Recent results on gravity wave
penetration to the
thermosphere and ionosphere
Kazuo Shiokawa, Yuichi Otsuka, and Shin Suzuki
(Solar-Terrestrial Environment Laboratory,
Nagoya University)
CAWSES-II
(Climate And Weather of the Sun-Earth System - II)
http://www.cawses.org/wiki/index.php/Main_Page
International programs operated by SCOSTEP
1976-1979: IMS (International Magnetosphere Study)
1982-1985: MAP (Middle Atmosphere Program)
1990-1997: STEP (Solar-Terrestrial Energy Program)
1998-2002: Post-STEP（S-RAMP, PSMOS, EPIC, and ISCS)
2004-2008: CAWSES (Climate and Weather of the Sun-Earth System）
2009-2013: CAWSES-II (Climate and Weather of the Sun-Earth System-II）
TG1. What are the solar influences on climate?
TG2. How will geospace respond to an altered climate?
TG3. How does short-term solar variability affect the geospace
environment?
TG4. What is the geospace response to variable inputs from the
lower atmosphere?
Capacity building
Escience and informatics (Virtual Institute)
TG 4 – Overall Objective
TG4 will elucidate the dynamical coupling
from the low and middle atmosphere to the
geospace including the upper atmosphere,
ionosphere, and magnetosphere, for various
frequencies and scales, such as gravity
waves, tides, and planetary waves, and for
equatorial, middle, and high latitudes.
An essential part of TG4 is to encourage
interaction between atmospheric and plasma
scientists!
TG4 Newsletter, Web page, and Mailing lists
encourage interaction between
atmospheric and plasma scientists!
Web page: http://www.cawses.org/wiki/index.php/Task_4
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TG4 Newsletter (editor: Michi Nishioka)
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Articles , Short news, Young scientists, Meeting
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Gravity Waves
ionosphere
thermosphere
F layer
630nm airglow
secondary
gravity
waves
electron
density
E layer
mesopause
OH airglow
wave breaking and
momentum flux release
mesosphere
atmospheric
temperature
troposphere
gravity waves
tropospheric
disturbance
Penetration of
sound waves and
gravity waves
caused by tsunami
into the ionosphere.
Tsugawa et al. (EPS,
2012)
Possible path of GW to
the thermosphere
from convective plume
(top) and results of
model calculation
(right)
Vadas and Crowley
(JGR, 2010)
Evidence of small-scale ducting waves in the mesopause region
thermosphere
atmospheric
temperature
OH airglow images at
altitudes of 80-90km
mesopause
OH airglow
mesosphere
gravity waves
Suzuki et al. (submitted to GRL, 2012)
troposphere
tropospheric
disturbance
630nm
OH
Smith et al.
(JGR, 2013)
Mapped on 87 km
(630nm is not contamination from OH)
630nm airglow
secondary
gravity
waves
wave breaking and
OH airglow
momentum flux release
gravity waves
tropospheric
disturbance
Gravity Waves
ionosphere
thermosphere
F layer
630nm airglow
secondary
gravity
waves
electron
density
E layer
mesopause
OH airglow
wave breaking and
momentum flux release
mesosphere
atmospheric
temperature
troposphere
gravity waves
tropospheric
disturbance
Makela et al. (GRL, 2010)
Takahashi et al. (AnnGeo, 2009)
Correlation between plasma bubble
spacing and mesospheric GW scale
Correlation between plasma
bubble spacing spectrum (bars)
and modeled GW scale (line by
Vadas and Crowley, 2010)
Ogawa et al. (EPS, 2005)
Tsunoda et al. (GRL, 2010)
Close relationship between large-scale wave structure (LSWS) and
the equatorial spread F (ESF)/plasma bubbles, when the post-sunset
rise (PSSR) of the F layer was absent.
Medium-Scale Traveling Ionospheric Disturbances
(MSTIDs)
Saito et al. (GRL, 1998)
MSTID on GPS map
Kubota et al.(GRL, 2000); Saito et al. (GRL, 2001)
MSTID observation using multi-point 630nm airglow imaging
Shiokawa et al. (JGR, 2003a)
Statistics in Japan
summer
mesopause region (80-100km)
control factor:
wind filtering
ducting?
source location
Shiokawa et al.
