Measuring Eddy Heat and Constituent Fluxes with High-Resolution Na and Fe Doppler Lidars

Chester S Gardner; Alan Z Liu

doi:10.1002/2013JD021074

Measuring Eddy Heat and Constituent Fluxes with High-Resolution Na and Fe Doppler Lidars

Chester S Gardner, Alan Z Liu

Research output: Contribution to journal › Article › peer-review

Abstract

<div class="line" id="line-5"> Vertical transport by turbulent mixing plays a fundamental role in establishing the thermal and </div><div class="line" id="line-7"> constituent structure of the upper mesosphere and lower thermosphere (MLT). Because of observational </div><div class="line" id="line-9"> challenges, eddy heat, constituent, and momentum fl uxes, and the associated coef fi cients for thermal ( k H ), </div><div class="line" id="line-18"> constituent ( k zz ), and momentum ( k M ), diffusion have not been well characterized in the MLT. We show that </div><div class="line" id="line-26"> properly con fi gured Na and Fe Doppler lidars, with suf fi cient resolution to observe the turbulence-induced wind, </div><div class="line" id="line-32"> temperature, and density fl uctuations, can make direct measurements of eddy fl uxes throughout the mesopause </div><div class="line" id="line-38"> region. When the horizontal ( z θ L with z = altitude and θ L = full width at half maximum laser divergence), vertical </div><div class="line" id="line-49"> ( Δ z ), and temporal ( Δ t ) resolutions of the lidar satisfy the condition L C &simeq; ð 3 z θ L Þ 2 þ ð 0 : 6 u Δ t Þ 2 þ ð 1 : 5 Δ z Þ 2 ≤ 270 m (125 m), where u is the mean horizontal wind velocity, the observations include more than 80% (90%) of the energy in the turbulence fl uctuations, and the observed fl uxes and derived diffusivities will be highly representative of the actual values. For existing Na and Fe Doppler lidars, which have modest power-aperture products of about 1 W m 2 , long averaging times (5 – 20 h) are required to obtain statistically signi fi cant estimates of the eddy fl uxes, k zz , k H , and k M pro fi les, and the turbulent Prandtl number ( Pr = k M / k H ) between about 85 and 100 km. These systems are capable of measuring the weekly or monthly mean fl ux and diffusivity pro fi les. Systems with power-aperture products of 5 – 100 W m 2 or larger could be used to study the eddy fl uxes generated by the dissipation and breaking of individual gravity waves to altitudes as high as the turbopause (~110 km).  </div>

Original language	American English
Journal	Journal of Geophysical Research
Volume	119
DOIs	https://doi.org/10.1002/2013JD021074
State	Published - Sep 15 2014
Externally published	Yes

Disciplines

Earth Sciences
Atmospheric Sciences

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Cite this

@article{841c34bd27a64ad0b64ac5c9ec89d956,

title = "Measuring Eddy Heat and Constituent Fluxes with High-Resolution Na and Fe Doppler Lidars",

abstract = " Vertical transport by turbulent mixing plays a fundamental role in establishing the thermal and constituent structure of the upper mesosphere and lower thermosphere (MLT). Because of observational challenges, eddy heat, constituent, and momentum fl uxes, and the associated coef fi cients for thermal ( k H ), constituent ( k zz ), and momentum ( k M ), diffusion have not been well characterized in the MLT. We show that properly con fi gured Na and Fe Doppler lidars, with suf fi cient resolution to observe the turbulence-induced wind, temperature, and density fl uctuations, can make direct measurements of eddy fl uxes throughout the mesopause region. When the horizontal ( z θ L with z = altitude and θ L = full width at half maximum laser divergence), vertical ( Δ z ), and temporal ( Δ t ) resolutions of the lidar satisfy the condition L C &simeq; ð 3 z θ L Þ 2 þ ð 0 : 6 u Δ t Þ 2 þ ð 1 : 5 Δ z Þ 2 ≤ 270 m (125 m), where u is the mean horizontal wind velocity, the observations include more than 80% (90%) of the energy in the turbulence fl uctuations, and the observed fl uxes and derived diffusivities will be highly representative of the actual values. For existing Na and Fe Doppler lidars, which have modest power-aperture products of about 1 W m 2 , long averaging times (5 – 20 h) are required to obtain statistically signi fi cant estimates of the eddy fl uxes, k zz , k H , and k M pro fi les, and the turbulent Prandtl number ( Pr = k M / k H ) between about 85 and 100 km. These systems are capable of measuring the weekly or monthly mean fl ux and diffusivity pro fi les. Systems with power-aperture products of 5 – 100 W m 2 or larger could be used to study the eddy fl uxes generated by the dissipation and breaking of individual gravity waves to altitudes as high as the turbopause (~110 km).  ",

author = "Gardner, {Chester S} and Liu, {Alan Z}",

year = "2014",

month = sep,

day = "15",

doi = "10.1002/2013JD021074",

language = "American English",

volume = "119",

journal = "Journal of Geophysical Research",

issn = "2156-2202",

}

TY - JOUR

T1 - Measuring Eddy Heat and Constituent Fluxes with High-Resolution Na and Fe Doppler Lidars

