Earths Upper Atmosphere

1
Earths Upper Atmosphere

• Qian Wu
• National Center for Atmospheric Research

2
Overview

• Mesosphere and lower thermosphere dynamics
• Nightglow emissions
• Ground based Fabry-Perot interferometer
• Results from ground based Fabry-Perot
  interferometer
• Spaceborne Fabry-Perot interferometer TIDI
• Observation from TIDI
• Summary

3
Upper Atmosphere
4
Forbes, Comparative Aeronomy, 2002
5
Mesosphere and Lower Thermosphere Tides and Large
Scale Waves

• Migrating tides
• Diurnal tide
• Semidiurnal tide
• Planetary Waves
• Non-migrating tides

6
Dynamics Equations
7
Tidal Wave Function
8
(No Transcript)
9
Diurnal Tide in Zonal Winds
10
Aurora and Nightglow
11
Mesosphere and Lower Thermosphere Nightglow
Volume Emission Rates
Altitude (km)
12
Thermosphere Nightglow Volume Emission Rates
Altitude (km)
13
Airglow Emission Sources
O 6300 Å red line
O 5577 Å green line
Electron impact
Electron impact
Photodissociation of O2
Photodissociation of O2
Collisional deactivation of N2
Dissociative recombination
OH emission
14
Fabry-Perot Interferometer
15
Etalon
16
Fabry-Perot Fringe Pattern
17
FPI Configuration

• Major Components
• Sky scanner
• Filters filter wheel
• Etalon chamber
• Thermal pressure control
• Focusing lens
• Detector
• Computer system

• Highlights
• Computerized micrometer
• Daily laser calibration
• High degree automation
• Michigan heritage
• NCAR enhancement

18
Instrument Operation
19
FPI at Resolute
20
FPI at Resolute
21
Instrument Electronics
22
FPI Operational Mode
23
Polar Cap Observatory 75N
24
Mesosphere Wind 12h Wave
25
Lower Thermosphere Wind 12h Wave
26
8-Hour Wave
27
Resolute OH Wind 10-Hour Wave
28
Thermosphere Wind
29
TIMED

• A satellite mission to study
• Thermosphere Ionosphere Mesosphere
• Energetics and Dynamics (TIMED)
• Instruments
• TIMED Doppler Interferometer (TIDI)
• Global Ultraviolet Imager (GUVI)
• Solar Extreme Ultraviolet Experiment (SEE)
  Sounding of the Atmosphere using Broadband
• Emission Radiometry (SABER)

30
TIMED Fact Sheet
31
The TIDI Instrument
The TIMED Doppler Interferometer (TIDI) is a
Fabry-Perot interferometer for measuring winds in
the mesosphere and lower thermosphere. Primary
measurement Global neutral wind field, 60120
km Primary emission observed O2 1S (0-0)
P9 Additional emissions observed O2 1S (0-0)
P15, O2 1S (0-1) P7, O(1S) green line
Telescope Assembly
Profiler
32
Limb-Scan Measurements
Airglow layer
33
TIDI Measurement Viewing Directions
4
1
3
2
9 minutes
Satellite Travel direction
4
1
3
2
34
TIDI Local Time Coverage Day 80 2002
35
TIDI Neutral Wind Measurements
36
Neutral Winds From TIDI
37
TIDI Neutral Wind Observation
38
Observed Diurnal and Semidiurnal Tides
39
GSWM00 Tidal Amplitudes and Phases Feb
40
Summary

• Earths upper atmosphere is very dynamic region,
  which is affected by lower atmosphere and space
  weather.
• Fabry-Perot interferometer is an effective
  instrument for upper atmosphere dynamics studies.
• Ground based instrument has a very high accuracy
  and can detect very small tidal waves.
• Ground based instrument can only provide local
  coverage during nighttime under clear sky.
• Satellite Fabry-Perot interferometer can provide
  a global view during day and night.
• We need more observation in the mesosphere and
  thermosphere to order to have a better
  understanding of the region.