scholarly journals Calculated Height Tendencies in Two Southern Hemisphere Blocking and Cyclone Events: The Contribution of Diabatic Heating to Block Intensification

2008 ◽  
Vol 136 (9) ◽  
pp. 3568-3578 ◽  
Author(s):  
Douglas E. Tilly ◽  
Anthony R. Lupo ◽  
Christopher J. Melick ◽  
Patrick S. Market
Keyword(s):  
Southern Hemisphere ◽  
Diabatic Heating ◽  
Latent Heating ◽  
Atmospheric Research ◽  
Vorticity Advection ◽  
Surface Cyclone ◽  
Advection Term ◽  
Environmental Prediction ◽  
Vorticity Tendency

Abstract The Zwack–Okossi vorticity tendency equation was used to calculate 500-hPa height tendencies in two intensifying Southern Hemisphere blocking events. The National Centers for Environmental Prediction–National Center for Atmospheric Research gridded reanalyses were used to make each of these calculations. The block intensification period for each event was associated with a deepening surface cyclone during a 48-h period beginning at 1200 UTC 28 July and 1200 UTC 8 August 1986, respectively. These results demonstrate that the diabatic heating forces height rises through the sensible and latent heating terms in these two Southern Hemisphere blocking events. The sensible heating was the larger contributor, second only to (about the same as) the vorticity advection term in the first (second) event. The vorticity advection term has been shown by several studies to be associated with block intensification.

scholarly journals The Vorticity Budgets of North Atlantic Winter Extratropical Cyclone Life Cycles in MERRA Reanalysis. Part I: Development Phase*

2014 ◽  
Vol 71 (9) ◽  
pp. 3109-3128 ◽  
Author(s):  
Roohollah Azad ◽  
Asgeir Sorteberg
Keyword(s):  
North Atlantic ◽  
Indirect Effect ◽  
Life Cycles ◽  
Total Effect ◽  
Latent Heating ◽  
Vorticity Advection ◽  
Friction Term ◽  
Forcing Mechanisms ◽  
Adiabatic Term ◽  
Vorticity Tendency

Abstract This series of papers (parts I and II) examines the vorticity budgets of winter North Atlantic extratropical cyclones during the period 1979–2009 using the Modern-Era Retrospective Analysis for Research and Application (MERRA). The authors use a new partitioning technique to combine the Zwack–Okossi (Z–O) equation with the omega equation. The combination provides a possibility to partition the adiabatic term in the Z–O equation into its different forcing mechanisms. Thus, both the direct effect of the dynamic and thermodynamic forcings and their indirect effect on the adiabatic term can be calculated to provide the total effect (direct plus indirect) on the 950-hPa geostrophic vorticity tendency. It is demonstrated that the total-effect diagnostic is a suitable tool to identify the dynamically consistent characteristics of cyclone development in midlatitudes because it possesses less case-to-case variability. The authors found that the vorticity advection is the major forcing process, the tendencies attributed to the ageostrophic vorticity tendency term are considerable, and the opposing effect of the friction term in moderating the deepening is significant. In general, the upper-level dynamics drive the deepening of the cyclones, except at the end of development, where a combination of midlevel latent heating, positive ageostrophic vorticity tendency, and positive indirect effect of vorticity advection contribute to the development. Additionally, the total effects of temperature advection and latent heating on the intensification of cyclones are reduced because of the inclusion of counteractive indirect effects, as are their variabilities within the cyclone composite.

scholarly journals Método objetivo de identificação dos vórtices ciclônicos de altos níveis na região Tropical Sul: validação

2010 ◽  
Vol 25 (3) ◽  
pp. 311-323 ◽  
Author(s):  
Michelyne Duarte Leal Coutinho ◽  
Manoel Alonso Gan ◽  
Vadlamudi Brahmananda Rao
Keyword(s):  
Atmospheric Research ◽  
Environmental Prediction

Neste estudo foi desenvolvido um Método Objetivo (MO) para identificar Vórtices Ciclônicos de Altos Níveis (VCANs) na região Tropical Sul, baseado na vorticidade relativa e no escoamento horizontal do vento ao redor do centro dos sistemas. O MO foi elaborado usando dados de reanálises do National Centers for Environmental Prediction - National Centers for Atmospheric Research (NCEP-NCAR) e validado, para o período de cinco anos (2002 a 2006), através da comparação entre os resultados obtidos pelo MO e os obtidos pela Análise dos Campos (AC) de vento e vorticidade relativa. Por outro lado, uma avaliação da AC em identificar os VCANs foi feita, para o mesmo período, através da comparação entre os resultados desta e os obtidos usando Imagem de Satélite (IS) no canal espectral do vapor d'água. As AC apresentaram resultados satisfatórios e, portanto, o conjunto dos dados de reanálises do NCEP-NCAR foi aplicado ao MO. Foi observado um bom desempenho do MO em identificar os sistemas, bem como algumas características associadas, tais como: número de ocorrência, número de dias com atuação, posicionamento, direção de deslocamento e região de formação.

