TEMPERATURE LAPSE RATE ESTIMATION BY DOPPLER SODAR

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TEMPERATURE LAPSE RATE ESTIMATION BY DOPPLER
SODAR Jean-Michel FAGE, PRESIDENT, REMTECH INC,
2 Red Oak Road, St James NY 11780, USA Tel
(303) 772 68 25, Fax [phone],
sales_at_remtechinc.com
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• OBJECTIVE
• The goal of the study is to determine if it is
  possible to use the data from a Doppler SODAR to
  determine the lapse rate under stable conditions.
• Compare data from SODAR with tall tower to
  develop empirical coefficients for further use
  and algorithm development.

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DATA SOURCE FOR INITIAL ALGORITHM
DEVELOPMENT Kernforschungszentrum (Nuclear
Research Center), Karlsruhe, Germany) 200 meter
measurement tower
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The PA2 SODAR, similar to the system at
Kernforschungszentrum (Nuclear Research Center)
in Karlsruhe (West Germany)
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THEORY
The following approach corresponds to the
so-called Level 2 of Mellor Yamda where
advection and diffusion terms are neglected in
the Fluid Mechanics equations, which leads to (in
the PBL approximation)  q3/ ?1 uw (?U / ?z)
vw (?V/?z) ?g w?  q ??²/?2 w?
(??/?z)   where - ??? ?? characteristics
lengths - u, w horizontal and vertical
speed fluctuations - ? potential
temperature fluctuation - q kinetic
energy - ?? sigma of the potential
temperature fluctuations
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THEORY
The derivation resolves down to ? ?/ ?z ? E 3/2
?w-1   The empirical formula, which is applied
to the SODAR data reads ? ?/ ?z A B E 3/2
?w-1 A and B are empirical coefficients which
have been estimated using previous data.
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THEORY
A and B coefficients of the lapse rate formula
vary They are constantly recalibrated using two
techniques - if the RASS is not present we
infer that the atmosphere is adiabatic at least
for a few hundred meters above the surface layer
during the afternoon - if the RASS is present we
use the RASS data themselves by a least square
optimization between the RASS data derived lapse
rate and the lapse rate obtained from the Sodar
only.
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6.0C/100m

-___ TOWER ----- SODAR
3.0C/100m
0.0C/100m
-3.0C/100m
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STATISTICS Correlation Between SODAR and Tower
0.78 Standard Deviation of the difference between
the SODAR and tower, by level (in C/100
m) 180 m 0.63 160 m 0.54 140
m 0.60 120 m 0.64 100 m 0.78 80
m 0.98 60 m 1.13
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PA0 SODAR Antenna
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WIND SPEED DATA FROM PA0 ON ROOF
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LAPSE RATE DATA FROM PA0 ON ROOF
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Radio Acoustic Sounding System (RASS)
RASS Antennas
PA5 Antenna
Solar Power Array
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CONCLUSIONS

1. Possible to measure lapse rate with SODAR
2. Can be included with all versions of the SODAR
3. Empirical nature of system requires it to learn
   at each site for a period of time
4. System improves with RASS as part of the system