Quality of “Ground Truth” DataEliminate Validator Subjectivity

Make Edits Uniform and Consistent Reduce Manual Effort And Production Time

Reason For AutomationPrevious System In Use Since Early 1990’s

Time For An Update


“GROUND TRUTH” DATA

Use Of Approximately 900 ASOS SitesUse Of Approximately 450 AWOS SitesUse Of Approximately 300 Canadian ASOS SitesData Is Gridded On A ½ Degree Resolution Using

GMT SoftwareInverse Distance Squared Interpolation

Data Undergoes A “Bull’s Eye” Grid TestSlope Test Comparing A Grid Point Intersection Value

With Surrounding Grid Point Values


HOW DOES TEMPVAL WORK?

Computes Daily Max/Min Departure From Monthly Mean Max/Min (same as previous system)

Builds 1/2 Degree Grid Fields By Reader Time From Quality Controlled ASOS/AWOS Hourly And Summary Of Day Data

Compares Cooperative Daily Departure With ASOS/AWOS Grid Departures

Generates Edits By Adding Grid Departure To The Cooperative Station Monthly Mean Max/Min


TEMPVAL FLOWCHARTBuild ASOS Daily Max/Min

Departure Grid Analyses (AM,PM,Mid)

Test Cooperative Max/Min Departure Against Grid

Value

Validates/Not Missing?|OV - grid| < 7 + grad

Apply Grid Departure To Station Mean Max/Min

Detect and Remove Bull’s Eyes

Edit OVContinue

End

No

Yes

Note: stations on “Exception List” bypass this process

Note: OV represents the coop max/min departure value.


PARALLEL TESTING RESULTS

Tested for |COOP - GRID| >= 7.0 + Gradient TEMPVAL Generated 12,904 (8.63%) EditsTEMPVAL Generated 6060 (4.05%) Temperatures

For Missing Observed TemperaturesManually Validated 100 Outlier Cases (Operational

Aerial Edit versus TEMPVAL)TEMPVAL Results Are More Realistic Than

Operational Results In 90% Of Cases


GEA vs ASOS VALIDATION6 Nov 2001 R2 = 0.9665y = 0.986x + 0.4098

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

GEA Values

ASOS Values


GEA vs ASOS VALIDATION15 DEC 2000

R2 = 0.9547y = 0.9696x + 1.0937

-20

-10

0

10

20

30

40

50

60

70

80

90

-20 -10 0 10 20 30 40 50 60 70 80 90

GEA Values

ASOS Values


TempVal Edit DistributionNov 2001

0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10

Difference of the TempVal Value and the Observed Value

Skewness = 1.279


SHORTFALLS OF TEMPVALLimited In Capability To Effectively Interpret Particular

Types Of Weather, Such AsWarm Air Advection Episodes For High Elevation

StationsInversionsStrong Frontal Passages“Backdoor Cold Fronts”

Lack Of Sufficient ASOS/AWOS Data Does Not Allow TempVal To Be Performed In Puerto Rico, Virgin Islands, Or The Remaining Territories


BENEFITS OF TEMPVAL

Fully Automated “Plug-In” ModuleEdits Are Uniform and SystematicGenerate Daily Replacement Temperature ValuesRe-Analysis Is PossibleAdditional Algorithms Easily Added

Currently Testing A “Time Shifter” AlgorithmRetain Original Data

Database Contains Original And Edited Values– Same As Previous System


CONCLUSIONS

ASOS/AWOS Station Density And Data Quality Are Sufficient To Produce Departure Grid Fields

Parallel Testing Shows That TEMPVAL Outperforms The Previous System

Eliminates Manual Processing And Removes Associated Validator Subjectivity

TEMPVAL Been Operational Since The January 2002 Data MonthCurrently Processing November 2002 Data


QUESTIONS - COMMENTS

THANKS!

automated validation for summary of the day temperature data

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