scholarly journals Modelagem da maré meteorológica utilizando redes neurais artificiais: uma aplicação para a Baía de Paranaguá-PR, parte 2: dados meteorológicos de reanálise do NCEP/NCAR

2007 ◽  
Vol 22 (1) ◽  
pp. 53-62 ◽  
Author(s):  
Marilia Mitidieri F. de Oliveira ◽  
Nelson Francisco F. Ebecken ◽  
Isimar de A. Santos ◽  
Claudio F. Neves ◽  
Luiz P. Caloba ◽  
...  
Keyword(s):  
Atmospheric Research ◽  
Environmental Prediction

A variabilidade do nível do mar observado e a maré meteorológica na Baía de Paranaguá-PR foram analisadas, neste trabalho, com os dados maregráficos utilizados na Parte 1 e os dados meteorológicos de reanálise do "National Centers for Environmental Prediction" (NCEP) e do "National Center Atmospheric Research" (NCAR) pontos de grade no oceano, próximos ao local de estudo, referentes ao mesmo período. As componentes de alta freqüência contidas nos dados de reanálise foram retiradas com o filtro passa-baixa de Thompson, descrito na Parte 1, adaptado para intervalos de 6 horas. Analisou-se as influências das variáveis meteorológicas mais remotas, nas sobre-elevações e abaixamentos do nível do mar observado, utilizando dados de reanálise de pressão e vento. Conforme descrito na Parte 1, as séries foram analisadas, estatisticamente, no domínio do tempo e da freqüência. A série maregráfica filtrada de Cananéia (SP), utilizada para verificar a existência de correlação com a série de Paranaguá, confirmou os estudos de Mesquita (1997) para o litoral Sudeste. Essa correlação foi verificada devido à proximidade da estação de Cananéia ao ponto de grade relativo à pressão. A Rede Neural Artificial (RNA) desenvolvida na Parte 1 foi, então, utilizada com os dados de reanálise, mantendo-se a mesma arquitetura de rede com as máximas correlações entre as variáveis de entrada e saída, ajustando-se os parâmetros de taxa de aprendizado e momento para alcançar o melhor desempenho. Os resultados obtidos com ambas as fontes de dados foram comparados e a eficiência da rede foi semelhante à Parte 1 para as simulações de 6h e 12 h. Para as simulações de 18h e 24h, os resultados foram inferiores como os encontrados para a estação de superfície, sugerindo também, o desenvolvimento de outras arquiteturas de rede, visando melhorar as previsões para períodos maiores. Os resultados obtidos com os dados de reanálise sugerem a sua utilização na falta de estações meteorológicas convencionais próximas a estações maregráficas.

scholarly journals The influence of direct radiative forcing versus indirect sea surface temperature warming on southern hemisphere subtropical anticyclones under global warming

2021 ◽  
Author(s):  
Abdullah A. Fahad ◽  
Natalie J. Burls
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Southern Hemisphere ◽  
Radiative Forcing ◽  
Diabatic Heating ◽  
Sea Surface ◽  
Atmospheric Response ◽  
Austral Winter ◽  
Subtropical Anticyclone ◽  
Surface Temperature Warming

AbstractSouthern hemisphere subtropical anticyclones are projected to change in a warmer climate during both austral summer and winter. A recent study of CMIP 5 & 6 projections found a combination of local diabatic heating changes and static-stability-induced changes in baroclinic eddy growth as the dominant drivers. Yet the underlying mechanisms forcing these changes still remain uninvestigated. This study aims to enhance our mechanistic understanding of what drives these Southern Hemisphere anticyclones changes during both seasons. Using an AGCM, we decompose the response to CO2-induced warming into two components: (1) the fast atmospheric response to direct CO2 radiative forcing, and (2) the slow atmospheric response due to indirect sea surface temperature warming. Additionally, we isolate the influence of tropical diabatic heating with AGCM added heating experiments. As a complement to our numerical AGCM experiments, we analyze the Atmospheric and Cloud Feedback Model Intercomparison Project experiments. Results from sensitivity experiments show that slow subtropical sea surface temperature warming primarily forces the projected changes in subtropical anticyclones through baroclinicity change. Fast CO2 atmospheric radiative forcing on the other hand plays a secondary role, with the most notable exception being the South Atlantic subtropical anticyclone in austral winter, where it opposes the forcing by sea surface temperature changes resulting in a muted net response. Lastly, we find that tropical diabatic heating changes only significantly influence Southern Hemisphere subtropical anticyclone changes through tropospheric wind shear changes during austral winter.

