Dearth of data

... or is that one 'r' too many?

More about the final slide from my talk at Brisbane. But before I start, I thought I should mention that my prediction of an early demise of this year’s ozone hole may have been premature. It has continued to weaken, but it’s less distorted now, so is still alive and kicking.

As I mentioned in an earlier substack, satellite measurements unfortunately still can’t capture the effects of absorbing aerosols, so tend to overestimate UV in polluted places, including most of the northern hemisphere.

So, we’re left with ground-based measurements. Recent evidence doesn’t bode well for their continuation. It’s the availability of long-term UV data at currently pristine sites that will be the most valuable in future because it’s only there that we have a baseline against which further changes can be measured. High quality measurements of UV are also needed in Asia, especially in China, where future effects of climate change on clouds and aerosols are potentially large, but highly uncertain.

Instruments to measure UV accurately are expensive to buy and even more expensive to maintain for long periods. Finding somebody to pay for this future knowledge is a big problem. Funders need instant gratification for their dollars. And we’re not alone. It’s the same problem as averting climate change. Short-term governments have short-term goals to help them get re-elected.

I fervently hope we’ll still have the measurement capability to capture UV changes in the decades ahead. Sadly, the prospects for that don’t look good.

For the last two decades, NIWA received funding from Australia’s Bureau of Meteorology to maintain calibration for state-of-the-art UV measurement systems in Melbourne and Alice Springs. But, despite my best efforts, the plug has been pulled on that funding, and those invaluable long time series have been discontinued - at least for now. It’s a huge shame because you only get one opportunity to measure in real time. The measurements at Alice Springs will be specially missed. The site is representative of a huge geographical area, and measurements have been available for long enough to establish a good baseline. Being affected by desert dust, it’s not the cleanest site in the world, but at least the aerosols are natural rather than man-made.

Alice Springs is one of a scarily small number of worldwide sites that report UV data to the Network for the Detection of Atmospheric Composition Change (NDACC). As you can see from the map below, the network comprises only a small number of sites, of which very few are in the southern hemisphere. The colours represent 5 broad regions: Arctic (black), Northern mid-latitude (blue), Equatorial (red), southern mid-latitude (green), and Antarctic (purple). And not all of them have the capability of measuring UV. In a paper we wrote 5 years ago, where we showed that UV hasn’t increased since the turn of the century and is now decreasing at some sites, there were fewer than 20 NDACC sites with long term data suitable for the trend analysis. Of those, only 5 (now 4) were in the southern hemisphere. The northern hemisphere had the remainder, though two of those (Summit and Thule) have since been discontinued.

The other main UV data repository is the World Ozone and UV Data Centre (WOUDC) in Toronto. The map below shows that number of sites that contribute UV data is also small. Again, especially for the southern hemisphere.

Similarly, as shown below, the amount of data being archived at the WOUDC has also diminished alarmingly in recent years, after an all-too-brief spurt of interest around the turn of the century.

This is all especially concerning. I don’t think the AI beacon of hope will be able to fill the gap, because our future atmosphere won’t mirror that in the past (so any ‘learnings’ will have to be revised). Perhaps RI (real intelligence) will have to suffice instead?

Satellite measurements don’t currently have the capability of accurately measuring surface UV amounts, especially under cloud and in aerosol-affected regions. It’s difficult. I doubt if they’ll ever be able to match the capabilities of the vanishing ground-based measurements (though, as a scientist, I should never say never).

It looks like we’ll be running blind, in uncharted waters.

If any of you have the interest and money to help solve this problem by funding the operation of one of our research-grade UV spectrometers at a site of your choice - but preferably in Australia or China - please let me know. I’m all ears.