Monthly Archives: January 2015

Snow in Lapland

Finnish Meteorological Institute (FMI) Open Data API has been with us for over a year already. Like any other specialist data source, it takes some time before a lay person like me is able to get a grasp on it. Now, thanks to the fmi R package by the collaborative effort of Jussi Jousimo and other active contributors, the road ahead is much easier. A significant leap forward came just before New Year, when Joona Lehtomäki submitted a posting on fmi and FMI observation stations to the rOpengov blog.

Unlike many other Finns, I am relatively novice when it comes to Finnish Lapland. I’ve never been there during summertime, for example, and never farther North than the village of Inari. Yet, I count cross-country skiing in Lapland among the best memories of my adulthood years so far; pure fun in the scorchio April sun, but maybe even more memorable under the slowly shifting colors of the polar night.

Snow is of course a central element in skiing. Although warmer temperatures seem to be catching us up here, there has still been plenty of snow in Lapland during the core winter months. But how much, exactly, and when did it rain, when melt?

I followed Joona’s steps, and queried the FMI API of snow depth observations at three weather stations in Lapland, from the beginning of 2012 to the end of 2014: Kilpisjärvi, Saariselkä and Salla. Note that you have to repeat the query year-wise because the API doesn’t want to return all the years in one go.

Being lazy, I used the get_weather_data utility function by Joona as is, meaning I got more data than I needed. Here I filter it down to time and snow measurements, and also change the column name from ‘measurement’ to ‘snow’

snow.Salla.2014 <- salla.2014 %>%
  filter(variable == "snow") %>%
  mutate(snow = measurement) %>%
  select(time, snow)

and then combine all data rows of one station:

snow.Salla <- rbind(snow.Salla.2012, snow.Salla.2013, snow.Salla.2014)

One of the many interesting new R package suites out there is htmlwidgets. For my experiment of representing time-series and weather stations on a map, dygraphs and leaflet looked particularly useful.

Last time I was in Lapland was in mid-December 2014, in Inari, Saariselkä. BTW, over 40 cm of snow! During some trips I left Endomondo on to gather data about tracks, speed etc. I have to point out that I'm not into fitness gadgets as such, but it's nice to experiment with them. Endomondo is a popular app in its genre. Among other things it lets you export data in a standard GPX format, which is a friendly gesture.

For the sake of testing how to add GeoJSON to a leaflet map, I needed to convert the GPX files to GeoJSON. This turned out to be easy with the ogr2ogr command line tool that comes with the GDAL library, used by the fmi R package too. Here I convert the skiing ("hiihto") route of Dec 14th:

ogr2ogr -f "GeoJSON" hiihto1214.geojson hiihto1214.gpx tracks

One of the many aspects I like about dygraphs is how it lets you zoom into the graph. You can try it yourself in my shiny web application titled (a bit too grandiously I'm afraid) Snow Depth 2012-2014. Double-clicking resets. To demonstrate what one can do with the various options that the R shiny package provides, and how you can bind a value to a dygraphs event - pick a day from the calendar, and notice how it is drawn as a vertical line onto the graph.

The tiny, blue spot on the map denotes my skiing routes in Saariselkä. You have to zoom all the way in to see them properly.

The shiny application R code is here.

Edit 11.1: Winter and snow do not follow calendar years, so added data from the first leg of the 2012 winter period.