scholarly journals The Global Distribution of Atmospheric Eddy Length Scales

2012 ◽  
Vol 25 (9) ◽  
pp. 3409-3416 ◽  
Author(s):  
Elizabeth A. Barnes ◽  
Dennis L. Hartmann
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Seasonal Cycle ◽  
Winter Season ◽  
Global Distribution ◽  
Correlation Lengths ◽  
Weather Forecasts ◽  
European Centre ◽  
Medium Range ◽  
Upper Level

The correlation lengths of vorticity anomalies from temporal averages are examined in the 40-yr European Centre for Medium-Range Weather Forecasts Re-Analysis dataset. It is shown that, in the annual mean, eddies in the Southern Hemisphere are significantly larger than those in the Northern Hemisphere. The eddy vorticity lengths exhibit a strong seasonal cycle, with the largest scales occurring in the winter season. The maximum zonal eddy lengths closely follow the contours of the strong upper-level winds, while the maximum meridional lengths are found in jet exit regions and in the stratosphere.

scholarly journals Potential Vorticity Anomalies of the Lowermost Stratosphere: A 10-Yr Winter Climatology

2010 ◽  
Vol 138 (4) ◽  
pp. 1234-1249 ◽  
Author(s):  
Sarah F. Kew ◽  
Michael Sprenger ◽  
Huw C. Davies
Keyword(s):  
Life Cycle ◽  
Spatial Structure ◽  
Northern Hemisphere ◽  
Potential Vorticity ◽  
Weather Forecasts ◽  
European Centre ◽  
Medium Range ◽  
High Topography ◽  
Ubiquitous Presence ◽  
Shed Light

Abstract Inspection of the potential vorticity (PV) distribution on isentropic surfaces in the lowermost stratosphere reveals the ubiquitous presence of numerous subsynoptic positive PV anomalies. To examine the space–time characteristics of these anomalies, a combined “identification and tracking” tool is developed that can catalog each individual anomaly’s effective amplitude, location, overall spatial structure, and movement from genesis to lysis. A 10-yr winter climatology of such anomalies in the Northern Hemisphere is derived for the period 1991–2001 based upon the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40). The climatology indicates that the anomalies are frequently evident above high topography and in a quasi-annular band at about 70°N, are long lived (days to weeks), and that their effective amplitude is typically 2 PV units (PVU) higher than that of the ambient environment. In addition, the derived climatologies and associated composites pose questions regarding the origin of the anomalies, detail their life cycle, and shed light on their dynamics and role as long-lived precursors of surface cyclogenesis.

scholarly journals Role of Cross-Equatorial Waves in Maintaining Long Periods of Low Convective Activity over Southern Africa

2015 ◽  
Vol 72 (2) ◽  
pp. 682-692 ◽  
Author(s):  
J. V. Ratnam ◽  
Swadhin K. Behera ◽  
Toshio Yamagata
Keyword(s):  
Northern Hemisphere ◽  
Southern Africa ◽  
Wave Train ◽  
Longwave Radiation ◽  
Convective Activity ◽  
Weather Forecasts ◽  
Medium Range ◽  
Tropical Temperate Trough ◽  
Upper Level

Abstract Periods of low convective activity over southern Africa during the peak rainy season from December to February are known to be due to the northeastward displacement of the tropical temperate trough (TTT) systems from the landmass. In this study, using Interim European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-Interim) data, the authors show that the displacement of the TTT systems during long periods of low convective activity has origins in the Northern Hemisphere. Using standardized area-averaged outgoing longwave radiation (OLR) daily anomalies over southern Africa, long periods of low convective activity are defined as periods of positive OLR anomalies lasting consecutively for 5 or more days with a standard deviation of 1 or more. An eddy streamfunction anomaly composite of the periods of low convective activity shows an upper-level anomalous wave originating in the Northern Hemisphere and extending to southern Africa from the eastern Pacific and displacing the tropical–extratropical cloud bands from the southern African landmass into the southwestern Indian Ocean. The wave train is also seen to generate an anticyclonic anomaly over southern Africa, resulting in suppressed convective activity. Understanding the causes of the long periods of low convective activity will help in improving their predictability and also the predictability of seasonal rainfall over southern Africa.

