Barrier Jets in the Gulf of Alaska: Causes, Impacts and Interactions with other Phenomena
Project sponsored by the mesoscale dynamic meteorology program at the National Science Foundation
Project Principal Investigators:
Nick Bond: JISAO / University of Washington
Brian Colle: SUNY - Stony Brook
Nathaniel Winstead - Johns Hopkins University Applied Physics Laboratory
George Young - The Pennsylvania State University
Field Campaign conducted by the King Air Aircraft operated by the University of Wyoming with assistance from
The National Weather Service - Juneau Forecast Office
Project Objectives:
This field campaign is part of a larger project studying barrier jets in the Gulf of Alaska. The purposes of the parent project are as follows: 1) document the spatial and frequency climatology and morphology of barrier jets in Alaskan coastal waters, 2) Study the dynamics of barrier jets using mesoscale modeling, high resolution synthetic aperture radar wind estimates and in situ measurements, 3) Examine the impact of barrier jets on the coastal ocean and 4) Transfer knowledge of barrier jets to the operational forecasting community.
Barrier Jet Description:
During the cool season, extratropical cyclones over the Pacific Ocean frequently make landfall along the west coast of North America. Interaction of these synoptic-scale disturbances with the steeply rising coastal terrain can result in the development of high winds oriented primarily in the along-coast direction. These winds are often referred to as barrier jets (Parish 1982, Doyle 1997). It is well known that these wind maxima are deflected to a more terrain-parallel direction by the blocking of the stably stratified synoptic flow by the steep coastal terrain (Chen and Smith 1987, Bell and Bosart 1988).
Barrier Jet Dynamics:
Flow blocking is determined locally by a Froude Number: Fr = U/HN where U is the upstream flow, N is the static stability, and H is the height of the terrain barrier. When the Froude number is less than unity, blocking occurs (Pierrehumbert and Wyman 1988). The traditional barrier jet conceptual model has the blocked flow and associated pressure ridge extending upstream of the barrier approximately one Rossby radius (NH/f where f is the Coriolis parameter) for blocking to the crest level and U/f when the flow blocked well below the crest level (Fr << 1) (Overland and Bond 1993).
Synthetic Aperture Radar:
This project plans to make extensive use of the high-resolution wind speed estimates available from the synthetic aperture radars aboard the RADARSAT-1 and ENVISAT satellites. For an in-depth look at SAR, see the following SAR review page or Monaldo et al (2001). Essentially, SAR makes use of the same relationship that is used by the scatterometer community to convert the normalized radar backscatter cross-section to the 10-m neutral wind speed. The primary disadvantage of SAR is that an independent estimate of the surface wind direction is required. This direction is typically provided either from structures within the SAR image itself (Wackermann, 1996; Horstmann et all 2000) or from a numerical weather prediction model (Monaldo et al 2000). These techniques have typically compared to buoys and scatterometer wind estimates to within 1.5 m/s - 2.0 m/s RMS. See the following link to our operational near-real-time SAR wind maps kept at APL:
SAR Wind Speed Archive at JHU/APL
SARJET Experiment Goals and Design:
The Wyoming King Air Aircraft will be used in conjunction with synthetic aperture radar wind speed imagery to study the dynamics of barrier jets. Of particular interest is the hybrid jet which has elements of both classical barrier jets and gap flows. These types of jets tend to exhibit a morphology that is different from classical barrier jets. Rather than an exponential increase in speed and turning down the mountain range, hybrid jets are more likely to show a "blocking front" marked by a sharp offshore speed and direction gradient.
The objective of SARJET is to sample both hybrid and classical jets to determine the dynamics that govern their morphology. Particular attention will be paid to the offshore front through the flight tracks shown in the next section. An additional objective is to generate a series of case studies and supporting data. These data will be used to compare high-resolution numerical weather prediction model simulations in order to 1) validate the model's capability to reproduce these flows and 2) once validated, study the three-dimensional structure and dynamics of these flows.
Finally, all of this data will be used to assist in the development of forecasting tools which will be used to aid the coastal marine forecasting community.