(EPS, 2009)
winter
thermosphere (200-300km)
northern/southern midlatitudes
equatorward/westward waves, conjugacy
 instability?
equatorial latitudes
southward waves  gravity waves?
1．Perkins instability
Generation of MSTIDs
2．Gravity waves
ionosphere
MSTID
gravity waves
atmospheric
disturbances
Perkins (1973)
NW-SE phase
surface
Questions:
How the nighttime MSTID are created?
(gravity wave or Perkins instability?)
Why they propagate only to southwestward?
Oscillating E-field
associated with
MSTIDs
 Suggesting
Perkins instability
Shiokawa et al.
(JGR, 2003b)
Sata
Darwin
Otsuka et al. (GRL, 2004)
Shiokawa et al.
(JGR, 2003b)
Linear growth rate of Perkins instability is too small.
Otsuka et al. (JGR, 2007) Es-layer and MSTID
Es layer
F layer
Yokoyama et al. (JGR, 2009) Coupling of E and F layers
・Es-layer creates the seed of MSTIDs, F-layer Perkins instability amplifies the MSTIDs
・Southward wind in the Es layer makes southwestward MSTID propagation.
140km
140km
Neutral wind
Vew
80km
south
west
Ne
Vns
north
east
80km
N
Larsen et al. (GRL, 1998)
Es layer during the SEEK rocket campaign
southward wind is expected at the center of the Es
layer if Es wind shear is caused by tides.
110km
100km
S
Neutral
wind
E
Questions:
How the nighttime MSTID are created?
(gravity wave or Perkins instability?)
Coupled E-F instability can create MSTIDs at
middle latitudes
Why they propagate only to southwestward?
Southward wind in the Es layer makes
southwestward motion of MSTIDs.
Aug.19, 2007
1010-1636UT
(1910-0236LT)
630nm (ch.2)
Paratunka,
Russia
Shiokawa et al.
(JGR, 2008)
NE
SW
NE
SW
Shiokawa et al. (JGR, 2008)
summer
winter
・low-latitude boundary of mid-latitude MSTID
Okinawa (MLAT=18N) MSTID (top) and no MSTID but
equatorailanomaru (bottom) Shiokawa et al. (EPS, 2002)
Collision of MSTID and bubble
Otsuka et al. (GRL, 2012)
KTB（MLAT=10S) only one middle-latitude type MSTID event for 7-years
raw data
deviation from 1-h
running averages
period: ~40min,
phase velocity: ~300m/s
Shiokawa et al.
(JGR, 2006)
Fukushima et al. (JGR, 2012)
Fukushima et al. (JGR, 2012)
summer
winter
summer
winter
Kubota et al.
(JGR, 2011)
Kubota et al. (JGR, 2011)
Neutral wind is northward  Opposite to Perkins
Instability. GW from aurora?
summer
winter
Kubota et al.
(2004)
occurrence rate
Tromso: Half of
them are
southwestward,
but other are
EASTWARD!
fossil after
instability?
Shiokawa et al.
(JASTP, submitted, 2013)
Eastward-moving MSTIDs at Tromsoe
Shiokawa et al. (JASTP, 2013)
Sudden motion of MSTIDs at subauroral latitudes (E-field penetration) in 630nm airglow images
Tromsoe, Dec.8, 2009 15-19 UT (16-20 LT)
Shiokawa et al. (JGR, 2012)
15UT
Dec. 8, 2009 15-19UT
19UT
summer
winter
Kubota et al.
(2004)
Summary
CAWSES-II TG4: What is the geospace response to variable
inputs from the lower atmosphere?
Results are coming out showing significant penetration of
atmospheric waves into the ionosphere in all frequency ranges
(acoustic waves, gravity waves, tides, and planetary waves (SSW)).
For all scales, controversy tends to occur between
(1) Direct penetration of atmospheric waves into the thermosphere
and then to ionosphere (M  T  I)
(2) Electromagnetic coupling from E to F region and then to the
thermosphere (M  I  T)
MTI or MIT: Which is more important for what case?
The source of MSTIDs seems to be different at different latitudes.
equatorial latitudes: direct penetration of gravity waves
middle latitudes: coupled Perkins and E-F layer instability.
near the auroral zone: auroral E-field and auroral heating may also
affect the generation and propagation of MSTIDs.