AU - Gardner, Chester S

AU - Liu, Alan Z

PY - 2014/9/15

Y1 - 2014/9/15

N2 - Vertical transport by turbulent mixing plays a fundamental role in establishing the thermal and constituent structure of the upper mesosphere and lower thermosphere (MLT). Because of observational challenges, eddy heat, constituent, and momentum fl uxes, and the associated coef fi cients for thermal ( k H ), constituent ( k zz ), and momentum ( k M ), diffusion have not been well characterized in the MLT. We show that properly con fi gured Na and Fe Doppler lidars, with suf fi cient resolution to observe the turbulence-induced wind, temperature, and density fl uctuations, can make direct measurements of eddy fl uxes throughout the mesopause region. When the horizontal ( z θ L with z = altitude and θ L = full width at half maximum laser divergence), vertical ( Δ z ), and temporal ( Δ t ) resolutions of the lidar satisfy the condition L C &simeq; ð 3 z θ L Þ 2 þ ð 0 : 6 u Δ t Þ 2 þ ð 1 : 5 Δ z Þ 2 ≤ 270 m (125 m), where u is the mean horizontal wind velocity, the observations include more than 80% (90%) of the energy in the turbulence fl uctuations, and the observed fl uxes and derived diffusivities will be highly representative of the actual values. For existing Na and Fe Doppler lidars, which have modest power-aperture products of about 1 W m 2 , long averaging times (5 – 20 h) are required to obtain statistically signi fi cant estimates of the eddy fl uxes, k zz , k H , and k M pro fi les, and the turbulent Prandtl number ( Pr = k M / k H ) between about 85 and 100 km. These systems are capable of measuring the weekly or monthly mean fl ux and diffusivity pro fi les. Systems with power-aperture products of 5 – 100 W m 2 or larger could be used to study the eddy fl uxes generated by the dissipation and breaking of individual gravity waves to altitudes as high as the turbopause (~110 km). 

AB - Vertical transport by turbulent mixing plays a fundamental role in establishing the thermal and constituent structure of the upper mesosphere and lower thermosphere (MLT). Because of observational challenges, eddy heat, constituent, and momentum fl uxes, and the associated coef fi cients for thermal ( k H ), constituent ( k zz ), and momentum ( k M ), diffusion have not been well characterized in the MLT. We show that properly con fi gured Na and Fe Doppler lidars, with suf fi cient resolution to observe the turbulence-induced wind, temperature, and density fl uctuations, can make direct measurements of eddy fl uxes throughout the mesopause region. When the horizontal ( z θ L with z = altitude and θ L = full width at half maximum laser divergence), vertical ( Δ z ), and temporal ( Δ t ) resolutions of the lidar satisfy the condition L C &simeq; ð 3 z θ L Þ 2 þ ð 0 : 6 u Δ t Þ 2 þ ð 1 : 5 Δ z Þ 2 ≤ 270 m (125 m), where u is the mean horizontal wind velocity, the observations include more than 80% (90%) of the energy in the turbulence fl uctuations, and the observed fl uxes and derived diffusivities will be highly representative of the actual values. For existing Na and Fe Doppler lidars, which have modest power-aperture products of about 1 W m 2 , long averaging times (5 – 20 h) are required to obtain statistically signi fi cant estimates of the eddy fl uxes, k zz , k H , and k M pro fi les, and the turbulent Prandtl number ( Pr = k M / k H ) between about 85 and 100 km. These systems are capable of measuring the weekly or monthly mean fl ux and diffusivity pro fi les. Systems with power-aperture products of 5 – 100 W m 2 or larger could be used to study the eddy fl uxes generated by the dissipation and breaking of individual gravity waves to altitudes as high as the turbopause (~110 km). 

U2 - 10.1002/2013JD021074

DO - 10.1002/2013JD021074

M3 - Article

SN - 2156-2202

VL - 119

JO - Journal of Geophysical Research

JF - Journal of Geophysical Research

ER -