SARJET
Flight
Tracks:
The Gulf of Alaska is an ideal location for studying barrier jets. The combination of complex coastal mountain ranges (barriers) and frequent landfalling storms (onshore flow events) and high latitude (good polar orbiting satellite coverage) make this region an ideal location for this study. Flight operations will be conducted from Juneau. Two flight tracks will be used to sample both classical barrier jets and hybrid jets as they occur. These tracks are shown below.
MM5
Simulations over the Flight Track Area from Stony Brook University
SARJet
Imagery
A total of 27 complete RADARSAT and ENVISAT Wide Swath images have been scheduled for the duration of the potential flight hours. In addition, 22 partial images (covering at least half the box shown above) have also been ordered. The following table shows the dates, times, mode and satellite of the requested imagery. As the imagery is processed and becomes available, links will be added to the processed wind speed images. Unfortunately, it is not likely that ENVISAT imagery will be available until after flight operations are concluded due to differences in processing these data.
Flight Data:
Flight data is being examined and processed for each of the IOP's listed below. Results of interest will be posted as the project continues. Every effort will be made to continue to keep the page updated with updated information and results as they come in. For now, a link to dates and times of flight legs from each of the research flights is contained in separate web page (link under the Description/Notes column). Eventually, track maps will be made available and posted as well.
MM5 Simulations over the Flight Track Area from Stony Brook University
A complete archive of MM5 simulations that were conducted at Stony Brook University during the period of operations. This collection of data provides important synoptic and mesoscale forecast information throughout the Gulf of Alaska for each IOP.
QuikSCAT Images from September 2004 in the Gulf of Alaska
QuikSCAT Images from October 2004 in the Gulf of Alaska
A complete archive of QuikSCAT imagery archived during field operations for September and October 2004. Additional links to full data passes are available under the "Links to Data" column for each IOP. Keep in mind that for each day with full passes there may be additional partial passes which can only be obtained from the above two links.
Penn State University VRML Flight Tracks
A very nice set of tools for visualizing the flight tracks associated with SARJET. This site includes a description, links to the appropriate plugins and links to the actual flight track data.
Project Publications:
Loescher, K. A., G. S. Young, B. A. Colle, and N S Winstead, 2005: Climatology of barrier jets along the Alaskan Coast, Part I: Spatial and temporal distributions. Monthly Weather Review. In press.
Colle, B. A., K. A. Loescher, G. S. Young and N S Winstead, 2005: Climatology of barrier jets along the Alaskan Coast, Part II: Large-scale and sounding composites. Monthly Weather Review. In press.
Winstead, N. S., B. A. Colle, J. B. Olson, G. S. Young, K. Loescher, 2005: Improving the forecasting of barrier jets using
remote sensing, modeling and a SARJET field study. Preprints: 21st Conference on Weather Analysis and
Forecasting, August 1 - 6 Washington D.C. (pdf abstract: here)
Winstead, N. S., B. Colle, and N. Bond, 2004: Using synthetic aperture radar and high-resolution MM5 simulations to study
barrier jets in the Gulf of Alaska. Preprints: IEEE International Geoscience and Remote Sensing Symposium,
Anchorage, AK 20 - 24 September 2004. (pdf abstract: here )
Loescher, K., G. Young, N. S. Winstead, and B. A. Colle, 2004: Application of a SAR image archive to climatological
analysis of coastal wind storms. Preprints: IEEE Interntaional Geoscience and Remote Sensing Symposium,
Anchorage, AK 20 - 24 September 2004. (pdf abstract: here )
A total of 27 complete RADARSAT and ENVISAT Wide Swath images have been scheduled for the duration of the potential flight hours. In addition, 22 partial images (covering at least half the box shown above) have also been ordered. The following table shows the dates, times, mode and satellite of the requested imagery. As the imagery is processed and becomes available, links will be added to the processed wind speed images. Unfortunately, it is not likely that ENVISAT imagery will be available until after flight operations are concluded due to differences in processing these data.
| Satellite | Date
- Time (UTC) |
Date
- Time (Local Time) |
Coverage | Link to Imge |
| RADARSAT-1 | Sep. 21, 2004 02:57:17 | Sep.
