Observations of the Arctic Stratosphere In Support of YOPP (OASIS-YOPP).
PI: Giovanni Muscari email:email@example.com
Increasing concern on the weather and climate of the Polar regions led the World Meteorological Organization to establish in 2013 a ten-year Polar Prediction Project (PPP), whose key element will be the Year Of Polar Prediction (YOPP) with intensive activities in both Polar regions from mid-2017 to mid-2019. Polar stratospheric processes impact tropospheric circulation, climate, and weather patterns. As a result, coupled chemistry climate models (CCMs) have recently improved their representation of the stratosphere and extended upwards their altitude coverage. One of the most important processes occurring in the stratosphere is the springtime final breakdown of the stratospheric polar vortices (Stratospheric Final Warming, SFW). It impacts stratospheric chemistry and transport and, by propagating downward into the troposphere, affects tropospheric circulation. The timing of yearly SFWs is critical, due to its sensitivity to stratospheric ozone in the Southern Hemisphere and its role in tropospheric predictability. In the Arctic, SFWs may follow two different patterns: they can start at around 10 hPa and then proceed upward and downward or, as it occurs in the Antarctic, SFWs can start in the lower mesosphere and progress downward with time. These two paths lead to different tropospheric pressure and temperature patterns in the following month. Both the timing and the vertical profile of Arctic SFWs can therefore be employed as predictive tools and verification parameters. SFWs occur too late in most CCMs, however, indicating that the representation of the Polar winter and springtime stratosphere still requires improvements. This opportunity driven research proposal aims at contributing to the PPP and to YOPP activities. It will contribute to two of the main PPP research goals:
- implement additional observations in the Polar regions to support the understanding of Polar processes and modeling;
- establish and apply verification methods for modeling efforts appropriate for Polar regions.
The proponents will provide daily ground-based and in situ measurements of lower and middle atmospheric chemical and physical parameters during the period of occurrence of SFWs in the Arctic, from mid-February to the end of April, for the YOPP year 2017. Measurements will be carried out from Thule (76.5°N, 68.8°W), Greenland, in a region where conventional observations supporting YOPP appear to be very scarce. In particular, this research effort can contribute to YOPP with stratospheric vertical profiles of N2O, H2O, CO, and O3, observed by means of two ground-based millimeter-wave spectrometers, temperature and pressure stratospheric vertical profiles carried out by means of a lidar system, and daily launches of radio soundings which will provide vertical profiles from the ground to 25-30 km altitude of pressure, temperature, humidity and wind. Additional useful measurements of column contents of various chemical species and ozone soundings data will be provided to the project through the collaboration with NCAR and DMI. The observed chemical species act as tracers at various levels of the Polar stratosphere. The use of vertical profiles and column contents of chemical species and stratospheric temperature profiles, as well as radio sounding data which are otherwise absent in a radius of more than 500 km around Thule, will provide highly resolved measurements, from the lower stratosphere to the mesosphere, of a SFW in the Arctic and will be used by the proponents and by the whole PPP community to verify CCMs prediction of the timing and the vertical profile of SFWs. The produced data will also contribute to the improvement of CCMs description of processes occurring in the winter and springtime Polar stratosphere. Although the campaigns are carried out in the Arctic, where the instrumentation is already set up (making the campaigns cost efficient), this contribution to the PPP has a clear impact on both Polar regions.
This proposal focuses on providing the Polar Prediction Project with a set of atmospheric observations in a region, north-western Greenland, where measurements during YOPP are otherwise very scarce. We plan to carry out measurements of middle atmospheric tracers and temperature (the latter will be available as long as a few hours of dusk take place), and radio sounding launches during one intensive spring field campaign at Thule, in 2017. This will require:
- upgrading some of the existing instrumentation;
- activate a radio sounding launching program at the NDACC station of Thule.
The improvement and upgrade of instruments dedicated to the polar regions and the increase of observational data are
among the main goals of PPP.
These data sets at Thule will provide highly resolved measurements of a SFW in the Arctic and will be used by the proponents and by the whole PPP community to verify CCMs prediction of the timing and the vertical profile of the SFW, a third objective of the proposal which once again matches a goal of the PPP. The produced data will be made available to the PPP community in order to help assessing CCMs prediction capabilities and contribute to the improvement of their parameterization of processes occurring in the winter and springtime Polar stratosphere. Although the campaign is carried out in the Arctic, where the instrumentation is already set up (making the campaigns cost efficient), this contribution to the PPP has a clear impact on both Polar regions.
An additional objective of this proposal is the comparison of radio sounding data with meteorological reanalyses, in order to evaluate the capabilities of reanalyses to describe correctly the status of the atmosphere over the region around Thule.
This research effort will strengthen the Italian role within the international Polar community.