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2. In general, what advantages and disadvantages do lidar and sodar offer compared
to a 60-m tilt-up tower? Discuss both positive and negative aspects for each type
of remote sensing system.
3. Both lidar and sodar measure a “volume” of air. How is this different from an
anemometer? What are the implications associated with this difference? Assume
the wind speed increases across a range of heights from 90 to 110 m according
to the power law (Chapter 3), with an exponent of 0.50. Assume further that
the speed at 100 m is exactly 10 m/s. What is the average of the speeds at 90,
100, and 110 m? What percent error does this represent compared to the true
100-m speed?
4. What is “SNR,” and how does it apply to ground-based remote sensing devices?
5. You are conducting a wind resource assessment campaign and want to determine
how wind shear will affect your choice of turbine hub height. You decide to
supplement your current assessment campaign, which uses two 60-m met towers,
with a ground-based remote sensing device. The available monitoring location
is near woods with 30-m-tall trees and a road with frequent traffic. Your budget
allows for either a lidar or a sodar, and both are available from a supplier who
can meet your schedule. (i) Which type of device would you choose? (ii) Why
is the chosen device appropriate for the site? (iii) What siting considerations
should be addressed during deployment?
6. Your candidate wind project site faces up a steep slope in the prevailing wind
direction. What adjustments might be considered when comparing the wind data
collected on a monitoring tower using cup anemometers with that collected with
either lidar or sodar? Explain the item or parameter to be considered or adjusted
for and if it applies to all remote sensing systems or just a particular type.
SUGGESTIONS FOR FURTHER READING
Deolia RA. Characterization of winds through the rotor plane using a phased array
SODAR, Sandia National Laboratory, Report SAND2009-7895, Feb 2010. Available at
http://prod.sandia.gov/techlib/access-control.cgi/2009/097895.pdf. (Accessed 2012).
Kelly ND, et al. Comparing pulsed doppler LIDAR with SODAR and direct measurements for
wind assessment. National Renewable Energy Laboratory, Conference Paper CP-500-41792,
2005. Available at http://www.nrel.gov/wind/pdfs/41792.pdf. (Accessed 2012).
Moore K. Recommended practices for the use of sodar in wind energy resource assessment,
Integrated Environmental Data, June 2010. Available at www.iedat.com/documents/
SODARRecommendedPractices_IEARevised22June.doc. (Accessed 2012).
Weitkamp C, editor. Lidar: range-resolved optical remote sensing of the atmosphere, Springer
series in optical sciences. 2005. p. 460.
Wharton S, Lundquist JK. Atmospheric stability impacts on power curves of tall wind turbines,
Lawrence Livermore National Laboratory, Report LLNL-TR-424425, Feb 2010. Available
at https://e-reports-ext.llnl.gov/pdf/387609.pdf. (Accessed 2012).
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