Centennial scale warming over Japan: are the rural stations really rural?

In this study, we used two novel methods to estimate urban contamination in the Japanese temperature record of the last century. First, we tested different criteria for choosing the rural stations, and found little sensitivity to the method, though the presence of a decreasing local population trend appeared to be a useful indicator. Second, we investigated the relationship between the regional sea surface temperature (SST) and surface air temperature over land, and found a very strong relationship across the coupled model intercomparison project phase 3 multi-model ensemble. Applying this relationship to observational SST data indicates little or no contamination of the trends from the stations identified as rural.