PRISM Approach to Producing PRISM Approach to Producing Analysis of RecordAnalysis of Record

Christopher Daly, Ph.D., DirectorChristopher Daly, Ph.D., DirectorSpatial Climate Analysis ServiceSpatial Climate Analysis Service

Oregon State UniversityOregon State University

Corvallis, Oregon, USACorvallis, Oregon, USA

Spatial Climate Analysis Service Spatial Climate Analysis Service MissionMission

• Service• Provide innovative, state-of-the science

spatial climate products and services to clients worldwide

• Research• Maintain scientific research and

development programs that provide the basis for products and services

• Education• Advance “geospatial climatology” as an

emerging discipline

SCAS and PRISM are UniqueSCAS and PRISM are Unique

• SCAS is the only center in the world dedicated solely to the mapping of climate

• PRISM climate mapping technology has been continuously developed, and repeatedly peer-reviewed, since 1991

• PRISM climate maps are the “gold standard” by which others are evaluated

• SCAS has become a leader in climate mapping products and technology worldwide

- Generates gridded estimates of climatic parameters (e.g., P, T, DP)

- Moving-window regression of climate vs. elevation for each grid cell- Uses nearby station observations

- Spatial climate knowledge base weights stations in the regression function by their climatological similarity to the target grid cell

PRISM

Parameter-elevation Regressions on Independent Slopes Model

PRISM KBS accounts for spatial variations in climate due to:

- Elevation- Terrain orientation – rain shadows- Terrain profile – orographic enhancement- Moisture regime – trajectory model- Coastal proximity – trajectory model- Two-layer atmosphere – inversion layer, free atmosphere- Topographic position – susceptibility to cold air pooling

PRISM

Parameter-elevation Regressions on Independent Slopes Model

PRISM Moving-Window Regression Function

1961-90 Mean April Precipitation, Qin Ling Mountains, China

Weighted linearregression

Rain Shadows: 1961-90 Mean Annual PrecipitationOregon Cascades

Portland

Eugene

Sisters

Redmond

Bend

Mt. Hood

Mt. Jefferson

Three Sisters

N

350 mm/yr

2200 mm/yr

2500 mm/yr

Dominant PRISM KBSComponents

Elevation

Terrain orientation

Terrain profile

Moisture Regime

Coastal Effects: 1971-00 July Maximum TemperatureCentral California Coast

Monterey

San Francisco

San Jose

Santa Cruz

Hollister

Salinas

Stockton

Sacramento

Pac

ific

Oce

an

Fremont

N

PreferredTrajectories

DominantPRISM KBS Components

Elevation

Coastal Proximity

Inversion Layer

34°

20° 27°

Oakland

Inversions – 1971-00 January Minimum TemperatureCentral Colorado

DominantPRISM KBS Components

Elevation

Topographic Index

Inversion Layer

Gunnison

Lake City

Crested ButteTaylor Park Res.

-18°C-13°

-18°

N

US and W Canada mean monthly climate grids (NRCS, EC)

• Used in thousands of applications• NWS RFC Mountain Mapper• NWS MDL/MOS Experimental Gridded Forecasts

• Heavily peer-reviewed• Official USDA digital climate layers• All 50 states, plus YT,BC,AB,SK,MB• Tmin, Tmax, Precip• 1961-90 (1971-2000 update for CONUS)• 4-km resolution

Relevant PRISM DatasetsAvailable Now

http://www.ocs.oregonstate.edu/prism/

• Sequential monthly climate grids (NOAA, USFS) “Monthly version of Analysis of Record”

• Jan 1895 – present (ongoing project)• CONUS• Tmin, Tmax, Precip, Dew Pt• 4-km resolution• Current methodology uses 1961-90 mean monthly grids as predictors

Relevant PRISM DatasetsAvailable Now

http://www.ocs.oregonstate.edu/prism/

• Hi-res 71-00 mean monthly climate grids (NRCS, NPS, USFS)

• All states/territories but Alaska (not funded)• Tmin, Tmax, Precip• 1971-2000• 800-m resolution or better• Expected completion 2005

Relevant PRISM DatasetsUnder Development

800m

4 km

Suggested MethodsSuggested Methods

“PRISM Climatologically Aided Interpolation” (CAI)

Most spatial patterns are repeatable, no need to construct them from scratch every timeUses a high-quality mean climatology as the predictor grid, rather than a DEMHighly robust to varying data densityMethod is proven and operational

Variant of CAI: “PRISM Model Aided Interpolation” (MAI) Not attempted, yetHigh-resolution numerical model output used as predictor gridPRISM acts as a sophisticated data assimilation tool

Suggested ImprovementsSuggested Improvements

Use climatologies that are “targeted” to better match current pattern

Use forecast or analysis model grids output to identify large-scale pattern Select predictor grid with best pattern match NWS Western Region is interested in developing targeted climatologies for Mountain Mapper

In central and eastern US, use radar and satellite precip estimates as ancillary predictive data for PRISM

Q & AQ & AWhat basic met variables have been mapped with PRISM?

Temp, Precip, Dew Pt, Solar RadiationWind speed and direction have not been mapped

12-day accumulated precip, Dec 1-12, 1999, western Oregon

Is a daily or sub-daily Analysis of Record feasible with PRISM?• Generally, yes

• Daily mapping of T,P,DP,SR performed successfully for western Oregon• Biggest problem is variable time of obs (COOP) for precip.• In plains and eastern US, using radar and satellite precip estimates as ancillary predictive data for PRISM would be helpful

Q & AQ & A

Can daily or sub-daily observations be QC’ed with PRISM technology?

Yes, we are developing a spatial, probabilistic QC system for NRCS’ daily SNOTEL data

What is a ballpark cost for developing a daily retrospective Analysis of Record using current PRISM methods?

$100-150K Tmax, Tmin, Ppt, Dew Pt Jan 1971- Dec 2003 (or more recent) CONUS, 4-km grid resolution Enhancements and scheduled updates extra

OSU SCAS Web SiteOSU SCAS Web Site

http://www.ocs.oregonstate.edu/prism/

• Near real time monthly maps for US• Long-term average maps• Graphics, map server, and data