Status report for PACJET-2002 field activities23 January 2002
NOAA/Environmental Technology Laboratory
See PACJET 2003 for information about the 2003 field season.
See PACJET 2001 for information about the 2001 field season.
A Brief Background
- PACJET-2002 is the third in a series of field experiments, preceded by
CALJET in 1997/98 and PACJET in 2001, to focus on improving short-term
forecasts of land-falling Pacific winter storms on the U.S. West Coast.
- As with earlier years, the effort focuses on both research and direct operational applications.
- Results from CALJET and PACJET-2001 are appearing in conferences, journals, and patents, and have identified issues that help focus the 2002 field phase.
- Input at the PACJET-2001 Workshop in Monterey from 24-26 October
contributed to refining both short-term goals for winter 2001/2002 and
for long-term program development.
- PACJET-2002 incorporates ground-based, satellite, aircraft and modeling activities.
- Data collected in PACJET-2002, which is characterized as a neutral
phase of ENSO, will complement those gathered in the strong El Niño of
1997/98 and the weak La Niña of 2001.
Research Priorities in 2002 Data Collection
- Assessing QuickScat satellite winds in the low-level jet: P-3
aircraft activities will focus on evaluation of QuickScat satellite-derived
surface winds and on exploring how conditions aloft in the boundary layer
may be inferred. This will increase the sample-size of high wind conditions
for assessing model PBL parameterizations. This effort is partly
funded by NASA (Persson and Walter) and is coordinated with NOAA's Ocean Winds
- Assessing the value of GOES rapid scan winds in mesoscale data
assimilation: The RUC model (Benjamin and Weygandt) is being run at
10-km resolution in the west, and will be used retrospectively to assess
the impact of assimilating rapid scan GOES winds as part of
the GOES Winds Experiment-GWINDEX (Velden, Stettner, Daniels, Bresky).
- Documenting the frequency of occurrence of non-bright band rain found
in CALJET: Results from a new ETL high-dynamic range S-band radar
deployed in CALJET indicate that roughly 30% of all rain that fell at a
key coastal site that year occurred without a bright band (White et al. 2002),
however <5% did so in 2001. The same radar has returned to the site in
2002 and another is being used in the western Sierra Foothills to
extend this study.
- Exploring the Weather-Climate Connection: The severity of flooding
in specific watersheds is very sensitive to low-level wind conditions,
which vary with the phase of ENSO (Ralph et al. 2002). Coastal wind
profilers are being used to add to data collected in other phases of ENSO
during CALJET and PACJET-2001. These will provide ground truth for assessing
the accuracy of NCEP reanalyses in this data sparse area for this
Forecast Applications Priorities in the 2002 Field Phase
- Direct forecaster use of experimental data will be systematically
evaluated (Nance): Forecaster use of wind profiler, GOES rapid-scan
winds, and the RUC model will be tracked through an on-line feedback form,
referencing in area forecast discussions, and by
other means. Plans for training are being developed. Due to funding
limitations for staff needed on the P-3 and on the ground, P-3 data will
be available in real time on a more limited basis.
- GOES Rapid-Scan Winds-the GWINDEX Experiment (Velden): In
addition to the research associated with documenting the impact of
assimilating GOES rapid scan winds in the RUC model as described above,
the data are viewable on line for direct forecaster use, e.g., evaluating
the position and intensity of key wind features using the enhanced
capabilities of the rapid scan winds.
- The Rapid Update Cycle model (RUC) (Benjamin and Weygandt):
A special version of the RUC model is being run that assimilates the
GWINDEX data every 3 hours, and includes a nest in the west with 10-km
grid spacing. These data will be available directly on the standard
AWIPS workstations that are in use in NWS Weather Forecast
- Experimental wind profiler array (Ralph, Neiman and White):