Hochaufgelöste Simulation von meteorologischen Feldern in urbanen Räumen mit dem Weather Research and Forecasting (WRF) Modell

2021 ◽  
Author(s):  
Lukas N. Pilz ◽  
Sanam N. Vardag ◽  
Joachim Fallmann ◽  
André Butz
Keyword(s):  
Greenhouse Gas ◽  
Monitoring System ◽  
Weather Research And Forecasting ◽  
Gas Monitoring ◽  
Weather Forecasts ◽  
European Centre ◽  
Medium Range ◽  
Erste Ergebnisse ◽  
Weather Research

<p><span>Städte und Kommunen sind für mehr als 70% </span><span>der globalen, fossilen CO2-Emissionen</span><span> verantwortlich, sodass hier ein enormes Mitigationspotential besteht. Informationen über (inner-)städtische CO2-Emissionen stehen allerdings oft nicht </span><span>in hoher zeitlicher und räumlicher Auflösung</span><span> zur Verfügung und sind </span><span>meist</span><span> mit großen Unsicherheiten behaftet. Diese Umstände erschweren eine zielgerichtete und effiziente Mitigation im urbanen Raum. </span><span>Städtische Messnetzwerke können als unabhängige Informationsquelle einen Beitrag leisten, um CO2-Emissionen in Städten zu quantifizieren und Mitigation zu verifizieren</span><span>. </span><span>Verschiedene denkbare Beobachtungsstrategien sollten</span><span> im Vorfeld abgewägt werden, um urbane Emissionen bestmöglich, d.h. mit der erforderlichen Genauigkeit und </span><span>Kosteneffizienz</span><span> zu quantifizieren. So können Messnetzwerke die Basis für zielgerichtete und kosteneffiziente Mitigation legen.</span></p><p><span>Im Rahmen des Verbundvorhabens „Integrated Greenhouse Gas Monitoring System for Germany“ (ITMS) werden wir verschiedene Beobachtungsstrategien für urbane Räume entwerfen und mit Hilfe von Modellsimulation evaluieren und abwägen. Notwendige Voraussetzung für </span><span>die Evaluation der Strategien</span><span> ist eine akkurate Repräsentation des atmosphärischen Transports im Modell.</span></p><p><span>Diese Studie zeigt</span><span> erste Ergebnisse der hochauflösenden (1kmx1km) meteorologischen Simulationen für den Rhein-Neckar-Raum mit dem WRF Modell. </span><span>Die in WRF simulierten meteorologischen Größen werden für verschiedene Modellkonfigurationen mit </span><span>re-analysierten Daten des European Centre for Medium-Range Weather Forecasts (ECMWF) und ausgewählten Messstationen verglichen. Damit evaluieren wir </span><span>den Einfluss unterschiedlicher Nudging-Strategien, Parametrisierungen physikalischer Prozesse und urbaner Interaktionen</span><span> auf </span><span>die Modellperformance</span> <span>von</span><span> Lufttemperatur, Windrichtung, Windgeschwindigkeit und Grenzschichthöhe. Durch diese Analysen gewährleisten wir, dass die Simulation der Beobachtungsstrategien auf robuste</span><span>m</span><span> und realistische</span><span>m</span><span> atmosphärischen Transport basieren und schlussendlich repräsentative Empfehlungen für den Aufbau von Messnetzwerken liefern können. </span></p>

Evaluierung des nichthydrostatischen mesoskaligen Modells GRAMM-SCI anhand der Richtlinie VDI 3783 Blatt 7/Evaluation of the nonhydrostatic mesoscale model GRAMM-SCI based on the guideline VDI 3783 Part 7

Gefahrstoffe ◽  
2020 ◽  
Vol 80 (07-08) ◽  
pp. 318-324
Author(s):  
D. Öttl
Keyword(s):  
Mesoscale Model ◽  
Weather Forecasts ◽  
European Centre ◽  
Medium Range

