[GTP] Joint GTP-EOL-MMM seminar

[Silvia Gentile]

Joint GTP EOL MMM Seminar

The CIRES Tethered Lifting System: A State-of-the-art Tethersonde for 
the Measurement and Study of the Structure, Dynamics, and Turbulent 
Properties of Atmospheric Boundary Layers
Yannick Mellier
CIRES (Cooperative Institute for Research in Environmental Sciences), 
Boulder


Understanding the various structures, turbulent properties, and dynamics 
characterizing atmospheric boundary layers is of the utmost importance 
for a large number of applications such as Numerical Weather 
Predictions, Transport & Diffusion, wind energy applications, as well as 
agricultural and aeronautical meteorology.
The tethered lifting system (TLS) is a specialty-designed tethersonde 
system that was developed by the Cooperative Institute for Research in 
Environmental Sciences (CIRES) at the University of Colorado to 
complement current measurement systems with unique high-resolution 
insitu measurements of temperature, velocity, and turbulence.
Specialty-designed low noise and low power hot-wire (HW) and cold-wire 
(CW) sensors used in conjunction with a custom-built 16 bit high-rate 
data acquisition cards measure with high accuracy and precision the 
changes and fine-scale fluctuations of temperature, windspeed, and 
turbulence. Inertial range turbulence metrics such as the temperature 
structure constant CT2 and energy dissipation ε are estimated via 
spectral processing. The high sensitivity of the detector, low noise 
properties of the CW/HW circuit cards, and high sampling rate 
capabilities of the digitizer, allow accurate measurements of high 
resolution profiles of turbulence at a vertical resolution of 0.5 m or 
better, and down to extremely weak levels of turbulence of CT2~10-7 
K2m-2/3 and ε~10-8 m2s-3 (1/10th of a m oC and mm/s fluctuations). In 
addition to CT2 and ε, the turbulence payload can also measure critical 
turbulence and dimensionless parameters such as the Kolmogorov and 
Taylor microscales, the Ozmidov scale, temperature and velocity 
turbulent length scales, Reynolds number, and turbulent Froude number. 
The TLS is also ideally suited for accurate measurements of local 
vertical gradients of temperature and velocity and thus stability 
parameters such as the gradient Richardson number.
The TLS is not only highly complementary of current measuring systems 
such as instrumented meteorological towers and remote sensors but also, 
thanks to the unique resolution and unprecedented sensitivity of its 
temperature, velocity, and turbulence measurements, provide new research 
opportunities. Such research applications include the empirical 
verification of stably stratified turbulent scaling laws, the validation 
of remote-sensors measurements of turbulence profiles, an improved 
understanding of boundary layer (BL) structures and dynamics.
This seminar will begin with a technical presentation of the TLS system, 
its principle of operation, measurement performances, and calibration 
accuracies. The second part of the talk will cover some of the research 
applications that the TLS has been used for to date and will open the 
door to suggestions on how such a system could benefit the research 
interests of NCAR’s Mesoscale and Microscale Meteorology division as 
well as complement EOL’s current measurement capabilities.


Thursday October 27, 2011
Lecture: 11:30am (Coffee at 11:15)
Foothills Laboratory 2, Main Auditorium

This seminar will be recorded

-- 
Silvia Gentile
NCAR IMAGe
1850 Table Mesa Drive
Boulder, CO 80305
303 497 2480
www2.image.ucar.edu/IMAGe