Research in the Steiner group is focused on understanding the role of the terrestrial biosphere in atmospheric chemistry and climate. Why is the biosphere important? From the climate perspective, it can exchange energy and moisture to the atmosphere and affect the atmospheric boundary layer, clouds and precipitation. For chemistry, the terrestrial vegetation emits a large suite of gases and particles that affect atmospheric composition. Chemistry and climate processes at this interface are closely linked. We're interested in understanding the feedbacks between the atmosphere and biosphere for both chemistry and climate, and are working to answer the following questions:
How will changes in the land surface impact regional climate, and how do the spatial scales and model representations of the land surface affect climate?
What are the climatic controls on biogenic VOC emissions, and how do these affect tropospheric ozone and aerosols on interannual time scales?
How do short-lived species such as tropospheric ozone and atmospheric aerosols affect regional climate?
What will be the impacts of changing biogenic and anthropogenic emissions on regional climate?Regional Climate and the Land Surface
One area of research in the group on the parameterization of the land surface in regional climate models using the International Centre for Theoretical Physics (ICTP) Regional Climate Model (RegCM). Early work on this topic with the CLMv0 (Steiner et al., 2005) has evolved into a more complex understanding of the role of the land surface and soil moisture as a driver of regional climate. For example, improvements in the representation of soil texture and soil infiltration processes can propagate from the surface to the upper atmosphere, affecting the migration of the monsoon and key wind patterns throughout the atmosphere (Steiner et al., 2009). Graduate student papers from my research group (Tawfik and Steiner, 2011; Bryan et al., 2015) have identified key model deficiencies in simulated soil moisture and evapotranspiration and quantified their impacts on regional climate.Atmospheric Chemistry
Another research topic in the group is the role of emissions from vegetation and their impact on short-lived climate forcing agents such as tropospheric ozone and aerosols. Specifically, this includes understanding how biogenic VOC emissions and ozone formation will change under warmer climates. We study these interactions on several scales to understand the role of the biosphere in these processes, including:
1-Dimensional canopy-chemistry model to investigate the role of detailed in-canopy chemistry (Bryan et al., 2012; Ashworth et al., 2015);
Large Eddy Simulation model with Chemistry (Li et al., 2016), and
Regional atmospheric chemistry models, including CMAQ (Steiner et al., 2006, 2007, 2008), RegCM-Chem (Shalaby et al.,2008; Steiner et al., 2014), and WRF-Chem (Kawecki et al., 2016)
We compare model simulations with ground-based observations to identify key mechanisms that can alter ozone and aerosol formation in models.
We are trying to understanding processes that bridge atmospheric chemistry and climate by delving into the details of both chemical mechanisms and land surface models. One example of this cross-disciplinary work is is the role of atmospheric aerosols on surface processes, with studies that couple the role of atmospheric chemistry on surface processes such as surface energy partitioning and carbon uptake (Steiner and Chameides, 2005; Steiner et al., 2013; Cheng et al., 2015). Additionally, we are looking at the role of pollen in the atmosphere to understand its role on climate and cloud formation (Steiner et al., 2015; Wozniak and Steiner, 2017; Wozniak et al. 2018).