Tropical Gravity Waves and Latent Heating: Making the Invisible Visible

Northwest Research Associates, Incorporated, Seattle WA

Investigators

Abstract

The research will involve a synergistic use of gravity wave, precipitation, and cloud observations together with local-area models for new constraints on convective updraft-scale latent heating and wave drag on circulation. Gravity waves surrounding convective clouds are complex, three-dimensional, time-varying phenomena. Through application of two specially designed regional model tools together with available observations, the research can make the invisible features of both the latent heating and the waves visible. The project focuses on applying this new knowledge to the problem of subgrid-scale gravity wave drag for global climate prediction and weather forecasting. Gravity wave resolving models that have been observationally validated indicate that the scales and propagation of gravity waves emitted from convective clouds carry the signature of the four-dimensional properties of the localized, rapid variations in latent heating inside the clouds. The team will examine the following two hypotheses: (1) Observations of gravity waves and precipitation constrain the local, instantaneous properties of latent heating inside convective clouds; and (2) Knowledge of the latent heating can be used to construct the missing features of the wave field needed to accurately assess their remote effects on circulation. Tropical gravity wave drag is the leading force driving the quasibiennial oscillation (QBO) in lower stratospheric winds, which itself is a leading factor in Northern Hemisphere wintertime seasonal and interannual climate predictability and tropical intraseasonal and interannual precipitation predictability. The knowledge of gravity waves gained from this project will provide a clear picture of the gravity wave momentum flux variability and relation to convective clouds, which will permit more accurate predictions and future climate projections. The research will have substantial scientific and societal impacts. These include: (a) forecasting clear air turbulence felt by aircraft; (b) early warning of hurricane intensification over remote ocean areas; (c) improving tropical weather forecast skill; (d) nonmigrating tidal influences on middle atmosphere winds; and (e) forecasting ionospheric disturbances and communication channel disruptions. The project will provide training to an early career scientist. The project would also support a female PI, a member of an under-represented group in STEM research. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.