dyrland

High-latitude atmospheric gravity waves
observed in images of OH airglow
& some other stuff
Margit Dyrland
The University Centre in Svalbard
(Now visiting scholar at the Centre of Atmospheric and Space sciences, Utah State University)
&
Fred Sigernes (UNIS), Chris Hall (UIT), Mike Taylor & Dominique Pautet (USU)
5th NDMC meeting
Oberpfaffenhofen, 8-9. May 2012
Instrumentation
 The KeoSentry4ix imager is
designed to image near-infrared
emissions from the OH(6-2) band of
airglow.
KeoSentry4ix airglow imager. (1) Mamiya RB67
fish-eye lens, (2) collimator lens, (3) filter
wheel, (4) Smart motor system, (5) relay optics,
and (6) CCD detector.
 The 1m EbertFastie spectrometer
in use at Svalbard
since early 80’s.
 The Nippon/Norway Svalbard
Meteor Radar (owned by NIPR and
operated by UiT).
OH airglow imaging the first two seasons
Exposures in sequence that takes ~8 minutes to complete:
•
•
•
•
•
•
[CH1] Blocked (dark images) (2 min)
[CH2] Wide 750-1000nm + notch filter @ 844.6nm;
BP 18.5 nm (30sec)
[CH3] Bandpass filter @ 844.6nm; BP 1.8 nm (2min)
[CH4] Open (VIS & NIR) (2sec)
[CH5] Bandpass filter @ 846.5nm; BP 1.8 nm (2min)
[CH6] Bandpass filter @ 840.0nm; BP 1.8 nm (2min)
Filter in CH2 was chosen to notch away the OI
844.6nm auroral line – not very successful..
First season: 1024x1024 pixels
Second season: 512x512 pixels (2x binning on chip)
KeoSentry4ix airglow imager
hanging underneath the acrylic
dome at KHO (note the aluminium
dome cover is on).
Initial image analysis
Raw images converted from .img format to .tif by IDL
1. Identify wave events
(not always easy..)
2. Remove stars from images
3. Calibrate images
4. Unwarp images
N
E
W
Example: Data from 24 January 2012
01:00-01:14
S
Analysis of wave event 24 January 2012 00:3001:24 UT (auroral event after that)
Phase speed: 47.5 m/s
Direction: 305°
Horiz. wavelength: 25 km
Period: 8,8 min
Gravity wave activity 19-25 January 2012
9 wave events
____________
Phase speeds: 17-47 m/s
Horiz. wavelengths: 11-39 km
Periods: 6-17 min
Mainly northward direction.
Example of wideband NIR images (22 Jan 2012)
Simultaneous meteor wind radar
measurements
Daily averaged mean
wind @ 82-91 km
Zonal wind mainly
eastward in our time
period. So intrinsic
horizontal phase
speed is even larger
than the observed.
And for 22 January,
zonal wind is
westward (and wave
propagated eastward).
Summary of wave properties
Date
19.01.2012
19.01.2012
22.01.2012
22.01.2012
23.01.2012
23.01.2012
24.01.2012
24.01.2012
25.01.2012
Time (UT)
16:05
21:20
03:35
04:03
20:48
21:15
00:53
04:15
02:36
Phase speed
(m/s)
31,4
17,5
41,8
35,3
37,5
38,5
47,5
44,0
24,8
Wavelength (km)
10,9
17,5
31,5
18,8
34,5
21,7
24,9
39,4
18,6
Direction (°)
37,7
16,9
312,9
3,6
293,6
295,6
304,5
281,3
227,5
Period (min)
5,8
16,7
12,6
8,9
15,3
9,4
8,7
14,9
12,5
Intrinsic phase speed
(m/s)
33,2
19,4
40,0
33,3
42,4
43,6
61,2
64,4
34,1
Temperatures measured during the
2011/2012 winter season
Wind influence on temperature
All 2011-2012
season 
15-31 January
Cause of signature in mesopause temperature?
Minor stratospheric warming – peak in mid January?
Solar proton events?
Summary
- Two seasons of data obtained from all-sky airglow
imager at Longyearbyen (78°N).
- A bit disappointing s/n ratio. Difficult to identify clear
wave structures.
- Most waves observed propagate northward.
- A good season for the spectrometer :o)
- Temperatures agree well with Alomar AMTM
temperatures (not shown).
- There seems to be a relationship between meridional
wind strength and direction, and the temperature. For
certain conditions.
Further work
- Still a lot of data to analyze..
- Investigate the propagation characteristics of the
waves observed (freely propagating, ducted etc.)
- Compare with Alomar and Antarctic data.
- Explore the cameras potential as a temperature
mapper.
OH(6-2) P1(2) emission 
19 January 2012
Trend paper just published:
Temperature trends at 90 km over Svalbard, Norway (78°N 16°E), seen
in one decade of meteor radar observations
C.M. Hall, M.E. Dyrland, M. Tsutsumi, and F.J. Mulligan
JGR Atmospheres, VOL. 117, D08104, 8 PP., 2012
doi:10.1029/2011JD017028
Negative temperature
trend of -4 ± 2 K per
decade found after
seasonal and solar cycle
dependence were
substracted.
Meteor radar temperatures “calibrated” by Aura MLS temperatures.
A negative trend in pressure (expected) is shown to augment the cooling.
Thank you for your attention!