This is a short post about a relatively new data series from the European Commission's Joint Research Centre. It comes from their 'Spatiotemporal activity and population mapping in Europe (ENACT)' project and - in simple terms - it provides gridded population data for the daytime and nighttime, so that we can compare population patterns at different points in the day. It's very similar to the GHSL data that I've written about before but the key difference is that we can compare the population of 1km cells in the daytime vs the nighttime. The data are from 2011 and it is available for each month of the year, and in two different projections, for the EU28 (as it was when the project began). But what does it look like? See below for a snapshot of nighttime population for January.
|This is basically a 'where people live' map|
The data were released in mid to late 2020 so many people might have missed it but I think it's a great new addition to the European data infrastructure. You can read more about the specifics of the project and the data fusion approach in this open access Nature Communications paper written by the research team. It's a nice piece, and it also sets out why - if you weren't aware - it is important to understand both the spatial and the temporal distribution of population. These issues have of course come into focus more during 2020 and beyond with the rise of Covid-19.
As for the data, I'll let you explore that yourself if you're interested but I'd certainly recommend spending some time on the website and also reading the notes and information about it. For now, here's another map of the January data, but this time for during the day (so I've turned the lights up). You can see how the settlement patterns thin out as the population is concentrated in towns and cities. Greater London's daytime population normally swells to over 10 million, for example - although this has all changed since the advent of Covid-19. Will it ever rise so high again?
|Daytime population - notice the higher spikes|
You can find the actual values for each 1km cell by importing the data into QGIS (or any other software that will read a tif) and then querying it. I've done this below for the January data for a small area of central London so you can see how the day and night populations differ. I've added the raster cell values to the images - these are the populations for each 1km cell either at night or during the day, so you can really see how the population changes with commuting in this example. You may have to click on the image and zoom in so you can read the numbers.
|Day vs night population|
Right, that's all for now. This is a great new dataset and even though the time point is 2011 it provides a really useful resource for spatiotemporal analysis. It will be very interesting to see what things look like in future in relation to daytime vs nighttime populations with the impact of Covid-19 on the nature and location of employment.
Download the data (each tif file is about 14.5MB)
ENACT seasonal nighttime and daytime population grids for 2011. Values are expressed as decimals (Float). The data is published at 1 km resolution in Lambert Azimuthal Equal Area (EPSG:3035), 12 monthly nightime grids and 12 daytime grids, and at 30 arc-seconds in WGS-84 (EPSG:4326), 12 monthly nightime grids and 12 daytime grids. The compressed ZIP file contain TIF files and short documentation.
Schiavina, Marcello; Freire, Sergio; Rosina, Konstantin; Ziemba, Lukasz; Marin Herrera, Mario; Craglia, Massimo; Lavalle, Carlo; Kemper, Thomas; Batista, Filipe (2020): ENACT-POP R2020A - ENACT 2011 Population Grid. European Commission, Joint Research Centre (JRC) [Dataset] doi:10.2905/BE02937C-5A08-4732-A24A-03E0A48BDCDA PID: http://data.europa.eu/89h/be02937c-5a08-4732-a24a-03e0a48bdcda