Study on the impact of sudden stratospheric
warmings in mid-latitude MLT region
according to ground-based and satellite
temperature measurements
Medvedeva I.V.(1), Semenov A.I.(2)
Chernigovskaya M.A.(1), Perminov V.I.(2)
1 - Institute of Solar-Terrestrial Physics (ISTP), Siberian Branch, Russian
Academy of Sciences, Irkutsk, Russia;
2- Obukhov Institute of Atmospheric Physics (IAP), Russian Academy of
Sciences, Moscow, Russia
e-mail: ivmed@iszf.irk.ru
38th annual European Meeting on Atmospheric Studies by Optical Methods,
Siuntio, Finland, 22-26 August 2011
Sudden stratospheric warmings (SSW) are an
important manifestation of vertical dynamical
coupling in the atmosphere. During strong SSW
variations of dynamic and temperature regime in
the middle atmosphere are observed, the
disturbances during SSW cover large atmospheric
range from troposphere to MLT heights.
• Major SSW occur when the westerly winds at 60N and
10hPa (geopotential height) reverse, i.e. become
easterly (westwards). A complete disruption of the
polar vortex is observed.
• Minor SSW are similar to major warmings however
they are less dramatic, the westerly (eastward) winds
are slowed, however do not reverse. Therefore a
breakdown of the vortex is never observed.
Background
It is known that mesospheric coolings are associated
with SSWs.
The key mechanism by Matsuno (1971) is now widely accepted: the
growth of upward propagating planetary waves from the troposphere and
their interaction with the mean flow. Liu and Roble (2002) predicted
mesospheric cooling extending up to the heights of ~ 110 km with a
secondary warming between 110-170 km.
Experimental results confirmed impact of SSW on MLT region were
presented in (Myrabo et. al., 1984; Matveeva & Semenov, 1985;
Walterscheid, 2000; Sigernes et al., 2003). Using the data of OH
rotational temperature the authors revealed the mesopause
temperature decrease.
Background
However, association between SSW events and the MLT region is not
fully understood.
• Questions about the timing of stratospheric and mesospheric
disturbances remain. Myrabo et al. (1984) report a 1–2 day delay
in the mesospheric response to a stratospheric event, and
Hernandez (2004) suggests the mesosphere cooling is a 1–2
month leading indicator of stratospheric warmings, while the
model result of Liu and Roble (2002) indicates little, if any, phase
lag or lead between the temperature anomalies in the mesosphere
and stratosphere.
•
The height distribution of mesosphere cooling associated with
SSW events is also not yet well established. Thus, (Siskind, et.al.,
2005) using the SABER temperature data revealed that
mesospheric temperatures between 0.7 hPa and 0.01 hPa (~52-80
km) show a significant anticorrelation with stratospheric
temperatures during SSW. However, for pressures <0.01 hPa, this
anticorrelation breaks down and near 0.002 hPa (~88 km), which
is the pressure associated with the peak of the OH* emission, the
correlation coefficient is close to zero or slightly positive, in
disagreement with calculations of Liu and Roble (2002).
Objective
- Study of variations in atmospheric temperature at the MLT heights during the
winter stratospheric warming in 2008-2011 using ground-based and satellite
measurements data;
- Comparison of satellite and ground-based measurements data on
temperature at MLT height
The study is based on measurements of the atmospheric temperature,
obtained in different longitudinal zones – Irkutsk (52N, 103E) and
Zvenigorod (56N, 37E)
Analyzed Data :
data about the variations of mesopause temperature (~87 km)
obtained from ground-based spectrographic measurements of
the OH emission (834.0 nm, band (6-2)) at ISTP and IAP
observatories near Irkutsk (52N, 103E) and Zvenigorod (56N,
37E) respectively;
satellite data on vertical temperature distribution in the
atmosphere from MLS (Microwave Limb Sounder) aboard the
spacecraft EOS Aura
[http://disc.sci.gsfc.nasa.gov/Aura/MLS/index.shtm];
ECMWF stratosphere temperature data presented by
Stratospheric Research Group of FU Berlin [http://stratwww.met.fu-berlin.de/cgi-bin/winterdiagnostics];
data on zonal temperature and wind of NCEP GDAS and CPC
[http://www.cpc.noaa.gov/products/stratosphere/strat-trop];
annual NCEP data for the Northern Hemisphere [http://acdbext.gsfc.nasa.gov/Data_services/met/ann_data.html]
Analyzed Data
Mesopause temperature in Irkutsk and Zvenigorod was determined using
the emission spectrum of OH(6-2). Measurements and data handling at
both observatories were carried out by the same method. High-aperture
diffraction spectrographs with receivers on the CCD matrix allowing to
register the emission spectrum of the night sky in the near infrared region
with high spectral (~ 2-3 A) and temporal (~ 2 min) resolutions were
used. To determine the rotational temperature we used the first 3 lines of
P-branch of the vibration-rotation band of OH(6-2). The temperature is
determined with 1-2 K accuracy.
