Map of the 2014 KAIRA storm damage

Today, we've plotted where there has been damage to KAIRA. The map is a bit scary, but actually as we have seen from yesterday things are not so bad and we've come out of it fairly well.

As can be seen, we have lost two antennas completely. These are tile #H75 and aerial #L34.

We've had two aerials (#L05 and #L21) seriously damaged. These will need to be replaced.

There are three aerials (#L22, #L35 and #L36) which have been damaged but have been repaired to the point where they are operating normally again. However additional work will be required in the summer when the snow has melted and we can access them properly.

There are many aerials with minor damage. The aerials are still operational, but will require some attention in the summer to ensure they remain robust for the following winter. The problem has been buffeting to the aerial wires causing cracks in the PVC moulding and coatings. These can be patched, but it does require warmer weather.

System status

Following the storm and the repair work, we carried out remote system checks for the bandpasses for all antennas. Here are the results, starting with the High-Band Antenna (HBA) array:

As seen, RCUs 80 and 81 (= tile #H75) remain dead. These are the two channels from this destroyed tile.

Here is the Low-Band Antenna (LBA) array results:

Here you can see RCUs 68 and 69 (= aerial #34) remain dead. This aerial was destroyed and we have not even found the remains of it! Following repairs, there remain two other damaged signal channels. These are RCU 11 (= aerial #L05, Y-polarisation) and RCU 42 (= aerial #L21, X-polarisation). These two aerials have suffered broken wires and are thus impared in this polarisation. Temporary repairs have been effected, but more work remains to be done.

However, in total, we only have lost 6 out of 192 signal channels. Throughout the storm and the repair work, KAIRA has continued to observe our riometry and interferometry programmes. That's pretty good.

What a week!

It has been a nerving week with all the KAIRA storm damages! Fortunately, most of the site has survived and we can continue operations! The damaged aerials and the destroyed HBA panel will be serviced or replaced during the coming weeks or next summer!

Hence, even though we had bad luck, we are very happy to see that KAIRA is back in business!

Have a nice weekend! ... and let's hope that there won't be another storm on Saturday :) !!!

Thursday morning photo - service operations in progress!

Day 2: Robust fixes - storm repairs

Our team in Kilpisjärvi had a long day in the KAIRA site on Thursday fixing bits and pieces here and there. The repairs, maybe not elegant, but they are robust and should give us time to plan a full-scale repair operations in the site! We let the photos to speak for themselves! ... And of course - many thanks to all the staff up in Kilpisjärvi!

We will post more pics in the coming days!

Correlating gusts and failures

From the last few days, we've been looking at the loss of signal from the LBA aerial #L34 and today we've correlated that with the wind-gust speeds. Although the average speed is often of interest, it is the gusts that usually determine points of failure or direct damage.

In the graph we have plotted the 10-minute gust maxima for Kilpisjärvi village and Saana mountain (the two nearest official weather stations to KAIRA). Also plotted is a vertical line showing the point at which signal was suddenly lost from LBA aerial #L34.

Not surprisingly, it corresponds to a strong peak. However it is good to note that we tolerated up to that value and that the failure did not occur earlier at lower gust speeds.

The failure time is slightly ahead of the peak. This also not surprising, as the weather stations were both downwind of the KAIRA site (by a few km) at the time of the failure.


Data courtesy from the Finnish Meteorological Institute (www.fmi.fi)

KAIRA storm damage repairs - Day 1

A three-person SGO team travelled up to Kilpisjärvi today. They have investigated the storm damages as well as the protection cover constructed by local craftsmen on Monday. The cover is of good quality and seems to protect the HBA field fully, despite we have one HBA tile totally destroyed. 

The LBA field has been damaged during the storm. We suspect that this is due to the HBA debris which has flown through the LBA field. Altogether around 8 antennas require different levels of maintenance. One antenna is flat-lining!

Below are a set of photos from the Day 1 of the SGO team damage inspection and emergency repair expedition! The weather is continuing to be challenging in Kilpisjärvi! Despite of that, our courageous team is doing their best with the repairs! 

Good work chaps! … and good luck for Thursday!

Moment of death

We trawled back through the subband statistics (SST) data to find the exact instant that LBA aerial #L34 was destroyed. The critical moment seemed to be around 18:50:20 UTC.

As can be seen, there is a possible preliminary event some 12 seconds earlier. Not sure what this could have been. Flying debris, perhaps?

In any case, this was the point when we lost aerial #L34, which probably was due to flying debris  from tile #H75.