Once again, because of your bias 'blindly' believing they are infallible instruments, you miss my key points about SQM limitations - even from your own posted reference papers author in his last sentence of his review.
"They offerl little meaningful spatial resolution in most applications, making them generally unsuitable for monitoring the behavior of light domes near the horizon. Lastly, there are differences among commercially available devices in terms of photometric passbands that complicate comparison of results among different device types." I've added the bold and underlines so no one misses the points.
In other words comparing their data to a satellite' broad spatial data - the topic of this OP - is comparing apples to oranges, especially for monitoring change of LP through time. Thanks for making my point with that paper. It is unfortunate most amateurs can't afford the other types he goes on to review in the paper. Clear, dark skies. Do the best with what you have. But don't pretend its more than what it is.
On the contrary, I made sure to include the limitations of the SQM as noted in the article so the reader would have a better understanding of the issue. Of course, most amateurs don't monitor light pollution domes at the horizon and the sqmL model would obviate that anyway since it has a narrow field compared to the standard sqm, either of which is readily available toa potential user.
And, of course, the SQM is not going to have the same spatial resolution as an orbiting satellite and I can't imagine someone assuming that it would.
That said, there's an analogous situation between the satellites and the sqm since their present predicament is essentially the same. Most satellites monitoring light pollution are functioning just fine but aren't providing desired data. What has changed is the lighting technologies in the last decade or so with the advent of widespread LED installations in the cities and towns that didn't have as much or any when the satellites were launched. If the LED sources were suddenly shut off, the recorded data would be accurate. Similarity, if the sqm is utilized under a dark sky environment without LED interference, as reportedly found in bortle 1 and 2 skies, then the data is accurate, too.
Of course, newer satellites are being modified to launch with the capability to monitor the spectral response of LED installations. Various experiments involving detectors, filters, photometers and the like have been conducted to help solve the problem. Likewise, on a lessor and far more simplistic approach, amateurs can experiment with their sqms and filter replacements as noted by unihedron.
