The PRISM Approach to Mapping Climate in Complex Regions

1. PRISM GROUP The PRISM Approach to Mapping Climate in Complex Regions Christopher Daly Director, PRISM Group Northwest Alliance for Computational Science and Engineering Department of Geosciences Oregon State University Corvallis, Oregon, USA

2. PRISM GROUP PRISM Group Facts • 5-FTE applied research team at Oregon State University, 100% externally funded • The PRISM Group is the only center in the world dedicated solely to the spatial analysis of climate • PRISM climate mapping technology has been continuously developed, and repeatedly peer-reviewed, since 1991 • The PRISM Group is the de facto climate mapping center for the US • The PRISM Group is advancing “Geospatial Climatology” as an emerging discipline

4. Oregon Annual Precipitation

5. Oregon Annual Precipitation

6. Oregon Annual Precipitation

7. Oregon Annual Precipitation

8. Oregon Annual Precipitation

9. PRISM GROUP Rationale • Observations are rarely sufficient to directly represent the spatial patterns of climate • Human-expert mapping methods often produce the best products, but are slow, inconsistent, and non-repeatable • Purely statistical mapping methods are fast and repeatable, but rarely provide the best accuracy, detail, and realism • Therefore… • The best method may be a statistical approach that is automated, but developed, guided and evaluated with expert knowledge

10. PRISM GROUP Knowledge-Based SystemKBS • Knowledge acquisition capability – Elicit expert information • Knowledge base – Store of knowledge • Inference Engine – Infer solutions from stored knowledge • User interface – Interaction and explanation • Independent verification – Knowledge refinement

11. PRISM GROUP PRISM Parameter-elevation Regressions on Independent Slopes Model • Generates gridded estimates of climatic parameters • 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 physiographic similarity to the target grid cell

12. Oregon Annual Precipitation Interface

13. PRISM GROUP PRISM Knowledge Base • Elevation Influence on Climate

14. 1961-90 Mean January Precipitation, Sierra Nevada, CA, USA Oregon Annual Precipitation

15. 1961-90 Mean August Max Temperature, Sierra Nevada, CA, USA Oregon Annual Precipitation

16. 1963-1993 Mean November Precipitation, Puerto Rico

17. 1963-93 Mean June Maximum Temperature, Puerto Rico

18. 1971-90 Mean February Precipitation, European Alps

19. 1961-90 Mean September Max Temperature, Qin Ling Mountains, China Oregon Annual Precipitation

20. PRISM Moving-Window Regression Function Oregon Annual Precipitation 1961-90 Mean April Precipitation, Qin Ling Mountains, China Weighted linear regression

21. PRISM GROUP Governing Equation Moving-window regression of climate vs elevation y = β1x + β0 Y = predicted climate element x = DEM elevation at the target cell β0 = y-intercept β1 = slope x,y pairs - elevation and climate observations from nearby climate stations

22. PRISM GROUP Station Weighting Combined weight of a station is: W = f {WdWzWcWfWpWl Wt We} • Distance • Elevation • Clustering • Topographic Facet (orientation) • Coastal Proximity • Vertical Layer (inversion) • Topographic Index (cold air pooling) • Effective Terrain Height (orographic profile)

23. PRISM GROUP PRISM • Terrain-Induced Climate Transitions (topographic facets, moisture index) Knowledge Base • Elevation Influence on Climate

25. Rain Shadow: 1961-90 Mean Annual Precipitation Oregon Cascades Portland Mt. Hood Eugene Dominant PRISM KBS Components Elevation Terrain orientation Terrain steepness Moisture Regime Mt. Jefferson 2500 mm/yr 2200 mm/yr Sisters Three Sisters 350 mm/yr Redmond N Bend

27. 1961-90 Mean Annual Precipitation, Cascade Mtns, OR, USA

28. 1961-90 Mean Annual Precipitation, Cascade Mtns, OR, USA

29. Olympic Peninsula, Washington, USA Flow Direction

30. Topographic Facets  = 4 km  = 60 km

31. Mean Annual Precipitation, 1961-90 Oregon Annual Precipitation Max ~ 7900 mm Full Model 3452 mm 3442 mm 4042 mm Max ~ 6800 mm

32. Mean Annual Precipitation, 1961-90 Max ~ 4800 mm 3452 mm 3442 mm 4042 mm Facet Weighting Disabled

33. Mean Annual Precipitation, 1961-90 Oregon Annual Precipitation Max ~ 3300 mm 3452 mm 3442 mm 4042 mm Elevation = 0

34. Mean Annual Precipitation, 1961-90 Oregon Annual Precipitation Max ~ 7900 mm Full Model 3452 mm 3442 mm 4042 mm Max ~ 6800 mm

37. PRISM GROUP PRISM • Terrain-Induced Climate Transitions (topographic facets, moisture index) Knowledge Base • Elevation Influence on Climate • Coastal Effects

38. Coastal Effects: 1971-00 July Maximum Temperature Central California Coast – 1 km Sacramento Stockton Dominant PRISM KBS Components Elevation Coastal Proximity Inversion Layer 34° SanFrancisco Oakland Fremont SanJose Preferred Trajectories Santa Cruz 27° 20° Pacific Ocean Hollister Monterey Salinas N

39. 1961-90 Mean July Maximum Temperature, Central California, USA Coastal Proximity Weighting OFF Coastal Proximity Weighting ON

40. PRISM GROUP PRISM • Terrain-Induced Climate Transitions (topographic facets, moisture index) Knowledge Base • Elevation Influence on Climate • Coastal Effects • Two-Layer Atmosphere and Topographic Index

41. 1971-2000 January Temperature, HJ Andrews Forest, Oregon, USA TMAX-Elevation Plot for January Layer 1 Layer 2 TMIN-Elevation Plot for January Layer 1 Layer 2

42. Mean Annual Precipitation, Hawaii

43. United States Potential Winter Inversion

44. Western US Topographic Index

45. Central Colorado Terrain and Topographic Index Gunnison Gunnison Terrain Topographic Index

46. January Minimum Temperature Central Colorado Gunnison Gunnison Valley Bottom Elev = 2316 m Below Inversion Lapse = 5.3°C/km T = -16.2°C

47. January Minimum Temperature Central Colorado Gunnison Mid-Slope Elev = 2921 m Above Inversion Lapse = 6.9°C/km T = -12.7°C

48. January Minimum Temperature Central Colorado Gunnison Ridge Top Elev = 3779 m Above Inversion Lapse = 6.0°C/km T = -17.9°C

49. Inversions – 1971-00 January Minimum Temperature Central Colorado N Dominant PRISM KBS Components Elevation Topographic Index Inversion Layer Taylor Park Res. Crested Butte -18° Gunnison -13° -18°C Lake City

50. PRISM 1971-2000 Mean January Minimum Temperature, 800-m “Banana Belt” Cold air drainage Snake Plain