National Water and Climate Center PRISM Probabilistic-Spatial QC (PSQC) System for SNOTEL Data...
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National Water and Climate Center National Water and Climate Center P P R R I I S S M M Probabilistic-Spatial QC (PSQC) System for SNOTEL Data Probabilistic-Spatial QC (PSQC) System for SNOTEL Data MTNCLIM 2006 CONFERENCE September 19-22, 2006 at Timberline Lodge, Mt. Hood, Oregon PRISM to help with Quality Control (QC) When installation first began in the middle 1970s, the SNOTEL (SNOwTELemetry) network was never envisioned as a data source for climate change studies; however the network has become a de facto source for middle and higher elevation snowpack, precipitation and temperature data in the West. While sensor technology and communication capability continue to improve the quality of observations at these remote sites, PRISM methodology is now being employed to correct or back-fill COLORADO SNOTEL SITES COLORADO SNOTEL SITES 46 Colorado SNOTEL sites with more than 5,000 daily (Tmax & Tmin) observations. Missing days Missing days account for ~5.15% of POR. PRISM determined suspect observations suspect observations account for ~1.75% of POR. B B ackground ackground O O riginal riginal D D ata ata Q Q uality uality P P R R I I S S M M M M ethodology ethodology http://mistral.oce.orst.edu/www/snotelqc/ http://mistral.oce.orst.edu/www/snotelqc/ “Advances in climate mapping technology now make it possible to estimate a reasonably accurate ‘expected value’ for an observation based on surrounding stations. Assumption: Spatial consistency is related to observation validity.” – Dr. Chris Daly Electronic Sensors and Electronic Sensors and Modern Applications Create Modern Applications Create Challenges for Traditional Challenges for Traditional QC Systems QC Systems • Errors tend to be Errors tend to be continuous drift, rather continuous drift, rather than categorical than categorical mistakes mistakes • Increasing usage of Increasing usage of computer applications computer applications that rely on climate that rely on climate observations observations • Continuous Continuous estimates, estimates, rather than categorical rather than categorical tests, of observation tests, of observation validity validity • Quantitative estimates of Quantitative estimates of observational uncertainty, observational uncertainty, not just flags not just flags Situation Need PRISM Regression of “Weather vs. Climate” PR ISM R esults 18 20 22 24 26 28 30 32 34 16.5 17.5 18.5 19.5 20.5 21.5 22.5 23.5 24.5 25.5 26.5 71-00 M ean July M axim um T em perature Daily M axim um Tem perature (C) 21D 12S 21D 35S 21D 13S 353402 21D 08S 5211C 70E 324045C C 3240335C 21D 14S Regression Stn: 21D12S Date: 2000-07-20 Climate: 21.53 Obs:26.0 Prediction: 25.75 Slope: 1.4 Y-Intercept: -4.37 20 July 2000 Tmax vs. 1971-2000 Mean July Tmax This is a scatter-plot showing how this method can be used for daily interpolation. On the x- axis is the mean July temperature, and it is being regressed with the daily maximum temperature for July 20, 2000. This plot, for a location new Mount Hood in Oregon, shows that even though the temperature is nearly 5C above the mean, the spatial patterns are remarkably similar. SNOTEL QC SNOTEL QC W W ebsite ebsite Issues to Issues to Consider* Consider* • How far can the assumption be taken that spatial How far can the assumption be taken that spatial consistency equates with validity? consistency equates with validity? • Are continuous and probabilistic QC systems useful for Are continuous and probabilistic QC systems useful for manual observing systems? manual observing systems? • Can a high-quality QC system ever be completely automated? Can a high-quality QC system ever be completely automated? • If a QC system works effectively, can it be used for If a QC system works effectively, can it be used for SNOTEL site selection? If so, then SNOTEL site selection? If so, then • What criteria should be employed for SNOTEL site What criteria should be employed for SNOTEL site selection? selection? Jan Curtis NRCS - National Water & Climate Center 1201 NE Lloyd Blvd., Suite 802 Portland, OR 97232 [email protected] (503) 414-3017 • Range of applications Range of applications is increasingly is increasingly rapidly, and each has rapidly, and each has a difference a difference tolerance for tolerance for outliers outliers • Data are often more Data are often more voluminous and voluminous and disseminated in a disseminated in a more timely manner more timely manner • Probabilistic information Probabilistic information from which a decision to from which a decision to use an obs can be made, use an obs can be made, not up-front decision not up-front decision • Automated QC methods Automated QC methods
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Transcript of National Water and Climate Center PRISM Probabilistic-Spatial QC (PSQC) System for SNOTEL Data...
