Due to the current gap in continued funding from the U.S. National Science Foundation (NSF), the NSF Unidata Program Center has temporarily paused most operations. See NSF Unidata Pause in Most Operations for details.
Due to the current gap in continued funding from the U.S. National Science Foundation (NSF), the NSF Unidata Program Center has temporarily paused most operations. See NSF Unidata Pause in Most Operations for details.
On Tue, 2 Aug 2011, Chad Johnson wrote:
All, We found that the high rate of retransmitted products ended on Monday 08/01 - around 14:44 UTC. Up until that point, we were seeing retransmissions at a rate of thousands per hour and the difference between the time of original transmission and the time of retransmission was around 6000 seconds or between 1.5 to 2.0 hours. Then, there was a half hour gap between 14:44 and 15:13 where no retransmissions were sent, followed by the typical random low rate of restrans we're used to seeing. The time difference between the original and the retrans product also settled down to a typical 30 and 60 seconds. After 8/01 14:44, I'd guesstimate that we had already seen 95% of the retransmissions. Before that, I'd say it was the inverse (possibly because products were no longer in the "seen it" list). Anyway...something happened at 14:44 on the 1st. Is anybody aware of any changes made by the NCF/TOC around that time? I talked to the TOC late yesterday afternoon and they said everything was fine. Which I guess, technically, at the time was true but they didn't provide any additional information. What seems really odd to me, is the length of time between the original transmission and the restransmission. It's almost as if there is a rogue NWS office out there requesting retransmissions long after the product has been transmitted. Here, a slug of radar products were retransmitted nearly two hours after the original was broadcast. We were also seeing the same for some GRIB data. 2011/08/01 00:03:07 Retranmission already exists: skipping "SDUS54 KOUN 312215"; Secs=6370 2011/08/01 00:03:07 Retranmission already exists: skipping "SDUS54 KOUN 312215"; Secs=6370 2011/08/01 00:03:07 Retranmission already exists: skipping "SDUS23 KIND 312211"; Secs=6370 2011/08/01 00:03:07 Retranmission already exists: skipping "SDUS23 KARX 312214"; Secs=6370 2011/08/01 00:03:07 Retranmission already exists: skipping "SDUS23 KIND 312211"; Secs=6370 They may have even retransmitted the same product multiple times, unless multiple unique products are transmitted under the SDUS54 KOUN header (not up on my WMO headers like I used to be). 2011/07/31 22:16:21 Retranmission doesn't exist: saving "SDUS54 KOUN 312215" 2011/08/01 00:01:34 Retranmission already exists: skipping "SDUS54 KOUN 312215"; Secs=6335 2011/08/01 00:01:34 Retranmission already exists: skipping "SDUS54 KOUN 312215"; Secs=6335 2011/08/01 00:03:07 Retranmission already exists: skipping "SDUS54 KOUN 312215"; Secs=6370 2011/08/01 00:03:07 Retranmission already exists: skipping "SDUS54 KOUN 312215"; Secs=6370
At that time, we lost all METARs. The NWS sent out a memo saying that a SAN had gone crazy; they had switched to a "backup system" and that SAN was having issues. Once fixed, the METARs came back and the duplicate products stopped. So it wasn't the satellite broadcast or NWS offices having trouble getting the broadcast.
******************************************************************************* Gilbert Sebenste ******** (My opinions only!) ****** Staff Meteorologist, Northern Illinois University **** E-mail: sebenste@xxxxxxxxxxxxxxxxxxxxx *** web: http://weather.admin.niu.edu ** Twitter: http://www.twitter.com/NIU_Weather ** Facebook: http://www.facebook.com/niu.weather * *******************************************************************************
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