Large differences in reanalyses of diabatic heating in the tropical upper troposphere and lower stratosphere

Wright, Jonathon S.; Fueglistaler, S.

doi:10.5194/acp-13-9565-2013

Cited by 91 publications

(141 citation statements)

References 33 publications

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“…This in turn brings us to the hypothesis that the transition between different observational data sets, which are included in the reanalyses, are of minor importance. Wright and Fueglistaler (2013) have found large differences in the climatologies of diabatic heating rates among different reanalyses. These diabatic heating rate differences (and connected differences on shorter timescales) can be expected to have an impact on the distributions of the SAH centre location (on daily and pentad basis) with respect to the various reanalyses.…”

Section: Discussionmentioning

confidence: 99%

Movement, drivers and bimodality of the South Asian High

2016

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Abstract. The South Asian High (SAH) is an important component of the summer monsoon system in Asia. In this study we investigate the location and drivers of the SAH at 100 hPa during the boreal summers of 1979 to 2014 on interannual, seasonal and synoptic timescales using seven reanalyses and observational data. Our comparison of the different reanalyses focuses especially on the bimodality of the SAH, i.e. the two preferred modes of the SAH centre location: the Iranian Plateau to the west and the Tibetan Plateau to the east. We find that only the National Centers for Environmental Prediction-National Center of Atmospheric Research (NCEP-NCAR) reanalysis shows a clear bimodal structure of the SAH centre distribution with respect to daily and pentad (5 day) mean data. Furthermore, the distribution of the SAH centre location is highly variable from year to year. As in simple model studies, which connect the SAH to heating in the tropics, we find that the mean seasonal cycle of the SAH and its centre are dominated by the expansion of convection in the South Asian region (70-130 • E × 15-30 • N) on the south-eastern border of the SAH. A composite analysis of precipitation and outgoing long-wave radiation data with respect to the location of the SAH centre reveals that a more westward (eastward) location of the SAH is related to stronger (weaker) convection and rainfall over India and weaker (stronger) precipitation over the western Pacific.

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Section: Discussionmentioning

confidence: 99%

Movement, drivers and bimodality of the South Asian High

2016

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“…We also use the total diabatic heating [Wright and Fueglistaler, 2013] and the moist Froude number (Fr m ) as diagnostic tools for flow over topography [Reeves and Lin, 2006]. To calculate the Fr m , we used constant meridional flow (v = 5 m/s), mountain height (h = 5 km), and the saturated Brunt-Väisälä Frequency (N m ) [Kirshbaum and Durran, 2004;Reeves and Lin, 2006] when a negative N m layer above topography is observed, latent heat is strong, and the Fr m is negative.…”

Section: Methodsmentioning

confidence: 99%

The neglected Indo‐Gangetic Plains low‐level jet and its importance for moisture transport and precipitation during the peak summer monsoon

Acosta

Huber

2017

Geophysical Research Letters

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Accurately simulating the Indo‐Asian monsoon (IAM) using atmospheric general circulation models (AGCMs) is challenging but crucial. This study uses reanalysis products European Centre of Medium‐Range Forecast Interim reanalysis, Japanese Reanalysis year 55, and High Asia Reanalysis to highlight an easterly, low‐level barrier jet along the Indo‐Gangetic Plain (referred from here as IG LLJ), which we identify as the primary moisture transport mechanism for the northeastern branch of the IAM. We show that the NCAR family of AGCMs (Community Atmospheric Model (CAM)) does not capture this circulation until 1/2° or greater spatial horizontal resolution is used. The IG LLJ develops due to a persistent low‐pressure system centered over the Ganges basin and is enhanced by the Himalayas. Using diabatic heating rates and the moist Froude number as diagnostics, we find that in CAM, this branch of the IAM displays two different dynamical regimes as a function of resolution. At low resolution, the atmosphere near the Himalayas is statically unstable, diabatic heating is strong, and the moisture flow is southwesterly from the Arabian Sea and moves over the terrain (unblocked). At high resolution, the moist static stability near the Himalayan Mountains is stable, diabatic heating is weak, and the flow primarily enters easterly from the Bay of Bengal and moves parallel to the terrain (blocked). During the summer season, the low‐resolution CAM is locked into the unblocked mode, which has serious implications for interpreting topography‐monsoon interactions. For a broader context, we demonstrate that more than half of the CMIP5 models do not capture the IG LLJ, which further highlights model‐data mismatch across the IAM region.

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“…The MERRA data were also used to provide background wind and temperature fields for our GROGRAT simulations. More detailed information about MERRA data as well as convective parameterization in MERRA can be found, for instance, in Rienecker et al (2011), Kim and Alexander (2013) and Wright and Fueglistaler (2013).…”

Section: Global Gravity Wave Simulationmentioning

confidence: 99%

A comprehensive observational filter for satellite infrared limb sounding of gravity waves

Trinh¹,

Kalisch²,

Preusse³

et al. 2015

Atmos. Meas. Tech.

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Abstract. This paper describes a comprehensive observational filter for satellite infrared limb sounding of gravity waves. The filter considers instrument visibility and observation geometry with a high level of accuracy. It contains four main processes: visibility filter, projection of the wavelength on the tangent-point track, aliasing effect, and calculation of the observed vertical wavelength. The observation geometries of the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) and HIRDLS (High Resolution Dynamics Limb Sounder) are mimicked. Gravity waves (GWs) simulated by coupling a convective GW source (CGWS) scheme and the gravity wave regional or global ray tracer (GROGRAT) are used as an example for applying the observational filter. Simulated spectra in terms of horizontal and vertical wave numbers (wavelengths) of gravity wave momentum flux (GWMF) are analyzed under the influence of the filter. We find that the most important processes, which have significant influence on the spectrum are the visibility filter (for both SABER and HIRDLS observation geometries) and aliasing for SABER and projection on tangent-point track for HIRDLS. The vertical wavelength distribution is mainly affected by the retrieval as part of the "visibility filter" process. In addition, the short-horizontalscale spectrum may be projected for some cases into a longer horizontal wavelength interval which originally was not populated. The filter largely reduces GWMF values of very short horizontal wavelength waves. The implications for interpreting observed data are discussed.

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Large differences in reanalyses of diabatic heating in the tropical upper troposphere and lower stratosphere

Cited by 91 publications

References 33 publications

Movement, drivers and bimodality of the South Asian High

Movement, drivers and bimodality of the South Asian High

The neglected Indo‐Gangetic Plains low‐level jet and its importance for moisture transport and precipitation during the peak summer monsoon

A comprehensive observational filter for satellite infrared limb sounding of gravity waves

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