Tuesday 29 January 2013

Seminar on the riometer application

On behalf of our reseach team*, I'd like to show a few slides on the recent development of KAIRA as a multi-frequency riometer with a title 

"Electron density height profiles derived from a broad-band riometer"

Photo by Sami Kero
Thursday, 31 January 2013,  
2 pm (Finnish local time) at SGO. That is 12 UTC for all our friends abroad.

The plan is to stream the presentation here
 for anyone to follow. Just login as "guest" and type your name in it.

See also earlier posts related to the topic here and here.
Welcome, physically or virtually,

*Antti Kero, Juha Vierinen, Derek McKay-Bukowski, Carl-Fredrik Enell, Malefia Sinor, Lassi Roininen, Yasunobu Ogawa

Friday 25 January 2013

A light in the dark

A couple of photos to end the week. These were from a recent expedition to the site. Although most of our images are from the daylight/tilight hours, it's not always like this and in the dead of winter total darkness is more typical.

Pulling up to site. (Photo: D. McKay-Bukowski)

As close and you can get. The last 30m to the RF-container are on foot. (Photo: D. McKay-Bukowski)

Saturday 19 January 2013

Ice skating

Spring is here! The Sun already makes a several hour appearance above the horizon each day. Today the temperature was pretty warm (-4 C) so we went skating with the kids. I got a nice gopro camera as a present when I defended my doctoral thesis, so I thought I'd try filming the game of tag that we often play when skating. No children were harmed during the shooting of this film.

Friday 18 January 2013

Kitinen River Sunset

Aren't Arctic skies just beautiful? Today's photograph is taken looking at the set sun over the Kitinen river just after midday.

Kitinen River (D. McKay-Bukowski)

Have a nice weekend!

Monday 14 January 2013

Announcement — 5th EISCAT_3D User Meeting

For those in the EISCAT community, the 5th EISCAT_3D User Meeting will take place in Uppsala, Sweden, on May 6-8, 2012. For more information please see the meeting web page: http://www.space.irfu.se/workshops/EISCAT-3D_User2013/

Friday 11 January 2013

EISCAT 32m dish at SGO

Just a nice photograph to end the week. Today's is the 32m dish at Sodankylä Geophysical Observatory.
The EISCAT 32m dish at SGO. (Photo: D. McKay-Bukowski)

Have a nice weekend!

Wednesday 9 January 2013

Inversion of electron density from multi-frequency absorption measurements

Riometers were discussed a while ago on this blog. In essence, these are instruments that measure how much radio waves are absorbed in the D-region of the ionosphere (50-100 km). The more electron density in this region, the more absorption is observed. The absorption is also dependent on frequency of the radio wave. The higher the frequency, the lower the absorption. The amount of absorption is determined by comparing cosmic radio noise power to typical values for "normal" quiet day, where we would expect to know the amount of absorption based on ionospheric models. 

A few months ago we managed to capture an auroral precipitation event that caused clear absorption. This aurora was also captured at the Sodankylä Geophysical Observatory by the all-sky camera. 
Aurora at approximately 4:50 UT on 14.11.2012 captured by the UCL all-sky camera located at the Sodankylä Geophysical Observatory. Note: Image Copyright by University College London, UK. All rights reserved.
KAIRA was running in wide band riometer mode during this time with 244 subbands observing the vertical direction. You can see the measured values of absorption in the following figure. 
Measured absorption on the vertical beam of the LBA, starting from 12 UT on 13.11.2012.  Notice that while there is some man-made radio interference, most of the LBA band is pretty clean. 
Since then, we have been developing software to translate these kinds of measurements into physical quantities, namely electron density profiles. A few days ago we got the first results, and even though this is still work in progress, we are proud to show them to you now! The following image shows the resulting fit to the measurement.
The best model fit the the measurements. 
 And the following image shows the electron density profiles that our fitting routine gives for the data.
The resulting electron density (N_e/cm^3) profile that was fitted. 

Friday 4 January 2013

The EISCAT building at SGO

Here is the EISCAT building at the Sodankylä Geophysical Observatory. It is where the KAIRA team have their offices. It lies in the shadow of the 32m EISCAT receiver dish (now converted to operate at VHF frequencies).

The EISCAT building at Sodankylä. (Photo: D. McKay-Bukowski)

It is always difficult to take photographs in such low light levels. Incidentally, the white dot in the photograph at the top right is the moon and the structure next to it is the edge of the 32m dish.