Aufgrund der komplexen Orografie in den Alpen sind einfache, auf diagnostischen Ansätzen beruhende Windfeldmodelle in Österreich kaum anwendbar. Daher wird in den meisten österreichischen Bundesländern das mesoskalige Modell GRAMM im Rahmen von Luftschadstoffuntersuchungen eingesetzt. In diesem Beitrag werden Ergebnisse der Modellevaluierung anhand jener drei Datensätze der Richtlinie VDI 3783 Blatt 7 präsentiert, die auf teils umfangreichen Messkampagnen basieren. Das Modell GRAMM wurde mittlerweile erweitert (Version GRAMM-SCI) und kann nun auch mit den Reanalysedaten ERA5 des Europäischen Wetterdienstes (European Centre for Medium-Range Weather Forecasts, ECMWF) angetrieben werden. Um die Qualität der ERA5-Daten zu prüfen, wurden zusätzliche Simulationen für die drei Evaluierungsdatensätze aus VDI 3783 Blatt 7 durchgeführt. Es zeigt sich, dass Modellsimulationen mit GRAMM-SCI, die auf ERA5-Daten basieren, die Strömungs- und Temperaturverhältnisse grundsätzlich gut wiedergeben. Allerdings sind die Abweichungen zu den Messungen der Sondermesskampagnen teilweise etwas zu groß, um die hohen Anforderungen von VDI 3783 Blatt 7 an die Modellergebnisse vollständig zu erfüllen.

scholarly journals CARACTERIZAÇÃO ATMOSFÉRICA QUANDO DA OCORRÊNCIA DE EVENTOS EXTREMOS DE CHUVA NA REGIÃO SUL DE MINAS GERAIS

2017 ◽  
Vol 21 ◽  
Author(s):  
Michelle Simões Reboita ◽  
Diogo Malagutti Gonçalves Marietto ◽  
Amanda Souza ◽  
Marina Barbosa
Keyword(s):  
Climate Prediction ◽  
Minas Gerais ◽  
Weather Forecasts ◽  
European Centre ◽  
Medium Range ◽  
Climate Prediction Center

O objetivo deste estudo é apresentar uma descrição das características da atmosfera que contribuíram para elevados totais de precipitação no sul de Minas Gerais e que foram precursores de dois episódios de inundação e alagamento na cidade de Itajubá: um em 16 de janeiro de 1991 e outro em 02 de janeiro de 2000. Para tanto, foram utilizados dados do Climate Prediction Center e da reanálise ERA-Interim do European Centre for Medium-Range Weather Forecasts (ECMWF). Entre os resultados, têm-se que os episódios de inundação e alagamento ocorridos na cidade de Itajubá, em ambos os anos, estiveram associados à atuação da Zona de Convergência do Atlântico Sul, que se estendia da Amazônia, passando pelo sudeste do Brasil, e chegava ao Atlântico Sul.

scholarly journals An “island” in the stratosphere – on the enhanced annual variation of water vapour in the middle and upper stratosphere in the southern tropics and subtropics

2017 ◽  
Vol 17 (18) ◽  
pp. 11521-11539 ◽  
Author(s):  
Stefan Lossow ◽  
Hella Garny ◽  
Patrick Jöckel
Keyword(s):  
Water Vapour ◽  
Atmospheric Chemistry ◽  
Annual Variation ◽  
Trace Gases ◽  
Michelson Interferometer ◽  
Full Account ◽  
Weather Forecasts ◽  
European Centre ◽  
Atmospheric Sounding ◽  
Medium Range

Abstract. The amplitude of the annual variation in water vapour exhibits a distinct isolated maximum in the middle and upper stratosphere in the southern tropics and subtropics, peaking typically around 15° S in latitude and close to 3 hPa (∼  40.5 km) in altitude. This enhanced annual variation is primarily related to the Brewer–Dobson circulation and hence also visible in other trace gases. So far this feature has not gained much attention in the literature and the present work aims to add more prominence. Using Envisat/MIPAS (Environmental Satellite/Michelson Interferometer for Passive Atmospheric Sounding) observations and ECHAM/MESSy (European Centre for Medium-Range Weather Forecasts Hamburg/Modular Earth Submodel System) Atmospheric Chemistry (EMAC) simulations we provide a dedicated illustration and a full account of the reasons for this enhanced annual variation.

scholarly journals Sixty years of radiocarbon dioxide measurements at Wellington, New Zealand 1954–2014

