Tuning of a convective gravity wave source scheme based on HIRDLS observations

Trinh, Quang Thai; Kalisch, Silvio; Preusse, Peter; Ern, Manfred; Chun, Hye‐Yeong; Eckermann, Stephen D.; Kang, Min‐Jee; Riese, Martin

doi:10.5194/acp-16-7335-2016

Cited by 43 publications

(73 citation statements)

References 57 publications

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“…In the subtropics a weaker annual cycle with maxima during summertime and minima during wintertime is found. These summertime maxima have been observed before (e.g., Jiang et al, 2004b;Ern and Preusse, 2012;Hoffmann et al, 2014), and they have been attributed to stronger activity of deep convective sources during summer (e.g., Choi et al, 2012;Trinh et al, 2016). Additionally, a major effect is the modulation of wave amplitudes by the background winds.…”

Section: Time Series Of Gravity Wave Variancesmentioning

confidence: 88%

“…The main advantage of HIRDLS is that 2-D spectral information of observed gravity waves is provided in terms of along-track and vertical wavelengths. This information has been utilized for studying the average spectrum of gravity waves in different regions (e.g., Lehmann et al, 2012;Ern and Preusse, 2012;Trinh et al, 2016). We will use this information here to comprehensively compare AIRS and HIRDLS gravity wave observations, which is the main aim of our study.…”

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confidence: 99%

“…For example, it is known that deep convection excites a broad spectrum of gravity wave phase speeds (e.g., Beres et al, 2004), as well as a broad range of gravity wave vertical and, in particular, horizontal wavelengths. There are indications that the horizontal scales range from several tens to several hundreds of kilometers (e.g., Choi et al, 2012;Trinh et al, 2016;Kalisch et al, 2016;Ern et al, 2017). Similarly, gravity waves emitted from jets and fronts cover horizontal wavelengths from less than 100 km to more than 500 km (e.g., Plougonven and Zhang, 2014, and references therein), and the horizontal scales of mountain waves cover a range of less than 10 km to several hundred kilometers (e.g., Fritts et al, 2016;Ehard et al, 2017, and references therein).…”

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confidence: 99%

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Intercomparison of AIRS and HIRDLS stratospheric gravity wave observations

Meyer¹,

Ern²,

Hoffmann³

et al. 2018

Atmos. Meas. Tech.

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Abstract. We investigate stratospheric gravity wave observations by the Atmospheric InfraRed Sounder (AIRS) aboard NASA's Aqua satellite and the High Resolution Dynamics Limb Sounder (HIRDLS) aboard NASA's Aura satellite. AIRS operational temperature retrievals are typically not used for studies of gravity waves, because their vertical and horizontal resolution is rather limited. This study uses data of a high-resolution retrieval which provides stratospheric temperature profiles for each individual satellite footprint. Therefore the horizontal sampling of the high-resolution retrieval is 9 times better than that of the operational retrieval. HIRDLS provides 2-D spectral information of observed gravity waves in terms of along-track and vertical wavelengths. AIRS as a nadir sounder is more sensitive to short-horizontal-wavelength gravity waves, and HIRDLS as a limb sounder is more sensitive to short-vertical-wavelength gravity waves. Therefore HIRDLS is ideally suited to complement AIRS observations. A calculated momentum flux factor indicates that the waves seen by AIRS contribute significantly to momentum flux, even if the AIRS temperature variance may be small compared to HIRDLS. The stratospheric wave structures observed by AIRS and HIRDLS often agree very well. Case studies of a mountain wave event and a non-orographic wave event demonstrate that the observed phase structures of AIRS and HIRDLS are also similar. AIRS has a coarser vertical resolution, which results in an attenuation of the amplitude and coarser vertical wavelengths than for HIRDLS. However, AIRS has a much higher horizontal resolution, and the propagation direction of the waves can be clearly identified in geographical maps. The horizontal orientation of the phase fronts can be deduced from AIRS 3-D temperature fields. This is a restricting factor for gravity wave analyses of limb measurements. Additionally, temperature variances with respect to stratospheric gravity wave activity are compared on a statistical basis. The complete HIRDLS measurement period from January 2005 to March 2008 is covered. The seasonal and latitudinal distributions of gravity wave activity as observed by AIRS and HIRDLS agree well. A strong annual cycle at mid-and high latitudes is found in time series of gravity wave variances at 42 km, which has its maxima during wintertime and its minima during summertime. The variability is largest during austral wintertime at 60 • S. Variations in the zonal winds at 2.5 hPa are associated with large variability in gravity wave variances. Altogether, gravity wave variances of AIRS and HIRDLS are complementary to each other. Large parts of the gravity wave spectrum are covered by joint observations. This opens up fascinating vistas for future gravity wave research.

