Diagnostic Comparison of Meteorological Analyses during the 2002 Antarctic Winter

Abstract Several meteorological datasets, including U.K. Met Office (MetO), European Centre for Medium-Range Weather Forecasts (ECMWF), National Centers for Environmental Prediction (NCEP), and NASA’s Goddard Earth Observation System (GEOS-4) analyses, are being used in studies of the 2002 Southern Hemisphere (SH) stratospheric winter and Antarctic major warming. Diagnostics are compared to assess how these studies may be affected by the meteorological data used. While the overall structure and evolution of temperatures, winds, and wave diagnostics in the different analyses provide a consistent picture of the large-scale dynamics of the SH 2002 winter, several significant differences may affect detailed studies. The NCEP–NCAR reanalysis (REAN) and NCEP–Department of Energy (DOE) reanalysis-2 (REAN-2) datasets are not recommended for detailed studies, especially those related to polar processing, because of lower-stratospheric temperature biases that result in underestimates of polar processing potential, and because their winds and wave diagnostics show increasing differences from other analyses between ∼30 and 10 hPa (their top level). Southern Hemisphere polar stratospheric temperatures in the ECMWF 40-Yr Re-analysis (ERA-40) show unrealistic vertical structure, so this long-term reanalysis is also unsuited for quantitative studies. The NCEP/Climate Prediction Center (CPC) objective analyses give an inferior representation of the upper-stratospheric vortex. Polar vortex transport barriers are similar in all analyses, but there is large variation in the amount, patterns, and timing of mixing, even among the operational assimilated datasets (ECMWF, MetO, and GEOS-4). The higher-resolution GEOS-4 and ECMWF assimilations provide significantly better representation of filamentation and small-scale structure than the other analyses, even when fields gridded at reduced resolution are studied. The choice of which analysis to use is most critical for detailed transport studies (including polar process modeling) and studies involving synoptic evolution in the upper stratosphere. The operational assimilated datasets are better suited for most applications than the NCEP/CPC objective analyses and the reanalysis datasets (REAN/REAN-2 and ERA-40).

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Intercomparison of meteorological analyses and trajectories in the Antarctic lower stratosphere with Concordiasi superpressure balloon observations

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-8045-2017 ◽

2017 ◽

Vol 17 (13) ◽

pp. 8045-8061 ◽

Cited By ~ 12

Author(s):

Lars Hoffmann ◽

Albert Hertzog ◽

Thomas Rößler ◽

Olaf Stein ◽

Xue Wu

Keyword(s):

Large Scale ◽

Lower Stratosphere ◽

Transport Model ◽

Polar Vortex ◽

Small Scale ◽

Trajectory Calculations ◽

Major Interest ◽

Meridional Winds ◽

Environmental Prediction ◽

The Antarctic

Abstract. In this study we compared temperatures and horizontal winds of meteorological analyses in the Antarctic lower stratosphere, a region of the atmosphere that is of major interest regarding chemistry and dynamics of the polar vortex. The study covers the European Centre for Medium-Range Weather Forecasts (ECMWF) operational analysis, the ERA-Interim reanalysis, the Modern-Era Retrospective analysis for Research and Applications version 1 and 2 (MERRA and MERRA-2), and the National Centers for Environmental Prediction and National Center for Atmospheric Research (NCEP/NCAR) reanalysis. The comparison was performed with respect to long-duration observations from 19 superpressure balloon flights during the Concordiasi field campaign in September 2010 to January 2011. Most of the balloon measurements were conducted at altitudes of 17–18.5 km and latitudes of 60–85° S. We found that large-scale state temperatures of the analyses have a mean precision of 0.5–1.4 K and a warm bias of 0.4–2.1 K with respect to the balloon data. Zonal and meridional winds have a mean precision of 0.9–2.3 m s−1 and a bias below ±0.5 m s−1. Standard deviations related to small-scale fluctuations due to gravity waves are reproduced at levels of 15–60 % for temperature and 30–60 % for the horizontal winds. Considering the fact that the balloon observations have been assimilated into all analyses, except for NCEP/NCAR, notable differences found here indicate that other observations, the forecast models, and the data assimilation procedures have a significant impact on the analyses as well. We also used the balloon observations to evaluate trajectory calculations with our new Lagrangian transport model Massive-Parallel Trajectory Calculations (MPTRAC), where vertical motions of simulated trajectories were nudged to pressure measurements of the balloons. We found relative horizontal transport deviations of 4–12 % and error growth rates of 60–170 km day−1 for 15-day trajectories. Dispersion simulations revealed some difficulties with the representation of subgrid-scale wind fluctuations in MPTRAC, as the spread of air parcels simulated with different analyses was not consistent. However, although case studies suggest that the accuracy of trajectory calculations is influenced by meteorological complexity, diffusion generally does not contribute significantly to transport deviations in our analysis. Overall, evaluation results are satisfactory and compare well to earlier studies using superpressure balloon observations.

