IAGA: AUGUST, 2013, Merida, Mexico, PAPER J7-11

LARGE MESOPAUSE BRIGHTNESS EVENTS, OBSERVATIONS AND EXPLANATIONS

Bright, wall, or large amplitude planar wave events in airglow

Very bright, single planar event (but period 1.5-7 hours, same as a medium scale gravity wave present with the same intrinsic phase speed, and horizontal alignment as the the medium scale gw present)

Leading dark (cooling) followed by sharp brightening (warming)

A large amplitude wave, or a large instability overturning event (billow) (note, the instability ‘surfs’ on the medium scale wave)

Gary Swenson1, Alan Liu2, Mike Taylor3, Dominique Pautet3, Fabio Vargas1, Tony Mangognia1

1: University of Illinois2: Embry Riddle University

3: Utah State University

Waves (AGWs) and Airglow Response

WAVE ExamplesAug 9, 1993 (ALOHA, Aircraft, Swenson and Espy) and August 10, 93 (ALOHA-Taylor et al.)*Aug 12, 2004, Li et al., 2005 (Maui, 22o N)*

Others observed by lidar, MauiJan 24, 2012 (Cerro Pachon, Chile, 30o S)

SummaryLarge amplitude, medium scale gravity wave coupling with a large amplitude tide,for a single planar wave.

Both Convective and Shear Instabilities Result

OH O2(b) O (1S)

Fig. 4

Vargas et al., 2007.

Mesospheric Airglow Layers

Mesosphere, Lower ThermosphereRemote Sensing Instrumentation Andes Lidar Observatory (ALO)(Cerro Pachon, Chile, 30o S)

Na Doppler Lidar (U of I; Liu,ERAU)OH Temperature Mapper (Taylor, USU)Meteor Radar (Franke, U of I)OH, 90o imager, 1.6μ (Hecht, Aerospace)OH, Na, O2, O(1S) Allsky Imager (U of I)Multi-Channel Photometer, Zenith, OH, O2, O(1S), BG (Mangognia, U of I)

August 9, 93 (ALOHA, Aircraft, Swenson and Espy)

August 10, 93 (ALOHA-Taylor et al.)*

Note:Direction of propagation, and event time of the‘wall’ of airglow was ~23.5 hours after the Aug 9 event.

O2 OH

Analysis showed that this event was caused by a large-amplitude, upward-propagating gravity wave with a period of about 4–5 hours and a vertical wavelength of about 20 km, i.e., a ‘‘wall’’ wave.

This wall wave induced dramatic changes in temperature (T’/T 30 K), airglow intensity (doubled in the OH and tripled in the O2 emissions), and Na abundance (tripled).

Feng Li et al., Investigation of a ‘‘wall’’ wave event, JGR,2007

Li et al., 2005 (Maui)* (Zonal, propagated from West)

Superadiabatic

80

90

100

Altitude(km)

150 250Temperature (K)

Convective Instabilites

Swenson et al., 1998

Dynamic Instabilites

F. Li et al., 2005

Δt~45 min

.

Large amplitude for 1 h

h 300-1300 km, ~1.5-7 hours

Trailing, phase front aligned, hf wave

And

Z Inversion, dT/dz = 0

LAW zone

Large Amplitude Wave

Cool--WarmDim-Bright

Other Maui Waves

MCP data

O(1S)

OH

λx = 100 kmλz = 16 kmΦ = 349 °τo= 132 minco= 15 m/s(from NNW)

3 4 5 6 UT

Temperature Mapper Keogram

OH Temperature

Bright EventN-S

E-W

4 5 6 7 8 9

Time, UT

3 4 5 6 7 8

Summary11/14 Event Winds, Z~15 km,consistent with OH and O 1S phase. 60 m/s phase speed, AGW~6 hr wave; h = 1300 km

Events--Common features:Z (and phase speeds)-Similar, 15-20 km.All source directions from NW or W*All events have downward phase progression below

T inversionh varies-300 to 1300 km, + trailing SS waves All have one, large magnitude, ~1 h leading feature

Upwelling then downwellingT, cold then warm; Airglow dim then brightThickness of the ‘enhanced’ wave 4-8 km.

01/24/2012 Cerro Pachon Event, Forced instabilities, a surfing billow?

Wall Waves

• Spatial x=150-400 km, y= 1000’s km, z=5-10 km• Temperature T, 30K cooling, followed by warming• AGW couples with tide to force instability• Large scale, well capable of bubble scale• Observed in mesopause region (90-105 km)• Predicted for next tidal VWL, i.e. 115-130 km• In Northern Hemisphere, propagate from NW-SE

Observe and study with ICON

• Readily observed along the phase front• T profiles from 90-150 km• Plot T separately from both FOV of Mighty