scholarly journals Validation of the Aura High Resolution Dynamics Limb Sounder geopotential heights

2014 ◽  
Vol 7 (2) ◽  
pp. 1001-1025
Author(s):  
L. L. Smith ◽  
J. C. Gille
Keyword(s):  
High Resolution ◽  
System Model ◽  
Weather Forecasts ◽  
Atmospheric Research ◽  
Earth Observing System ◽  
Medium Range ◽  
High Bias ◽  
Environmental Prediction ◽  
The Tropics ◽  
Data Screening

Abstract. Global satellite observations from the EOS Aura spacecraft's High Resolution Dynamics Limb Sounder (HIRDLS) of temperature and geopotential height (GPH) are discussed. The accuracy, resolution and precision of the HIRDLS version 7 algorithms are assessed and data screening recommendations are made. Comparisons with GPH from observations, reanalyses and models including European Center for Medium-Range Weather Forecasts Interim Reanalysis (ERA-Interim), National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis, Goddard Earth Observing System Model (GEOS) version 5, and EOS Aura Microwave Limb Sounder (MLS) illustrate the HIRDLS GPH have a precision ranging from 2 m to 30 m and an accuracy of ±100 m. Comparisons indicate HIRDLS GPH may have a slight low bias in the tropics and a slight high bias at high latitudes. Geostrophic winds computed with HIRDLS GPH qualitatively agree with winds from other data sources including ERA-Interim, NCEP and GEOS-5.

scholarly journals Stratospheric semi-decadal oscillations in NCEP data

2008 ◽  
Vol 26 (8) ◽  
pp. 2143-2157 ◽  
Author(s):  
H. G. Mayr ◽  
J. G. Mengel ◽  
F. T. Huang ◽  
E. R. Talaat ◽  
E. R. Nash ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Data Analysis ◽  
Temperature Data ◽  
Spectral Features ◽  
Altitude Range ◽  
Quasi Biennial Oscillation ◽  
Atmospheric Research ◽  
Zonal Winds ◽  
Environmental Prediction ◽  
Biennial Oscillation

Abstract. An analysis of the National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) data is presented to provide a more complete description of the stratospheric 5-year semi-decadal (SD) oscillation (Mayr et al., 2007). The zonal-mean temperature and zonal wind data from the Atmospheric Research R-1 analysis are employed, covering the years from 1962 to 2002 in the altitude range from 10 to 30 km. For diagnostic purposes, the data are separated into the hemispherically symmetric and anti-symmetric components, and spectral analysis is applied to identify the signatures of the SD oscillations. Through the synthesis or filtering of spectral features, the SD modulations of the annual oscillation (AO) and quasi-biennial oscillation (QBO) are delineated. In agreement with the earlier findings, the magnitude of the SD oscillation is more pronounced when the 30-month QBO dominates during the years from 1975 to 1995. This is consistent with results from a numerical model, which shows that such a QBO generates the SD oscillation through interaction with the 12-month AO. In the zonal winds, the SD oscillation in the NCEP data is confined to equatorial latitudes, where it modulates the symmetric AO and QBO by about 5 m/s below 30 km. In the temperature data, the effect is also seen around the equator, but it is much larger at polar latitudes where the SD oscillation produces variations as large as 2 K. Our data analysis indicates that the SD oscillation is mainly hemispherically symmetric, and it appears to originate at equatorial latitudes where most of the energy resides.

scholarly journals Arctic precipitation as represented in the NCEP/NCAR reanalysis

1997 ◽  
Vol 25 ◽  
pp. 429-433 ◽  
Author(s):  
Mark C. Serreze ◽  
James A. Maslanik
Keyword(s):  
Sea Ice ◽  
Temporal Patterns ◽  
Annual Precipitation ◽  
Model Output ◽  
Atmospheric Research ◽  
Spatio Temporal ◽  
Environmental Prediction ◽  
Climate Studies