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Teleconnection between the Asian Polar Vortex and surface PM2.5 in China

Scientific Reports ◽

10.1038/s41598-020-76414-6 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Lihua Zhou ◽

Jing Zhang ◽

Xiaohui Zheng ◽

Siguang Zhu ◽

Yueming Hu

Keyword(s):

Large Scale ◽

Meteorological Data ◽

Fine Particulate Matter ◽

Polar Vortex ◽

Atmospheric Circulations ◽

Fine Particulate ◽

Heavy Pollution ◽

Pollution Emissions ◽

The Impact ◽

East West

Abstract Atmospheric fine particulate matter (PM2.5) pollutions are of particular concern because of their direct and indirect harm to humans and organisms. China has suffered from severe air pollution for the past ten years, related to heavy pollution emissions and compounded by the effects of atmospheric circulation. This study applied statistical methods, observational data of ground pollutants, and meteorological data to analyze the impact of large-scale atmospheric circulations on PM2.5 pollution over China. Empirical orthogonal function (EOF) analysis was used to evaluate the main PM2.5 patterns and total contributions of the leading four EOFs. The results indicate that the total contributions of the leading four EOFs accounted for 50.5% of the total variance, reflecting four main types of PM2.5 pollution, namely, overall pollution phase, north–south phase, east–west phase and north–center–south phase, with contributions of 28.4%, 9.7%, 6.5% and 5.9%, respectively. We selected indices of the Asian Polar Vortex (APV) to analyze the impact of large-scale atmospheric circulations on PM2.5 pollution over China. The most pronounced APV control occurred in Beijing and its surroundings, specifically, along the Bohai Sea and the Northeast Plain.

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A Global Atmospheric Analysis Dataset Downscaled from the NCEP–DOE Reanalysis

Journal of Climate ◽

10.1175/jcli-d-11-00534.1 ◽

2012 ◽

Vol 25 (7) ◽

pp. 2527-2534 ◽

Cited By ~ 4

Author(s):

Jung-Eun Kim ◽

Song-You Hong

Keyword(s):

Large Scale ◽

Hydrological Cycle ◽

Analysis Data ◽

Reanalysis Data ◽

Horizontal Resolution ◽

Department Of Energy ◽

Quality Analysis ◽

Resolution Model ◽

Decadal Trend ◽

Environmental Prediction

Abstract A global atmospheric analysis dataset is constructed via a spectral nudging technique. The 6-hourly National Centers for Environmental Prediction (NCEP)–Department of Energy (DOE) reanalysis from January 1979 to February 2011 is utilized to force large-scale information, whereas a higher-resolution structure is resolved by a global model with improved physics. The horizontal resolution of the downscaled data is about 100 km, twice that of the NCEP–DOE reanalysis. A comparison of the 31-yr downscaled data with reanalysis data and observations reveals that the downscaled precipitation climatology is improved by correcting inherent biases in the lower-resolution reanalysis, and large-scale patterns are preserved. In addition, it is found that global downscaling is an efficient way to generate high-quality analysis data due to the use of a higher-resolution model with improved physics. The uniqueness of the obtained data lies in the fact that an undesirable decadal trend in the analysis due to a change in the amount of observations used in reanalysis is avoided. As such, a downscaled dataset may be used to investigate changes in the hydrological cycle and related mechanisms.

