1. A NEW APPROACH TO THE ESTIMATION OF PRECIPITATION FIELDS IN MOUNTAINOUS ENVIRONMENTS Elsa Nickl and Cort Willmott University of Delaware Department of Geography

2. HIGH-RESOLUTION DIGITAL ELEVATION INFORMATION GTOPO30 (USGS) 30 arc sec resolution EROS Data Center (used by PRISM) 3 arcsec resolution Shuttle Radar Topography Mission (USGS) 1 arcsec resolution

3. METHODS OF PRECIPITATION FIELDS ESTIMATION 1.Precipitation interpolation methods: e.g. ordinary kriging, elevational cokriging, etc Few have been able to adequately explain the complex variability of precipitation in mountain regions 2. The PRISM model

4. Principal aspects taken into account in PRISM model: 1.Relationship between precipitation and elevation: Precipitation increases with elevation, with a maximum in mountain crests Relationship between precipitation and elevation can be described by a linear function 2. Spatial scale of orographic precipitation (orographic elevation) Mismatch in scale when using actual elevation of stations “Orographic” elevation estimation in order to avoid this mismatch The orographic scale depends on the scale of the prevailing storm type 5 min-DEM appears to approximate the scale of orographic effects explained by available data 3. Spatial patterns of orographic precipitation (facets) PRISM divides the mountainous areas into “facets “ Each “facet” is a contiguous area of constant slope orientation

5. OBJECTIVES To explore the relationships between the spatial arrangements of orientation, slope, winds and precipitation. To develop a new approach for estimating precipitation fields in mountain regions DATA Monthly precipitation National Climatic Data Center (NCDC) (2001-2005) Digital Elevation information 2.5 minutes (used by PRISM, derived from EROS Data Center 3 arc sec)

6. ELEVATION, ORIENTATION AND PRECIPITATION GREATER THAN 200 mm December DECEMBER, JANUARY, FEBRUARY (seasonal? MAM, JJA, SON?, zoom?)

7. December dz/dx dz/dy

8. January

9. dz/dx dz/dy

10. February

11. dz/dx dz/dy MAM, JJA, SON?, ZOOMS?

12. ELEVATION, ORIENTATION, STEEPNESS AND PRECIPITATION (2.5min) DJF (December-February)

13. JJA (June-August) ELEVATION, ORIENTATION, STEEPNESS AND PRECIPITATION (2.5min)

14. December

15. January ELEVATION, ORIENTATION, STEEPNESS AND PRECIPITATION (2.5min)

16. February ELEVATION, ORIENTATION, STEEPNESS AND PRECIPITATION (2.5min)

17. CELLS TO TAKE INTO ACCOUNT FOR DIFFERENT RESOLUTIONS 5 min (~9.2 km)

18. CELLS TO TAKE INTO ACCOUNT FOR DIFFERENT RESOLUTIONS 7 min (~12.8 km)

19. CELLS TO TAKE INTO ACCOUNT FOR DIFFERENT RESOLUTIONS 10 min (~18.3 km)

20. ELEVATION, ORIENTATION, STEEPNESS AND PRECIPITATION (7.5min) DJF (December-February)

21. ELEVATION, ORIENTATION, STEEPNESS AND PRECIPITATION (7.5min) JJA (June-August)

22. ELEVATION, ORIENTATION, STEEPNESS AND PRECIPITATION (12.5min)

23. CONCLUSIONS FUTURE RESEARCH Most largest precipitation events take place in lower-elevation areas (0-500m) with no-orientation (flat terrain) During DJF period, strong precipitation events in moderate elevation (500-1000m), present a SW orientation tendency. During JJA period, strong precipitation events are more related to convection. To quantify relationships between precipitation and elevation, steepness and orientation. To identify relationship between wind and precipitation based on these relationships.