Arctic precipitation as depicted in the National Center for Environmental Prediction (NGEP) and the National Center for Atmospheric Research (NCAR) reanalysis effort is evaluated using 6 hourly model output for the period 1986–93 in conjunction with gauge-corrected climatologies. Climatological fields from the model agree favorably with observations in terms of general spatio-temporal patterns, but with some notable differences. In particular, the precipitation maximum over the central Arctic (the region north of 70°N) is depicted in July, one month too early. Values are too low from August through December, resulting in underestimates of annual precipitation of about 40 mm. Despite these shortcomings, the modeled precipitation fields appear to be sufficiently realistic to represent a base for blending with other data to provide gridded fields suitable for use in climate studies and sea-ice models.

scholarly journals Validation of the Aura High Resolution Dynamics Limb Sounder geopotential heights

2014 ◽  
Vol 7 (8) ◽  
pp. 2775-2785 ◽  
Author(s):  
L. L. Smith ◽  
J. C. Gille
Keyword(s):  
High Resolution ◽  
High Latitudes ◽  
Weather Forecasts ◽  
Atmospheric Research ◽  
Earth Observing System ◽  
Medium Range ◽  
High Bias ◽  
Environmental Prediction ◽  
The Tropics ◽  
Data Screening

Abstract. The geopotential height (GPH) product created from global observations by the High Resolution Dynamics Limb Sounder (HIRDLS) instrument on NASA's Earth Observing System (EOS) Aura spacecraft is discussed. The accuracy, resolution and precision of the HIRDLS version 7 algorithms are assessed and data screening recommendations are made. Comparisons with GPH from observations, reanalyses and models including European Centre for Medium-Range Weather Forecasts Interim Reanalysis (ERA-Interim), and National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis illustrate the HIRDLS GPHs have a precision ranging from 2 to 30 m and an accuracy of ±100 m up to 1 hPa. Comparisons indicate HIRDLS GPH may have a slight low bias in the tropics and a slight high bias at high latitudes. Geostrophic winds computed with HIRDLS GPH qualitatively agree with winds from other data sources including ERA-Interim.

scholarly journals Análise da contribuição das variáveis meteorológicas no estresse térmico associada à morte de cortadores de cana-de-açúcar

2012 ◽  
Vol 28 (1) ◽  
pp. 65-74 ◽  
Author(s):  
Daniel Pires Bitencourt ◽  
Álvaro César Ruas ◽  
Paulo Alves Maia
Keyword(s):  
Sao Paulo ◽  
São Paulo ◽  
Atmospheric Research ◽  
Environmental Prediction

Os cortadores de cana-de-açúcar exercem atividade muito pesada e em condições precárias de trabalho. Além disso, fatores ambientais podem ser um importante agravante à sobrecarga térmica desses trabalhadores. Neste artigo, analisa-se a condição atmosférica no dia da morte de 14 trabalhadores do corte de cana-de-açúcar no Estado de São Paulo, Brasil. Compara-se valores estatísticos históricos da temperatura, umidade, vento e radiação com os valores destas variáveis meteorológicas observadas no dia de cada óbito. Os dados atmosféricos foram obtidos da reanálise do National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR). Em 10 dos 14 casos analisados, as temperaturas observadas nos dias dos óbitos foram maiores ou iguais à média somada ao desvio-padrão. Em seis desses casos o valor da temperatura atingiu ou ficou muito próxima do recorde histórico. Constatou-se que a condição atmosférica pode ser um fator importante a ser considerado na análise das condições gerais de trabalho dos cortadores de cana-de-açúcar.

scholarly journals The Application of Diabatic Heating inQ-Vectors for the Study of a North American Cyclone Event

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Katie L. Crandall ◽  
Patrick S. Market ◽  
Anthony R. Lupo ◽  
Laurel P. McCoy ◽  
Rachel J. Tillott ◽  
...  
Keyword(s):  
United States ◽  
Life Cycle ◽  
North American ◽  
Diabatic Heating ◽  
Latent Heating ◽  
Extended Version ◽  
Vector Form ◽  
Central United States

An extended version of theQ-vector form for theω-equation that includes diabatic (in particular latent) heating in theQ-vector itself is derived and tested for use in analyzing the life-cycle of a midlatitude cyclone that developed over the central United States during 24–26 December 2009. While the inclusion of diabatic heating in theQ-vectorω-equation is not unique to this work, the inclusion of diabatic heating in theQ-vector itself is a unique formulation. Here it is shown that the diabaticQ-vector gives a better representation of the forcing contributing to the life-cycle of the Christmas Storm of 2009 using analyses derived from the 80-km NAM.

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