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Small-scale processes with large-scale impacts: Investigating canopy structure controls on energy fluxes to the forest snowpack

10.5194/egusphere-egu2020-19027 ◽

2020 ◽

Author(s):

Giulia Mazzotti ◽

Richard Essery ◽

Johanna Malle ◽

Clare Webster ◽

Tobias Jonas

Keyword(s):

High Resolution ◽

Land Surface ◽

Large Scale ◽

Meteorological Data ◽

Canopy Structure ◽

Model Performance ◽

Turbulent Fluxes ◽

Temporal Variations ◽

Small Scale ◽

Forest Stands

Forest canopies strongly affect snowpack energetics during wintertime. In discontinuous forest stands, spatio-temporal variations in radiative and turbulent fluxes create complex snow distribution and melt patterns, with further impacts on the hydrological regimes and on the land surface properties of seasonally snow-covered forested environments.As increasingly detailed canopy structure datasets are becoming available, canopy-induced energy exchange processes can be explicitly represented in high-resolution snow models. We applied the modelling framework FSM2 to obtain spatially distributed simulations of the forest snowpack in subalpine and boreal forest stands at high spatial (2m) and temporal (10min) resolution. Modelled sub-canopy radiative and turbulent fluxes were compared to detailed meteorological data of incoming irradiances, air and snow surface temperatures. These were acquired with novel observational systems, including 1) a motorized cable car setup recording spatially and temporally resolved data along a transect and 2) a handheld setup designed to capture temporal snapshots of 2D spatial distributions across forest discontinuities.The combination of high-resolution modelling and multi-dimensional datasets allowed us to assess model performance at the level of individual energy balance components, under various meteorological conditions and across canopy density gradients. We showed which canopy representation strategies within FSM2 best succeeded in reproducing snowpack energy transfer dynamics in discontinuous forests, and derived implications for implementing forest snow processes in coarser-resolution models.

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Comparisons of polar processing diagnostics from 34 years of the ERA-Interim and MERRA reanalyses

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-3873-2015 ◽

2015 ◽

Vol 15 (7) ◽

pp. 3873-3892 ◽

Cited By ~ 23

Author(s):

Z. D. Lawrence ◽

G. L. Manney ◽

K. Minschwaner ◽

M. L. Santee ◽

A. Lambert

Keyword(s):

Meteorological Data ◽

Polar Vortex ◽

Reanalysis Data ◽

Cloud Formation ◽

Data Sets ◽

Weather Forecasts ◽

Stratospheric Temperature ◽

Vortex Size ◽

Comprehensive Comparison ◽

Modern Era

Abstract. We present a comprehensive comparison of polar processing diagnostics derived from the National Aeronautics and Space Administration (NASA) Modern Era Retrospective-analysis for Research and Applications (MERRA) and the European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Reanalysis (ERA-Interim). We use diagnostics that focus on meteorological conditions related to stratospheric chemical ozone loss based on temperatures, polar vortex dynamics, and air parcel trajectories to evaluate the effects these reanalyses might have on polar processing studies. Our results show that the agreement between MERRA and ERA-Interim changes significantly over the 34 years from 1979 to 2013 in both hemispheres and in many cases improves. By comparing our diagnostics during five time periods when an increasing number of higher-quality observations were brought into these reanalyses, we show how changes in the data assimilation systems (DAS) of MERRA and ERA-Interim affected their meteorological data. Many of our stratospheric temperature diagnostics show a convergence toward significantly better agreement, in both hemispheres, after 2001 when Aqua and GOES (Geostationary Operational Environmental Satellite) radiances were introduced into the DAS. Other diagnostics, such as the winter mean volume of air with temperatures below polar stratospheric cloud formation thresholds (VPSC) and some diagnostics of polar vortex size and strength, do not show improved agreement between the two reanalyses in recent years when data inputs into the DAS were more comprehensive. The polar processing diagnostics calculated from MERRA and ERA-Interim agree much better than those calculated from earlier reanalysis data sets. We still, however, see fairly large differences in many of the diagnostics in years prior to 2002, raising the possibility that the choice of one reanalysis over another could significantly influence the results of polar processing studies. After 2002, we see overall good agreement among the diagnostics, which demonstrates that the ERA-Interim and MERRA reanalyses are equally appropriate choices for polar processing studies of recent Arctic and Antarctic winters.

