Ozone Loss

==========

Shown here is the chemical ozone loss in northern winter as well its

effects on mid latitudes in Europe.  For example, in winter 2010/2011

there was a very high ozone depletion in the area of the Arctic polar

vortex. In the frame of the `Knowledge Platform "Earth and Environment" (ESKP)`_

the effects this ozone loss at mid latitudes are explained and

documented on a daily basis.  An early warning system for such events

is thus established.  The basis is simulations with the Jülich

chemical transport model `CLaMS`_, which uses innovative transport and

mixing algorithms to calculation of the exchange of air masses between

polar and mid Latitudes (e.g. interference of low-ozone air in

Europe). The realistic simulations are initialized by satellite

observations and driven by ECMWF meteorological analyzes.

The ozone depletion in the polar vortex is determined by the

temperature.  For polar ozone loss, the temperature must drop below a

threshold of approximately -78°C. For the Arctic winters of 2010-2020

the `Calculations of ozone loss`_ and `Estimates from temperature`_

are shown.  To explain and assess the results, it is also explained

how the `UV increase`_ on the ground develops in the course of spring

for the case of different ozone losses.  Calculated ozone loss and

ozone column as well as the calculated from it maximum UV index (at

noon with a clear sky) are considered `Map display`_ shown for the

individual days.

Typically, the ozone columns in the Arctic are still higher than in

the Antarctic despite ozone depletion, so that in the Arctic spring

there is so far at most a moderate UV radiation at the ground.

Current

--------

The calculations **for the current winter 2019/2020** show so far

somewhat above average ozone depletion. Towards the end of January

the stratospheric Temperatures are very low, i.e. high ozone depletion

could follow if the polar vortex remains stable.

Previous years

--------------

Last winter 2018/2019 the stratospheric temperatures were too high for

significant chlorine-catalyzed ozone depletion.  A so-called "major

warming" in early January led to the warming the stratosphere to split

off a part of the polar vortex.

In recent years, Winter 2010/2011 and 2015/2016 were particularly

noteworthy, as they were characterized by a cold, stable polar vortex,

which with clear corresponding ozone depletion. This yielded only a

slight increase in UV radiation, which is typically low in our

latitudes in March.  Extremely high UV values ​​like in the Antarctic

spring under the ozone hole did not occur so far in the Arctic.

Winter 2015/2016:

-----------------

The stratospheric temperatures in winter 2015/2016 were as low as

never seen in recent decades before with the result of a very high

ozone loss of over 100 DU.  The lower ozone columns resulted in a

slight increase in UV radiation on the ground. However, the UV

radiation is in these latitudes is low at this time of year. When

these air masses of the polar vortex moved towards mid-latitudes, the

UV index in early March is as high as normally expected in late

March. Extremely high UV values ​​as in the Antarctic spring under the

ozone hole did not yet occur in the Arctic.

Winter 2010/2011:

-----------------

The images below show the geographical distribution of the calculated

ozone column (top) and ozone loss (bottom) for March 28, 2011. Shown

is the total column between 12 and 22 km altitude in Dobson Units (DU).

.. _Calculations of ozone loss: /ozoneloss/clams/2020

.. _Estimates from temperature: /ozoneloss/vpsc/2020

.. _UV increase: /ozoneloss/uvi

.. _Map display: /ozoneloss/uvmap/200119

.. _Knowledge Platform "Earth and Environment" (ESKP): /eskp

.. _CLaMS: http://en.wikipedia.org/wiki/CLaMS