Ground-based Measurements Part II

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Ground-based MeasurementsPart II

• Measurements
• Retrieving the Desired Information
• Comparison Between Instruments
• Satellite Validation
• Toward Model-Measurement Comparison

Prepared by Dr. Stella M L Melo University of
Toronto
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AIRGLOW

• What it is?
• Proxy for MLT temperature, concentration and
  dynamics
• How we measure?
• Comparing T measurements using airglow with LIDAR
  T measurements.

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AIRGLOW

• What is it?
• - Spontaneous luminescence that rises from
  discrete transitions of the constituents of the
  atmosphere (A. García-Muñoz, in preparation)
• Has been used as proxy for atmospheric
  temperature, constituents and dynamics since back
  to the end of the 1950s.
• Main source atomic oxygen photodissociated at
  higher altitudes.

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AIRGLOW

• O O M ? O2 M ? 2501270 nm bands emission
• O2 O ? O(1S) O2 ? 557.7 nm emission
• Not including ionosphere
• N O ? NO ? 180280 nm emission
• H O3 ? OH(v 6-9) O2 ? 5003000 nm bands
  emission (excess of energy 3.3 eV)

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O2
O2
O2(b-x) 0-1 band measured by Keck I/HIRES (50 min
integration)
Slanger and Copeland, 2003
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Airglow Rocket measurements
Rocket measurements Alcantara (20S, 440W)
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OH
Dyer et al., 1997
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(No Transcript)
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Mars Airglow Modeling OH
By A. García Muños
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Mars Airglow Modeling OH
Diurnal variation
By A. García Muños
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MLT Temperature from airglow

• Atmospheric temperature is a basic parameter.
• Mesopause (85-100 km)
• Low temperature/low pressure
• Transition from turbulent to molecular diffusion
• Airglow can be used as proxy for MLT temperature
• - OH vibrational bands
• - well dispersed rotational lines
• - extending from 400nm to 4mm
• - intensity is relatively easy to measure

Other planets!
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AIRGLOW
rotational temperature

• Precision improve
• - as the signal to noise ratio improves (DR/R
  decreases
• as the difference in rotational energy of the
  states (Fb-Fa) increases
• -gt two lines that are farther apart in the
  spectrum will give a more precise measurement of
  the temperature

Issues about LTE
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Airglow imager
Iwagami et al., JASTP, 2002
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MLT Temperature from airglow

• Airglow (nadir) observations do not contain
  direct altitude information
• At the end of the 80s - narrow-band sodium lidar
  begun to be used to remotely measure the altitude
  profile of the atmospheric temperature between
  85-105 km
• Data-set show
• bimodal character of the mesopause altitude
• the occurrence of the Temperature Inversion
  Layer above 85 km
• Lidar do not normally provide information about
  the horizontal structures

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Lidar T profile

• LIDAR Light Detection and Range
• Normally Lidar technique is used to measure
  Rayleigh scattering from which air density
  distribution is obtained.
• By assuming hydrostatic and local thermodynamic
  equilibrium atmospheric temperature profiles can
  be calculated from the molecular backscatter
  profile.
• Measurements are reliable form 30km up to 80 km
  altitude
• Upper mesosphere Na Lidar
• Na fluorescence cross-section is 14 orders
  higher than the Rayleigh-scattering cross-section
  at 589 nm
• Technique first proposed by Gibson et al., 1979

More on LIDAR? Carlos poster!
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Lidar T profile

1. Energy levels NaD2 lines
2. - Doppler-broadened fluorescence spectra of NaD2
   transition.

She et al., Applied Optics, 1992
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Lidar T profile
Melo et al., 2001
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Compare Lidar and OH Temperature

• First proposed by von Zahn et al. (1987) -
  determine OH altitude
• OH layer at 86 ? 4 km
• differences in temperature sometimes of up to 10
  K
• influence of
• clouds
• differences in field of view
• fast motions of the OH layer due to gravity
  waves
• assumed OH layer shape

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Lidar and OH Temperature

• She and Lowe (1998) compared temperature measured
  with lidar (Fort Collins) and from OH airglow
  (FTS)
• Shape OH profile taken form WINDII measurements
• Generally, OH rotational temperature can be used
  as a proxy of the atmospheric temperature at 87
  4 km

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Observations at Fort Collins (41?N, 105?W)
November 2-3, 1997
Nocturnal average Lidar 30 K gt OH At 4.38
UT Lidar 65 K gt OH
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Airglow Model

• Photochemical model

O3H ? OHO2 (3.3 eV) O O2 M ? O3
M OH(n) O ? H O2 OH(n) O2 ?
OH(n-1) O2 OH(n) N2 ? OH(n-1) N2 OH(n)?
OH(n-n) hn
(Based on Makhlouf et al. 1995)
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Comparing Model and Observations
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OH Rotational Temperature - Observations
OH response to a gravity wave based on Swenson
and Gardner (1998) Lz 25 km
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Recovering Mesospheric Atomic Oxygen Density
Profile from Airglow Measurements
Reed and Chandra (1975) parameterization Upper
mesosphere-lower thermosphere
Oz Omax EXP (0.5 1.0 (Zmax - Z) / SH
- EXP((Zmax - Z) / SH))
Melo et al, 2001
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Nightglow emissions - 80-110 km
OI 5577 Green line O(1S? 1D)
O2 Atmospheric bands O2 (b1Sg ? X3Sg-)
OH Meinel bands OH(X3Pn ? X3Pn )
OOM O2M O2O O(1S )
O2 O2O2 O2O2 O(1S )O2 O O2
O O M O2M O2 O2
O2(b1Sg)O2 O2 O O2
O2 O2(b1Sg )M Prod.
H O3 OH O2 OH M
Prod. O O2 M O3 M
2
O M O M
2
IOH ?
IO2 ?
O M
IOI ?
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Recovering Mesospheric Atomic Oxygen Density
Profile from Airglow Measurements
O-parameters recovered from the technique (solid
line) compared to the input (dashed lines).
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Recovering Mesospheric Atomic Oxygen Density
Profile from Airglow Measurements
Atomic oxygen density profiles (atoms/cm3) input
(a) compared to retrieved (b) and the percentage
difference (c).
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TOH
TO2
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Hydroxyl Profile Measured by WINDII (symbols) and
calculated (line)
(13-06-93)
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Airglow Imaging Systems for Gravity Wave
Observations in the Martian Atmosphere

• Stella M L Melo and K. Strong, University of
  Toronto
• R. P. Lowe and P. S. Argall University of
  Western Ontario
• A. Garcia Munoz, J. McConnell, I. C. McDade,
  York University
• T. Slanger and D. Huestis, SRI International,
  California, USA
• M. J. Taylor, Utah State University, USA
• K. Gilbert, London, Canada
• N. Rowlands, EMS Technologies

Picture by Calvin J. Hamilton
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Mars Airglow REmote Sounding - MARES
MARES-Ground is a zenith-sky imaging system for
ground-based observation of wave activity in the
Martian atmosphere through measurement of the
contrast in images of selected airglow features.
MARES-GWIM is a satellite-borne nadir-viewing
imager which will produce static images of
wave-induced radiance fluctuations in two
vertically separated night airglow layers in the
atmosphere.
- GWIM has been developed for Earths
atmosphere - MARES-GWIM will be an adaptation of
GWIM for the Martian atmosphere.