Saturday, October 13, 2007

Not too successful measurements

Sometimes measurements fail. Especially if carrying them out successfully requires certain kind of weather. And if the certain kind of weather you are waiting for is a standard overcast sky (and especially no rain!). And if it's September or October at our latitudes.

From this introduction you can already guess that my LAI-2000 measurements in Järvselja turned out non-existent last week. I've been carrying out a series of measurements to catch the seasonal change in LAI (and reflectance): first measurements at the study plots were made already in April before budburst, the next ones in July with fully developed foliage. My purpose was to catch the final situation too: yellow (or red) leaves or green needles in early October. But it rained. And rained. And rained. And I got absolutely no measurements done even though I spent hours with the instruments and my field assistant sitting in the car next to the reference site, waiting for the rain to stop. The good news is that while we sat in the car, we ate a lot of sandwiches, cookies and bananas - at least we didn't go hungry...

I must admit that I was quite frustrated not to get the last set of measurements done. But there is nothing I can do about that - the leaves are now on the ground, turning brown. And I'm already waiting for next year and new measurements - I guess.

Leaving the car for a few minutes to see if the rain had stopped. But no, it hadn't...

Field assistant playing with autumn leaves in the rain.

Järvselja in October.

Friday, October 12, 2007

Physical models in remote sensing –course in Helsinki

Graduate school in Forest sciences organized this course 9.-11.10.2007 in Helsinki. Two members of LAI Detectives participated the event: Pola as course leader and I as a student. Our four-member Joensuu student delegation took a train to Helsinki already in Monday and accommodated in hotel omena. In the hotel we met other long distance participants from Estonia and Norway, so we could share the problem of finding the place of lectures, Gardenia building in Viikki. Fortunately we found the right place without any severe straying.

Apart from the opening words from Pola and Jari Varjo, the first two days consisted of lectures by Tiit Nilson and Andres Kuusk. The main theme was the physical basis of remote sensing: radiative transfer in atmosphere and vegetation, ground and canopy reflectance models, measurement techniques, and practical applications. As we Joensuu students are mostly dealing with forest inventory (=statistics with forest and/or remote sensing data), difficulties in following the physics and equations were inevitable, but I think that all of us got a good general overview of the problems and aims of more physically oriented remote sensing. To me personally the most interesting part was the practical demonstration of the FRT-model, of which I had heard many details but never got a general idea how it actually functions.

In the final day lectures were given by Jouni Pullianen and Sanna Kaasalainen, whose lectures covered the physical basis of radar and lidar remote sensing. These were more familiar to our Joensuu group, as Jouni had lectured about microwave remote sensing in Joensuu earlier this year, and laser scanning is currently the most important research topic in Joensuu's forest inventory group. It was still good to hear a laser lecture from a different perspective, and also the microwave part was considerably easier to follow with some existing background information. All in all this was a nice, well arranged course, but for some reason in these study trips the things happening outside the lecture hall tend to be even more interesting than the actual lessons...

Thursday, October 4, 2007

Sodankylä field campaign 2007

There’s nothing very exciting going on at the moment here in Joensuu, just the daily business of working with future research articles. But as I should somehow contribute to this new-born blog, I thought I could write something about last summers NORSEN field measurement campaign in Sodankylä. Altogether I spent two four weeks periods up there in Lapland, starting in the middle of July and ending well in September. Many people would probably get really frustrated about spending such a long time 130 km away from the closest supermarket together with reindeers and mosquitoes, but I took it more as a vacation. I had long before looked for some nice hiking and fishing places to visit in the weekends, but unfortunately I had also set a goal of coming back with at least 70 sample plots data set, which turned out to require more work than expected...

The center of the campaign was Finnish meteorological institutes arctic research centre in Tähtelä, 7 km south of the center of Sodankylä, by the side of “river” Kitinen. Tähtelä is also an important remote sensing research center, so it was useful to make measurements in an area where a lot of data were already available. Typical days included searching for new, different plot locations and measurements of forest stand variables, canopy cover and LAI. Originally I had planned to measure three plots per day (if weather was fine), but soon it became clear that two was a more realistic aim, and finally I had to content myself with 68 plots. Huge thanks for Pekka, who came there for two weeks to help me with the measurements, otherwise the plot quantity would have been even smaller. Even though the days in the forest became often fairly long and the plentiful mosquito population was a real nuisance especially during the first weeks, I still liked to be there. It was easy remember the long winter full of office work, so it was better to enjoy the summer while it lasted!

To end with I’ll tell one special incident that happened somewhere out there, in an unusually distant place tens of kilometers away from the closest inhabited place. I was doing some standard canopy measurements when I heard something rustling somewhere behind me. I turned to look expecting to see a reindeer, but it was - a berry picker. Well, normally that would have been nothing special, but this one was from Thailand! That was a small surprise, as I knew that the Finnish berry refiners bring labour from Far East, but I from what I had heard they like to move around in big groups. However, this one was clearly on his own, and I had seen no signs of other people when coming there, so I was really amazed how he had got there. We had no common language so we just waved to each other, and continued with our own businesses, one picking lingonberries and the other measuring trees with some funny instruments, tape measures set all around. I think that he was even more amazed of me than I was of him! After a while I heard a van approaching, honking as it came closer, clearly giving signals to the lost one. And so the puzzle of a mysterious berry picker had its solution - the van was filled with others belonging to the same group, so the one I met only had his own ideas about the best berry sites.

PHYSENSE workshop in Tartu

To get the blog properly started I'll write about the latest news from Tartu. Last week we hosted the first seminar of the PHYSENSE (Physically-based remote sensing of forests) network here in Tartu. It's meant for the younger generation of Nordic and Baltic researchers working in our field. Everything went smoothly: the presentations were interesting and covered both measurements and modeling, and there was plenty of food to eat.
Soon it's time to start making plans for the next workshop of the network. I've had quite positive feedback from participants by email - may be there is a point in organizing the next event! (And in trying to gather a bigger crowd for audience.)

Wednesday, October 3, 2007

LAI Detectives blog started!

We decided to start a LAI Detectives blog, Lauri came up with this good idea just last week!