High-aperture diffraction
spectrograph SP-50
An example of the emission spectrum of the night
airglow in the area of 780-1030 nm.
Top side – OH and O2 bands.
Maximum temperature of the stratosphere at 10 hPa isobaric level
(~31 km) for each analyzed SSW event
Year
Tmax
Data
Tmax site coordinates
2008
283 K
23.01.08
72.5°N, 90°E
2009
287 K
23.01.09
77.5°N, 40°W
2010
272 K
25.01.10
62.5°N, 122.5°E
2011
273 K
30.01.11
67.5°N, 122.5°E
The mean temperature of winter stratosphere at that altitude in quite
conditions is ~ 210 К
NCEP Data for the Northern Hemisphere.
In January-February 2008, January 2009 and January 2010, there were very
intense, long time winter SSW, covering large part of the Northern
Hemisphere. The SSW in January 2011 was less intense, however wellpronounced in zonal stratospheric temperature at 50 N. SSWs in 2008-2009
are among the most intense events in the Northern Hemisphere since 1978.
Especially remarkable was the SSW in January 2009, when the stratospheric
temperature reached record values. This event is described in a number of
publications (Labitzke, 2009, Harada et al. 2009) . Ellipse – periods of analyzed
SSW events
Zonal Mean Temperature (60-90N)
SSW 2008 - oscillatory nature during period
of about a month
2009
Zonal Mean Temperature (50N)
2010
2011
Zonal Mean Wind 50-80N
2008
2010
2009
Major SSW 2009 – 10 hPa zonal
circulation reversal
SSW in January 2009
3 hPa (~40 km)
10 hPa (~31 km)
Results
Altitude-temporal maps of the atmospheric temperature distribution
according to the MLS AURA for the region of Irkutsk and Zvenigorod
(search radius is 900 km)
2008
During SSW 2008-2011,
stratospheric temperature
disturbances of large spatial
scales were observed.
The temperature disturbances in almost
the entire middle atmosphere and
significant change in the vertical
distribution of temperature occured.
2009
2010
The
largest
temperature
increases were observed in
the stratosphere at altitudes
of 40-50 km. Registered
cooling of the atmosphere at
altitudes
of
MLT
was
distributed very irregularly in
both altitude and time.
Irkutsk, December 2010 - February 2011
01/12/10
100
15/12/10
01/01/11
15/01/11
01/02/11
15/02/11
100
90
90
80
80
70
70
60
60
50
50
40
40
30
30
20
20
305
295
275
265
255
245
235
225
215
205
195
185
175
10
01/12/10
10
15/12/10
01/01/11
15/01/11
01/02/11
15/02/11
165
T, K
Date
15/12/2010; Tmax = 276,5 К (3,5 С); h = 46 km
09/01/2011; Tmax = 267 К (-6 С); h = 46 km
30/01/2011; Tmax = 276 K (3 С); h = 43 km
26/02/2011; Tmax = 266 K (-7 С); h = 49 km
Zvenigorod, December 2010 - February 2011
01/12/10
100
15/12/10
01/01/11
15/01/11
01/02/11
15/02/11
100
90
90
80
80
70
70
60
60
50
50
40
40
30
30
20
20
305
295
285
2011
Height, km
Height, km
285
275
265
255
245
235
225
215
205
195
185
175
10
01/12/10
10
15/12/10
01/01/11
15/01/11
01/02/11
Date
14/12/2010; Tmax = 284,7 К (11,7 С); h = 46 km
08/01/2011; Tmax = 286,5 K (13,5 С); h = 43 km
08/02/2011; Tmax = 278,2 K (5,2 С); h = 46 km
15/02/11
165
T, K
a) Т of the stratosphere
averaged for 3.16-1 hPa
(39-49 km) levels, Aura data;
b) T of the mesopause region
averaged for
0.005-0.002 hPa (84-88 km)
levels, Aura data;
с) Т ОН (~87 km), groundbased data
Zvenigorod: During all analyzed
SSW events decrease in T of the
mesopause region was observed.
