[meteorite-list] Radar update - bad news

From: Marc Fries <mfries8_at_meteoritecentral.com>
Date: Sun, 31 Aug 2014 11:30:34 -0500
Message-ID: <BLU436-SMTP172622CB059F24AB761FF23F1D90_at_phx.gbl>

Howdy, all

        It has been a while since I?ve posted to the list, and unfortunately I have to do so with bad news. You may have noticed that it has been a while since we?ve found a new meteorite fall in weather radar imagery. We recently found out why. It turns out that the NEXRAD radar system lost sensitivity in the last major ?upgrade?. The radars were upgraded to allow two polarization modes instead of one, which improves meteorologists? ability to discern different types of precipitation. That upgrade came with a ~3 dBz sensitivity loss. I?ve gone back to West, TX and found that 3 dBz of sensitivity loss results in the loss of about 90% of all the meteorite reflectivity signal for that fall. And it turns out the upgrade was in progress to the point that one of the nearby radars was upgraded to dual-polarization in time for the Sutter?s Mill fall. The upgraded radar produced considerably less radar reflectivity from the Sutter?s Mill fall than another, single-polarization radar that was about the same distance awa
y. To put it simply, we?ve lost a lot of our capability to find meteorite falls using the NEXRAD system.
        It is not all gloom, however. The next round of NEXRAD upgrades will install a modern, more sensitive detector to replace the 1980?s-vintage detectors currently on the NEXRAD sets. Pending availability of funding, that will commence in 2016 and should get us back to where we were before the upgrade. Also, now that we know what to look for, I?ll start going back to recent probable fall events and look for fall signatures. The Columbus OH, northern Arkansas, and Dec 2013 event outside Tucson are worthy of re-examination. I?m also looking into alternative sources of radar data.
        So at least our extended dry spell has been explained. NOAA couldn?t care less about meteorite falls and so they don?t communicate this sort of information widely, and we?re freeloading on their data and don?t have a voice in whether these ?upgrades? are truly useful. If I had my druthers, I would have asked them to upgrade the detectors first and then install the dual-polarization capability. In my more official capacities I will try to arrange a voice for the meteoritics community in radar dealings, but that may take a while.

Cheers,
Marc Fries
Received on Sun 31 Aug 2014 12:30:34 PM PDT