The current estimates are produced by analyzing a range of variables like rainfall, temperature and evaporation.

BBC: Predicting the next big flood

In Israel, Solaris Synergy has developed a concentrated photovoltaic technology for a floating farm, which includes an innovative evaporation cooling technology called Aquasun that keeps the silicon elements at a low and stable temperature.

FORBES: Napa Winery Pioneers Solar Floatovoltaics

As with the earlier paper that showed that offshore windmills will lower the air temperature around them by 1 degree or so: I assume from that same mixing increasing the evaporation rate of the sea water.

FORBES: Wind Farms Cause Global Warming!