The Spatiotemporal Variability of Nonorographic Gravity Wave Energy and Relation to Its Source Functions

2020 ◽  
Vol 148 (12) ◽  
pp. 4837-4857
Author(s):  
Mozhgan Amiramjadi ◽  
Ali R. Mohebalhojeh ◽  
Mohammad Mirzaei ◽  
Christoph Zülicke ◽  
Riwal Plougonven
Keyword(s):  
Regression Analysis ◽  
Large Scale ◽  
Spatial Filter ◽  
Spatiotemporal Variability ◽  
Zonal Wavenumber ◽  
Secondary Circulations ◽  
Low Pass ◽  
Weighted Integrals ◽  
Large Scale Flow ◽  
The Tropics

AbstractThe way the large-scale flow determines the energy of the nonorographic mesoscale inertia–gravity waves (IGWs) is theoretically significant and practically useful for source parameterization of IGWs. The relations previously developed on the f plane for tropospheric sources of IGWs including jets, fronts, and convection in terms of associated secondary circulations strength are generalized for application over the globe. A low-pass spatial filter with a cutoff zonal wavenumber of 22 is applied to separate the large-scale flow from the IGWs using the ERA5 data of ECMWF for the period 2016–19. A comparison with GRACILE data based on satellite observations of the middle stratosphere shows reasonable representation of IGWs in the ERA5 data despite underestimates by a factor of smaller than 3. The sum of the energies, which are mass-weighted integrals in the troposphere from the surface to 100 hPa, as given by the generalized relations is termed initial parameterized energy. The corresponding energy integral for the IGWs is termed the diagnosed energy. The connection between the parameterized and diagnosed IGW energies is explored with regression analysis for each season and six oceanic domains distributed over the globe covering the Northern and Southern Hemispheres and the tropics. While capturing the seasonal cycle, the domain area-average seasonal mean initial parameterized energy is weaker than the diagnosed energy by a factor of 3. The best performance in regression analysis is obtained by using a combination of power and exponential functions, which suggests evidence of exponential weakness.

scholarly journals Options to correct local turbulent flux measurements for large-scale fluxes using a LES-based approach

2021 ◽  
Author(s):  
Matthias Mauder ◽  
Andreas Ibrom ◽  
Luise Wanner ◽  
Frederik De Roo ◽  
Peter Brugger ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Large Scale ◽  
Heat Fluxes ◽  
Eddy Covariance Method ◽  
Boundary Layer Height ◽  
Secondary Circulations ◽  
Low Pass ◽  
Measurement Height ◽  
Flux Measurements ◽  
Dispersive Fluxes

Abstract. The eddy-covariance method provides the most direct estimates for fluxes between ecosystems and the atmosphere. However, dispersive fluxes can occur in the presence of secondary circulations, which can inherently not be captured by such single-tower measurements. In this study, we present options to correct local flux measurements for such large-scale transport based on a non-local parametric model that has been developed from a set of idealized LES runs for three real-world sites. The test sites DK-Sor, DE-Fen, and DE-Gwg, represent typical conditions in the mid-latitudes with different measurement height, different terrain complexity and different landscape-scale heterogeneity. Different ways to determine the boundary-layer height, which is a necessary input variable for modelling the dispersive fluxes, are applied, either from operational radio-soundings and local in-situ measurements for the flat site or from backscatter-intensity profile obtained from collocated ceilometers for the two sites in complex terrain. The adjusted total fluxes are evaluated by assessing the improvement in energy balance closure and by comparing the resulting latent heat fluxes with evapotranspiration rates from nearby lysimeters. The results show that not only the accuracy of the flux estimates is improved but also the precision, which is indicated by RMSE values that are reduced by approximately 50 %. Nevertheless, it needs to be clear that this method is intended to correct for a bias in eddy-covariance measurements due to the presence of large-scale dispersive fluxes. Other reasons potentially causing a systematic under- or overestimation, such as low-pass filtering effects and missing storage terms, still need to be considered and minimized as much as possible. Moreover, additional transport induced by surface heterogeneities is not considered.

scholarly journals Stochastic resonance in a nonlinear model of a rotating, stratified shear flow, with a simple stochastic inertia-gravity wave parameterization

