3-year trends to April 2015

Parametric plots of smoothed climate variables at Manilla
“April 2015: equable”

Trends to April 2015

  April raw anomaly data (orange)

In April, daily maximum temperature anomaly became very low (-2.1°) while daily minimum temperature anomaly remained high (+0.7°). Other anomalies, except subsoil temperature, moved down the graphs, showing moist conditions. The extremely low temperature range anomaly (-3.0°) shows that the climate was equable, as it had been in the spring of 2010 (a smoothed record value).

Fully smoothed data (red)

The latest fully-smoothed data anomalies (October 2014) moved little, being warm and slightly dry.

Loops in the subsoil anomaly graph

The parametric plot of subsoil temperature anomaly against that of daily maximum temperature (bottom right) shows several clockwise loops. That is, peaks or troughs of subsoil temperature precede those of daily maximum (air) temperature by a month or more. This is not what one would expect. Indeed, where graphs of these variables earlier in this sixteen-year record show such loops, they are always anti-clockwise. Subsoil temperature anmalies lag those of daily maximum air temperature. See the graphs for August 2002, August 2004, August 2006, August 2008, May 2010, and April 2012.

In the last mentioned graph, the three extreme points included show no lag between the two variables. That period, from early 2009 to late 2011 marks the transition from a stable regime of subsoil temperature lagging daily maximum air temperature to the current regime of subsoil temperature leading daily maximum air temperature.


Fully smoothed data – Gaussian smoothing with half-width 6 months – are plotted in red, partly smoothed data uncoloured, and raw data for the last data point in orange. January data points are marked by squares.
Blue diamonds and the dashed blue rectangle show the extreme values in the fully smoothed data record since September 1999.

Normal values are based on averages for the decade from March 1999.* They appear on these graphs as a turquoise (turquoise) circle at the origin (0,0). A range of anomalies called “normal” is shown by a dashed rectangle in aqua (aqua). For values in degrees, the assigned normal range is +/-0.7°; for cloudiness, +/-7%; for monthly rainfall, +/-14 mm.

 * Normal values for rainfall are based on averages for the 125 years beginning 1883.

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