Mid-winter lower stratosphere temperatures in the Antarctic vortex: comparison between observations and ECMWF and NCEP operational models

Parrondo, M. C.; Yela, Margarita; Gil, Manuel; Gathen, Peter von der; Ochoa, Hector A.

doi:10.5194/acp-7-435-2007

Cited by 25 publications

(32 citation statements)

References 20 publications

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“…Similar height-dependent features were also found (Parrondo et al, 2007) June-August 2003 (Gobiet et al, 2007). None of the other dataset differences showed features consistent with ECMWF, nor were any two consistent with each other; e.g., GEOS-4 displayed an Antarctic cold bias relative to CHAMP at 25-30 km, whereas NCEP REAN displayed a warm bias in roughly the same range.…”

Section: Reanalysis Temperatures Compared To Liq and Ice Reference Posupporting

confidence: 56%

Accuracy and precision of polar lower stratospheric temperatures from reanalyses evaluated from A-Train CALIOP and MLS, COSMIC GPS RO, and the equilibrium thermodynamics of supercooled ternary solutions and ice clouds

Lambert

Santee

2018

Atmos. Chem. Phys.

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Abstract. We investigate the accuracy and precision of polar lower stratospheric temperatures (100-10 hPa during [2008][2009][2010][2011][2012][2013] reported in several contemporary reanalysis datasets comprising two versions of the Modern-Era Retrospective analysis for Research and Applications (MERRA and MERRA-2), the Japanese 55-year Reanalysis (JRA-55), the European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-I), and the National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (NCEP-CFSR). We also include the Goddard Earth Observing System model version 5.9.1 near-real-time analysis (GEOS-5.9.1). Comparisons of these datasets are made with respect to retrieved temperatures from the Aura Microwave Limb Sounder (MLS), Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) Global Positioning System (GPS) radio occultation (RO) temperatures, and independent absolute temperature references defined by the equilibrium thermodynamics of supercooled ternary solutions (STSs) and ice clouds. Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) observations of polar stratospheric clouds are used to determine the cloud particle types within the Aura MLS geometric field of view. The thermodynamic calculations for STS and the ice frost point use the colocated MLS gas-phase measurements of HNO 3 and H 2 O. The estimated bias and precision for the STS temperature reference, over the 68 to 21 hPa pressure range, are 0.6-1.5 and 0.3-0.6 K, respectively; for the ice temperature reference, they are 0.4 and 0.3 K, respectively. These uncertainties are smaller than those estimated for the retrieved MLS temperatures and also comparable to GPS RO uncertainties (bias < 0.2 K, precision > 0.7 K) in the same pressure range.We examine a case study of the time-varying temperature structure associated with layered ice clouds formed by orographic gravity waves forced by flow over the Palmer Peninsula and compare how the wave amplitudes are reproduced by each reanalysis dataset. We find that the spatial and temporal distribution of temperatures below the ice frost point, and hence the potential to form ice polar stratospheric clouds (PSCs) in model studies driven by the reanalyses, varies significantly because of the underlying differences in the representation of mountain wave activity.High-accuracy COSMIC temperatures are used as a common reference to intercompare the reanalysis temperatures. Over the 68-21 hPa pressure range, the biases of the reanalyses with respect to COSMIC temperatures for both polar regions fall within the narrow range of −0.6 K to +0.5 K. GEOS-5.9.1, MERRA, MERRA-2, and JRA-55 have predominantly cold biases, whereas ERA-I has a predominantly warm bias. NCEP-CFSR has a warm bias in the Arctic but becomes substantially colder in the Antarctic.Reanalysis temperatures are also compared with the PSC reference temperatures. Over the 68-21 hPa pressure range, the reanalysis tem...

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Section: Reanalysis Temperatures Compared To Liq and Ice Reference Posupporting

confidence: 56%

Accuracy and precision of polar lower stratospheric temperatures from reanalyses evaluated from A-Train CALIOP and MLS, COSMIC GPS RO, and the equilibrium thermodynamics of supercooled ternary solutions and ice clouds

Lambert

Santee

2018

Atmos. Chem. Phys.

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“…A large number of studies have described the quality of these temperature measurements. In particular, comparisons of CHAMP RO measurements with analyses and radiosonde observations display excellent agreement (Wickert et al, 2004;Gobiet et al, 2005;Parrondo et al, 2007;Wang and Lin, 2007). For example, Wickert et al (2004) compared CHAMP dry temperature with interpolated data from ECMWF meteorological analyses with co-located and near simultaneous radiosonde observations between 10 and 35 km.…”

Section: Champ Ro and Met Office Observationsmentioning

confidence: 99%

Can gravity waves significantly impact PSC occurrence in the Antarctic?

