OSIRIS data helps to unravel complex behaviour of ozone layer recovery

After decades of depletion in the 20th century, near-global ozone now shows clear signs of recovery in the upper stratosphere.  In the tropical lower stratosphere, ozone is expected to decrease as a consequence of enhanced upwelling driven by increasing greenhouse gas concentrations, and this is consistent with observations. There is recent evidence, however, that mid-latitude ozone continues to decrease as well, contrary to model predictions. We use OSIRIS ozone profile measurements to show that these differences might be related to changes in atmospheric circulation. 

OSIRIS provides a new view of NOx in the Asian Summer Monsoon

Deep convection within the Asian summer monsoon (ASM) transports surface level air into the upper troposphere-lower stratosphere (UTLS). We use the long record of OSIRIS data to reveal a new understanding of the distribution of NOx in the lower stratosphere in the region of the ASM.  These results largely agree with climate model simulations. 

Increased wildfires may slow recovery of Earth's ozone layer

A new study reveals that an expected increase in wildfires due to climate change may lead to chemical reactions that cause destruction of the Earth’s protective ozone layer and slow its ability to recover. As global warming continues, it is likely that the scale and frequency of wildfires will increase, raising questions about how this will impact the planet’s protective ozone layer over time.

2020 Arctic Ozone Hole is Largest Ever Observed

The largest recorded ozone layer hole over the Arctic has been detected by the OSIRIS instrument. Normally, holes of this magnitude form only over the South Pole, as the conditions required to form an ozone hole over the North Pole are rare. The last hole to form over the North Pole was in 2011.

A stable polar vortex formed this year over the North Pole, which allowed the ozone-depleting CFCs to reduce the region's ozone layer without being dissipated by the surrounding atmosphere.

Figure 1 shows ten days of OSIRIS measurements over mid-March at various altitudes. The hole is apparent, especially when compared to all of the March 2018 measurements shown in Figure 2, which represent typical values.

Figure 3 shows OSIRIS ozone profiles from different areas around the Pole, some profiles inside the ozone hole region and others outside for comparison.

Figure 1: The 2020 Northern Ozone Hole. Scatterplot of OSIRIS ozone number density measurements from March 10 to March 20. Compared to 2008 (a typical year) the measurements are very low (cf. Figure 2).
Figure 2: A scatterplot of typical March ozone number density over the North Pole. There are more data points as this plots all the data from March 1 to 31.
Figure 3: A selection of ozone profiles measured by OSIRIS inside and outside of the 2020 North Pole ozone hole. The ozone values are very low around 20km where they should be at their peak value.