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Section: Time Series Of Gravity Wave Variancesmentioning

confidence: 88%

mentioning

confidence: 99%

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confidence: 99%

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Intercomparison of AIRS and HIRDLS stratospheric gravity wave observations

Meyer¹,

Ern²,

Hoffmann³

et al. 2018

Atmos. Meas. Tech.

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“…Several reasons are likely candidates for this weaker similarity. Very likely reasons are the difference in observation geometry, differences in the convective GW spectrum between the Northern Hemisphere and Southern Hemisphere (e.g., Ern and Preusse, 2012;Trinh et al, 2016) as well as the more complex terrain in the Northern Hemisphere, which leads to a less stable polar vortex. Another possible reason is the larger difference in orbit altitudes.…”

Section: Correlation Between Champ Observations and Saber Observationsmentioning

confidence: 99%

“…Between most prominent source regions in the troposphere and the T/I there are many scale heights, regions of saturation and dissipation and often critical layer filtering. The observational constraints for free parameters of GW parametrization schemes successfully guiding middle atmosphere simulations (Ern et al, 2006;Orr et al, 2010;Trinh et al, 2016) are hence not necessarily helpful for the T/I. For the T/I region thus dedicated experimental evidence is needed to compare GW distributions in the middle atmosphere and in the T/I.…”

Section: Q T Trinh Et Al: Satellite Observations Of Vertical Couplmentioning

confidence: 99%

Satellite observations of middle atmosphere–thermosphere vertical coupling by gravity waves

et al. 2018

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Abstract. Atmospheric gravity waves (GWs) are essential for the dynamics of the middle atmosphere. Recent studies have shown that these waves are also important for the thermosphere/ionosphere (T/I) system. Via vertical coupling, GWs can significantly influence the mean state of the T/I system. However, the penetration of GWs into the T/I system is not fully understood in modeling as well as observations. In the current study, we analyze the correlation between GW momentum fluxes observed in the middle atmosphere (30-90 km) and GW-induced perturbations in the T/I. In the middle atmosphere, GW momentum fluxes are derived from temperature observations of the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite instrument. In the T/I, GW-induced perturbations are derived from neutral density measured by instruments on the Gravity field and Ocean Circulation Explorer (GOCE) and CHAllenging Minisatellite Payload (CHAMP) satellites. We find generally positive correlations between horizontal distributions at low altitudes (i.e., below 90 km) and horizontal distributions of GW-induced density fluctuations in the T/I (at 200 km and above). Two coupling mechanisms are likely responsible for these positive correlations: (1) fast GWs generated in the troposphere and lower stratosphere can propagate directly to the T/I and (2) primary GWs with their origins in the lower atmosphere dissipate while propagating upwards and generate secondary GWs, which then penetrate up to the T/I and maintain the spatial patterns of GW distributions in the lower atmosphere. The mountain-wave related hotspot over the Andes and Antarctic Peninsula is found clearly in observations of all instruments used in our analysis. Latitude-longitude variations in the summer midlatitudes are also found in observations of all instruments. These variations and strong positive correlations in the summer midlatitudes suggest that GWs with origins related to convection also propagate up to the T/I. Different processes which likely influence the vertical coupling are GW dissipation, possible generation of secondary GWs, and horizontal propagation of GWs. Limitations of the observations as well as of our research approach are discussed.

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Directional gravity wave momentum fluxes in the stratosphere derived from high‐resolution AIRS temperature data

Ern

Hoffmann

Preusse

2017

Geophysical Research Letters

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136

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In order to reduce uncertainties in modeling the stratospheric circulation, global observations of gravity wave momentum flux (GWMF) vectors are required for comparison with distributions of resolved and parametrized GWMF in global models. For the first time, we derive GWMF vectors globally from data of a nadir‐viewing satellite instrument: we apply a 3‐D method to an Atmospheric Infrared Sounder (AIRS) temperature data set that was optimized for gravity wave (GW) analysis. For January 2009, the resulting distributions of GW amplitudes and of net GWMF highlight the importance of GWs in the polar vortex and the summertime subtropics. Net GWMF is preferentially directed opposite to the background wind, and, interestingly, it is dominated by large‐amplitude GWs of relatively long horizontal wavelength. For convective GW sources, these large horizontal scales are in contradiction with traditional thoughts. However, the observational filter effect needs to be kept in mind when interpreting the results.

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Tuning of a convective gravity wave source scheme based on HIRDLS observations

Cited by 43 publications

References 57 publications

Intercomparison of AIRS and HIRDLS stratospheric gravity wave observations

Intercomparison of AIRS and HIRDLS stratospheric gravity wave observations

Satellite observations of middle atmosphere–thermosphere vertical coupling by gravity waves

Directional gravity wave momentum fluxes in the stratosphere derived from high‐resolution AIRS temperature data

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