Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder

John J. Cassano

Research Interests

My research group studies the weather and climate of the polar regions to better understand the processes that link the atmosphere to the underlying ocean, sea ice, ice sheet and land surfaces. We conduct field work in both polar regions and deploy automatic weather stations and unmanned aerial systems (UAS) to observe the polar atmospheric boundary layer. We use satellite and reanalysis data and output from weather and climate models to provide a broader perspective than is possible with our in-situ observations alone. We synthesize our understanding of polar climate through the application of regional climate models in our research.

Current Research

Our group’s observational activities in the polar regions focus on the atmospheric boundary layer. In the Antarctic we deploy automatic weather stations as well as instrumented towers to observe the near-surface atmospheric state. The use of UAS allows us to observe a greater depth of the atmosphere than is possible with ground-based in-situ observations alone. Taken together the surface based and UAS observations provide us with data over the entire depth of the boundary layer - the portion of the atmosphere that directly interacts with the underlying surface. We have led or taken part in 6 UAS field campaigns in the Antarctic since 2009 including several late winter campaigns. Currently our Antarctic research is focused in West Antarctica where the largest ice sheet warming on the continent has been observed over the past several decades.

In 2020 our group will take part in the largest Arctic field campaign ever - the Multi-disciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC). During the MOSAiC campaign the German Polarstern icebreaker will be frozen into the Arctic sea ice and drift across the Arctic for an entire year. More than 300 scientists from 17 nations will make measurements of the atmosphere, ocean, sea ice, and biogeochemistry of the central Arctic. Our group will conduct hundreds of UAS flights, from late winter to summer, to provide high time and space resolution observations of the atmospheric boundary layer. The data that we collect will be one piece of a comprehensive dataset for understand the physical processes that shape the Arctic climate system.

Our larger-scale studies of the polar climate system, using reanalysis data and climate modeling, currently focuses on the role of storms and other high impact weather events on the coupled climate system. We are developing a comprehensive database of Arctic cyclones in several atmospheric reanalysis products as well as from the Regional Arctic System Model (RASM) to determine how cyclones of varying intensity impact Arctic sea ice as they traverse thick and thin ice and areas of open water, low and high ice concentration. Evidence suggests that episodic events, such as individual storms, can have a large impact on sea ice loss and our study seeks to gain insights into the physical processes that are most critical for modulating storm - ice interactions.



Small Unmanned Meteorological Observer (SUMO) circling over the Antarctic ice sheet near McMurdo Station during late winter 2016. Photo: John Cassano

Projected drift track of the Polarstern during the MOSAiC field campaign from September 2019 to October 2020. Courtesy: https://www.mosaic-expedition.org/

Path of cyclones identified in ERA-I reanalysis for January 2012. Photo: Elizabeth Cassano