| NSF Org: |
AGS Division of Atmospheric and Geospace Sciences |
| Recipient: |
|
| Initial Amendment Date: | August 29, 2016 |
| Latest Amendment Date: | August 2, 2018 |
| Award Number: | 1632829 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
Chungu Lu
AGS Division of Atmospheric and Geospace Sciences GEO Directorate for Geosciences |
| Start Date: | September 1, 2016 |
| End Date: | August 31, 2020 (Estimated) |
| Total Intended Award Amount: | $497,736.00 |
| Total Awarded Amount to Date: | $497,736.00 |
| Funds Obligated to Date: |
FY 2017 = $135,050.00 FY 2018 = $139,269.00 |
| History of Investigator: |
|
| Recipient Sponsored Research Office: |
3100 MARINE ST Boulder CO US 80309-0001 (303)492-6221 |
| Sponsor Congressional District: |
|
| Primary Place of Performance: |
3100 Marine St., 572 UCB Boulder CO US 80309-0572 |
| Primary Place of
Performance Congressional District: |
|
| Unique Entity Identifier (UEI): |
|
| Parent UEI: |
|
| NSF Program(s): | Physical & Dynamic Meteorology |
| Primary Program Source: |
01001718DB NSF RESEARCH & RELATED ACTIVIT 01001819DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): | |
| Program Element Code(s): |
|
| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
The vertical structure of the free atmosphere under stable conditions from very low altitudes into the stratosphere and above is often characterized by thin, strongly stable, non-turbulent "sheets" separated by thicker, more weakly stratified, and often turbulent "layers". The occurrence and morphology of "sheet-and-layer" (S&L) structures in the free atmosphere are believed to be governed by larger-scale wind shears, gravity waves (GWs) at various frequencies, local S&L instability dynamics, turbulence and mixing, and their interactions.
S&L structures have been known for several decades to play important roles in optical and radiowave propagation and in transport and mixing of heat, momentum, and constituents. There is also evidence that these small-scale flow features can have important implications for larger-scale dynamics, including instabilities and momentum transport accompanying GWs propagating to higher altitudes. However, little progress has been made in understanding the underlying dynamics or addressing the roles of instabilities and turbulence, the interactions among them, or the consequences of these flows for transport and mixing. In particular, the sources, morphologies, and statistics of intermittent turbulence events in stable stratification, and their dependence on environmental conditions remain to be defined observationally (e.g., instability character and statistics of S&L thicknesses, turbulence structure parameters and scales, and mechanical and thermal energy dissipation rates).
Our lack of understanding of these dynamics to date can largely be attributed to observational and computational challenges in capturing the relevant atmospheric structures and dynamics with sufficient spatial and temporal resolution. The research program IDEAL, Instabilities, Dynamics, and Energetics accompanying Atmospheric Layering will conduct ground-based and in-situ measurements and associated modeling combined to quantify these processes and provide key insights into S&L dynamics and effects throughout the stratified atmosphere. The IDEAL will perform measurements either at Dugway Proving Ground (DPG) in Utah or at Camp Guernsey Joint Training Center (CG) in Wyoming, where restricted airspace is already assured.
Intellectual Merit:
For the first time, the dynamics underlying ubiquitous S&L structures in the free troposphere will be observed with multiple, coordinated, high-resolution, in-situ sensors together with the integrated sounding radar profiler and radiosondes from ~50 m to 4 km. Guidance and interpretation of the observations will be aided by high-resolution DNS, enabling identification of key dynamics and evaluation of theories and models of stratified turbulence, mixing, and transport.
Broader Impacts:
A more quantitative understanding of S&L dynamics in the stably stratified atmosphere will contribute to parameterization of their implications for transport and mixing and improve predictive capabilities of relevance to many research communities. These include applications as diverse as pollution and fugitive emission impacts, micro-climate forecasting, and aviation safety. The project will train two graduate students in state-of-the-art studies in atmospheric science, aerospace engineering, and computational fluid dynamics. Measurement technologies and techniques developed in this work will benefit future field research campaigns and regulatory compliance mandates.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
Note:
When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external
site maintained by the publisher. Some full text articles may not yet be available without a
charge during the embargo (administrative interval).
