The tropopause inversion layer in models and analyses

Birner, Thomas; Sankey, David; Shepherd, T. G.

doi:10.1029/2006gl026549

Cited by 86 publications

(88 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is, however, the region of the tropical tropopause and its related TTIL. Note that it is on purpose that we refer to the tropical tropopause inversion layer as TTIL instead of the more commonly known TIL, since the latter term has usually only been used for the midlatitude TIL and not the tropical one that we are dealing with here (Birner et al, 2002(Birner et al, , 2006Pilch Kedzierski et al, 2016). That this is indeed the case for the here considered data set is demonstrated in Fig.…”

Section: Discussionmentioning

confidence: 69%

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: 69%

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

“…The latter applies also to CO, and this extratropical transition region was first identified from simultaneous aircraft measurements of ozone and CO (Fischer et al 2000). The transition region may well be related to the tropopause inversion layer identified by Birner (2006) from highvertical-resolution temperature profiles, as the vertical scales are comparable, although this has yet to be established.…”

Section: July 2007 Tg Shepherdmentioning

confidence: 99%

“…The concept of equivalent latitude was first introduced to deal with deformations of the polar vortex. While the concept extends in principle to the tropopause region, there are issues in practice because equivalent latitude is not well defined where PV gradients are weak, and the accuracy of PV in meteorological analyses may be suspect (see Birner et al 2006). Moreover tracers in the tropopause region tend not to be as uniform along PV contours as they are in the polar vortex, because the PV tropopause is not as effective a mixing barrier as is the polar vortex: the PV deformations are generally much more extensive and irreversible, and so air parcels cannot be expected to circumnavigate the PV tropopause several times around the globe, as they are observed to do along the polar vortex edge (cf., Fig.…”

Section: July 2007 Tg Shepherdmentioning

confidence: 99%

Transport in the Middle Atmosphere

Shepherd

2007

Journal of the Meteorological Society of Japan

169

132

View full text Add to dashboard Cite

An overview is provided of the current understanding of transport in the middle atmosphere. Over the past quarter century this subject has evolved from a basic recognition of the Brewer-Dobson circulation to a detailed appreciation of many key features of transport such as the stratospheric surf zone, mixing barriers, and the dynamics of filamentation. Whilst the elegant theoretical framework for middle atmosphere transport that emerged roughly twenty years ago never fulfilled its promise, useful phenomenological models have been developed together with innovative diagnostic methods. These advances were made possible by the advent of plentiful satellite and aircraft observations of long-lived chemical species together with developments in data assimilation and numerical modeling, and have been driven in large measure by the problem of stratospheric ozone depletion. This review is primarily focused on the stratosphere, where both the interest and the knowledge are the greatest, but a few remarks are also made on the mesosphere.

show abstract

“…However, the difference makes it somewhat difficult to relate the differences in T CPT to differences in water vapor (shown by Eyring et al (2006) for these runs). The reanalysis systems have warmer T CPT than most models, which may be a bias in the analysis (Pawson and Fiorino, 1999), or due to coarse vertical resolution (Birner et al, 2006). The inter-annual variability, shown as a 2σ confidence interval for the reanalysis in Fig.…”

Section: Multi-model Climatologymentioning

confidence: 99%

The Tropical Tropopause Layer 1960–2100

et al. 2009

Self Cite

View full text Add to dashboard Cite

Abstract. The representation of the Tropical Tropopause Layer (TTL) in 13 different Chemistry Climate Models (CCMs) designed to represent the stratosphere is analyzed. Simulations for 1960 and 1980 -2100 are analyzed. Simulations for 1960 are compared to reanalysis model output. CCMs are able to reproduce the basic structure of the TTL. There is a large (10 K) spread in annual mean tropical cold point tropopause temperatures. CCMs are able to reproduce historical trends in tropopause pressure obtained from reanalysis products. Simulated historical trends in cold point tropopause temperatures are not consistent across models or reanalyses. The pressure of both the tropical tropopause and the level of main convective outflow appear to have decreased (increased altitude) in historical runs as well as in reanalyses. Decreasing pressure trends in the tropical tropopause and level of main convective outflow are also seen in the future. Models consistently predict decreasing tropopause and convective outflow pressure, by several hPa/decade. Tropical cold point temperatures are projected to increase by 0.09 K/decade. Tropopause anomaCorrespondence to: A. Gettelman (andrew@ucar.edu) lies are highly correlated with tropical surface temperature anomalies and with tropopause level ozone anomalies, less so with stratospheric temperature anomalies. Simulated stratospheric water vapor at 90 hPa increases by up to 0.5-1 ppmv by 2100. The result is consistent with the simulated increase in temperature, highlighting the correlation of tropopause temperatures with stratospheric water vapor.

show abstract

The tropopause inversion layer in models and analyses

Cited by 86 publications

References 7 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

Transport in the Middle Atmosphere

The Tropical Tropopause Layer 1960–2100

Contact Info

Product

Resources

About