2004 ◽  
Vol 11 (1) ◽  
pp. 127-135 ◽  
Author(s):  
P. D. Williams ◽  
T. W. N. Haine ◽  
P. L. Read
Keyword(s):  
Shear Flow ◽  
Gravity Wave ◽  
Stochastic Resonance ◽  
Potential Vorticity ◽  
Large Scale ◽  
Zonal Wavenumber ◽  
Stratified Shear Flow ◽  
Balanced Flow ◽  
Large Scale Flow ◽  
The Impact

Abstract. We report on a numerical study of the impact of short, fast inertia-gravity waves on the large-scale, slowly-evolving flow with which they co-exist. A nonlinear quasi-geostrophic numerical model of a stratified shear flow is used to simulate, at reasonably high resolution, the evolution of a large-scale mode which grows due to baroclinic instability and equilibrates at finite amplitude. Ageostrophic inertia-gravity modes are filtered out of the model by construction, but their effects on the balanced flow are incorporated using a simple stochastic parameterization of the potential vorticity anomalies which they induce. The model simulates a rotating, two-layer annulus laboratory experiment, in which we recently observed systematic inertia-gravity wave generation by an evolving, large-scale flow. We find that the impact of the small-amplitude stochastic contribution to the potential vorticity tendency, on the model balanced flow, is generally small, as expected. In certain circumstances, however, the parameterized fast waves can exert a dominant influence. In a flow which is baroclinically-unstable to a range of zonal wavenumbers, and in which there is a close match between the growth rates of the multiple modes, the stochastic waves can strongly affect wavenumber selection. This is illustrated by a flow in which the parameterized fast modes dramatically re-partition the probability-density function for equilibrated large-scale zonal wavenumber. In a second case study, the stochastic perturbations are shown to force spontaneous wavenumber transitions in the large-scale flow, which do not occur in their absence. These phenomena are due to a stochastic resonance effect. They add to the evidence that deterministic parameterizations in general circulation models, of subgrid-scale processes such as gravity wave drag, cannot always adequately capture the full details of the nonlinear interaction.

scholarly journals Forecast Uncertainty Dynamics in the THORPEX Interactive Grand Global Ensemble (TIGGE)

2016 ◽  
Vol 144 (7) ◽  
pp. 2739-2766 ◽  
Author(s):  
Michael A. Herrera ◽  
Istvan Szunyogh ◽  
Joseph Tribbia
Keyword(s):  
Large Scale ◽  
Baroclinic Instability ◽  
Low Frequency ◽  
Systematic Errors ◽  
Sustainable Growth ◽  
Initial Growth ◽  
Classic Theory ◽  
Zonal Wavenumber ◽  
Frequency Changes ◽  
Large Scale Flow

Abstract This paper employs local linear, spatial spectral, and Lorenz curve–based diagnostics to investigate the dynamics of uncertainty in global numerical weather forecasts in the NH extratropics. The diagnostics are applied to ensembles in the THORPEX Interactive Grand Global Ensemble (TIGGE). The initial growth of uncertainty is found to be the fastest at the synoptic scales (zonal wavenumbers 7–9) most sensitive to baroclinic instability. At later forecast times, the saturation of uncertainties at the synoptic scales and the longer sustainable growth of uncertainty at the large scales lead to a gradual shift of the wavenumber of the dominant uncertainty toward zonal wavenumber 5. At the subsynoptic scales, errors saturate as predicted by Lorenz’s classic theory. While the ensembles capture the general characteristics of the uncertainty dynamics efficiently, there are locations where the predicted magnitude and structure of uncertainty have considerable time-mean errors. In addition, the magnitude of systematic errors in the prediction of the uncertainty increases with increasing forecast time. These growing systematic errors are dominated by errors in the prediction of low-frequency changes in the large-scale flow.

scholarly journals Nonlinear Zonal Propagation of Organized Convection in the Tropics

2019 ◽  
Vol 76 (9) ◽  
pp. 2837-2867
Author(s):  
Joaquin E. Blanco ◽  
David S. Nolan ◽  
Brian E. Mapes
Keyword(s):  
Large Scale ◽  
Water Model ◽  
Local Approach ◽  
Time Space ◽  
Cloud Clusters ◽  
Wide Range ◽  
Westerly Wind Burst ◽  
Large Scale Flow ◽  
The Tropics ◽  
Zonal Propagation

