Salut!
I think Linnunniemi is the same as Linnunlahti. In Finnish language
niemi = cape and
lahti = bay. The word
linnun is genetive form of
lintu ( = bird). So the names are Linnunniemi = Bird's Cape, Linnunlahti = Bird's Bay.
The foreword is meant to help to explain the Linnuniemi "airfield". There is/was no such thing as the air"field" was actually on the ice of Linnunlahti bay. IIRC some summer houses/cottages at Linnunniemi cape were used for lodging of the personnell. Matti Hämäläinen writes about this in his new book "Lentolaivue 46" (the FinnAF Dornier 17 squadron).
(
http://www.koalakustannus.fi/kirjat/...alainen_46.htm , only in Finnish like the book(s). Rest of Koala publishing aviation books at:
http://www.koalakustannus.fi/kirjat/ilmailu/index.htm )
Using for example this map server:
http://pk-kartat.jns.fi/map.php
The map navigation is a bit difficult as it is a search by yourself-type now. One can find map of Joensuu which show both Linnunlahti bay and Onttola airport. I couldn't make the search function to work - only result was "not foundt" (Sic!, KL). English language is available though.
Onttola aifield is the same as Joensuu Airport today. Search with ICAO code EFJO should gives some information about the situation today. Please check for example this Joensuu aerodrome chart from Finnish CAA webserver:
http://www.ilmailulaitos.fi/ais/aipc.../efjo/joad.pdf
The runways seem to be in same directions as during war. In wartime photos though there was third runway some 10 degrees different direction than the main runway (RWY 10/28 ).
Mr. C-F Geust might have knowledge where to find wartime maps etc. about the Onttola base. He is member of this forum and as such within reach of private message.
With Best Regards,
Kari Lumppio