Maps and models

This spectacular map from the National Geospatial-Intelligence Agency was circulating yesterday on Twitter. I got it from Christopher Jackson (@seis_matters). It shows antineutrino emissions from around the earth

Our local (sub)continent of Zealandia shows up nicely at the bottom right. The black dots are nuclear reactors, and the dark smudge is just the immense rock mass of the Himalayas.

This next map is a style you’ve seen before. It shows New Zealand’s winds at the moment: the storm is passing over.

What these maps have in common is a very high ratio of model to actual data.  The `live’ wind map isn’t based on detailed live reports from a fine grid of weather stations. There aren’t any — especially out in the Pacific. It’s a map of the NOAA Global Forecast System, but forecasting the very near future rather than the long range. It isn’t going to give you more up-to-date information than the Met Service.

The antineutrino map is even more model-based. In the scientific paper I was struck by the sentence

Recently, the blossoming field of neutrino geoscience, first proposed by Eder¹⁵, has become a reality with 130 observed geoneutrino interactions^12,13 confirming Kobayashi’s view of the Earth being a “neutrino star”¹⁶. 

It looks like the map has well over a million pixels per observed geophysical neutrino. When it comes to nuclear reactors, the paper says “These exciting geophysical capabilities have significant overlap with the non-proliferation community where remote monitoring of antineutrinos emanating from nuclear reactors is being seriously considered“. That is, the reactors are black dots on the map because they know where the reactors are and how many neutrinos they’d make, not because they measured them. The observations do go into the model, and they probably provide actual information about the deeper bits of the earth’s crust, but the map is of the model, not the observaations.