Wednesday, April 16, 2014

Lightning Strike or Not? Photo Analysis

[n.b. This is a backdated post, part of a May/2014 blog catchup.  This post's content is a slightly edited version of an email sent on April 16th, 2014, about our analysis of recent photos of the station and whether they supported the theory that a lightning strike had been the cause of the station's December communications failure.]

Thanks very much for sending photos! A picture really is worth a thousand words. I've looked over those six photos very carefully and my armchair-quarterbacking opinion is that there isn't any evidence of lightning damage, at least nothing observable from these photos.

Just to refresh everyone's memories, here is your Feb 26th report:

There must have been a large lightning strike, a couple of instruments at the top of the pylon showed blackened burn marks, and the lighting rod looked toasted, so we are assuming that a massive strike may have taken place.

Begging everyone's patience, here is my analysis of the state of the aerial instruments as shown in these photos. I am attaching a copy of your 008 photo that I've scribbled on to identify which instruments I'm talking about, which might help.

Marlon's photo as marked up by Mike Jankulak.  Click on the photo to see a larger version.


There are four bright white objects at the top of the station -- BIC (light sensor), WXT (integrated wind/weather transmitter), windbird (anemometer) and GOES antenna. The air temp in its radiation shield is also up there but somewhat lower down than the others.

I don't see any "blackened burn marks" on any of these, at least not visible in these photos. The closest to a black mark is on the BIC, on its S/SE side, visible from photos 007, 008, 009 and 017 (the side showing in photos 010 and 015 appears to be completely white). Here you can see the BIC's logo/label (see attached closeup photo of the BIC on my workbench) on the upper side. Also there appears to be some rust stains, orange/brown, below this, probably from the hose clamps that are holding the BIC to the aluminum mast. Some may recall that when we were there last August the BIC I'd brought with me was found to be dead on arrival, so I simply reattached the same BIC that had been there since 2011. So this same instrument has now been out there for almost 3 years.

A closeup of a Surface BIC on my workbench, showing its label/logo.  Click on this photo to see a larger version.


The windbird and the GOES antenna, as far as I can tell, are completely white.

The WXT too shows no signs of discoloration. At first I thought photo 007 might show that one of its three protruding acoustic wind sensors is bent or broken. Looking more closely though I think I'm just seeing one of the think metal bird spikes, slightly bent, and a little blurriness is making it look thicker than it really is.

Finally the lightning diffuser brush looks pretty good to me for its age, about the same as I remember (see attached photo from last August). Note that this is not a lightnight "rod", i.e. its purpose is not to attract lightning. Rather it is a diffuser, and when properly grounded it serves to "hide" the whole station from lightning activity and make it "appear" to the clouds as though it's just a stretch of featureless ocean. This lightning diffuser actually looks a lot healthier than the one at our Puerto Rico station, which has been under constant mistreatment by boobies.

Mike Jankulak in August of 2013, including a view of the station's lightning diffuser brush.  Click on this photo to see a larger version.


Anyhow, please speak up if you feel like there is something in these photos that I'm missing, or if you believe that there are further signs of lightning damage at the station that aren't well represented in these photos. But for now I am going to tentatively (and happily) conclude that a direct strike by lightning did not occur.

Naturally we will plan this next visit, as much as possible, to arrive carrying everything we would need to repair the station following an actual lightning strike. Better to be as prepared as possible.

(signed)
Mike Jankulak