scholarly journals Interannual to decadal variability within and across the major Eastern Boundary Upwelling Systems

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Giulia Bonino ◽  
Emanuele Di Lorenzo ◽  
Simona Masina ◽  
Doroteaciro Iovino
Keyword(s):  
Climate Change ◽  
Climate Variability ◽  
Sea Level ◽  
Low Frequency ◽  
Global Ocean ◽  
Thermocline Depth ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Eastern Boundary ◽  
Low Frequency Variability

AbstractClimate variability and climate change in Eastern Boundary Upwelling Systems (EBUS) affect global marine ecosystems services. We use passive tracers in a global ocean model hindcast at eddy-permitting resolution to diagnose EBUS low-frequency variability over 1958–2015 period. The results highlight the uniqueness of each EBUS in terms of drivers and climate variability. The wind forcing and the thermocline depth, which are potentially competitive or complementary upwelling drivers under climate change, control EBUS low-frequency variability with different contributions. Moreover, Atlantic and Pacific upwelling systems are independent. In the Pacific, the only coherent variability between California and Humboldt Systems is associated with El Niño Southern Oscillation. The remaining low-frequency variance is partially explained by the North and South Pacific expressions of the Meridional Modes. In the Atlantic, coherent variability between Canary and Benguela Systems is associated with upwelling trends, which are not dynamically linked and represent different processes. In the Canary, a negative upwelling trend is connected to the Atlantic Multi-decadal Oscillation, while in the Benguela, a positive upwelling trend is forced by a global sea level pressure trend, which is consistent with the climate response to anthropogenic forcing. The residual variability is forced by localized offshore high sea level pressure variability.

scholarly journals Effect of Synoptic Systems on the Variability of the North Atlantic Oscillation

2005 ◽  
Vol 133 (10) ◽  
pp. 2894-2904 ◽  
Author(s):  
Ulrike Löptien ◽  
Eberhard Ruprecht
Keyword(s):  
North Atlantic Oscillation ◽  
Sea Level ◽  
North Atlantic ◽  
Low Frequency ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
The North ◽  
Low Frequency Variability ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract The North Atlantic Oscillation (NAO) represents the dominant mode of atmospheric variability in the North Atlantic region. In the present study, the role of the synoptic systems (cyclones and anticyclones) in generating the NAO pattern is investigated. To study the intermonthly variations of the NAO, NCEP–NCAR reanalysis data are used, and for the interdecadal variations the results of a 300-yr control integration under present-day conditions of the coupled model ECHAM4/OPYC3 are analyzed. A filtering method is developed for the sea level pressure anomalies. Application of this method to each grid point yields the low-frequency variability in the sea level pressure field that is due to the synoptic systems. The low-frequency variability of the filtered and the original data are in high agreement. This indicates that the low-frequency pressure variability, and with it the variability of the NAO, is essentially caused by the distribution of the synoptic systems. The idea that the distribution of the synoptic systems is the cause of the variation of the NAO is confirmed by high correlation between the latitudinal position of the polar front over the North Atlantic and the NAO index. Since most of the low-frequency variability in sea level pressure can be explained through the distribution of the synoptic systems, the NAO seems to be a reflection of the distribution of the synoptic systems, rather than the source for variations in the cyclone tracks.

scholarly journals New Insights into Annual and Semiannual Cycles of Sea Level Pressure

2012 ◽  
Vol 140 (4) ◽  
pp. 1347-1355 ◽  
Author(s):  
Ge Chen ◽  
Chengcheng Qian ◽  
Caiyun Zhang
Keyword(s):  
Sea Level ◽  
Southern Oscillation ◽  
Global Ocean ◽  
Boreal Winter ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
The North ◽  
Dominant Feature ◽  
The One ◽  
The North Pacific