Abstract A wide range of the observed variability in the ITCZ is frequently explained in terms of equatorially trapped modes arising from Matsuno’s linear shallow-water model. Here, a series of zonally constant, meridionally symmetric aquachannel WRF simulations are used to study the propagation of tropical cloud clusters (CCs; patches of deep cloudiness and precipitation) in association with eastward-moving super cloud clusters (SCCs), also called convectively coupled Kelvin waves (CCKWs). Two independent but complementary methods are used: the first, from a local approach, involves a CC-tracking algorithm, while the second uses Lagrangian trajectories in a nonlocal framework. We show that the large-scale flow in low to midlevels advects the CCs either eastward or westward depending on model climatology, proximity to the CCKW axis, and latitude. Moreover, for most analyzed cases, sequences of CCs oscillate, describing qualitatively sinusoidal-like paths in longitude–time space, although with sharp transitions from westward to eastward motion due to westerly wind burst activity associated with the CCKWs. We also find that the discrete precipitation elements (CCs) are embedded in continuous tracks of positive moisture anomalies, which are parallel to the Lagrangian trajectories themselves. A conceptual model of the nonlinear SCC–CC interaction is presented.

scholarly journals Global climatology and trends in convective environments from ERA5 and rawinsonde data

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Mateusz Taszarek ◽  
John T. Allen ◽  
Mattia Marchio ◽  
Harold E. Brooks
Keyword(s):  
Large Scale ◽  
Climate Models ◽  
Global Climate ◽  
Convective Available Potential Energy ◽  
Global Climate Models ◽  
Convective Precipitation ◽  
The Past ◽  
The Tropics ◽  
Rawinsonde Data

AbstractGlobally, thunderstorms are responsible for a significant fraction of rainfall, and in the mid-latitudes often produce extreme weather, including large hail, tornadoes and damaging winds. Despite this importance, how the global frequency of thunderstorms and their accompanying hazards has changed over the past 4 decades remains unclear. Large-scale diagnostics applied to global climate models have suggested that the frequency of thunderstorms and their intensity is likely to increase in the future. Here, we show that according to ERA5 convective available potential energy (CAPE) and convective precipitation (CP) have decreased over the tropics and subtropics with simultaneous increases in 0–6 km wind shear (BS06). Conversely, rawinsonde observations paint a different picture across the mid-latitudes with increasing CAPE and significant decreases to BS06. Differing trends and disagreement between ERA5 and rawinsondes observed over some regions suggest that results should be interpreted with caution, especially for CAPE and CP across tropics where uncertainty is the highest and reliable long-term rawinsonde observations are missing.

scholarly journals Cross-Sectional Association between Hypercholesterolemia and Knee Pain in the Elderly with Radiographic Knee Osteoarthritis: Data from the Korean National Health and Nutritional Examination Survey

2021 ◽  
Vol 10 (5) ◽  
pp. 933
Author(s):  
Byung Woo Cho ◽  
Du Seong Kim ◽  
Hyuck Min Kwon ◽  
Ick Hwan Yang ◽  
Woo-Suk Lee ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Regression Analysis ◽  
Knee Pain ◽  
Logistic Regression Analysis ◽  
National Health ◽  
Large Scale ◽  
Metabolic Diseases ◽  
The Elderly ◽  
Cross Sectional ◽  
Ordinal Logistic Regression Analysis

Few studies have reported the relationship between knee pain and hypercholesterolemia in the elderly population with osteoarthritis (OA), independent of other variables. The aim of this study was to reveal the association between knee pain and metabolic diseases including hypercholesterolemia using a large-scale cohort. A cross-sectional study was conducted using data from the Korea National Health and the Nutrition Examination Survey (KNHANES-V, VI-1; 2010–2013). Among the subjects aged ≥60 years, 7438 subjects (weighted number estimate = 35,524,307) who replied knee pain item and performed the simple radiographs of knee were enrolled. Using multivariable ordinal logistic regression analysis, variables affecting knee pain were identified, and the odds ratio (OR) was calculated. Of the 35,524,307 subjects, 10,630,836 (29.9%) subjects experienced knee pain. Overall, 20,290,421 subjects (56.3%) had radiographic OA, and 8,119,372 (40.0%) of them complained of knee pain. Multivariable ordinal logistic regression analysis showed that among the metabolic diseases, only hypercholesterolemia was positively correlated with knee pain in the OA group (OR 1.24; 95% Confidence Interval 1.02–1.52, p = 0.033). There were no metabolic diseases correlated with knee pain in the non-OA group. This large-scale study revealed that in the elderly, hypercholesterolemia was positively associated with knee pain independent of body mass index and other metabolic diseases in the OA group, but not in the non-OA group. These results will help in understanding the nature of arthritic pain, and may support the need for exploring the longitudinal associations.

