FISAPS – Fine Scale Atmospheric Processes and Structures

Many atmospheric processes that are important for large-scale dynamics and chemical constituent distributions occur on vertical scales less than 1 km. These include energy and momentum dissipation, momentum fluxes by waves, constituent mixing by turbulence, etc. High vertical-resolution radiosonde data (HVRRD) can be used to obtain information on many of the dynamical processes, but such data are only readily available from a few countries.

Fine-scale atmospheric modelling now has unprecedented capabilities for modelling wave transitions to turbulence. FISAPS brings together modelling and observational communities to improve our understanding of atmospheric fine-scale processes. It also seeks to widen the availability of HVRRD, and advocate and advise for the archiving of these and other high resolution data (GPS, research balloons and aircraft data).

The objective of this activity is to realise the full potential of large volumes of HVRRD archived worldwide, as well as other high-resolution data. Providing coordination for the growing community of HVRRD users will promote the development of innovative applications of HVRRD by facilitating the sharing of expertise on analysis techniques, data handling, and technical capabilities and limitations. This sharing of expertise will be of similar benefit for the refinement and improvement of existing fields of research using HVRRD as well as the use of other high-resolution data. Due to restrictions on access to HVRRD, previous studies have been limited to relatively small geographic coverage. This activity aims to address this limitation by two means, first, by coordinating broader regional intercomparisons and global studies that bring together researchers from the global HVRRD community. The second is to provide improved access to existing HVRRD to the research community.

While the initial focus of FISAPS is on fine-scale dynamical structures, it is anticipated that FISAPS may expand its scope to fine-scale constituent structures and processes. It is clear that troposphere and stratosphere observations of atmospheric constituents show considerable fine-structure, yet chemistry-transport models display relatively smooth structures. Quantifying how the absence of fine-scale structures in modelled chemical constituents affects computed chemical reaction rates would be a focus of this expanded activity.

Scientific goals include:

• What information can be obtained on gravity wave source formulations (e. g., jet emission)?
• To what extent can we broaden the availability of high vertical-resolution radiosonde data?
• What is the distribution of unstable layers and atmospheric turbulence?
• Can we better understand fine-scale signatures in atmospheric chemical constituents, and the implications of these fine structures for atmospheric chemistry?

In addition to its basic research goals, FISAPS should also contribute to important applications such as a better understanding of processes that contribute to turbulence effects on aviation and the prediction of clear-air-turbulence for aviation.