National Water and Climate CenterNational Water and Climate Center
PPRRIISSM M Probabilistic-Spatial QC (PSQC) System for SNOTEL DataProbabilistic-Spatial QC (PSQC) System for SNOTEL DataMTNCLIM 2006 CONFERENCE
September 19-22, 2006 at Timberline Lodge, Mt. Hood, Oregon
PRISM to help with Quality Control (QC)
When installation first began in the middle 1970s, the SNOTEL (SNOwTELemetry) network was never envisioned as a data source for climate change studies; however the network has become a de facto source for middle and higher elevation snowpack, precipitation and temperature data in the West. While sensor technology and communication capability continue to improve the quality of observations at these remote sites, PRISM methodology is now being employed to correct or back-fill all archived SNOTEL data that is suspect or missing. The results of this effort may indeed provide the basis for identifying a “benchmark” SNOTEL network for climate change studies.
COLORADO SNOTEL SITESCOLORADO SNOTEL SITES
46 Colorado SNOTEL sites with more than 5,000 daily (Tmax & Tmin) observations. Missing daysMissing days account for ~5.15% of POR. PRISM determined suspect observationssuspect observations account for ~1.75% of POR.
BBackgroundackground OOriginal riginal DData ata QQualityuality PPRRIISSMM MMethodologyethodology
http://mistral.oce.orst.edu/www/snotelqc/http://mistral.oce.orst.edu/www/snotelqc/“Advances in climate mapping technology now make it possible to estimate a reasonably accurate ‘expected value’ for an observation based on surrounding stations.
Assumption: Spatial consistency is related to observation validity.” – Dr. Chris Daly
Electronic Sensors and Modern Electronic Sensors and Modern Applications Create Challenges for Applications Create Challenges for
Traditional QC SystemsTraditional QC Systems
• Errors tend to be continuous Errors tend to be continuous drift, rather than categorical drift, rather than categorical mistakesmistakes
• Increasing usage of Increasing usage of computer applications that computer applications that rely on climate observationsrely on climate observations
• ContinuousContinuous estimates, rather estimates, rather than categorical tests, of than categorical tests, of observation validityobservation validity
• Quantitative estimates of Quantitative estimates of observational uncertainty, not observational uncertainty, not just flagsjust flags
Situation Need
PRISM Regression of “Weather vs. Climate”
PRISM Results
18
20
22
24
26
28
30
32
34
16.5
17.5
18.5
19.5
20.5
21.5
22.5
23.5
24.5
25.5
26.5
71-00 Mean July Maximum Temperature
Dai
ly M
axim
um
Tem
per
atu
re (
C)
21D12S
21D35S
21D13S
353402
21D08S
5211C70E
324045CC
3240335C
21D14S
Regression
Stn: 21D12SDate: 2000-07-20Climate: 21.53Obs:26.0Prediction: 25.75Slope: 1.4Y-Intercept: -4.37
20 July 2000 Tmax vs. 1971-2000 Mean July Tmax
This is a scatter-plot showing how this method can be used for daily interpolation. On the x-axis is the mean July temperature, and it is being regressed with the daily maximum temperature for July 20, 2000. This plot, for a location new Mount Hood in Oregon, shows that even though the temperature is nearly 5C above the mean, the spatial patterns are remarkably similar.
SNOTEL QCSNOTEL QC WWebsiteebsite
Issues to Consider*Issues to Consider*• How far can the assumption be taken that spatial consistency How far can the assumption be taken that spatial consistency
equates with validity?equates with validity?
• Are continuous and probabilistic QC systems useful for manual Are continuous and probabilistic QC systems useful for manual observing systems?observing systems?
• Can a high-quality QC system ever be completely automated?Can a high-quality QC system ever be completely automated?
• If a QC system works effectively, can it be used for SNOTEL site If a QC system works effectively, can it be used for SNOTEL site selection? If so, thenselection? If so, then
• What criteria should be employed for SNOTEL site selection?What criteria should be employed for SNOTEL site selection?
Jan CurtisNRCS - National Water & Climate Center
1201 NE Lloyd Blvd., Suite 802Portland, OR 97232
[email protected](503) 414-3017
• Range of applications is Range of applications is increasingly rapidly, and increasingly rapidly, and each has a difference each has a difference tolerance for outlierstolerance for outliers
• Data are often more Data are often more voluminous and voluminous and disseminated in a more disseminated in a more timely mannertimely manner
• Probabilistic information from Probabilistic information from which a decision to use an obs which a decision to use an obs can be made, not up-front can be made, not up-front decisiondecision
• Automated QC methodsAutomated QC methods
![Auditing and Assurance Standards C ouncil · Appendix 1: Specific Requirements in [Proposed] PSQC 1 (Redrafted) And Other PSAs that Refer to Communications with Those charged with](https://static.fdocuments.in/doc/165x107/5f54f6e19419386398702b01/auditing-and-assurance-standards-c-ouncil-appendix-1-specific-requirements-in-proposed.jpg)
