ICT to get Dual Pol. radar

[Jeff Snyder]

This will be a very nice upgrade to the current radars. The shape (and therefore type) of the hydrometeor will be able to be determined and radar rainfall estimates should improve. As of now, when high reflectivity values are seen, one cannot be sure if heavy rain or hail exists in that region. With dual-polarimetric radar we will be able to combine dBZ and ZDR (differential reflectivity) values to determine what type of precip is occurring.

Don't forget about rho_hv, which is very helpful in terms of determining hydrometeor classes. Additionally, KDP serves an important purpose as well, even outside of QPE.

Honestly, I think for many chasers (both in the field and armchair) the recent super-res upgrade is bigger than the DP upgrade will be. The one exception I can think of is what RDale brought up -- the tornado debris signature. However, we don't really have a good gauge on how "common" this signature is since there are only a handful of polarimetric weather radars that have sampled tornadic supercells. Having worked with X-band polarimetric data for the past few years, I think availability of polarimetric data from the WSR88D network is going to be confusing and not particularly useful for the vast majority of casual radar observers. Nearly all of us on this forum can interpret ZH and Vr imagery, but adding more variables (KDP, RHOhv, ZDR) can greatly complicate the interpretation of the data. In fact, I'm not sure the additional data are going to be very useful for most folks, particularly in a real-time situation with casual interrogation. Of course, for op mets or those who want to interrogate intensely a storm, the additional data will often be extremely useful.

For those who are interested in the , the paper outlining the WSR88D hydrometeor classification scheme was recently published in Wea. and Forecasting:
Park, S-G, A. V. Ryzhkov, D. S. Zrnić, and K-E Kim, 2009: The hydrometeor classification algorithm for the polarimetric WSR-88D: Description and application to an MCS. Wea. and Forecasting, 24, 730-748.

I'll point out the following to interested readers:
Kumjian, M., and A. V. Ryzhkov, 2008: Polarimetric signatures in supercell thunderstorms. J. Appl. Met., 47, 1940-1961.
Kumjian, M., and A. V. Ryzhkov, 2009: Storm-relative helicity revealed from polarimetric radar observations. J. Atmos. Sci., 66, 667-685.
Romine, G. S., D. W. Burgess, and R. B. Wilhelmson, 2008: A dual-polarization-radar-based assessment of the 8 May 2003 Oklahoma City area tornadic supercell. Mon. Wea. Rev., 136, 2849-2870.

 

[rdale]

Good points above... Will the "casual chaser" get a ton of value? Probably not other than better hail info and possible debris. Will you be doing a ton of RHOhv interpretation while chasing? No way. But if you have a support team back home, they'll have plenty more to play with.

 

[Shane Adams]

I was under the impression DP radar could scan (and therefore update) every 30-45 sec as opposed to the 5-6 min scans with current radar. That's what I meant when talking about the possible advantages for chasing. This would give you a much better look at a storm real-time as it evolves.

If I'm wrong, the volume scans are not 30-45sec apart now, and the only difference is knowing precip type...then that doesn't do much for me. Science is wonderful and all, but applied science is what matters to me.

 

[Charles Kuster]

I was under the impression DP radar could scan (and therefore update) every 30-45 sec as opposed to the 5-6 min scans with current radar.

Unfortunately, the DP upgrade will not decrease the time needed to obtain a volume scan. The phased-array radars will be able to scan very quickly, but that is still 15-20 years in the future.

 

[Damon Scott Hynes]

I'm thinking it may be in part for tropical activity.

If it were for tropical storms, I'd want the radar in Guam or Puerto Rico, but I'll be the first to admit I don't know everything.

 

[rdale]

Unfortunately, the DP upgrade will not decrease the time needed to obtain a volume scan. The phased-array radars will be able to scan very quickly, but that is still 15-20 years in the future.

On the other hand - there have been proposals for VCP scan strategies in the 2.5-3 minute range with the 88D, but it's been a while since I've heard anything about that. It might be more than the current hardware can handle?

 

[Greg Stumpf]

On the other hand - there have been proposals for VCP scan strategies in the 2.5-3 minute range with the 88D, but it's been a while since I've heard anything about that. It might be more than the current hardware can handle?

This is one way to achieve faster scan updates with a conventional antenna radar: http://www.roc.noaa.gov/wsr88d/NNOW/AVSET.aspx

 

[Mike Smith]

Greg, this is terrific.

Now the questions:

What is the status of getting this implemented?

Has anyone ever looked at an automatic sector scan function during severe weather? That would also speed things up. For example, if it is May 3, 1999, at 3pm, I doubt anyone cared whether the radar spun the full 360° to see nothing east of KTLX.

One could make the radar do a 360° every 10 minutes or so to see if anything has developed in the non-sampled area, but we would get much more frequent scans in the area of interest.

Mike

 

[Greg Stumpf]

AVSET has not yet been approved as to my latest information.

The system you describe, using sector scans, is done with CASA where the radars are networked and collaborating. It's also done with the phased-array radar, and since the scanning is electronic, you can have separate maximum elevation scans for each radial. Not sure if the WSR-88D program is considering any of this for their radars. However, any major changes like that would require approval from all three agencies that support the WSR-88D (NWS, DOD, FAA).

Here's another AVSET link: http://ams.confex.com/ams/pdfpapers/155324.pdf

Greg, this is terrific.

Now the questions:

What is the status of getting this implemented?

Has anyone ever looked at an automatic sector scan function during severe weather? That would also speed things up. For example, if it is May 3, 1999, at 3pm, I doubt anyone cared whether the radar spun the full 360° to see nothing east of KTLX.

One could make the radar do a 360° every 10 minutes or so to see if anything has developed in the non-sampled area, but we would get much more frequent scans in the area of interest.

Mike

 

[Shane Adams]

Unfortunately, the DP upgrade will not decrease the time needed to obtain a volume scan. The phased-array radars will be able to scan very quickly, but that is still 15-20 years in the future.

Ahhhhh yes....my mistake. I was thinking of PA. Thanks for the clarification.

 

[Jeff Duda]

Unfortunately, the DP upgrade will not decrease the time needed to obtain a volume scan. The phased-array radars will be able to scan very quickly, but that is still 15-20 years in the future.

15 - 20 years??? I was always hearing about how it should be arriving within the next 10. Man I hope it isn't that long before phased array becomes available. I'll be an old man by then!

 

[Jim Zandonai]

I hope so too ! By then I'll be 'arm chairing' everything
The technology is obviously already there so I assume the major thing that would stretch it out is budget..but I could be wrong. Time will tell.

 

[rdale]

The technology is obviously already there so I assume the major thing that would stretch it out is budget

I'd last heard an update about a year ago - the filtering and display of weather data vs. other returns was much more primitive than had been anticipated. That's probably why the schedule isn't going as fast as originally planned.

 

[rdale]

AVSET has not yet been approved as to my latest information.

There was a meeting earlier this week where the recommendation was made to have AVSET included in Build 13.

 

[Jeff Duda]

Build 12.1 upgrade

Resurrecting this thread as new TINs have been released lately regarding the scheduling of the dual-pol upgrades. Looks like there will be some upgrades to super res as well (including increased resolution for the higher tilts if I am understanding it correctly). References:

http://www.roc.noaa.gov/WSR88D/PublicDocs/Level_II/tin10-39_88d_super_res.pdf
http://www.roc.noaa.gov/WSR88D/DUALPOL/DPLevelII.aspx