The Internal Structure of Asteroid (25143) Itokawa as Revealed by Detection o...
SRS2015-Pugmire
1. Observations of mesospheric
gravity waves over the andes
Jonathan Pugmire
Center for Atmospheric and Space Sciences
Utah State University
Student Research Symposium
April 9, 2015
17. 0 60 120 180 240 300 360
0
10
20
30
TemperatureVariance(K2
)
Day
– 87 km
– 67 km
– 42 km
2010 temperature variances over
the Andes
87 km average: 9.6 K2
WinterIncreased wave activity observed
from space during the winter
along with fall and spring
20. References
• Eckerman, S.D. and P. Preusse (1999), Global Measurements of Stratospheric Mountain Waves from Space, Science,
286, 5444, 1534-1537.
• Fritts, D.C., and M.J. Alexander (2003), Gravity wave dynamics and effects in the middle atmosphere. Review of
Geophysics, 41, 1/1003.
• Goldman, A., Schoenfeld, W.G., Goorvitch, D., Chackerian Jr., C., Dothe, H., Me1en, F., Abrams, M.C., Selby, J.E.A.
(1998), Updated line parameters for the OH X2 П -X2П (v",v') transitions. J. Quant. Spectrosc. Radiat. Transfer, 59,
453-469.
• Jiang, J. H., Wu, D. L., & Eckermann, S. D. (2002). Upper Atmosphere Research Satellite (UARS) MLS observation of
mountain waves over the Andes.Journal of Geophysical Research: Atmospheres (1984–2012), 107(D20), SOL-15.
• John, S.R., and Kumar, K.K. (2012), TIMED/SABER observations of global gravity wave climatology and their
interannual variability from stratosphere to mesosphere lower thermosphere, Climate dynamics, 39(6), 1489-1505
• Meriwether, J.W. (1984), Ground based measurements of mesospheric temperatures by optical means. MAP
Handbook 13, 1-18.
• Pendleton Jr., W.R., Taylor, M.J., Gardner, L.C. (2000), Terdiurnal oscillations on OH Meinel rotational temperatures
for fall conditions at northern mid-latitude sites. GRL 27 (12), 1799-1802.
• Reisin, E. R., & Scheer, J. (2004), Gravity wave activity in the mesopause region from airglow measurements at El
Leoncito. Journal of Atmospheric and Solar-Terrestrial Physics, 66(6), 655-661.
• Remsberg, E. E., et al. (2008), Assessment of the quality of the Version 1.07 temperature-versus-pressure profiles of
the middle atmosphere from TIMED/SABER, J. Geophys. Res., 113, D17101, doi:10.1029/2008JD010013.
• Russell III, James M., et al. 1999, Overview of the SABER experiment and preliminary calibration results. SPIE's
International Symposium on Optical Science, Engineering, and Instrumentation. International Society for Optics and
Photonics Conference
• Taori, A. and M.J. Taylor (2006), Characteristics of wave induced oscillations in mesospheric O2 emission intensity and
temperature, Geophys. Res. Lett., 33.
• Zhao, Y., M. J. Taylor, and X. Chu (2005), Comparison of simultaneous Na lidar and mesospheric nightglow
temperature measurements and the effects of tides on the emission layer heights, J. Geophys. Res., 110, D09S07,
doi:10.1029/2004JD005115.
• Zhao, Y., Taylor, M.J., Liu, H.-L., Roble, R.G. (2007), Seasonal oscillations in mesospheric temperatures at low-
latitudes. JASTP 69, 2367-2378.
24. OH Rotational Temperature
OH (6,2) Band
))]4(/)2((ln[ 11 PPstuff
SomeNumber
TOH
Goldman et al., 1998
2 K Precision
25. Step 3: At each height estimate waves
with wavenumber 0-6.
26. Step 3: At each height estimate waves
with wavenumber 1.
27. Step 3: At each height estimate waves
with wavenumber 2.
28. Step 3: At each height estimate waves
with wavenumber 3.
29. Step 3: At each height estimate waves
with wavenumber 0-6.
Notas del editor
Atmosphere is “Stable”
Wind is perpendicular to mountain range
Strong winds
Stably stratified air that is lifted over mountains oscillates about its equilibrium level on the lee side of the mountain, producing waves.