20,
2004 18:57:17 |
Complete |
Image |
| ENVISAT |
Sep.
21,
2004 19:20:06 |
Sep.
21,
2004 11:20:06 |
Partial | Northern
Image Southern Image |
| ENVISAT |
Sep.
22,
2004 06:46:11 |
Sep.
21,
2004 22:46:11 |
Complete | Northern
Image Southern Image |
| RADARSAT |
Sep.
23,
2004 15:42:28 |
Sep.
23,
2004 07:42:28 |
Complete |
Image |
| ENVISAT |
Sep.
23,
2004 19:57:28 |
Sep.
23,
2004 11:57:28 |
Partial | Image |
| RADARSAT |
Sep. 24, 2004 03:09:48 | Sep.
23,
2004 19:09:48 |
Partial | Missing |
| RADARSAT |
Sep.
24,
2004 15:13:16 |
Sep.
24,
2004 07:13:16 |
Partial | Missing |
| ENVISAT |
Sep.
24,
2004 19:25:51 |
Sep.
24,
2004 11:25:51 |
Partial | Image |
| RADARSAT |
Sep.
25,
2004 02:40:37 |
Sep.
24,
2004 18:40:37 |
Complete |
Image |
| ENVISAT |
Sep.
25,
2004 06:51:56 |
Sep.
24,
2004 22:51:56 |
Complete | Southern
Image |
| RADARSAT | Sep. 26, 2004 15:53:20 | Sep. 24, 2004 07:53:20 | Partial | Image |
| RADARSAT |
Sep.
27,
2004 15:25:47 |
Sep.
27,
2004 07:25:47 |
Complete |
Image |
| ENVISAT |
Sep.
27,
2004 19:31:36 |
Sep.
27,
2004 11:31:36 |
Complete | Image |
| RADARSAT |
Sep.
28,
2004 02:53:07 |
Sep.
27,
2004 18:53:07 |
Complete |
Image |
| ENVISAT |
Sep.
28,
2004 06:57:41 |
Sep.
27,
2004 22:57:41 |
Partial | NA |
| ENVISAT |
Sep.
29,
2004 06:26:05 |
Sep.
28,
2004 22:26:05 |
Partial | NA |
| RADARSAT |
Sep.
30,
2004 15:38:18 |
Sep.
30,
2004 07:38:18 |
Complete |
Image |
| ENVISAT |
Sep.
30,
2004 19:37:22 |
Sep.
30,
2004 11:37:22 |
Complete | Image |
| RADARSAT |
Oct.
01,
2004 03:05:38 |
Sep.
30,
2004 19:05:38 |
Partial |
Northern
Image Southern Image |
| ENVISAT |
Oct.
01,
2004 07:03:26 |
Sep.
30,
2004 23:03:26 |
Partial | NA |
| RADARSAT |
Oct.
02,
2004 02:36:27 |
Oct.
01,
2004 18:36:27 |
Partial |
Image |
| ENVISAT |
Oct.
02,
2004 06:31:49 |
Oct.
01,
2004 22:31:49 |
Partial | Image |
| RADARSAT |
Oct.
03,
2004 15:50:47 |
Oct.
03,
2004 07:50:47 |
Partial |
Image |
| ENVISAT |
Oct.
03,
2004 19:43:06 |
Oct.
03,
2004 11:43:06 |
Complete | Image |
| RADARSAT |
Oct.
04,
2004 15:21:37 |
Oct.
04,
2004 07:21:37 |
Complete | Image |
| RADARSAT |
Oct.
05,
2004 02:48:57 |
Oct.
04,
2004 18:48:57 |
Complete | Image |
| ENVISAT |
Oct.
05,
2004 06:37:34 |
Oct.
04,
2004 22:37:34 |
Complete | NA |
| ENVISAT |
Oct.
06,
2004 19:48:50 |
Oct.
06,
2004 11:48:50 |
Complete | NA |
| RADARSAT |
Oct.
07,
2004 15:34:08 |
Oct.
07,
2004 07:34:08 |
Complete |
Image |
| RADARSAT | Oct.
08,
2004 03:01:27 |
Oct.