Research results from CALJET and PACJET have quantified the importance
of the low-level jet in determining rain rates in coastal storms, and
initial experience with the use of a prototype real-time bright-band
snow-level detection algorithm developed for PACJET-2001 will be extended
to additional sites. Eleven profilers will cover the coast from
S. California to Washington State.
Overview of major components of field deployments in PACJET 2002
|Ground-based, satellite, modeling|
|Dates for RUC, profilers, GWINDEX:||14 January - 31 March 2002|
|S-band vertically pointing radars:||Cazadero and Grass Valley, CA.|
|ETL and NPS Wind profiler sites:||
|Dates for P-3 deployment:||1 February - 2 March 2002|
|Flight hours for P-3:||100 h (70 h PACJET + 30 h Ocean Winds)|
|Location of aircraft operations base:||Portland, OR|
|P-3 operations area:||Offshore from California to Vancouver, Canada|
Detailed descriptions of key activities
- Ground-based observations (Ralph, Neiman, White):
Real-time data and a site map can be seen at http://www.etl.noaa.gov/et7/data/
The GOES Rapid-Scan Winds Experiment-GWINDEX (Velden, Stettner at UW-CIMSS, and Daniels and Bresky at NESDIS/FPDT):
Data web link: http://gale.ssec.wisc.edu/gwindex2/ Overall Objective: To demonstrate improved quantity and quality of cloud-motion winds using 7.5 minute rapid-scan visible and infrared imagery from GOES-10. Goals: To provide improved remotely-sensed data over the Eastern Paciafic for NWS forecasters, support PACJET and THORPEX initiatives, and assess data impact on the RUC model short-term forecasts. Experiment Duration: January 8 through March 31, 2002. Coverage Domain: Eastern North Pacific and west coast North America. Data Set Availability: Three hourly, around the clock. Real time: roughly 1 hour after image sequence. Participants: NOAA/NESDIS/ORA/FPDT and UWisc.-CIMSS, NWS, NOAA/ETL, NOAA/FSL, PACJET community. Point of Contact: Chris Velden (UW-CIMSS) email@example.com
- RUC modeling activities (Weygandt and Benjamin/FSL):
In support of PACJET 2002, the Regional Analysis and Prediction Branch of FSL is running a special high-resolution version of the Rapid-Update Cycle (RUC) model and distributing forecast fields to the NWS Western Region Headquarters for dissemination to local offices. The special RUC configuration consists of a 10-km grid covering all of the NWS Western Region, nested within a 20-km CONUS grid. For the 20-km CONUS grid, 24-h forecasts are produced every 3 h using a 1-h data assimilation cycle. In addition to ingesting all conventional observations, satellite-derived cloud-motion vectors determined at 3-h intervals (provided by C. Velden, U. Wisc./CIMMS) and special mesonet (including MesoWest) observations are being assimilated into the 20-km forecast cycle. For the 10-km grid, 24-h forecasts are produced every 6 h using the 20-km CONUS RUC as lateral boundary conditions. Forecast products can be viewed on the PACJET RUC web-page.
The goals of this effort are to:
- provide operational NWS forecasters with real-time
guidance products from a next-generation version of the RUC model,
- obtain forecaster
feedback on strengths and weaknesses of the model guidance products,
- evaluate the
impact on forecast skill from ingesting data from new observing systems.
- provide operational NWS forecasters with real-time guidance products from a next-generation version of the RUC model,
- NOAA P-3 Aircraft activities (Persson and Ralph):
The P-3 will be based in Portland, Oregon from Feb. 1 - March 2.
The operations center will be in the Portland NWS Weather Forecast
Office where weather briefings will be held at
10:30 AM PT. Contact Ola Persson for further details or updates.
The scientific foci of this year's program are:
- Validation of the low-level jet (LLJ) structure seen by satellite
(QuickScat) overpasses, and obtaining measurements of the thermodynamic
and kinematic structure of the low-level jet region to be used for
extrapolating the satellite measurements. An ETL/CIRES objective.
- Validation of NESDIS/UMass scatterometer(s) and microwave radiometer
in high winds and precipitation - obtain real-time surface winds and range
profiling of the effects of precipitation on the measurements. Some
problems with the scatterometers upgrades will narrow some of these
- Obtaining Doppler radar and in-situ measurements of the NCFR to
improve our understanding of the dynamics of the core and gap regions.
An ETL/NSSL objective.
- Participate in one objective targeting IOP (super-IOP) in collaboration
with NCEP-this objective still requires support for the dropsonde costs.
- Obtaining GPS backscatter surface winds - NASA project