2009

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Abstract.A combination of POAM III aerosol extinction and CHAMP RO temperature measurements are used to examine the role of atmospheric gravity waves in the formation of Antarctic Polar Stratospheric Clouds (PSCs). POAM III aerosol extinction observations and quality flag information are used to identify Polar Stratospheric Clouds using an unsupervised clustering algorithm.A PSC proxy, derived by thresholding Met Office temperature analyses with the PSC Type Ia formation temperature (T NAT ), shows general agreement with the results of the POAM III analysis. However, in June the POAM III observations of PSC are more abundant than expected from temperature threshold crossings in five out of the eight years examined. In addition, September and October PSC identified using temperature thresholding is often significantly higher than that derived from POAM III; this observation probably being due to dehydration and denitrification. Comparison of the Met Office temperature analyses with corresponding CHAMP observations also suggests a small warm bias in the Met Office data in June. However, this bias cannot fully explain the differences observed.Analysis of CHAMP data indicates that temperature perturbations associated with gravity waves may partially explain the enhanced PSC incidence observed in June (relative to the Met Office analyses). For this month, approximately 40% of the temperature threshold crossings observed using CHAMP RO data are associated with small-scale perturbations. Examination of the distribution of temperatures relative to T NAT shows a large proportion of June data to be close to this threshold, potentially enhancing the importance of gravity wave induced temperature perturbations. Inspection of the longitudinal structure of PSC occurrence in June 2005 also shows that regions of enhancement are geographically Correspondence to: A. J. McDonald (adrian.mcdonald@canterbury.ac.nz) associated with the Antarctic Peninsula; a known mountain wave "hotspot". The latitudinal variation of POAM III observations means that we only observe this region in June-July, and thus the true pattern of enhanced PSC production may continue operating into later months.The analysis has shown that early in the Antarctic winter stratospheric background temperatures are close to the T NAT threshold (and PSC formation), and are thus sensitive to temperature perturbations associated with mountain wave activity near the Antarctic peninsula (40% of PSC formation). Later in the season, and at latitudes away from the peninsula, temperature perturbations associated with gravity waves contribute to about 15% of the observed PSC (a value which corresponds well to several previous studies). This lower value is likely to be due to colder background temperatures already achieving the T NAT threshold unaided. Additionally, there is a reduction in the magnitude of gravity waves perturbations observed as POAM III samples poleward of the peninsula.

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“…Independent data from long-duration balloon flights therefore provide a valuable assessment of reanalysis accuracy. The balloon-reanalysis comparison reported on here adds to the body of knowledge encompassed in previous studies, which used a range of models and balloon flights (Knudsen et al, 2002;Hertzog et al, 2004;Knudsen et al, 2006;Hertzog et al, 2006;Parrondo et al, 2007;Boccara et al, 2008;McDonald and Hertzog, 2008;de la Camara et al, 2010;Podglajen et al, 2014). These previous studies have been performed in varied geographical regions, generally using fewer balloons than are used in the analyses reported here.…”

Section: S Friedrich Et Al: a Comparison Of Loon Balloon Observamentioning

confidence: 67%

A comparison of Loon balloon observations and stratospheric reanalysis products

et al. 2017

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Abstract. Location information from long-duration superpressure balloons flying in the Southern Hemisphere lower stratosphere during 2014 as part of X Project Loon are used to assess the quality of a number of different reanalyses including National Centers for Environmental Prediction Climate Forecast System version 2 (NCEP-CFSv2), European Centre for Medium-Range Weather Forecasts (ERAInterim), NASA Modern Era Retrospective-Analysis for Research and Applications (MERRA), and the recently released MERRA version 2. Balloon GPS location information is used to derive wind speeds which are then compared with values from the reanalyses interpolated to the balloon times and locations. All reanalysis data sets accurately describe the winds, with biases in zonal winds of less than 0.37 m s −1 and meridional biases of less than 0.08 m s −1 . The standard deviation on the differences between Loon and reanalyses zonal winds is latitude-dependent, ranging between 2.5 and 3.5 m s −1 , increasing equatorward.Comparisons between Loon trajectories and those calculated by applying a trajectory model to reanalysis wind fields show that MERRA-2 wind fields result in the most accurate simulated trajectories with a mean 5-day balloonreanalysis trajectory separation of 621 km and median separation of 324 km showing significant improvements over MERRA version 1 and slightly outperforming ERA-Interim. The latitudinal structure of the trajectory statistics for all reanalyses displays marginally lower mean separations between 15 and 35 • S than between 35 and 55 • S, despite standard deviations in the wind differences increasing toward the equator. This is shown to be related to the distance travelled by the balloon playing a role in the separation statistics.

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Mid-winter lower stratosphere temperatures in the Antarctic vortex: comparison between observations and ECMWF and NCEP operational models

Cited by 25 publications

References 20 publications

Accuracy and precision of polar lower stratospheric temperatures from reanalyses evaluated from A-Train CALIOP and MLS, COSMIC GPS RO, and the equilibrium thermodynamics of supercooled ternary solutions and ice clouds

Accuracy and precision of polar lower stratospheric temperatures from reanalyses evaluated from A-Train CALIOP and MLS, COSMIC GPS RO, and the equilibrium thermodynamics of supercooled ternary solutions and ice clouds

Can gravity waves significantly impact PSC occurrence in the Antarctic?

A comparison of Loon balloon observations and stratospheric reanalysis products

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