07,
2004 19:01:27 |
Partial |
Southern
Image Northern Image |
| ENVISAT |
Oct.
08,
2004 06:43:18 |
Oct.
07,
2004 22:43:18 |
Complete | Southern
Image |
| RADARSAT | Oct. 09, 2004 02:30:18 | Oct. 07, 2004 18:30:18 | Partial | Northern Image |
| ENVISAT |
Oct.
09,
2004 19:54:35 |
Oct.
09,
2004 11:54:35 |
Partial | NA |
| RADARSAT |
Oct.
10,
2004 15:46:37 |
Oct.
10,
2004 07:46:37 |
Partial |
Image |
| ENVISAT |
Oct.
10,
2004 19:22:58 |
Oct.
10,
2004 11:22:58 |
Partial | Image |
| ENVISAT |
Oct. 11, 2004 06:49:03 | Oct.
10,
2004 22:49:03 |
Complete | Southern
Image |
| RADARSAT |
Oct.
11,
2004 15:17:26 |
Oct.
11,
2004 07:17:26 |
Partial | Image |
| RADARSAT |
Oct.
12,
2004 02:44:47 |
Oct.
11,
2004 18:44:47 |
Complete | Image |
| ENVISAT |
Oct. 12,
2004 20:01:06 |
Oct. 12,
2004 12:01:06 |
Partial |
Image |
| ENVISAT |
Oct.
13,
2004 19:28:43 |
Oct.
13,
2004 11:54:48 |
Partial | Image |
| ENVISAT |
Oct.
14,
2004 06:54:48 |
Oct.
13,
2004 22:54:48 |
Partial | NA |
| RADARSAT | Oct.
14,
2004 15:29:58 |
Oct.
14,
2004 07:29:58 |
Complete |
Image |
| RADARSAT |
Oct.
15,
2004 02:57:17 |
Oct.
14,
2004 18:57:17 |
Complete |
Image |
| ENVISAT |
Oct.
16,2004
19:34:28 |
Oct.
16,
2004 11:34:28 |
Complete | NA |
| ENVISAT |
Oct.
17,
2004 07:00:33 |
Oct.
16,
2004 23:00:33 |
Partial | NA |
| RADARSAT |
Oct.
17,
2004 15:42:28 |
Oct.
17,
2004 07:42:28 |
Complete |
Image |
| RADARSAT |
Oct.
18,
2004 03:09:48 |
Oct.
17,
2004 19:09:48 |
Partial | Image |
| ENVISAT |
Oct.
18,
2004 06:28:56 |
Oct.
17,
2004 22:28:56 |
Partial | NA |
| RADARSAT |
Oct.
18,
2004 15:13:16 |
Oct.
18,
2004 07:13:16 |
Missing |
NA |
| RADARSAT |
Oct.
19,
2004 02:40:37 |
Oct.
18,
2004 18:40:37 |
Complete | Image |
| ENVISAT |
Oct.
19,
2004 19:40:13 |
Oct.
19,
2004 11:40:13 |
Complete | NA |
| ENVISAT |
Oct.
21,
2004 06:34:41 |
Oct.
20,
2004 22:34:41 |
Complete | NA |
| RADARSAT |
Oct. 21,
2004 15:24:25 |
Oct. 21,
2004 07:24:24 |
Complete |
Image |
| RADARSAT |
Oct. 22,
2004 02:51:26 |
Oct. 21,
2004 18:51:26 |
Complete |
Image |
Flight Data:
Flight data is being examined and processed for each of the IOP's listed below. Results of interest will be posted as the project continues. Every effort will be made to continue to keep the page updated with updated information and results as they come in. For now, a link to dates and times of flight legs from each of the research flights is contained in separate web page (link under the Description/Notes column). Eventually, track maps will be made available and posted as well.
Results:
MM5 Simulations over the Flight Track Area from Stony Brook University
A complete archive of MM5 simulations that were conducted at Stony Brook University during the period of operations. This collection of data provides important synoptic and mesoscale forecast information throughout the Gulf of Alaska for each IOP.
