osIRIs, OH!
Feb 2021
Anqi Li et al.
Overview
- OH nightglow and OSIRIS
- Seasonal variability
- Solar cycle influence
- Sudden stratospheric warming (SSW)
Disclaimer
- First time to present IRI OH dataset
- Based on our studies in the past few weeks
- Still seeking answers to explain
- Welcome critics and recommendations
OH nightglow
Motivation
- Rich information in dynamics and chemistry
- GW, tides, AO, SAO, solar, SSW...
- can be an O proxy
- Odin
- altitude resolution
- ~20 years of global coverage (poles)
- 6-18h (e.g. winter night, locked in local time)
OH nightglow
Baker et al. (2007)
SCIAMACHY results
OH nightglow
Baker et al. (2007)
OSIRIS
= OS + IRI
OH (8-3)
OH(9-4)
OH(5-1)
OH (3-1)
Sheese et al. (2014)
OH nightglow
Wave analysis:
not the focus of today!
Gaussian approx.
Peak intensity
Peak height
Thickness (fwhm)
Seasonal Variability
AO
SAO
Northern hem. is shfted by 6 months
Peak intensity
March > September equinox?
Dec < Jun solstice?
(Gao et al. 2010)
Seasonal Variability
AO
SAO
Northern hem. is shfted by 6 months
Peak height
Thickness
Note: Vertical scales are different!
Winter is expected to be lower
Seasonal Variability
- AO, SAO signatures in OH are well studied
- AO: downward transport of O -> more O3 -> [OH]
- Rare to find studies focus on OH in the polar regions
- Inter-hemispherical asymmetry
- Complex. Unclear.
- O3 + H -->(T) OH* + O2
- [O3] proportional to [O]
- GW, planetary wave...
Please suggest studies about OH at the poles...
Solar cycle
O3 + H -->(T) OH* + O2
More sun activity,
more O (O3), warmer T,
more OH?
- [Weill 1973, Batista et al. 1994, Pertsev 2009] shows OH intensity has a positive correlation with solar activity. Agrees with SABER data between 2002-2009 [Gao et al. 2010].
- [Liu & Shepherd 2006] argues that the emission altitude will be higher with increasing solar flux, in response to a stronger production of O.
From WINDII
- But SCIAMACHY [von Savigny 2015] failed to demo solar influence using this
Solar cycle
More sun activity,
more O (O3), warmer T,
more OH?
Solar cycle
More sun activity,
more O (O3), warmer T,
more OH?
Solar cycle
More sun activity,
more O (O3), warmer T,
more OH?
Solar cycle
O3 + H -->(T) OH* + O2
More sun activity,
more O (O3), warmer T,
more OH?
More sun activity,
more O2 heating,
more H escape to space?
Complicated, an open question.
Literature recommendation please...
Latitude dependence?
SSW
SSW
Limpasuvan et al. 2016
SSW
Sheese et al. 2014
Although the study is focused on peak hight climatology, not SSW
SSW
IRI OH has the high potential to study SSW-ES!
ES: elevated stratopause
Thanks to the fantastic polar coverage and longterm observations of Odin.
osIRIs, OH!
Great data to study
- SAO, AO variations
- any artefacts due to lock in 6-18h?
- clear evidence of solar cycle influence
- how? why?
- SSW
- captured four events!
Valuable dataset for ground-based OH measurements
SSW