Some links on this page may take you to non-federal websites. Their policies may differ from
this site.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
This was a collaborative research program between the University of Colorado and GATS, Inc., that built on recent successes to significantly advance the understanding of important sheet and layer dynamics in the lower troposphere. We sought to quantify these processes observationally and numerically, as a basis for developing key insights into sheet and layer dynamics and their effects throughout the stratified atmosphere.
Nocturnal observations were obtained during a one-month campaign at Dugway Proving Ground in Utah during the October-November 2017 time frame, utilizing multiple, simultaneous, autonomous DataHawk 2 unmanned aerial systems providing in-situ high-resolution measurements of turbulence parameters and winds along slant paths providing both vertical and horizontal sampling over a wide area, a portable NCAR/EOL ISS 915 MHz radar wind profiler and radiosonde system, and a tethered lifting system providing vertical profiling from a fixed location. These data are available in raw and processed form as a resource to support improved understanding and quantification of the behavior of stratified atmospheric flows.
Preparations for the Dugway campaign included upgrading the existing DataHawk 2 small Unmanned Aircraft System (sUAS) to support simultaneous sorties of up to 3 aircraft, development of a high-gain multi-antenna system that can communicate at long range with all aircraft without active steering, refinement of an existing fine-wire sensor for improved accuracy in measuring turbulent fluxuations in velocity and temperature, and miniaturization of a wind and turbulence sensor and associated tethered lifting system for making fixed location measurements.
Major outcomes from this program of technology development, field observation, and data analysis include:
- The DataHawk sUAS was proven to be a rugged, reliable, low cost vehicle for making fine-scale dynamics measurements in the lower troposphere in winds up to 15 m/s and up to about 4 km above the surface. Operations using multiple simultaneous aircraft was shown to be feasible, enabling a variety of sampling strategies, enhancing measurement coverage, and enabling temporal and spatial variations to be untangled.
- The smaller Tethered Lifting System is cost-effective for making long duration measurements in the boundary layer, up to about 1 km above the surface, provided winds are below about 5 m/s.
- Data processing from these flights has been automated to the point that same-day initial data products can be generated, providing useful insights for subsequent flights in a field campaign.
- The refined turbulence sensor provides protection against fine-wire breakage, without sacrificing accuracy in the 0.1-10 wavenumber inertial sub-range of interest.
- The multi-antenna Packet Controller system greatly reduces the complexity and personnel required in a field campaign, enabling sorties of 3 aircraft to be managed by an operating team of 3 personnel.
- The IDEAL campaign at Dugway produced 72 DataHawk flights in 31 sorties, many of these having 3 simultaneous aircraft observations in stably stratified nocturnal conditions, in combination with NCAR ISS wind profiler and over 95 radiosonde profiles. In this data we have so-far identified 58 individual stable sheet structures roughly 25 m to 50 m deep. Stability ducts, consisting of two stable sheets constraining weakly stable and weakly turbulent layers as deep as 400 m, were prevalent. Such structures, often persisting up to five hours under very stable conditions, were commonly observed at the peak altitude of Granite Peak Mountain (850 m to 900 m AGL). Altitude undulations in persisting stable structures during strong (8 to 10 m/s) westerly-wind forcing over Granite Peak Mountain suggest the prevalence of gravity waves, and temperature gradients as steep as 0.18 K/m were typically observed across most sheets bounding these structures.
- Post-flight calibration methods were developed for the hotwire anemometry and coldwire thermometry, as well as improved turbulence parameter extraction from spectral data, providing automated production of turbulent kinetic energy dissipation rate and temperature structure parameter retrievals with quantified uncertainty.
Last Modified: 01/11/2021
Modified by: Dale A Lawrence
Please report errors in award information by writing to: awardsearch@nsf.gov.
