New perspectives on mesospheric wave dynamics and oxygen photochemistry

Anqi Li

Licentiate seminar

Apr 2020

Topic A: Gravity wave

Topic B: Oxygen photo-chemistry

Future

Welcome

Topic B: 

Welcome to the mesosphere

Welcome to the mesosphere

  • Dynamics - waves
  • Chemistry - airglow, ozone
  • Radiations
  • ...

Energy balance is controlled by

Welcome to the mesosphere

Gravity wave

Topic A

Airglow

Topic B

Image from NASA

Image by Mike Taylor and Sonia MacNeil

Odin

SubMillimetre Radiometer (SMR)

Optical Spectrograph and InfraRed Imaging System (OSIRIS)

MATS

2 Ultraviolet Imagers 

4 InfraRed Imagers

2001~

2020~ ?

  • Limb viewing
  • Sun-synchronous, near-terminator, polar orbit
  • Observes mesosphere

Airglow

Odin-IRI-O2 channel

Observation

N pole

S pole

EQ

EQ

MATS - IR channel

Simulation

Topic A:

Topic B: Oxygen photo-chemistry

Future

Welcome

Gravity wave

Topic A:

Gravity wave

Topic A:

Internal wave

Dispersion relation

Q = A \cos(\textcolor{red}{k_x} x + \textcolor{red}{k_y} y + \textcolor{red}{k_z} z + \textcolor{red}{\omega} t)

3D wave

k_x, k_y, k_z, \omega,

 stratification

(inside medium)

Topic A:

Wind & waves

Doppler relation

\Omega = \omega - \vec{U} \cdot \vec{k}

Intrinsic freq.

Observed freq.

Koop and McGee (1986)

)

)

)

How to sense waves?

  • Ground-based vertical profiler (z, t)
  • Ground-based sky imager (x, y, t)
  • Limb imager (x, (y), z)

How to access intrinsic properties?

make use of

  • Doppler relation
  • Dispersion relation

Topic A:

Paper 2

Perspectives on

the interpretation of

a gravity wave event

recorded by ground-based lidar

Paper 2

Dörnbrack et al. (2017)

Observed by Rayleigh lidar

Sodankylä, Finland

Wave packet?

Monochromatic

+ Wind change!

Monochromatic

(filtered)

\Omega = \omega - \vec{U} \cdot \vec{k}

Doppler relation

Observed wind

matches

calculated wind

Paper 2

< 0 UTC

> 0 UTC

Observed

Simulated

Paper 2

Monochromatic

+ Wind shear change!

Topic A: Gravity wave

Topic B: Oxygen photo-chemistry

Future

Welcome

(airglow chemistry)

Topic B: 

\mathrm{O}(^1D)
\mathrm{O}_3
\mathrm{O}_2(^1\Delta)
\mathrm{O}_2(^1\Sigma)
\mathrm{O}_2
\mathrm{O}

Topic B

Oxygen photo-chemistry

Photochemical model

\mathrm{O}_2(^1\Delta)
\mathrm{O}_2(^1\Sigma)

Topic B

MATS

Odin-IRI

Paper 1

Retrieval of

daytime mesospheric ozone using OSIRIS observation of

O2 (        ) emission

a^1\Delta_g

Optimal estimation method

a.k.a.

Bayesian statistical approach

Inversion step 1

Limb radiance -> Volume emission rate

\mathbf{y = F (x)}

Limb

Volume

\mathrm{O}_2(^1\Delta)

Paper 1

Result step 1

Paper 1

Volume emission rate

Optimal estimation method

a.k.a.

Bayesian statistical approach

Inversion step 2

\mathbf{y = F (x)}
\mathrm{O}_2(^1\Delta)

Paper 1

\mathrm{O}_3

Non-linear

Levenberg-Marquardt method

Final result

Ozone from Odin compare

Paper 1

Ozone

N pole

S pole

EQ

EQ

Topic A: Gravity wave

Topic B: Oxygen photo-chemistry

Future

Welcome

The Future Is Bright!

  • Expansion of the retrievals
  • Mesospheric science 
  • MATS data

Thank you!

Complementary slides

Topic A:

Wave sources

Obstacle effect

Mechanical oscillator 

Spontaneous emission 

Vadas et. al (2018)

Koop and McGee (1986)

Summer school in Cambridge 2018

Paper 1

Odin- IRI

> 100 pixels vertically

\mathrm{O}_2(^1\Delta)

Check horizontal wind (ECMWF + radar)

Hodograph

Paper 2

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