Wave-Turbulence Interactions in Stable Atmospheric Boundary Layers (WINABL)

• Date: 23-27 July 2012 (Public sessions on July 25 and 26 only)
• Location: National Center for Atmospheric Research in Boulder, Colorado
• Building: Center Green Campus, Building 1, Center Auditorium

Organizing Committee

• Larry Mahrt, Oregon State University
• Carmen Nappo, CJN Research Meteorology
• Jielun Sun, NCAR

Scientific Committee

Theory Group

Observation Group

Parameterization Group

Motivation

A few “clean” gravity waves with nearly constant amplitude and period have been observed in the atmospheric boundary layer over smoother surfaces such as grass. In these cases the mechanics of gravity-wave turbulence interaction can be well described but it is difficult to generalize from these few examples. Most of the atmospheric “waves” or wave-like disturbances associated with turbulence intermittency in stable boundary layers over the smoother surfaces are characterized by only a few cycles with varying amplitude and period. These “wave packets” are often further degraded through generation of intermittent turbulence.

At nighttime over tall plant canopies, gravity waves are ubiquitous. Over tall canopies, gravity waves are persistent for many cycles, often lasting hours and can pose a significant challenge for tower flux measurements. Theoretical understanding of both these situations and, therefore, our ability to parameterize the very stable boundary layer in analytical and numerical models is embarrassingly incomplete. In both the smoother and tall canopy cases, we need to determine the origin of these wave motions, how they lead to intermittent turbulence, how turbulence feeds back on the wave-like disturbances, and how small-scale dissipation depends on the large-scale wave forcing. This is the objective of this workshop.

Objectives of the workshop

To review our understanding of:

1. gravity-wave theory, especially how gravity waves are generated in the nocturnal boundary layer and how they interact with turbulence over tall and short roughness
2. observational evidence of how gravity waves interact with turbulence in stable boundary layers
3. gravity-wave parameterizations in numerical models.

To address:

1. the formulation of theoretical frameworks and observational strategies to understand how gravity waves are generated and how they interact with or trigger turbulence, and how they anisotropize it.
2. comparison of theories and observations
3. identification of knowledge gaps, directions for future work, and the framing of fundamental hypotheses.
4. the application of better knowledge of gravity wave-turbulence interactions to improve the parameterizations in boundary layer and mesoscale numerical models.

Workshop Format

The Scientific Committee will meet for two days to summarize the state of the art for theory, observations, and gravity-wave parameterizations; and to recommend major scientific issues that we need to work on and discuss.

A two-day workshop (Wednesday and Thursday) will follow the Scientific Committee meetings. Overview talks will be given by the three working groups. The general presentations (15 min/each) will address the relevant issues following the overview talks. All the presentations will be video-taped for the Scientific Committee writing. Thursday afternoon, the general public will be split up to three breakout groups: theory, observation, and parameterization to discuss future directions. The general assembly will be held at the end of Thursday, where the reports from three breakout groups will be given and general discussions/comments will follow the reports. On Friday, the Scientific Committee will meet again to finalize the review paper(s).

The registration for the workshop is free but is required for all participants. The registration deadline is 31 May 2012. The participants are responsible for their own travel needs.

For those who would like to contribute to the workshop objectives by presenting their work at the workshop, a title and a short abstract (about a half page) are required at the registration site. Selection of abstracts for presentation will be completed by 15 June.