I understand that they've been using data collected by satellites since 1979, but they didn't even come up with the model until 99, and released the paper on it

I understand that they've been using data collected by satellites since 1979, but they didn't even come up with the model until 99, and released the paper on it in 2003, so the model was used retrospectively on data previously collected, not specifically collected for that project. You can see that in your own link.