Thanks for providing the reference.
Another term for "inferred" is "manufactured" and your reference was of no help. It contained between 8 and 9 data points from primarily 1992 until 2000. They are claiming that their data goes from 1990 until 2002, but only 4 of their 16 datasets includes 1990 and 2002. They also claim that they have data from 1960 through to 1990, but do not bother to provide that data or make any reference to that dataset. I looked up the papers references. They also make assumptions without supporting evidence. Such as:
Aerosols, Climate, and the Hydrological Cycle - Science, Volume 294, Pages 2119-2124 (2001)
They don't waste any time. The above paper comes right out and blames humans for all aerosols in the atmosphere, without providing any data to support their allegations. They completely ignore volcanic or other natural sources and just blame humans for absolutely everything. That isn't science either.
Or they have absolutely nothing to do with aerosols at all, such as:
Is the Hydrological Cycle Accelerating? - Science, Volume 298, Pages 1345-1346 (2002)
What does hydrology have to do with changes in solar radiation?
I often find that this is the case with bogus papers. They make all kinds of references, most of which have absolutely nothing to do with their paper. It is just another kind of fraud. Which is why I always check the references in any paper.
Furthermore, when you examine the minimal data that they do provide, you quickly discover that they only had between 8 and 9 data points during the entire 1990s, or one data point for an entire year. While they do distinguish between clear-skies and cloudy conditions, you still need more than one recorded data point per year. The readings from Barrow, Alaska, begin in 1993 and end in 2001 with only 9 recordings, for example. They do not include any dates for when this data was recorded. Presumably they took those readings sometime after January and before November, because the sun would not be shining otherwise, but they don't bother to say either way.
I cannot take this seriously with such minimal information. Nine recorded data points in an eight year period, with no metadata to show when the data was recorded, cannot be taken seriously. The deviation of just 3 W/m² over that 8 year period from 1993 until 2001 can be easily explained by the Pinatubo eruption of 1991. Of course those SO2 aerosols were not man-made (they were also not on the surface) so they immediately tossed out that possibility and began to manufacture one where humans were entirely to blame.
It does not matter how accurate their readings are, if they only take one reading per year in each location, and don't even bother recording when during that year they took the reading, then it is garbage and utterly meaningless data. So I am guessing that there has to be more than the spotty data they claim to have collected. Are they selectively choosing which data points to publish? Where is the actual data? Not even you know, or you would have provided it.