Stratospheric gravity wave momentum flux from radio occultations

Schmidt, T.; Alexander, P.; Torre, A. de la

doi:10.1002/2015jd024135

Cited by 61 publications

(116 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…14 by comparing them to E P values using a horizontal background determination method. Horizontal estimation of T 0 was previously found to be superior to a vertical background determination by Khaykin (2016) and Schmidt et al (2016). While the sampling statistics of the METOP RO data on a daily basis (i.e., only 1100 profiles distributed over the whole globe) is too poor to allow us to apply a horizontal background determination to them we may easily perform a corresponding analysis of the highresolution IFS data.…”

Section: Discussionmentioning

confidence: 95%

“…With minimum horizontal scales as small as 10 km GWs must still be parameterized in global climate models with typical horizontal resolutions of a few hundred kilometers. Hence, the development of physics-based parameterizations of GWs and their effect on the mean flow have been identified as a major research focus in the climate research community (Shepherd, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…However, global satellite observations are needed to determine dominant tropospheric source regions and processes as well as global propagation pathways and the resulting gravity wave drag imposed on the mean flow to constrain GW parameterizations for climate and weather prediction models (Alexander et al, 2010;Geller et al, 2013). Since the pioneering work by Fetzer and Gille (1994), Wu and Waters (1996), and Eckermann and Preusse (1999) there have been many attempts to characterize the global distribution of gravity wave activity using such different remote-sensing techniques as Limb (e.g., Ern et al, 2004Ern et al, , 2011Preusse et al, 2009;Zhang et al, 2012) and Nadir sounders (e.g., Hoffmann et al, 2016;Ern et al, 2017), as well as GPS-based radio occultation (RO) measurements (e.g., Tsuda et al, 2000;Hei et al, 2008;Schmidt et al, 2008Schmidt et al, , 2016Fröhlich et al, 2007;Hindley et al, 2015;Šácha et al, 2015;Khaykin et al, 2015;Khaykin, 2016). This paper focusses on the derivation of gravity wave potential energy densities (E P ) from GPS RO measurements on board the operational METOP-A and METOP-B satellites operated by EUMETSAT (European Organisation for the Exploitation of Meteorological Satellites) and the subsequent systematic comparison of E P fields with ECMWF (European Centre for Medium-Range Weather Forecasts) operational forecast and reanalysis data.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

An intercomparison of stratospheric gravity wave potential energy densities from METOP GPS radio occultation measurements and ECMWF model data

2018

View full text Add to dashboard Cite

Abstract. Temperature profiles based on radio occultation (RO) measurements with the operational European METOP satellites are used to derive monthly mean global distributions of stratospheric (20-40 km) gravity wave (GW) potential energy densities (E P ) for the period July 2014-December 2016. In order to test whether the sampling and data quality of this data set is sufficient for scientific analysis, we investigate to what degree the METOP observations agree quantitatively with ECMWF operational analysis (IFS data) and reanalysis (ERA-Interim) data. A systematic comparison between corresponding monthly mean temperature fields determined for a latitude-longitude-altitude grid of 5 • by 10 • by 1 km is carried out. This yields very low systematic differences between RO and model data below 30 km (i.e., median temperature differences is between −0.2 and +0.3 K), which increases with height to yield median differences of +1.0 K at 34 km and +2.2 K at 40 km. Comparing E P values for three selected locations at which also ground-based lidar measurements are available yields excellent agreement between RO and IFS data below 35 km. ERA-Interim underestimates E P under conditions of strong local mountain wave forcing over northern Scandinavia which is apparently not resolved by the model. Above 35 km, RO values are consistently much larger than model values, which is likely caused by the model sponge layer, which damps small-scale fluctuations above ∼ 32 km altitude. Another reason is the wellknown significant increase of noise in RO measurements above 35 km. The comparison between RO and lidar data reveals very good qualitative agreement in terms of the seasonal variation of E P , but RO values are consistently smaller than lidar values by about a factor of 2. This discrepancy is likely caused by the very different sampling characteristics of RO and lidar observations. Direct comparison of the global data set of RO and model E P fields shows large correlation coefficients (0.4-1.0) with a general degradation with increasing altitude. Concerning absolute differences between observed and modeled E P values, the median difference is relatively small at all altitudes (but increasing with altitude) with an exception between 20 and 25 km, where the median difference between RO and model data is increased and the corresponding variability is also found to be very large. The reason for this is identified as an artifact of the E P algorithm: this erroneously interprets the pronounced climatological feature of the tropical tropopause inversion layer (TTIL) as GW activity, hence yielding very large E P values in this area and also large differences between model and observations. This is because the RO data show a more pronounced TTIL than IFS and ERA-Interim. We suggest a correction for this effect based on an estimate of this "artificial" E P using monthly mean zonal mean temperature profiles. This correction may be recommended for application to data sets that can only be analyzed using a vertical background determination me...

show abstract

Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

An intercomparison of stratospheric gravity wave potential energy densities from METOP GPS radio occultation measurements and ECMWF model data

2018

View full text Add to dashboard Cite

show abstract

“…For estimating the direction of momentum fluxes or 25 net momentum fluxes real 3D information from multiple soundings of the same wave either by different instruments (e.g., Wang and Alexander, 2010;Faber et al, 2013;Alexander, 2015;Schmidt et al, 2016), or by multiple tracks measured simultaneously by the same instrument (e.g., Riese et al, 2005Riese et al, , 2014Preusse et al, 2014;Ern et al, 2017;Wright et al, 2017) Remsberg et al (2008), and they are also reproduced in our Table 2.…”

mentioning

confidence: 99%

GRACILE: A comprehensive climatology of atmospheric gravity wave parameters based on satellite limb soundings