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Impact of Lagrangian transport on lower-stratospheric transport timescales in a climate model

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-15227-2020 ◽

2020 ◽

Vol 20 (23) ◽

pp. 15227-15245

Author(s):

Edward J. Charlesworth ◽

Ann-Kristin Dugstad ◽

Frauke Fritsch ◽

Patrick Jöckel ◽

Felix Plöger

Keyword(s):

Atmospheric Chemistry ◽

Large Scale ◽

Climate Model ◽

Polar Vortex ◽

Transport Processes ◽

Lagrangian Model ◽

Trace Gas ◽

Lagrangian Transport ◽

Transport Barriers ◽

The Impact

Abstract. We investigate the impact of model trace gas transport schemes on the representation of transport processes in the upper troposphere and lower stratosphere. Towards this end, the Chemical Lagrangian Model of the Stratosphere (CLaMS) was coupled to the ECHAM/MESSy Atmospheric Chemistry (EMAC) model and results from the two transport schemes (Lagrangian critical Lyapunov scheme and flux-form semi-Lagrangian, respectively) were compared. Advection in CLaMS was driven by the EMAC simulation winds, and thereby the only differences in transport between the two sets of results were caused by differences in the transport schemes. To analyze the timescales of large-scale transport, multiple tropical-surface-emitted tracer pulses were performed to calculate age of air spectra, while smaller-scale transport was analyzed via idealized, radioactively decaying tracers emitted in smaller regions (nine grid cells) within the stratosphere. The results show that stratospheric transport barriers are significantly stronger for Lagrangian EMAC-CLaMS transport due to reduced numerical diffusion. In particular, stronger tracer gradients emerge around the polar vortex, at the subtropical jets, and at the edge of the tropical pipe. Inside the polar vortex, the more diffusive EMAC flux-form semi-Lagrangian transport scheme results in a substantially higher amount of air with ages from 0 to 2 years (up to a factor of 5 higher). In the lowermost stratosphere, mean age of air is much smaller in EMAC, owing to stronger diffusive cross-tropopause transport. Conversely, EMAC-CLaMS shows a summertime lowermost stratosphere age inversion – a layer of older air residing below younger air (an “eave”). This pattern is caused by strong poleward transport above the subtropical jet and is entirely blurred by diffusive cross-tropopause transport in EMAC. Potential consequences from the choice of the transport scheme on chemistry–climate and geoengineering simulations are discussed.

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Polar vortex shape-transition during SSW depending on preceding NAO conditions

10.5194/egusphere-egu2020-1925 ◽

2020 ◽

Author(s):

Hyesun Choi ◽

Wookap Choi ◽

Seong-Joong Kim ◽

Baek-Min Kim

Keyword(s):