Vertically propagating mountain waves have their highest amplitude well above the mountains. High lenticular clouds are often indicated of these waves.
Trapped less waves reach their highest amplitudes in the lee of mountains.
The above discussed equations of motion predict that vertical displacement of a flow almost always leads to the generation of AGWs. Terrain-generated gravity waves are created when stably stratified wind flows over terrain obstacles such as ridges, hills and mountains as well as depressions such as canyons, basins and valleys. Two types of terrain-generated waves exist: lees waves and mountain waves. Lee waves extend downwind from the ridge and are trapped in a layer close to the ground, and so their influence of the atmosphere above is negligible. Mountain waves (MWs) or orographically forced waves are terrain-generated gravity waves that propagate towards the middle and upper atmosphere transporting energy and momentum. This is an essential component of the global circulation. The spectrum of MWs is as wide as the spectrum of terrain widths. The amplitudes of MWs are proportional to the amplitude of the terrain as illustrated in Figure 4.
MWs are stationary relative to the ground surface, and they do not experience dispersion. All the waves have the same phase velocity, which is zero. Thus standing waves develop and amplitude of the mountain wave can grow as they move upward and eventually break or saturate. This breakdown, like waves on a beach, results in turbulence, commonly referred to as clear air turbulence (CAT) as shown in Figure 5.
MWs are stationary relative to the ground surface, and they do not experience dispersion. All the waves have the same phase velocity, which is zero. Thus standing waves develop and amplitude of the mountain wave can grow as they move upward and eventually break or saturate. This breakdown, like waves on a beach, results in turbulence, commonly referred to as clear air turbulence (CAT) as shown in Figure 5.
Stably stratified air that is lifted over mountains oscillates about its equilibrium level on the lee side of the mountain, producing waves.
Vertically propagating mountain waves have their highest amplitude well above the mountains. High lenticular clouds are often indicated of these waves.
Trapped less waves reach their highest amplitudes in the lee of mountains.
The above discussed equations of motion predict that vertical displacement of a flow almost always leads to the generation of AGWs. Terrain-generated gravity waves are created when stably stratified wind flows over terrain obstacles such as ridges, hills and mountains as well as depressions such as canyons, basins and valleys. Two types of terrain-generated waves exist: lees waves and mountain waves. Lee waves extend downwind from the ridge and are trapped in a layer close to the ground, and so their influence of the atmosphere above is negligible. Mountain waves (MWs) or orographically forced waves are terrain-generated gravity waves that propagate towards the middle and upper atmosphere transporting energy and momentum. This is an essential component of the global circulation. The spectrum of MWs is as wide as the spectrum of terrain widths. The amplitudes of MWs are proportional to the amplitude of the terrain as illustrated in Figure 4.
MWs are stationary relative to the ground surface, and they do not experience dispersion. All the waves have the same phase velocity, which is zero. Thus standing waves develop and amplitude of the mountain wave can grow as they move upward and eventually break or saturate. This breakdown, like waves on a beach, results in turbulence, commonly referred to as clear air turbulence (CAT) as shown in Figure 5.
Airglow – camera looks in the infrared. Each molecules produces light that is a distinct color or wavelength. Hydroxyl, OH, has a distinct signature.
ALO, Chile
UT Day 258 2012 (LT September 13 - 14 dt = -4 hrs)
MWFM is a parameterization that operates diagnostically on gridded atmospheric winds and temperatures. A key feature is the decomposition of global topography into a
list of quasi-two-dimensional ridges, each with a characteristic width, length, height, horizontal orientation and quality (degree of two-dimensionality) that define the types of
mountain waves forced by directional flow over the feature. Surface winds blowing over these ridges are used to calculate the spectrum of mountain waves at the surface.
From November 2001 to December 2006 the MTM instrument suite operated from the Air Force AMOS facility near the summit of Haleakala Crater, Maui, Hawaii (altitude 2970 m, 20.8°N, 156.2° W) [Zhao et al., 2005]. Temperature comparisons with the MTM and SABER were conducted from Maui. The MTM in Maui had an average temperature of 202.2 K and SABER’s average temperature was 197.0 K. They had a similar difference of 5.2 ± 0.2 K. What is of interest is the amount of variation that is apparent at ALO as opposed to Maui. The temperature difference between SABER and ALO measurements had a standard deviation of 16.9 K, where Maui’s had a standard deviation 8.9 K. This may be due to the increased mountain wave activity observed at ALO. This is shown in the two histograms in Figure 8 with Gaussian fits. Further investigation of evidence of mountain wave activity is ongoing.
