CYGNSS Wind Speed and Surface Heat Flux Observations of Low-Latitude Extratropical Cyclones and Fronts

While the synoptic-scale dynamics and evolution of extratropical cyclones (ETCs) have been well known for more than a century, questions remain unanswered regarding how changes in cyclone environment and circulation relate to variations to the vertical structure and horizontal distribution of clouds and precipitation. There are also questions as to how surface-atmosphere exchange processes, especially over the ocean where observations can be limited, relate to ETC development. Observations of surface processes within marine-based ETCs from existing in-situ and spaceborne instruments can be limited, with insufficient spatial and temporal resolution. Additionally, the presence of preciptation and clouds obscure the ocean surface around ETCs, limiting the ability of many remote sensing instruments to observe the surface processes in developing ETCs.

Though it is a tropical-oriented mission, pre-launch investigations indicated that the Cyclone Global Navigation Satellite System (CYGNSS) can observe surface winds in a significant number of low-latitude extratropical cyclones and fronts, possibly aiding in our understanding of surface process’s role in cyclogenesis and evolution at lower latitudes. By using CYGNSS’s surface wind speed observations, as well as the new CYGNSS Surface Heat Flux Product, we can better understand how ETCs develop and evolve in the lower-latitudes.

This presentation will focus on a statistical analysis of CYGNSS’s wind speed and surface heat fluxes around cold and warm fronts, as well as in the regions near ETC centers. MERRA-2 reanalysis data is used for comparison to CYGNSS observations as a tool to discuss the respective strengths and limitations of both datasets. Finally, preliminary work on the relations between CYGNSS surface fluxes and ETC genesis and evolution will be presented, complementing previous modelling studies.