North Atlantic ◽

Climate Model ◽

Polar Vortex ◽

Small Scale ◽

Vortex Center ◽

Shape Transition ◽

Sudden Stratospheric Warming ◽

Abrupt Decrease ◽

The North ◽

Stratospheric Temperature

Sudden stratospheric warming (SSW) characterized by a rapid increase in polar stratospheric temperature and an abrupt decrease in circumpolar westerly wind is accompanied by deformation in the shape of the polar vortex. The SSW type can be distinguished depending on the vortex shape. SSW events preceded by a displacement in polar vortex center are characterized by whether they retain their displaced form (displacement-displacement type) or split into two vortices (displacement-split type) after onset. Here, we show that existence of a polar vortex shape-transition during the course of the SSW life cycle can be attributable to the condition of North Atlantic Oscillation (NAO) preceding before onset: Positive NAO favors SSW of displacement-displacement type with no transition while negative NAO favors the displacement-split type. We show that, in positive NAO precondition, vertical flux of wave activity immediately before onset is mostly contributed only by wavenumber 1 component, which contrasts with the relatively stronger contribution of wavenumber 2 in negative NAO pre-condition. This study provides probability that the North Atlantic anomaly can induce a favorable condition for the development of small scale waves and lead to the occurrence of SSW type-transition. Whole Atmosphere Community Climate Model (WACCM) simulation results reproduce well the observational findings. Therefore, NAO can be regarded as a useful predictor for distinguishing the type of forthcoming SSW events.&#160;

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Large Interstellar Polarisation Survey

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731814 ◽

2018 ◽

Vol 611 ◽

pp. A5 ◽

Cited By ~ 5

Author(s):

R. Siebenmorgen ◽

N. V. Voshchinnikov ◽

S. Bagnulo ◽

N. L. J. Cox ◽

J. Cami ◽

...

Keyword(s):

High Resolution ◽

Interstellar Medium ◽

Southern Hemisphere ◽

Large Scale ◽

Small Scale ◽

Data Set ◽

Carbon Particles ◽

Prolate Shape ◽

Multiple Clouds ◽

H 20

It is well known that the dust properties of the diffuse interstellar medium exhibit variations towards different sight-lines on a large scale. We have investigated the variability of the dust characteristics on a small scale, and from cloud-to-cloud. We use low-resolution spectro-polarimetric data obtained in the context of the Large Interstellar Polarisation Survey (LIPS) towards 59 sight-lines in the Southern Hemisphere, and we fit these data using a dust model composed of silicate and carbon particles with sizes from the molecular to the sub-micrometre domain. Large (≥6 nm) silicates of prolate shape account for the observed polarisation. For 32 sight-lines we complement our data set with UVES archive high-resolution spectra, which enable us to establish the presence of single-cloud or multiple-clouds towards individual sight-lines. We find that the majority of these 35 sight-lines intersect two or more clouds, while eight of them are dominated by a single absorbing cloud. We confirm several correlations between extinction and parameters of the Serkowski law with dust parameters, but we also find previously undetected correlations between these parameters that are valid only in single-cloud sight-lines. We find that interstellar polarisation from multiple-clouds is smaller than from single-cloud sight-lines, showing that the presence of a second or more clouds depolarises the incoming radiation. We find large variations of the dust characteristics from cloud-to-cloud. However, when we average a sufficiently large number of clouds in single-cloud or multiple-cloud sight-lines, we always retrieve similar mean dust parameters. The typical dust abundances of the single-cloud cases are [C]/[H] = 92 ppm and [Si]/[H] = 20 ppm.

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Hemispheric ozone variability indices derived from satellite observations and as diagnostics for coupled chemistry-climate models

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-6-5671-2006 ◽

2006 ◽

Vol 6 (3) ◽

pp. 5671-5709

Author(s):

T. Erbertseder ◽

V. Eyring ◽

M. Bittner ◽

M. Dameris ◽

V. Grewe

Keyword(s):