87 km : 9.6, 67 km average: 3.54K^2, 42 km average 0.86
Mountain waves in the mesosphere are a relatively unexplored field.
Temperature variances increase due to mountain waves in winter and other sources in spring/fall.
SABER temperature variance technique has high potential for investigating gravity wave effects with other ground-based measurements around the world.
Use SABER data measure temperature variance to observe vertical propagation of mountain waves and study under what conditions they break or saturate.
Compare SABER measurements with ground-based observations of mountain waves over the Andes: July 1-8, 2008, July 22-23, 2011.
Use SABER to study other locations (Maui, Bear Lake, New Zealand, etc.) for quantitative ground-based comparison of mountain wave activity.
Use SABER data measure temperature variance to observe vertical propagation of mountain waves and study under what conditions they break or saturate.
Compare SABER measurements with ground-based observations of mountain waves over the Andes: July 1-8, 2008, July 22-23, 2011.
Use SABER to study other locations (Maui, Bear Lake, New Zealand, etc.) for quantitative ground-based comparison of mountain wave activity.
Wave phenomena are prevalent in planetary atmospheres and are a result of perturbations. They are induced by both external and internal sources. Waves can be classified into two main groups based on the spatial scale length of the wave. There are large scale waves known as planetary waves and tides. They are both global in nature and exhibit coherent patterns in both latitude and longitude. Planetary waves are caused by the coriolis effect. Tides have to do with solar radiation.
On a smaller scale atmospheric gravity waves (AGW) are generated due to buoyancy forces in the atmosphere. AGW usually have local sources and propagate with limited range of wavelengths. The sources of AGW are in the stratosphere and mesosphere and they propagate into the thermosphere. AGW can also be generated from thunderstorms, volcanoes, earthquakes, the jetstream, and the flow of air over mountains. They can also be generated at high altitudes. AGW have been studied for the last 50 years starting with the pioneering work of Hines (1960) and the study continues to intensify with quantitative advances in our understanding of AGW and advances in observational and computational techniques and capabilities. AGWs have a myriad of effects and are major contributors to atmospheric circulation, structure, and variability.
Ship waves… Amsterdam Island in the far southern Indian Ocean
All-sky imager, OH June 11, 2010, 300km by 300km
Figure 3. Emissions given by different OH vibrational mode transitions. The ratio of the P1(2) to P1(4) emissions (highlighted in red) is used to measure OH rotational temperature.
To date, over 1100 nights of quality data have been obtained, providing detailed information on the nocturnal and seasonal behavior of mesospheric temperature and its variability at the OH emission height.
Relative intensity measurements of the selected OH emission lines are used to determine absolute rotational temperatures with high precision ~1-2 K using the well-established ratio method [e.g. Meriwether, 1984, Goldman et al., 1998]. Based on typical OH emission levels measured at Cerro Pachon, the precision of the measurements were determined to be <1-2 K (in 2 min) for the derived OH rotational temperatures.
Relative band intensity from (S1c+S2c) and Temperature using simplified Local Thermodynamic Equalibrium calculation.
Figure 2. Picture of all-sky imaging system. Fish eye lens at top, followed by filter wheel. CCD imager and cooling system are positioned at bottom.
The CEDAR MTM is a high performance imaging system capable of precise measurement of the intensity and rotational temperatures of the near infrared OH and O2 nightglow emission layers. The MTM uses a high quantum efficiency CCD array coupled to a wide-angle telecentric lens system (90° field of view centered on the zenith) to observe selected emission lines in the OH(6,2) Meinel band as shown in Figure 3. Sequential measurements were made using a set of narrow band filters centered on selected emission lines, eg. the OH(6,2) P1(2) and P1(4) rotational emission lines at 840 and 846.5 nm respectively. Each emission is observed for 30 sec followed by a background sky measurement at 857 nm, resulting in a cycle time of ~2 min. The camera operates automatically from dusk to dawn (for solar depression angles >12°) for approximately 23 nights each month (centered on the new moon period). Data are stored locally on computer disk and are downloaded at regular intervals to USU for analysis.
