Vindeln station in northern Sweden reported a similar story with measurements showing a reading of 437 dobson units, 11 more units than Norrköping and a record there since the first measurements were taken in 1991.
The ”Dobson unit” or DU, named after the British scientist G.M.B. Dobson, indicates how much ozone there is in the air above a certain point on Earth.
In a statement, SMHI said: ”We have to go as far back to the measurements taken in Uppsala between 1951 and 1966 to find levels that high.” In Uppsala, the highest level for February was back in 1957, when a value of 439 DU was recorded.
Over the Earth’s surface, the ozone layer’s average thickness is about 300 Dobson Units. That’s a layer that is 3 millimeters thick. So in these days of thinning ozone layers, does this mean that the ozone is improving in general? The Swedish weather service, which only last year recorded the second thinnest levels of ozone ever, says that it was too early to tell.
SMHI says ”We would need to see more high values before we can say with certainty that the ozone layer is growing thicker. However we are now in a period where the decrease appears to have halted and we expect to see a thickening.”
The reason for the thickening of the ozone during February was attributed to the low temperatures which normally cause a rapid depletion of the ozone layer. Well they weren’t there because the high pressure column of cold air from the Arctic which develops during the long polar night disappeared very quickly in mid-January.
The ozone layer over Sweden usually reaches its thickest level during the spring, before thinning during the Summer and reaching a minimum during the winter.