scholarly journals Large-scale screening of natural genetic resource in the hydrocarbon-producing microalga Botrycoccus braunii identified novel fast-growing strains

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Koji Kawamura ◽  
Suzune Nishikawa ◽  
Kotaro Hirano ◽  
Ardianor Ardianor ◽  
Rudy Agung Nugroho ◽  
...  
Keyword(s):  
Large Scale ◽  
Biomass Productivity ◽  
Botryococcus Braunii ◽  
Algal Biofuel ◽  
Fast Growing ◽  
Wild Strains ◽  
Glass Tubes ◽  
The Tropics ◽  
Large Scale Screening ◽  
Hydrocarbon Productivity

AbstractAlgal biofuel research aims to make a renewable, carbon–neutral biofuel by using oil-producing microalgae. The freshwater microalga Botryococcus braunii has received much attention due to its ability to accumulate large amounts of petroleum-like hydrocarbons but suffers from slow growth. We performed a large-scale screening of fast-growing strains with 180 strains isolated from 22 ponds located in a wide geographic range from the tropics to cool-temperate. A fast-growing strain, Showa, which recorded the highest productivities of algal hydrocarbons to date, was used as a benchmark. The initial screening was performed by monitoring optical densities in glass tubes and identified 9 wild strains with faster or equivalent growth rates to Showa. The biomass-based assessments showed that biomass and hydrocarbon productivities of these strains were 12–37% and 11–88% higher than that of Showa, respectively. One strain, OIT-678 established a new record of the fastest growth rate in the race B strains with a doubling time of 1.2 days. The OIT-678 had 36% higher biomass productivity, 34% higher hydrocarbon productivity, and 20% higher biomass density than Showa at the same cultivation conditions, suggesting the potential of the new strain to break the record for the highest productivities of hydrocarbons.

scholarly journals Dipole patterns in tropical precipitation were pervasive across landmasses throughout Marine Isotope Stage 5

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Katrina Nilsson-Kerr ◽  
Pallavi Anand ◽  
Philip B. Holden ◽  
Steven C. Clemens ◽  
Melanie J. Leng
Keyword(s):  
Large Scale ◽  
Marine Isotope Stage ◽  
Convergence Zone ◽  
Inter Tropical Convergence Zone ◽  
Tropical Regions ◽  
Tropical Precipitation ◽  
Rainfall Patterns ◽  
Marine Isotope Stage 5 ◽  
Climate Cooling ◽  
The Tropics

AbstractMost of Earth’s rain falls in the tropics, often in highly seasonal monsoon rains, which are thought to be coupled to the inter-hemispheric migrations of the Inter-Tropical Convergence Zone in response to the seasonal cycle of insolation. Yet characterization of tropical rainfall behaviour in the geologic past is poor. Here we combine new and existing hydroclimate records from six large-scale tropical regions with fully independent model-based rainfall reconstructions across the last interval of sustained warmth and ensuing climate cooling between 130 to 70 thousand years ago (Marine Isotope Stage 5). Our data-model approach reveals large-scale heterogeneous rainfall patterns in response to changes in climate. We note pervasive dipole-like tropical precipitation patterns, as well as different loci of precipitation throughout Marine Isotope Stage 5 than recorded in the Holocene. These rainfall patterns cannot be solely attributed to meridional shifts in the Inter-Tropical Convergence Zone.

Large-scale flow field visualization for aneurysm treatment

2001 ◽  
Vol 9 (1) ◽  
pp. 3-7
Author(s):  
Damon Liu ◽  
Mark Burgin ◽  
Walter Karplus ◽  
Daniel Valentino
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Aneurysm Treatment ◽  
Large Scale Flow
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