Interannual Variability ◽

Southern Hemisphere ◽

Northern Hemisphere ◽

Total Ozone ◽

Large Scale ◽

Model Simulation ◽

Polar Vortex ◽

Satellite Observations ◽

Ozone Hole ◽

Wave Number

Abstract. Dynamics and chemistry of the lower and middle stratosphere are characterized by manifold processes on different scales in time and space. The total column density of ozone, measured by numerous instruments, can be used to trace the resulting variability. In particular, satellite-borne spectrometers allow global observation of the total ozone distribution with proven accuracy and high temporal and spatial resolution. In order to analyse the zonal and hemispherical ozone variability a spectral statistical Harmonic Analysis is applied to multi-year total ozone observations from the Total Ozone Monitoring Spectrometer (TOMS). As diagnostic variables we introduce the hemispheric ozone variability indices one and two. They are defined as the hemispheric means of the amplitudes of the zonal waves number one and two, respectively, as traced by the total ozone field. In order to demonstrate the capability of the diagnostic for intercomparison studies we apply the hemispheric ozone variability indices to evaluate total ozone fields of the coupled chemistry-climate model ECHAM4.L39(DLR)/CHEM (hereafter: E39/C) against satellite observations. Results of a multi-year model simulation representing ''2000" climate conditions with an updated version of E39/C and corresponding total ozone data of TOMS from 1996 to 2004 (Version 8.0) are used. It is quantified to what extent E39/C is able to reproduce the zonal and hemispherical large scale total ozone variations. The different representations of the hemispheric ozone variability indices are discussed. Summarizing the main differences of model and reference observations, we show that both indices, one and two, in E39/C are preferably too high in the Northern Hemisphere and preferably too low in the Southern Hemisphere. In the Northern Hemisphere, where the coincidence is generally better, E39/C produces a too strong planetary wave one activity in winter and spring as well as a too high interannual variability. For the Southern Hemisphere we conclude that model and observations differ significantly during the ozone hole season. In October and November amplitudes of wave number one and two are underestimated. This explains that E39/C exhibits a too stable polar vortex and a too low interannual variability of the ozone hole. Further, a strong negative bias of wave number one amplitudes in the tropics and subtropics from October to December is identified, which may also contribute to the zonal-symmetric polar vortex. The lack of wave two variability in October and November leads to weak vortex elongation and eventually a too late final warming. Contrary, too high wave number two amplitudes in July and August indicate why the polar vortex is formed too late in season by E39/C. In general, the hemispheric ozone variability indices can be regarded as a simple and robust approach to quantify differences in total ozone variability on a monthly mean basis. Therefore, the diagnostic represents a core diagnostic for model intercomparisons within the CCM Validation Activity for WCRP's (World Climate Research Programme) SPARC (Stratospheric Processes and their Role in Climate) regarding stratospheric dynamics.

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The DOE Systems Biology Knowledgebase (KBase)

10.1101/096354 ◽

2016 ◽

Cited By ~ 16

Author(s):

Adam P Arkin ◽

Rick L Stevens ◽

Robert W Cottingham ◽

Sergei Maslov ◽

Christopher S Henry ◽

...

Keyword(s):

Systems Biology ◽

Open Source Software ◽

Large Scale ◽

Community Dynamics ◽

Department Of Energy ◽

Small Scale ◽

Grand Challenge ◽

Web Browser ◽

Data Platform ◽

Computational Resources

AbstractThe U.S. Department of Energy Systems Biology Knowledgebase (KBase) is an open-source software and data platform designed to meet the grand challenge of systems biology — predicting and designing biological function from the biomolecular (small scale) to the ecological (large scale). KBase is available for anyone to use, and enables researchers to collaboratively generate, test, compare, and share hypotheses about biological functions; perform large-scale analyses on scalable computing infrastructure; and combine experimental evidence and conclusions that lead to accurate models of plant and microbial physiology and community dynamics. The KBase platform has (1) extensible analytical capabilities that currently include genome assembly, annotation, ontology assignment, comparative genomics, transcriptomics, and metabolic modeling; (2) a web-browser-based user interface that supports building, sharing, and publishing reproducible and well-annotated analyses with integrated data; (3) access to extensive computational resources; and (4) a software development kit allowing the community to add functionality to the system.

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