An important source of error in numerical model forecasts is believed to be linked to the various parameterized diabatic processes. Past research efforts have largely focused on warm conveyer belt dynamics in both mid-latitude baroclinic maritime cyclones and tropical cyclones undergoing extra-tropical transition. The majority of theoretical development and research in this area focused on dry atmospheric dynamics – however, this effort will advance our understanding beyond dry adiabatic potential vorticity arguments into moist thermodynamic processes. Potential vorticity advection and hydrostatic development largely address propagation phase speed while considering non-hydrostatic moist diabatic and multi-scale processes are essential to understanding storm intensity and effects such as gale and storm force winds, precipitation rate and flooding, and other hazardous weather phenomena. Recently, there is increased interest in characterization and predictability of atmospheric rivers – long, narrow streams of meridional and poleward moisture transport. Although the source regions for enhanced atmospheric moisture have been observed in microwave imagery, from a predictive perspective very little research has gone into the air-sea flux and transport processes leading to the “headwaters” of these features. Enhanced moisture plume–waveguide interactions are tied to a variety of disturbances, including Fall/Winter explosive cyclogenesis over western boundary currents, Summer/Fall transitioning tropical cyclones (TCs), Predecessor Rain Events (PRE) ahead of TCs, maritime deepening of extratropical cyclones, and diabatic Rossby vortices. Each of these interactions may strongly modify the PV waveguide and the role of ocean boundary currents and mesoscale features and variability on intensification in otherwise similar events has had minimal attention.
This DRI intends to increase our understanding of the physical processes associated with air-sea interaction and diabatic amplification (in which energy is transported through latent heating due to water vapor transport) that perturb the waveguide along sloping mid-latitude fronts interacting with warm water vapor reservoirs in the tropics, which in turn leads to strong baroclinic development in maritime midlatitude storms and additionally can launch deep propagating Rossby and gravity waves into the stratosphere. In particular, ONR will contribute to a large, multi-agency and international effort to better understand the role of ocean surface variability and vertical or slant-wise transport of moisture into the warm conveyer belt region of mid-latitude maritime cyclogenesis and decay by focusing on upstream development in atmospheric river source regions. It is anticipated that collaborative efforts will include a sea-based observational perspective, multi-modal air and space based profiles, and unique moist dynamics sensitivity analysis and predictability modeling studies.
Objective
The basic premise of the SAFARI DRI and collaborating projects is that, although significant improvement has been made in the average forecast skill of operational numerical ocean and weather prediction models, systematic errors continue, and that instances of extreme forecast failures or forecast “busts” do occur. Recent publications show that these skill drops are often associated with Rossby-wave breaking or waveguide perturbations in the midlatitudes waveguide that are initiated far upstream by under-resolved or poorly represented convection that results in upscale energy transfer. The resulting wave packets travel significantly faster than the mean flow. The dynamic processes we seek to understand are further affected by enhanced baroclinicity and enthalpy flux associated with air-sea processes and upper ocean temperature structure and variability. The SAFARI DRI will participate in and coordinate with the dynamic process studies and specifically focus on processes associated with maritime enthalpy flux and advective transport at the thermodynamic source regions.
In SAFARI, it is hypothesized that air-sea flux and diabatic processes associated with the interactions among synoptic-scale disturbances, the North Atlantic waveguide, and the sub-tropical ocean are significant sources of reduced predictability of downstream weather intensity and evolution. The target processes are often related to extratropical transition of tropical cyclones, warm conveyor belts associated with intense extratropical cyclones, high latitude tropopause polar vortices, and diabatic Rossby vortices. Since downstream evolution of the waveguide is determined by multiple factors, specific proposals that seek to join this effort should describe how research will improve understanding in these factors:
- The shape, intensity, and predictability of the traveling waveguides that interact with source disturbances and develop the atmospheric river
- The structure and amplitude of the source disturbances and their thermodynamic profiles
- The air-sea interaction and air-mass diabatic modulation that occur from diurnal through sub-seasonal timescales
Proposed methodologies should consider one or more of the following approaches in addressing the above studies:
- Contributing to, and/or leveraging, a successful observing strategy for measurements of key parameters associated with potential sources of waveguide perturbations and the waveguide itself. Beyond the measurements of key dynamic and physical processes, a concentrated effort will be to evaluate predictability in terms of impacts to data assimilation, initial condition sensitivities, utility of ensemble prediction systems, and improved model strategies and parameterizations.
- Predictability tools, including moist adjoint and ensemble-based methods, should be used to diagnose the behavior of rapidly growing perturbations as well as the best sampling strategy for the interaction between potential vorticity and energy cascade dynamic arguments in the triple-point region aloft and diabatic moist instability arguments in the Warm Conveyer Belt and lower tropospheric/Marine Boundary Layer. Efforts are encouraged to also address representation of the cloud microphysics to facilitate analysis of perturbation growth at much smaller scales than have been previously considered.
- State of the art numerical models are nonhydrostatic, allow accurate mesoscale representation, and offer variable resolution in global or regional areas. These dynamic model cores provide a tool that can, for the first time, directly simulate the multi-scale processes on a grid that is numerically non-dispersive, high-order, but also computationally affordable to run highly realistic cases using the field data directly. Numerical simulations leveraging this technology should describe how variable resolution modeling can support improved research of this topic.
Request for Planning Letters
The first step in the DRI process is for prospective investigators to prepare planning letters. The purpose of the planning letters is to allow investigators to submit a short (three pages maximum) summary of their ideas on this topic for ONR to evaluate, provide technical feedback and indicate whether a full proposal would have a reasonable chance of success.
Refer to the current Marine Meteorology Planning Letter guidelines and indicate your desire to work with the SAFARI project and team. Please note "SAFARI Planning Letter ‘Your Last Name’" in your email subject line. If you do not receive acknowledged receipt within 10 days, please follow-up with a resend.
Planning letters and full proposals for up to three year efforts will be accepted on a rolling basis, as funding allows through the course of the SAFARI program. Please submit by the below dates for full consideration.
Important Dates
July 31, 2023: Target date to submit planning letters for full consideration in FY24 (please submit by e-mail to below).
August 15, 2023: Last date ONR will respond to all submitted planning letters with proposal recommendation.
September 15, 2023: Last date for proposal submission where the evaluation will still be eligible for full consideration in the FY24 funding.
November 1, 2023: Earliest anticipated commencement of awards made with FY24 funding, depending on availability of funding and grant processing.
All planning letters should be submitted by email to the ONR Marine Meteorology team: Josh Cossuth (joshua.h.cossuth.civ@us.navy.mil) and Dan Eleuterio (daniel.p.eleuterio.civ@us.navy.mil).