Ern¹,

Trinh²,

Preusse³

et al. 2018

Preprint

106

View full text Add to dashboard Cite

Abstract. Gravity waves are one of the main drivers of atmospheric dynamics. The spatial resolution of most global atmospheric models, however, is too coarse to properly resolve the small scales of gravity waves, which range from tens to a few thousand kilometers horizontally, and from below 1 km to tens of kilometers vertically. Gravity wave source processes involve even smaller scales. Therefore, general circulation models (GCMs) and chemistry climate models (CCMs) usually parametrize the effect of gravity waves on the global circulation. These parametrizations are very simplified. For this reason, comparisons 5 with global observations of gravity waves are needed for an improvement of parametrizations and an alleviation of model biases.We present a gravity wave climatology based on atmospheric infrared limb emissions observed by satellite (GRACILE).GRACILE is a global data set of gravity wave distributions observed in the stratosphere and the mesosphere by the infrared limb sounding satellite instruments High Resolution Dynamics Limb Sounder (HIRDLS) and Sounding of the Atmosphere 10 using Broadband Emission Radiometry (SABER). Typical distributions (zonal averages and global maps) of gravity wave vertical wavelengths and along-track horizontal wavenumbers are provided, as well as gravity wave temperature variances, potential energies and absolute momentum fluxes. This global data set captures the typical seasonal variations of these parameters, as well as their spatial variations. The GRACILE data set is suitable for scientific studies, and it can serve for comparison with other instruments (ground based, airborne, or other satellite instruments) and for comparison with gravity wave distri-15 butions, both resolved and parametrized, in GCMs and CCMs.

show abstract

“…However, global satellite observations are needed to determine dominant tropospheric source regions and processes as well as global propagation pathways and the resulting gravity wave drag imposed on the mean flow to constrain GW parameterizations for climate and weather prediction models (Alexander et al, 2010;Geller et al, 20 2013). Since the pioneering work by Fetzer and Gille (1994), Wu and Waters (1996), and Eckermann and Preusse (1999) there have been many attempts to characterize the global distribution of gravity wave activity using such different remote-sensing techniques as Limb (e.g., Ern et al, 2004;Preusse et al, 2009;Ern et al, 2011;Zhang et al, 2012) and Nadir sounders (e.g., Hoffmann et al, 2016;Ern et al, 2016), as well as GPS-based radio occultation measurements (e.g., Tsuda et al, 2000;Hei et al, 2008;Schmidt et al, 2008;Fröhlich et al, 2007;Hindley et al, 2015;Šácha et al, 2015;Khaykin et al, 2015;Khaykin, 25 2016; Schmidt et al, 2016). This paper focusses on the derivation of gravity wave potential energy densities (E P ) from GPS radio occultation (RO) measurements onboard the operational METOP-A and METOP-B-satellites operated by EUMETSAT (=European Organisation for the Exploitation of Meteorological Satellites) and the subsequent systematic comparison of E P -fields with ECMWF (European Center for Medium range Weather Forecast) operational forecast and reanalysis data.…”

Section: Introductionmentioning

confidence: 99%

An intercomparison of stratospheric gravity wave potential energy densities from METOP GPS-radio occultation measurements and ECMWF model data

Rapp¹,

Dörnbrack²,

Kaifler³

2017

Preprint

View full text Add to dashboard Cite

Abstract. Temperature profiles based on radio occultation (RO) measurements with the operational European METOP-satellites are used to derive monthly mean global distributions of stratospheric (20 -40 km) gravity wave (GW) potential energy densities (E P ) for the period July 2014 -December 2016. In order to test whether the sampling and data quality of this data set is sufficient for scientific analysis we investigate to which degree the METOP-observations agree quantitatively with ECMWF operational analysis (IFS-data) and reanalysis (ERA-Interim) data. A systematic comparison between corresponding monthly 5 mean temperature fields determined for a latitude-longitude-altitude grid of 5• by 10• by 1 km is carried out. This yields very low systematic differences between RO and model data below 30 km (i.e., median temperature differences is between -0,2 and +0,3 K) which increases with height to yield median differences of +1,0 K at 34 km and +2,2 K at 40 km. Comparing data set of RO and model E P -fields shows large correlation coefficients (0.4 -1.0) with a general degradation with increasing altitude. Concerning absolute differences between observed and modelled E P -values, the median difference is relatively small at all altitudes (but increasing with altitude) with an exception between 20 and 25 km where the median difference between RO-and model-data is increased and where also the corresponding variability is found to be very large. The reason for this is identified as an artifact of the E P -algorithm: this erroneously interprets the pronounced climatological feature of the tropical 20 tropopause inversion layer (TTIL) as GW activity hence yielding very large E P -values in this area and also large differences between model and observations. This is because the RO-data show a more pronounced TTIL than IFS and ERA-Interim. We suggest a correction for this effect based on an estimate of this 'artificial' E P using monthly mean zonal mean temperature profiles. This correction may be used in the future to study, for example, the annual cycle of zonal mean GW activity using the here considered data.

show abstract

Stratospheric gravity wave momentum flux from radio occultations

Cited by 61 publications

References 50 publications

An intercomparison of stratospheric gravity wave potential energy densities from METOP GPS radio occultation measurements and ECMWF model data

An intercomparison of stratospheric gravity wave potential energy densities from METOP GPS radio occultation measurements and ECMWF model data

GRACILE: A comprehensive climatology of atmospheric gravity wave parameters based on satellite limb soundings

An intercomparison of stratospheric gravity wave potential energy densities from METOP GPS-radio occultation measurements and ECMWF model data

Contact Info

Product

Resources

About