CYGNSS Estimates of Surface Heat Fluxes

The Cyclone Global Navigation Satellite System (CYGNSS) was launched on 15 December 2016 with a mission to improve surface wind speed estimates within the core of tropical cyclones. While CYGNSS’s core mission focuses on the tropical and sub-tropical oceans, its orbit and observations can range as high as 40° in both hemispheres, allowing it to observe extratropical cyclones that form and develop in the lower latitudes. These cyclones that form in the lower latitudes can derive their energy and moisture from strong latent and sensible heat fluxes at the surface. These fluxes, driven by surface winds and strong vertical gradients of temperature and water vapor, can increase the instability within the boundary layer and contribute to rapid cyclogenesis.

It is challenging to estimate surface sensible and latent heat fluxes from spaceborne instruments, as these fluxes cannot be directly measured from space. While components of surface heat fluxes can be estimated with various remote sensing instruments, deficiencies in spatial coverage and attenuation from clouds and precipitation can lead to inaccurate measurements of these components, thus leading to inaccurate estimates of surface heat fluxes. Though CYGNSS only contributes surface wind speed measurements, we can combine these improved wind speed observations with other reanalysis and satellite data to improve estimates of surface sensible and latent heat flux. These improved surface heat flux estimates can be used to better understand and observe the role of these fluxes in extratropical cyclogenesis. Additionally, these improved surface heat flux estimates can be applied to the entire CYGNSS mission for other tropical meteorology and climate applications.