Title: The PRISM Approach to Mapping Climate in Complex Regions
1The 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 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
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4Oregon Annual Precipitation
5Oregon Annual Precipitation
6Oregon Annual Precipitation
7 Oregon Annual Precipitation
8Oregon Annual Precipitation
9Rationale
- 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
10Knowledge-Based System KBS
- 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
11PRISM
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
12Oregon Annual Precipitation
Interface
13PRISM
Knowledge Base
- Elevation Influence on Climate
141961-90 Mean January Precipitation, Sierra
Nevada, CA, USA
Oregon Annual Precipitation
151961-90 Mean August Max Temperature, Sierra
Nevada, CA, USA
Oregon Annual Precipitation
161963-1993 Mean November Precipitation, Puerto Rico
171963-93 Mean June Maximum Temperature, Puerto Rico
181971-90 Mean February Precipitation, European Alps
191961-90 Mean September Max Temperature, Qin Ling
Mountains, China
Oregon Annual Precipitation
20PRISM Moving-Window Regression Function
Oregon Annual Precipitation
1961-90 Mean April Precipitation, Qin Ling
Mountains, China
Weighted linear regression
21Governing Equation
- Moving-window regression of climate vs
elevation - y ß1x ß0
- Y predicted climate element
- x DEM elevation at the target cell
- ß0 y-intercept
- ß1 slope
- x,y pairs - elevation and climate observations
from nearby climate stations
22Station Weighting
- Combined weight of a station is
- W f Wd Wz Wc Wf Wp Wl Wt We
- Distance
- Elevation
- Clustering
- Topographic Facet (orientation)
- Coastal Proximity
- Vertical Layer (inversion)
- Topographic Index (cold air pooling)
- Effective Terrain Height (orographic profile)
23PRISM
Knowledge Base
- Elevation Influence on Climate
- Terrain-Induced Climate Transitions (topographic
facets, moisture index)
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25Rain 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
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271961-90 Mean Annual Precipitation, Cascade Mtns,
OR, USA
281961-90 Mean Annual Precipitation, Cascade Mtns,
OR, USA
29Olympic Peninsula, Washington, USA
Flow Direction
30Topographic Facets
? 4 km
? 60 km
31Mean Annual Precipitation, 1961-90
Oregon Annual Precipitation
Max 7900 mm
Full Model
3452 mm 3442 mm 4042 mm
Max 6800 mm
32Mean Annual Precipitation, 1961-90
Max 4800 mm
3452 mm 3442 mm 4042 mm
Facet Weighting Disabled
33Mean Annual Precipitation, 1961-90
Oregon Annual Precipitation
Max 3300 mm
3452 mm 3442 mm 4042 mm
Elevation 0
34Mean Annual Precipitation, 1961-90
Oregon Annual Precipitation
Max 7900 mm
Full Model
3452 mm 3442 mm 4042 mm
Max 6800 mm
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37PRISM
Knowledge Base
- Elevation Influence on Climate
- Terrain-Induced Climate Transitions (topographic
facets, moisture index)
38Coastal Effects 1971-00 July Maximum
Temperature Central California Coast 1 km
Sacramento
Stockton
Dominant PRISM KBS Components Elevation
Coastal Proximity Inversion Layer
34
San Francisco
Oakland
Fremont
San Jose
Preferred Trajectories
Santa Cruz
27
Pacific Ocean
20
Hollister
Monterey
Salinas
N
391961-90 Mean July Maximum Temperature, Central
California, USA
Coastal Proximity Weighting OFF
Coastal Proximity Weighting ON
40PRISM
Knowledge Base
- Elevation Influence on Climate
- Terrain-Induced Climate Transitions (topographic
facets, moisture index)
- Two-Layer Atmosphere and Topographic Index
411971-2000 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
42Mean Annual Precipitation, Hawaii
43United States Potential Winter Inversion
44Western US Topographic Index
45Central Colorado Terrain and Topographic Index
Gunnison
Gunnison
Terrain
Topographic Index
46January Minimum Temperature Central Colorado
Gunnison
Gunnison
Valley Bottom Elev 2316 m Below Inversion Lapse
5.3C/km T -16.2C
47January Minimum Temperature Central Colorado
Gunnison
Mid-Slope Elev 2921 m Above Inversion Lapse
6.9C/km T -12.7C
48January Minimum Temperature Central Colorado
Gunnison
Ridge Top Elev 3779 m Above Inversion Lapse
6.0C/km T -17.9C
49Inversions 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
-18C
Lake City
50PRISM 1971-2000 Mean January Minimum Temperature,
800-m
Banana Belt
Cold air drainage
Snake Plain
51Inversions 1971-00 July Minimum
Temperature Northwestern California
Pacific Ocean
N
Willits
9
Dominant PRISM KBS Components Elevation
Inversion Layer Topographic Index Coastal
Proximity
Ukiah
Lake Pilsbury.
10
17
16
Cloverdale
Lakeport
12
Clear Lake
17
52PRISM
Knowledge Base
- Elevation Influence on Climate
- Terrain-Induced Climate Transitions (topographic
facets, moisture index)
- Two-Layer Atmosphere and Topographic Index
- Orographic Effectiveness of Terrain (Profile)
53United States Effective Terrain
United States Orographically Effective Terrain
54Oregon Annual Precipitation
55PRISM
Knowledge Base
- Elevation Influence on Climate
- Terrain-Induced Climate Transitions (topographic
facets, moisture index)
- Two-Layer Atmosphere and Topographic Index
- Orographic Effectiveness of Terrain (Profile)
- Persistence of climatic patterns
(climatologically-aided interpolation)
56Oregon Annual Precipitation
Leveraging Information Content of High-Quality
Climatologies to Create New Maps with Fewer Data
and Less Effort
Climatology used in place of DEM as PRISM
predictor grid
57PRISM Regression of Climate vs Climate or
Weather vs Climate
20 July 2000 Tmax vs 1971-2000 Mean July Tmax
58Recent Projects
- Updated 1971-2000 mean monthly P, Tmax, Tmin maps
for the US at 800-m resolution (USDA-NRCS, NPS,
USFS) - Spatial-Probabilistic QC system for SNOTEL
observations (NRCS) - 1971-2000 monthly precipitation climatologies for
NW Oregon conditional on 700-mb flow direction
(NWS Western Region) - Extended monthly time series maps of P, Tmax,
Tmin, Tdew for climate monitoring (USFS)
59Future Directions
- Engage in collaborative projects to develop the
use of PRISM and PRISM climatologies for
downscaling numerical weather prediction models - Continue to develop technology to move to smaller
time steps and towards real time operation - Explore using remotely-sensed data to improve
PRISM accuracy in under-sampled areas (and
vice-versa) - Continue to develop PRISMs Spatial Climate
Knowledge Base