Historical Air Temperatures Across the Hawaiian Islands

Abstract:

This study focuses on an analysis of daily temperature from over 290 ground-based stations across the Hawaiian Islands from 1905-2015. Data from multiple stations were used to model environmental lapse rates by fitting linear regressions of mean daily T_max and T_min on altitude; piecewise regressions were also used to model the discontinuity introduced by the trade wind inversion near 2150m. Resulting time series of both model coefficients and lapse rates indicate increasing air temperatures near sea level (T_max: 0.09°C·decade^-1 and T_min: 0.23°C·decade^-1 over the most recent 65 years). Evaluation of lapse rates during this period suggest T_max lapse rates (~0.6°C·100m^-1) are decreasing by 0.006°C·100m^-1decade^-1 due to rapid high elevation warming while T_min lapse rates (~0.8°C·100m^-1) are increasing by 0.002°C·100m^-1decade^-1 due to the stronger increase in T_min at sea level versus at high elevation. Over the 110 year period, temperatures tend to vary coherently with the PDO index. Our analysis verifies warming trends and temperature variability identified earlier by analysis of selected index stations. This method also provides temperature time series we propose are more robust to station inhomogeneities.