“OLYMPEX”

•Physical validation •Precipitation estimation

•Hydrological applications

Field Experiment Proposed for November-December 2014

4th International Workshop for GPM Ground Validation 21-23 June 2010, Helsinki, Finland

R. Houze & S. Medina

The Olympic Peninsula is a natural “precipitation laboratory”

• Persistent southwesterly flow during the winter provides a reliable source of moisture

• Extremely large precipitation accumulation produced as the moist SWly flow impinges on coastal terrain

• Low 0ºC level rain at low elevations, snow at higher levels

The Olympic Peninsula is a natural “precipitation laboratory”

• Persistent southwesterly flow during the winter provides a reliable source of moisture

NCEP long-term mean sea level pressure (mb) for winter (December to January) and topography

The Olympic Peninsula is a natural “precipitation laboratory”

• Extremely large precipitation accumulation produced as the moist SWly flow impinges on coastal terrain

Annual average precipitation (PRISM)

Maximum

The Olympic Peninsula is a natural “precipitation laboratory”

• Low 0ºC level rain at low elevations, snow at higher ones

Distribution of Nov-Jan 0°C level for flow that is onshore and moist at low levels (KUIL sounding)

Mean 0°C level during storms = 1.5 km

See this full range in individual storms!

Fre

quen

cy o

f oc

curr

ence

0°C level Plot provided by Justin Minder

Resources and experience in the region

• 1965-2000: Cascade Project, CYCLES, COAST

• 2001: IMPROVE field experiment

• 2004-2008: Detailed observing network across a southwestern Olympics ridge

• 2009: NOAA Mobile Atmospheric River Monitoring System in Westport

• 2011/12: NWS Coastal radar expected to be in place

• Ongoing: Regional Environmental Prediction

Resources and experience in the region

• 2001: IMPROVE-1 field experiment (Stoelinga et al. 2003)

Coastline

Resources and experience in the region

• 2001: IMPROVE-2 field experiment (Stoelinga et al. 2003)

Woods et al. 2005

• 2004-2008: Detailed observing network across a southwestern Olympics ridge (Minder et al. 2008)

Resources and experience in the region

Detailed gauge network

SNOTELRAWS sitesCOOP siteAnemometersDisdrometers

Resources and experience in the region

• 2009: NOAA Mobile Atmospheric River Monitoring System in Westport

Time

Hei

ght

Hei

ght

Signal-to-noise ratio

Radialvelocity

Data from vertically-pointing S-band radar

Resources and experience in the region

• 2011/12: NWS Coastal radar expected to be in place

Dark gray areas indicate regions where the 0.5° elevation scans are blocked

Example of Olympic Mountain slopes views from coastal radar

Current radar coverage

Radar coverage with coastal radar

Resources and experience in the region

• Ongoing: Regional Environmental Prediction-- WRF, hydrology, air quality, etc (Mass et al. 2003)

Real-time mesoscale numerical simulations

dx = 4 kmdx = 36 km

Resources and experience in the region

• Ongoing: Regional Environmental Prediction-- WRF, hydrology, air quality, etc (Mass et al. 2003)

• Runs in ensemblemode

1.33 km spatial resolution

coming soon

Resources and experience in the region

• Ongoing: Regional Environmental Prediction-- WRF, hydrology, air quality, etc (Mass et al. 2003)

Verified by gauges: Minder et al. 2008

Long period of continuous mesoscale simulations provides model climatologye.g., 5-yr MM5 Nov-Jan precipitation climatology (mm)

Resources and experience in the region

• Ongoing: Regional Environmental Prediction-- WRF, hydrology, air quality, etc (Mass et al. 2003)

Ensemble forecasting probabilistic information e.g., probability that theprecipitation accumulated in a 3 h period > 0.1in

Resources and experience in the region

• Ongoing: Regional Environmental Prediction-- WRF, hydrology, air quality, etc (Mass et al. 2003)

Hydrological prediction:

Mesoscale numerical output drives a distributed hydrological model basin streamflow forecast

GPM components that are feasible to address in the Olympic Peninsula

• Physical validation of algorithms

• Rain and snow measurement

• Hydrological applications

Physical validation (i.e. experimentation with physical assumptions in GPM algorithms)

a. How well do retrieval algorithms handle transitions from rain to snow on sloping terrain?

b. How does the melting layer affect algorithm performance?

c. How do algorithms perform in different sectors of storms passing over mountains and in different types of precipitation?

Precipitation estimation (i.e. validation of its accuracy from satellite

instruments mounted on aircraft)

a. Do precipitation algorithms give realistic rainfall transition from ocean to land?

b. Do precipitation algorithms yield accurate orographic enhancement of rain amounts?

c. How can satellite rain measurements be downscaled accurately relative to the topography?

Hydrological applications(i.e. testing the efficacy of GPM to improve streamflow forecasting in complex terrain)

a. Can satellite rain estimates over mountains provide useful input to real-time hydrologic forecasting?

b. Does downscaling relative to topography improve hydrologic forecasting?

c. Can assimilation of satellite rain estimates into regional forecasting models improve hydrological forecasts?

Possible field experiment configuration

NPOL would have an unimpeded view of the Quinault valley and the Olympic mountains

DC8

ER2GH

P3

Conclusions• The Olympic Peninsula is an ideal natural laboratory

– Persistence of moist flow– complex terrain– huge precipitation amounts– low 0°C level

• Existing and planned resources plus past experience

– provide a strong framework for a field campaign

• Crucial NASA & NOAA facilities could be added

– NPOL, aircraft, profilers, etc

• Can address

– Physical validation of GPM algorithms– Rain and snow measurement– Hydrological applications

This research was supported byNSF Grant ATM-0820586 and NASA Grants NNX07AD59G and NNX10AH70G