Visible and UV-A radiation in greenhouses

Different cladding materials transmit different amounts of ultraviolet radiation, and we cannot see this with our eyes. The following UVA photographs give an idea of how different parts of the same greenhouse may differ without we being able to see it.

Roof of a greenhouse seen in visible light.
Roof of a greenhouse seen in UVA radiation.

Light distribution in greenhouses is not spatially even, neither irradiance (“intensity”) nor spectrum (colour) are uniform in space. Ventilation openings, supporting structures, differences in cladding materials and shade screens affect both. To some extent these patches move as the position of the sun moves, but not necessarily enough to even-out light conditions over the whole area of a greenhouse compartment. Other factors affecting the amount of radiation transmitted are the cleanliness of the cladding surface, and the angle between incoming direct solar radiation and the surface of the cladding. An example of how closed and open roof vents affect illumination.  Two visible light photographs taken only a few minutes apart under fully clear sky conditions around 2 pm solar time.

Visible light closed vents and open shade screen.
Visible, open vents and closed shade screen.

Paired photographs in UV-A radiation.

UVA radiation, closed vents and open shade screen.
UVA radiation, open vents and closed shade screen.

This highlights why design of experiments, and correct randomisation in space and time are crucial when using greenhouses in research or at early stages of crop breeding.

Update on: ‘Article titles in the era of the internet’

Exponential growth in read counts continues.

Reads in ResearchGate for my review of a book, published in the UV4Plants Bulletin.

As ResearchGate seems to assign subjects to papers based on the subjects in the author’s profile, rather than the paper itself, all sorts of astonishing achievements are being reported for this very modest one-page-long book review… and for myself… Continue reading “Update on: ‘Article titles in the era of the internet’”

Article titles in the era of the internet

A currently ongoing surprising event affecting what I considered one of my least important articles (, has made me rethink how search engines and the internet affect the impact of publications.

Among web site developers “SEO” is considered a very important factor in being successful in “drawing traffic or page reads” to a site. SEO means search-engine optimisation. For web pages, it involves much more than subjectively choosing suitable words for titles. In a way it is like reverse engineering how research engines like Google work, so as to write web pages in a way such that they will appear near the top of searches as frequently as possible. There exist different types of tools and software to help in the task of achieving good “SEO” and even companies that offer for a payment SEO for websites. My thoughts are: do we need similar tools for SEO of research papers? Needed or not, a more important question is how much do the properties of the algorithms  used by search engines affect the impact of the articles we write? I do not know the answers, but I think these are important questions.

What is the incident? To me it looks like a snowball effect, helped by accidental good SEO. I wrote a short review of a book in the UV4Plants Bulletin ( and as it is allowed, made it available through ResearchGate. It is being read and being followed and recommended… but much more than what would seem to me to be reasonable, to the point that it has already been on two weeks according to ResearchGate the most read article from a Finnish author! and more than once the most read forestry article worldwide (although neither the Bulletin, nor the reviewed book, have anything to do with forestry).

Using R to acquire spectral data

My talk at the Nordic Ozone Group meeting. Although this is a video, I used it as one would use slides, with me speaking live. A true video with sound or subtitles will be produced in the future. The presentation is a demo of the R package ‘ooacquire’, which I have written. It is currently in use at the SenPEP research group, CanSEE research group and the Finnish Meteorological Institute (including at a station in India). The package implements algorithms developed by our collaborator Lasse Ylianttila at the Radiation Authority Finland.

Researchers mentoring researchers

Mentoring has been an everyday activity for me as supervisor of students (PhD and MSc) and postdoctoral researchers. This mentoring has usually focused mainly on research itself, and the specific field of research I work in. In addition I have brought to the discussion more general topics but they had been mostly unplanned detours from other discussions. To some extent, answering questions in ResearchGate, StackOverflow and through e-mail, has also been small-scale mentoring. I have regularly taught at and organized training events for PhD students and early stage researchers. In recent years I have edited a handbook on methods in photobiology, and co-authored another one on calculations related to photobiology. I have written a text book on the R language, aimed mainly at independent learning. I have developed open-source software to make correct calculations and plotting of radiation data as used in photobiology easier. The aim behind all this work has been to make “good science” easier to carry out, and through mentoring and training, to encourage other researchers in my own field to pay more attention into avoiding methodological pitfalls. Continue reading “Researchers mentoring researchers”

Update on our R packages

We have been using R for our data analyses for several years, and accumulated expertise and scripts for calculations related to photobiology. After more than two years of work of programming and documentation writing, in the last year I have submitted eight packages to the CRAN repository, packages that are now widely available for anybody to use. All code and documentation is open-source and open-access.

There are still more packages under development of which the ones I find more interesting are two that allow direct acquisition of spectral data from within R allowing use of all the power of R to analyse spectra in almost real time during measurements. They also incorporate state of the art correction algorithms for array detector spectrometers.

The suite of packages has its own web site at and those already in CRAN can be searched through METACRAN.