Ensemble spread of trial fields

Every 6 hours, we compute the standard deviation, in Celsius, from the 96 trial fields used in the assimilation cycles of the temperature at a level at approximately 5 km of altitude. Where the standard deviation of the trial fields is large, the uncertainty is large. It is important to have good observations for these uncertain areas. One might target additional observations to such areas to try to diminish the uncertainty. On the map below, the mean of the 96 trial fields is shown by black solid lines at every 5 degrees Celsius. The standard deviation of the trial fields around the mean is displayed in colour on the same chart.