QuikSCAT Images from September 2004 in the Gulf of Alaska
QuikSCAT Images from October 2004 in the Gulf of Alaska
A complete archive of QuikSCAT imagery archived during field operations for September and October 2004. Additional links to full data passes are available under the "Links to Data" column for each IOP. Keep in mind that for each day with full passes there may be additional partial passes which can only be obtained from the above two links.
Penn State University VRML Flight Tracks
A very nice set of tools for visualizing the flight tracks associated with SARJET. This site includes a description, links to the appropriate plugins and links to the actual flight track data.
Project Publications:
Loescher, K. A., G. S. Young, B. A. Colle, and N S Winstead, 2005: Climatology of barrier jets along the Alaskan Coast, Part I: Spatial and temporal distributions. Monthly Weather Review. In press.
Colle, B. A., K. A. Loescher, G. S. Young and N S Winstead, 2005: Climatology of barrier jets along the Alaskan Coast, Part II: Large-scale and sounding composites. Monthly Weather Review. In press.
Winstead, N. S., B. A. Colle, J. B. Olson, G. S. Young, K. Loescher, 2005: Improving the forecasting of barrier jets using
remote sensing, modeling and a SARJET field study. Preprints: 21st Conference on Weather Analysis and
Forecasting, August 1 - 6 Washington D.C. (pdf abstract: here)
Winstead, N. S., B. Colle, and N. Bond, 2004: Using synthetic aperture radar and high-resolution MM5 simulations to study
barrier jets in the Gulf of Alaska. Preprints: IEEE International Geoscience and Remote Sensing Symposium,
Anchorage, AK 20 - 24 September 2004. (pdf abstract: here )
Loescher, K., G. Young, N. S. Winstead, and B. A. Colle, 2004: Application of a SAR image archive to climatological
analysis of coastal wind storms. Preprints: IEEE Interntaional Geoscience and Remote Sensing Symposium,
Anchorage, AK 20 - 24 September 2004. (pdf abstract: here )
Contacts:
Project Lead PI: Nathaniel
S. Winstead - Johns Hopkins University APL
Field Project Lead: Nick Bond, JISAO - University of
Washington
National Weather Service Contact: Carl Dierking - NWS Juneau
University of Wyomin King Air: Glenn
Gordon - University of Wyoming
References:
Bell, G. D. and L. F. Bosart, 1988: Appalachian cold air
damming. Mon. Wea. Rev., 116, 137-161.
Chen, W. - D., and R. B. Smith, 1987: Blocking and deflection of
airflow by the Alps. Mon. Wea. Rev.,115, 2578-2597.
Doyle, J. D., 1997: The influence of mesoscale orography on a coastal
jet and rainband. Mon. Wea. Rev.,121, 1493-1513.
Horstmann, J., W. Koch, S. Lehner, and R. Tonboe, 2000: Wind retrieval
over the ocean using synthetic aperture radar with C-band and HH
polarization. IEEE Trans. on Geosci.
and Remote Sensing, 38,
1113-1121.
Monaldo, F. M., 2000: The Alaska SAR Demonstration and near real-time
synthetic aperture radar winds. Johns
Hopkins APL Tech. Digest, 21,
75-79.
Monaldo, F. M., D. R. Thompson, R. C. Beal, W. G. Pichel, and P.
Clemente-Colon, 2001: Comparison of SAR-derived wind speeds with model
predictions and ocean buoy measurements. IEEE Trans. Geosci. and Remote Sensing,39, 2587-2600
Overland, J. E. and N. Bond, 1993: The influence of coastal orography:
The Yakutat Storm. Mon. Wea. Rev.,112, 2532-2536.
Parish,
T. R., 1982: Barrier winds along the Sierra Nevada Mountains. J. Appl. Meteor., 21, 925-930.
Pierrehumbert, R. T., and B. Wyman, 1985: Upstream effects of a
mesoscale mountain. J. Atmos. Sci.,
42, 977-1003.
Wackermann, C. C., C. L. Rufenach, R. A. Schuchman, J. A. Johannessen
and K. L. Davidson, 1996: Wind vector retrieval using ERS-1 synthetic
aperture radar imagery. J. Geophys.
Res., 34, 1343-1352