Evaluation

There are a myriad of analyses to be performed on the time series. Statistical evaluations of variance and trends await the time and resources to be performed. Where possible, synthetic results at individual stations should be placed on maps with results from all other stations (e.g. rates of change per decade of winter heating degree days derived from a regression analysis). As stated previously, we hope to join with scientists at the NJ Department of Environmental Protection in this phase of the project. We plan to attract students to participate in the analytic efforts as part of their undergraduate honors or master's research efforts.

While not a large state, most variables show variations in means and totals from one portion of NJ to another. Differences are a function of differences in elevation, latitude, proximity to the ocean and urbanization, as well as likely the result of microclimatic influences at particular sites. For instance, the number of days with precipitation exceeding selected thresholds is greater in the wetter north than in the south, a striking difference in the number of days with the maximum temperature failing to exceed the freezing point is observed from south to north, and there are fewer days with maximum temperatures >= 90° at coastal and higher elevation sites.

Detailed assessments of recognized statewide increases in temperature and precipitation, and the suggestion that these changes are accompanied by increases in climate variability need to be explored. One must remember to always scrutinize any observed changes in context with metadata, making sure that what is being observed is not attributable to station changes. For instance, Sussex days with minimum temperatures <= 32° increase in the middle 1950s around the time that there was a station move and a change from PM to AM observation times. There is no recognized change in the number of days at Sussex with maximum temperatures <= 32°, suggesting that the influence may be more from the observation time change rather than a move. However such a rise is not seen as prominently at other stations when they went from PM to AM observations.

Plainfield provides an example of urban warming, as seen in the rather continuous decline of heating degree days, especially during the last 50 years. Most other stations exhibit an increase in heating degree days in the 1960s and 1970s, followed by a decline, unlike the more monotonic Plainfield decrease. An increase in the number of days with minimum temperatures >= 70° is seen at the more urbanized stations, while not recognized at rural locations.

Statewide similarities are also seen for a number of variables, but often more than one outlier is recognized. For instance, the average summer maximum temperature is quite high in the 1930s and 1940s at many stations, yet shows little change at some (e.g. Hightstown) and a late 20th century maximum at others (e.g. Indian Mills).

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