Remedy 1: Expand coverage of differential absorption lidars to improve ability to characterise tropospheric ozone

An increase in data on tropospheric ozone is expected from various space-borne platforms with increased capabilities, such as OMPS, TES and TROPOMI and the instruments proposed for Sentinel 4 and 5. However, a reinforcement of the ground based observational capacity is also required to validate these space-borne observations and establish high-quality time series. An increase in the number of ozone balloon borne soundings is not likely due to the high costs involved (material and personnel). There is a potential for tropospheric ozone lidars (using the differential absorption lidar technique) to fill this gap. In the US, a network of tropospheric ozone lidars has been established (TOLNET). Similar initiatives could be pursued in Europe, where a latent tropospheric ozone lidar network could be revived. In Europe, such a network might become part of ACTRIS, the European Research Infrastructure which deals with short-lived greenhouse agents. Similar efforts are required in other areas of the globe to enable full characterisation of tropospheric ozone capabilities by future satellite missions.