https://www.medrxiv.org/content/10.1101/2020.03.09.20033217v2.full.pdf
Specifically "Both viruses exhibited exponential decay in virus titer across all experimental conditions". See the graphs on the last page for different surface types.
I have seen one source indicating that specifically on copper, there was a delay of half an hour or so followed by a rapid decline. I have also seen another source indicating that the effectiveness of sunlight in shortening the halflife declines with time. Wish I could find them...
There seem to be some pretty solid numbers on how long coronavirus will last on a given surface. But I’m curious what the curve looks like. Does it decay at a constant rate, like a radioactive substance? Or does it behave more like a group of animals denied food, where the population survives relatively intact for a while before hitting a point of rapid decay? I’m trying to evaluate the effectiveness of leaving things to sit for e.g. 24h if I can’t disinfect them and can’t wait the full recommended time.