Climate Change in Waikoloa, Hawaii

Spiral: A 3D helix where each loop represents one year. The radius indicates the smoothed temperature anomaly, and colors range from blue (cold) to red (warm). The top view shows the annual cycle, while the side view shows time progression.

Stripes: Each stripe represents one year's average anomaly (the mean of all monthly anomalies for that year). No additional smoothing is applied; yearly aggregation naturally reduces noise.

Color scale: Color bounds are set to the 5th and 95th percentile of anomalies to avoid outlier washout, with a neutral zone of approximately ±0.1°C.

Time of Observation Bias (TOBS)

Early cooperative weather stations typically read their min/max thermometers in the afternoon. This meant a single hot afternoon's peak temperature could be counted in two consecutive daily readings, inflating monthly maximums.

Between the 1950s and 1980s, most stations switched to morning or midnight observation times. This eliminated the warm bias but introduced a slight cool bias during the transition.

As a result, early decades in our data may read slightly warmer than they actually were, and the transition period may show an artificial cooling dip. Neither reflects actual temperature change. We use raw GSOM data without TOBS adjustments (NOAA's adjusted products like nClimDiv correct for this, but our station-level data does not).