2016 ◽  
Author(s):  
Jocelyn C. Turnbull ◽  
Sara E. Mikaloff Fletcher ◽  
India Ansell ◽  
Gordon Brailsford ◽  
Rowena Moss ◽  
...  
Keyword(s):  
New Zealand ◽  
Southern Ocean ◽  
Co2 Emissions ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Seasonal Cycle ◽  
Fossil Fuel ◽  
Anthropogenic Sources ◽  
Deep Waters ◽  
Cape Grim

Abstract. We present 60 years of Δ14CO2 measurements from Wellington, New Zealand (41° S, 175° E). The record has been extended and fully revised. New measurements have been used to evaluate the existing record and to replace original measurements where warranted. This is the earliest atmospheric Δ14CO2 record and records the rise of the 14C "bomb spike", the subsequent decline in Δ14CO2 as bomb 14C moved throughout the carbon cycle and increasing fossil fuel CO2 emissions further decreased atmospheric Δ14CO2. The initially large seasonal cycle in the 1960s reduces in amplitude and eventually reverses in phase, resulting in a small seasonal cycle of about 2 ‰ in the 2000s. The seasonal cycle at Wellington is dominated by the seasonality of cross-tropopause transport, and differs slightly from that at Cape Grim, Australia, which is influenced by anthropogenic sources in winter. Δ14CO2 at Cape Grim and Wellington show very similar trends, with significant differences only during periods of known measurement uncertainty. In contrast, Northern Hemisphere clean air sites show a higher and earlier bomb 14C peak, consistent with a 1.4-year interhemispheric exchange time. From the 1970s until the early 2000s, the Northern and Southern Hemisphere Δ14CO2 were quite similar, apparently due to the balance of 14C-free fossil fuel CO2 emissions in the north and 14C-depleted ocean upwelling in the south. The Southern Hemisphere sites show a consistent and marked elevation above the Northern Hemisphere sites since the early 2000s, which is most likely due to reduced upwelling of 14C-depleted and carbon-rich deep waters in the Southern Ocean. This developing Δ14CO2 interhemispheric gradient is consistent with recent studies that indicate a reinvigorated Southern Ocean carbon sink since the mid-2000s, and suggests that upwelling of deep waters plays an important role in this change.

Examination of the 2002 major warming in the southern hemisphere using ground-based and Odin/SMR assimilated data: stratospheric ozone distributions and tropic/mid-latitude exchange

2007 ◽  
Vol 85 (11) ◽  
pp. 1287-1300 ◽  
Author(s):  
H Bencherif ◽  
L El Amraoui ◽  
N Semane ◽  
S Massart ◽  
D Vidyaranya Charyulu ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Southern Hemisphere ◽  
Transport Model ◽  
Stratospheric Ozone ◽  
Three Dimensional ◽  
Polar Vortex ◽  
Low Latitude ◽  
Height Range ◽  
Weather Forecasts ◽  
European Centre

Following an exceptionally active winter, the 2002 Southern Hemisphere (SH) major warming occurred in late September. It was preceded by three minor warming events that occurred in late August and early September, and yielded vortex split and break-down over Antarctica. Ozone (O3 and nitrous oxide (N2O) profiles obtained during that period of time (15 August – 4 October) by the Sub-Millimetre Radiometer (SMR) aboard the Odin satellite are assimilated into MOCAGE (Modélisation Isentrope du transport Mésoéchelle de l'Ozone Stratosphérique par Advection), a global three-dimensional chemistry transport model of Météo-France. The assimilated algorithm is a three-dimensional-FGAT built by the European Centre for Research and Advance Training in Scientific Computation (CERFACS) using the PALM (Projet d'Assimilation par Logiciel Multi-méthode) software. The assimilated O3 and N2O profiles and isentropic distributions are compared to ground-based measurements (LIDAR and balloon-sonde) and to maps of advected potential vorticity (APV). The latter is computed by the MIMOSA (Modélisation Isentrope du transport Mésoéchelle de l'Ozone Stratosphérique par Advection) model, a high-resolution advection transport model, using meteorological fields from the European Centre for Medium-Range Weather Forecasts (ECMWF). It is found that O3 concentrations retrieved by the MOCAGE–PALM assimilation system show a reasonably good agreement in the 20–28 km height range when compared with ground-based profiles. This altitude range corresponds to the intersection between the MOCAGE levels (0–28 km) and SMR O3 retrievals (20–50 km). Moreover, comparison of N2O assimilated fields with MIMOSA APV maps indicates that the dramatic split and subsequent break-down of the polar vortex, as well as the associated mixing of mid- and low-latitude stratospheric air, are well resolved and pictured by MOCAGE–PALM. The present study demonstrates also that the tremendous dynamics and associated polar vortex deformations during the 2002-austral-winter have modified ozone and nitrous oxide distributions not only at the vicinity of the polar vortex, but over topics and subtropics as well. PACS Nos.: 92.60.H–, 92.60.Hd, 92.70.Cp, 92.70.Gt