Irkutsk: the pattern is not so
well-definite. Thus, during the
period of the SSW 2008,
oscillations of the atmospheric
temperature at altitudes both the
stratosphere and mesopause with
periods of about 6-8 days were
observed.
Quantitative characteristics of the relationship of day-to-day T stratosphere (3949 km) and T mesopause (84-88 km) values during the SSWs has been obtained
by regression analysis of Aura data
Irkutsk: Correlation between
Tmes and Tstr for the SSW
2008 and 2010 practically
absent.
For SSW 2008-2010, Zvenigorod and SSW 2009,
Irkutsk, the regression dependency was revealed:
Tmes= -(0.35±0.04)*Тstr + 288±12,
r - correlation coefficient
r = -0.55,
Probably, this is due to the
longitudinal manifestation of
nature of the interaction of
dynamic
and
thermal
processes during analyzed
periods of SSW. In any case,
this result as the result of the
work (Siskind et. al., 2005),
does not correspond to model
calculations (Liu & Roble,
2002), predicted a steady
decrease in MLT temperature
of up to heights ~110 km
during the SSW.
CrossCorrelation Functions of T strat (39-49 km) and T mes (84-88 km).
First variable: Tstrat, Lagged: Tmes.
2008
Zvenigorod
r=-0.62
2009
r=-0.59
Negative
correlation of
T str and T mes.
Maximal
correlation
coefficients at
Lag=0
2010
r=-0.57
In
the
European
longitudinal zone Tmes
decreased
almost
simultaneously
with
increase of the T strat.
CrossCorrelation Functions of T strat (39-49 km) and T mes (84-88 km).
First variable: Tstrat, Lagged: Tmes.
2008
2010
2009
Irkutsk
In the East Asian longitudinal zone a reaction temperature of the
mesopause on the SSW did not
reveal a stable tendency.
Manifestations of the influence of
SSW on the mesopause region in
the East Asian longitude zone is
more complicated than in the
European one.
Altitude of the mesopause is
changing as altitude of the
stratopause change also. We
compared the ratio of the
temperatures of the
stratopause and mesopause, at
the altitudes where mesopause
and stratopause were located
each day. The value of this ratio
changed from 1.1 up to 1.9
during analyzed SSWs.
This ratio could be probably
used as quantitative
characteristic of manifestation
of the complicated processes
of interaction between lower
and upper atmosphere during
SSW events.
Conclusions
•
The analysis of the atmospheric temperature variations according groundbased and satellite data during the events of winter stratospheric warming
in 2008-2011 revealed a disturbances in the middle atmosphere from the
stratosphere to the mesopause.
•
Regression and correlation dependency of day-to-day temperatures of the
stratosphere and mesopause during the SSW were obtained. It was
revealed that manifestations of the influence of SSW on the mesopause
region in the East Asian longitude zone is more complicated than in the
European one. In the European longitudinal zone Tmes decreased almost
simultaneously with rise of the T strat. In all these SSW events, when the
stratospheric temperature increases by ~ 30 K, the temperature in the
mesopause decreased by ~ 20 K. In East Asia - a reaction of the
mesopause temperature on the SSW did not reveal a stable tendency.
These results may indicate on a possible longitudinal effect of SSW on the
thermal and dynamic regimes of the middle and upper atmosphere.
•
The ratio of the temperatures at the stratopause and mesopause, at the
altitudes where mesopause and stratopause be located each day was
analyzed. This ratio could be probably used as quantitative characteristic
of manifestation of the complicated processes of interaction between
lower and upper atmosphere during SSW events.
•
Comparison of satellite and ground-based data on mesopause temperature
showed a pretty good agreement
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Thanks for attention!