Alasdair Rae Profile picture
Apr 21, 2021 14 tweets 8 min read Read on X
A short city population/datanerdfest coming up in this thread, beginning with a little panoramic tour of the Tokyo metro area - city as far as the eye can see

(I made this using Google Earth Studio btw, a very useful tool)
background: I have been using/playing with/analysing global city population data quite a bit over the years, most recently in an academic paper on the topic with @CJHoole and @stehincks

open access version: eprints.whiterose.ac.uk/149455/3/Conto… Image
we looked at population density for the whole world, using 1km resolution data from the EU's GHSL project - e.g. here's a little snapshot of how it looks across part of West Africa, from our paper Image
are there really a zillion people in Tokyo and not a zillion in London? That question can be answered using a simple but powerful tool like NASA's population estimator - e.g. here's what you get of you draw roughly 50km radius circles in Tokyo and London

sedac.ciesin.columbia.edu/mapping/popest… ImageImage
it can be quite addictive, but also useful - e.g. here's New York's wider metro area (using a boundary that doesn't officially exist, of course) Image
fair to say that geographers, planners and others have been looking at this kind of thing for zillions of years, of course, but it is interesting and important: e.g. take a look at the UN's 'World's Cities in 2018' report and their 'what is a city' page

un.org/en/events/citi… Image
here's one table from our paper showing the 'city' populations of different urban areas based on one particular boundary definition - we also added population density figures to the table Image
there's a much shorter extract of our work at p. 69 in the European Commission's Atlas of the Human Planet 2020

ghsl.jrc.ec.europa.eu/documents/Atla… ImageImage
I'll end this thread with a very badly drawn 'blue banana'* which, based on my bad artwork, has a population of about 115 million

(🍌😕 *blue what? - this explains the origins of the phrase undertheraedar.com/2009/03/colour…) Image
🚨 ADDENDUM 🚨

The Stoke-on-Trent Megaregion is 19 million people huge

(it can be quite amusing/enlightening drawing these arbitrary 100km circles on the estimator map, but watch out for varying area calcs) Image
more seriously, you can actually get boundaries from the GHSL dataset as well (their GHS-SMOD 'urban centre' definition), which is what we used to compare density in the 'cities' below

ghsl.jrc.ec.europa.eu/ucdb2018visual… Image
- I would not be doing my job if I didn't mention the fact that the wonderful team behind the European Commission's GHSL data have released the 'urban centre' boundary file as a GeoPackage that can be used in your GIS of choice

ghsl.jrc.ec.europa.eu/download.php?d… ImageImageImage
I've added this list of places in the Tokyo area - these are from the GHSL 'urban centres' boundary file - I've added all the places within the 'Tokyo' area, plus satellite background to show the extent of the urban fabric Image
and finally* - here are three different 'Tokyos', but as you can see, the '23 Special Wards' would be too tight a definition for a true 'urban area' population - for comparison, the 23 Special Wards of Tokyo cover 620 sq km and Greater London covers just under 1,600 sq km

*maybe Image

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More from @undertheraedar

Apr 4
I saw this Met Office 'UK climate districts map' online so naturally I decided to try and figure out the population of each area whilst eating my lunch and these are the incredibly interesting results
Image
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there is also the Met Office "climate regions" map but that's a can of worms that I don't want to open, not least because of the unwavering England N / England S line

metoffice.gov.uk/research/clima…
Image
when you plonk the Met Office climate districts on top of a map then you get something like this Image
Read 10 tweets
Feb 6, 2023
Okay, some European population density stuff now - starting with the top 100 1km grid squares by population across Europe, based on the most recent Eurostat data - more to follow
these are the top 3 by density, but I've shared a web folder with all 1km grid squares with more than 30,000 people living in them, as well as the top square in each of the 38 countries in the dataset

drive.google.com/drive/folders/…
they're all really interesting to me, but I particularly liked Gijón, Bucharest and Valletta
Read 35 tweets
Jan 13, 2023
Topical retweet because I've been watching The Rig but also the news - I remember first seeing these when I was about 10 when playing football in Invergordon and we couldn't believe the size of them
if you want to get a sense of the scale, look at the size of the people cutting up this old rig in Invergordon last summer
the Cromarty Harbour folk have done some nice street view imagery of the firth, e.g.

google.com/maps/@57.68775…
Read 4 tweets
Jan 13, 2023
Another very interesting recent England and Wales Census 2021 release is the passport data, so here's a map of % with no passport at MSOA level, will add a couple more below
these are all the different columns in the dataset (TS005Passports held) and the patterns are quite interesting, although I've only done a few maps as a way to explore the data

nomisweb.co.uk/sources/census…
the % with Irish passport map looks like this - probably about what I'd have expected
Read 11 tweets
Jan 6, 2023
Today's census map shows the most common housing tenure in each local authority in England and Wales 🏡
I'm working on my spelling of mortgage, probably due to the shock of seeing how many households own without a mortgage!
most common by area is of course a very first-past-the-posty representation of things but I'm interested in the pattern precisely because of this - will fix typo later, perhaps I should do by constituency too
Read 11 tweets
Jan 5, 2023
More Census age data today - a little animation of % by single year of age in each local authority. Probably needs a few watches to sink in - lots in here - but the final 10 seconds I find quite sombre, and you'll NEVER guess when lots of people leave home
and, just to go all dataviz retro, here are all the frames as small multiples
nerd note: lots of ways to make small multiples from image sets but I tend to use ImageMagick, and the image above was created using this command:

montage *.png -tile 10x10 -geometry +5+5 age-by-year.png

Once you have a set of files it only takes a few seconds to run
Read 4 tweets

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