scholarly journals Spatial-Temporal Pattern Changes of UTCI in the China-Pakistan Economic Corridor in Recent 40 Years

Atmosphere ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 858
Author(s):  
Di Zeng ◽  
Jinkui Wu ◽  
Yaqiong Mu ◽  
Mingshan Deng ◽  
Yanqiang Wei ◽  
...  
Keyword(s):  
Thermal Environment ◽  
Linear Trend ◽  
Temporal Variations ◽  
Reanalysis Data ◽  
Climate Index ◽  
Positive Trend ◽  
Growth Trend ◽  
Weather Forecasts ◽  
European Centre ◽  
Medium Range

This paper investigated the spatial and temporal variations of the Universal Thermal Climate Index (UTCI) of the China-Pakistan Economic Corridor (CPEC) from 1979 to 2018. The European Centre for Medium-Range Weather Forecasts Re-Analysis-Interim (ERA-Interim) reanalysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF) is selected for UTCI calculation in the region and analyzed by a linear trend and correlation analysis. The results showed that (1) the UTCI of CPEC is decreased with the increase of latitude and altitude. There is obvious spatial heterogeneity in the seasonal scale and the spatial distribution of different thermal stress categories. (2) UTCI generally exhibited a positive trend of 0.33 °C/10a over the past 40 years, and the seasonal variation characteristics of UTCI show an upward trend in all four seasons, of which spring is the fastest. On the space scale, the growth trend has significant spatial variations. (3) Temperature has a positive correlation with UTCI. The influence of temperature on UTCI is greater than that of wind speed. The results of this study will be helpful for regional planning and also contribute to comprehending the characteristics of the thermal environment in CPEC.

scholarly journals Global marine plankton functional type biomass distributions: coccolithophores

2012 ◽  
Vol 5 (2) ◽  
pp. 491-520 ◽  
Author(s):  
C. J. O'Brien ◽  
J. A. Peloquin ◽  
M. Vogt ◽  
M. Heinle ◽  
N. Gruber ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Seasonal Cycle ◽  
Marine Phytoplankton ◽  
The North ◽  
Carbon Biomass ◽  
Time Period ◽  
The Pacific ◽  
Individual Contributions ◽  
June July

Abstract. Coccolithophores are calcifying marine phytoplankton of the class Prymnesiophyceae. They are considered to play an import role in the global carbon cycle through the production and export of organic carbon and calcite. We have compiled observations of global coccolithophore abundance from several existing databases as well as individual contributions of published and unpublished datasets. We estimate carbon biomass using standardised conversion methods and provide estimates of uncertainty associated with these values. The database contains 58 384 individual observations at various taxonomic levels. This corresponds to 12 391 observations of total coccolithophore abundance and biomass. The data span a time period of 1929–2008, with observations from all ocean basins and all seasons, and at depths ranging from the surface to 500 m. Highest biomass values are reported in the North Atlantic, with a maximum of 501.7 μg C l−1. Lower values are reported for the Pacific (maximum of 79.4 μg C l−1) and Indian Ocean (up to 178.3 μg C l−1). Coccolithophores are reported across all latitudes in the Northern Hemisphere, from the Equator to 89° N, although biomass values fall below 3 μg C l−1 north of 70° N. In the Southern Hemisphere, biomass values fall rapidly south of 50° S, with only a single non-zero observation south of 60° S. Biomass values show a clear seasonal cycle in the Northern Hemisphere, reaching a maximum in the summer months (June–July). In the Southern Hemisphere the seasonal cycle is less evident, possibly due to a greater proportion of low-latitude data. The original and gridded datasets can be downloaded from Pangaea (http://doi.pangaea.de/10.1594/PANGAEA.785092).

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