Our group started around year 2000 under the direction of Prof. Emiliano Hernández, who is now retired and facing more difficult challenges. Climate variability at different temporal and spatial scales has always been our focus of interest. The research activity of STREAM is organized around five main topics: climate reconstruction in the last 500 years, tropospheric climate variability, dynamics of the middle atmosphere, extreme events and atmospheric composition.
The analysis of documentary sources is our main tool for climate reconstruction. We have worked with documents from different archives in Spain, Europa and S America. This has allowed us to recover early instrumental data from Spain, build precipitation and drought proxies for Spain from rogation ceremonies and tax records and identify extreme events such as hurricanes in the Caribbean and ENSO episodes in Northern Peru, where we have produced a new chronology. Our work within the CLIWOC project has been pioneer in the analysis of historical logbooks. Methods and data derived for this project have contributed to new SLP reconstructions over the Euro-Mediterranean region and the reanalysis of different extreme events.
Regarding tropospheric climate variability, we have invested a significant effort in producing algorithms capable of characterizing synoptic weather and climate patterns, mainly blockings, and including cut-off lows or jets. With this background we have produced new climatologies, which have allowed analyzing different questions. How low-frequency patterns, such as NAO or solar activity, impact on the system variability? Which is their effect on surface climate? Do they play a role in seasonal predictability? The results obtained have fed other research lines. Thus, we have analyzed how blockings impact on NH ozone mini-holes or how they can act as precursors of SSWs (Stratospheric Sudden Warmings).
Our research of the middle atmosphere dynamics is based on the analysis of simulations derived from climate models with high resolution in the stratosphere, in particular we have experience using the Whole Atmosphere Community Climate Model, WACCM (developed at NCAR) and the Middle Atmosphere version of the European Center Hamburg Model MAECHAM (developed at MPI). Here we have focused on understanding pathways for troposphere-stratosphere interactions, such as the impact of ENSO in the stratosphere, its interaction with the QBO and how they can modulate the polar vortex and the frequency of SSWs. We have also investigated changes in the intensity of the stratospheric circulation, or ozone distribution under climate change scenarios. Currently, we are interested in downward propagation of stratospheric signals and their impact in tropospheric climate.
Heat and cold waves and droughts are the events which have attracted our attention as extreme weather events. We have analyzed them from different perspectives such as the underlying dynamics, the changes in their frequency, even from the palaeo perspective and their impacts, especially on human health.
Finally, we investigate the role of atmospheric circulation on atmospheric composition. Currently our main focus is on understanding the effect that mid-latitude synoptic scale weather systems exert on the surface concentrations of air pollutants such as ozone (O3) and particulate matter (PM).