9-10 November 2011 Atmospheric Waves Workshop, ESTEC

Atmospheric Waves WorkshopScott Osprey1, Corwin Wright2

Evidence of atmospheric gravity waves and their effects from satellite data

1AOPP, University of Oxford; 2Laboratoire de Physique des Oceans, Universite de Bretagne Occidental

9-10 November 2011 Atmospheric Waves Workshop, ESTEC

Gravity Waves Above the Indian Ocean

source: MISR (NASA)

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Lenticular Clouds, Amsterdam Island

MODIS, December 2005

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Sandwich Islands, South Atlantic, January 2004

Source MODIS on AQUA (NASA)

9-10 November 2011 Atmospheric Waves Workshop, ESTEC

Outline• Radio-occultation retrievals of gravity waves• Limb-sounding instruments:

– NASA A-Train– S-Transform

• High Resolution Dynamics Limb Sounder (HIRDLS)– Tropospheric sources of gravity waves (monsoon)– Filtering by background winds (Sudden Stratospheric

Warmings)• Evidence for gravity wave induced circulations (Titan)• Summary

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Radio-Occultation: FORMOSAT-3/COSMIC

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Radio-Occultation Observations: FORMOSAT-3/COSMIC

• A “constellation” of six satellites, used for GPS (US, Taiwan)

• orbital altitude 800 km

• Currently being used for data assimilation (Met Office, ECMWF)

• Europe: Galileo

Launch on April 14, 2006Vandenberg AFB, CA

Measures:Pressure, Temperature, HumidityRefractivityIonospheric Electron Density

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Radio Occultation Profile locations 1 January 2007

Wang & Alexander (2010)

CHAMP 151COSMIC 1936

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A Typical GPS RO Profile

Wavenumbers 1-6 constitute ‘background’ Wang & Alexander (2010)

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Radio-Occultation: Wave-Momentum in the lower-stratosphere

Wang & Alexander (2010)

Vertical flux of horizontal momentum density

June-August 2007

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Limb Sounding Observations of Atmospheric Gravity Waves - HIRDLS

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Source: NASA

The NASA A-Train

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HIRDLS

• The High Resolution Dynamics Limb Sounder (HIRDLS)• Infrared limb sounder on the low-Earth orbiting Aura satellite• Launched July 2004, data coverage from 01/2005 –

01/2008• Data extend from ~tropopause to ~80km (version 6)• ~1km vertical resolution, measurements ~80km apart

Temperature Perturbations

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Temperature Perturbations

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The Stockwell Transform: T’ and the vertical wavelength

Temperature perturbation sizeVertical wavelength

In most cases, we select only the largest temperature perturbation at each height level for consideration( )

Stockwell et al (1996); Alexander et al (2006)

9-10 November 2011 Atmospheric Waves Workshop, ESTEC

The Stockwell Transform – Horizontal Wavelength

Horizontal wavelength

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Tropospheric Sources of Gravity Waves - Monsoon

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Monsoon and Gravity waves

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Precipitation, OLR and Gravity Waves

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Precipitation, OLR and Gravity Waves

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Background Wind Filtering of GW – Sudden Stratospheric Warmings

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NH Winter Zonal Wind 2005 & 2006

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Sudden Stratospheric Warming 2006

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HIRDLS zonal wind: 2006 60°N

Wright et al. (2010)

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HIRDLS GW MF: 2006 60°N

Wright et al. (2010)

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Daily GW MF: 2005-2008

Wright et al. (2010)

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>>Evidence for wind-based filtering of GWs during 2006 Sudden Stratospheric WarmingHigh GW activity near poles in 2005 and 2007

Significant reduction in 2006, corresponding to negative zonal winds

Gravity Wave Filtering

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Gravity Wave Filtering

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Evidence of a Gravity Wave Induced Circulation on Titan

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Brewer-Dobson Circulation on Earth

http://www.iau.uni-frankfurt.de/groups/PhysAtm/Research/Atmospheric_Transport1/index.html

Rossby Waves

Gravity Waves

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Evidence of GW induced circulations on Titan

Teanby et al, 2008

9-10 November 2011 Atmospheric Waves Workshop, ESTEC

Teanby et al, 2008

9-10 November 2011 Atmospheric Waves Workshop, ESTEC

Idealised meridional circulation on Titan

Teanby et al, 2008

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Summary

• Gravity waves are a ubiquitous dynamical feature of the Earths atmosphere.

• Significant regional sources of tropospheric gravity waves are seen during strong precipitation events (monsoon)

• Filtering by stratospheric winds is seen during extreme wintertime events in the stratosphere (SSW)

• Evidence of a gravity wave driven circulation is seen in the Earths mesosphere - lowest temperatures on earth being in the summer polar mesosphere.

• Tentative evidence of a similar circulation is seen in Titans polar mesosphere and via distributions of tracers.

• Radio-occultation and limb sounding observations provide useful quantitative measures of gravity waves.