Sea level pressure (SLP) acts, on the one hand, as a “bridge parameter” to which geophysical properties at the air–sea interface (e.g., wind stress and sea surface height) are linked, and on the other hand, as an “index parameter” by which major atmospheric oscillations, including the well-known Southern Oscillation, are defined. Using 144 yr (1854–1997) of extended reconstructed SLP data, seasonal patterns of its variability are reinvestigated in detail. New features on fundamental structure of its annual and semiannual cycles are revealed in two aspects. First, the spatiotemporal patterns of yearly and half-yearly SLPs are basically determined by a network of “amphidromes,” which are surrounded by rotational variations. Fourteen cyclonic and anticyclonic annual SLP amphidromes (half each and often in pair) are found in the global ocean, while the numbers of the two types of semiannual amphidrome are 11 and 9, respectively. The second dominant feature in SLP variability is the pattern of oscillation or seesaw for both annual and semiannual components. At least eight oscillation zones are identified for the annual cycle, which can be categorized into a boreal winter mode and an austral winter mode. As for the semiannual cycle, the seesaw pattern is geographically divided into three regimes: the North Pacific regime, the North Atlantic regime, and the Southern Ocean regime. These findings serve as a new contribution to characterizing and understanding the seasonality of the global ocean–atmosphere system.

scholarly journals Low-Frequency Sea Level Variability and the Inverted Barometer Effect

2006 ◽  
Vol 23 (4) ◽  
pp. 619-629 ◽  
Author(s):  
Rui M. Ponte
Keyword(s):  
Sea Level ◽  
Tide Gauge ◽  
Low Frequency ◽  
Anomalous Behavior ◽  
Global Ocean ◽  
Sea Level Pressure ◽  
Seasonal Signals ◽  
Global Mean Sea Level ◽  
Inverted Barometer ◽  
Linear Trends

Abstract For a dynamical interpretation of sea level records, estimates are needed of the isostatic, or so-called inverted barometer, signals (ηib) associated with the ocean response to atmospheric loading. Seasonal and longer-period ηib signals are evaluated over the global ocean for the period 1958–2000 using monthly sea level pressure fields from two different atmospheric reanalyses. Variability and linear trends in ηib agree well for the two reanalyses in most regions but less so over the Southern Ocean, where uncertainties in ηib seem to be largest. The standard deviation of ηib ranges from <1 cm in equatorial regions to >7 cm in the regions of the Aleutian and Iceland lows and parts of the Southern and Arctic Oceans. When compared to a global tide gauge dataset, both seasonal and interannual ηib signals are found to contribute importantly to the sea level variance in many mid- and high-latitude records, with seasonal signals important as well in tropical records from India and Southeast Asia. For these records, subtracting ηib from the data can lead to changes in variance of 40% or more. Over the period of study, linear trends in ηib are mostly negative at low and midlatitudes and can cause negative biases in tide gauge estimates of global mean sea level rise that are comparable in magnitude to the effects of postglacial rebound. In agreement with previous findings, ηib signals are found to introduce anomalous behavior in local records (e.g., substantially weaker upward trends in the Mediterranean), and their removal can also reduce formal trend uncertainties. Accounting for ηib effects can be even more important when analyzing relatively short (decadal) records, such as those available from satellite altimetry.

scholarly journals Influence of Sea Level Pressure on Inter-Annual Rainfall Variability in Northern Senegal in the Context of Climate Change

2022 ◽  
Vol 12 (01) ◽  
pp. 113-131
Author(s):  
Aichetou Dia-Diop ◽  
Malick Wade ◽  
Sinclaire Zebaze ◽  
Abdoulaye Bouya Diop ◽  
Eric Efon ◽  
...  
Keyword(s):  
Climate Change ◽  
Sea Level ◽  
Rainfall Variability ◽  
Annual Rainfall ◽  
Sea Level Pressure ◽  
Level Pressure

scholarly journals Global oscillatory modes in high-end climate modeling and reanalyses

2021 ◽  
Author(s):  
Yizhak Feliks ◽  
Justin Small ◽  
Michael Ghil
Keyword(s):  
Sea Level ◽  
Climate Modeling ◽  
Singular Spectrum Analysis ◽  
Low Frequency ◽  
Sea Level Pressure ◽  
The North ◽  
The Pacific ◽  
Low Frequency Variability ◽  
Community Earth System Model ◽  
Spatio Temporal

AbstractInterannual oscillatory modes, atmospheric and oceanic, are present in several large regions of the globe. We examine here low-frequency variability (LFV) over the entire globe in the Community Earth System Model (CESM) and in the NCEP-NCAR and ECMWF ERA5 reanalyses. Multichannel singular spectrum analysis (MSSA) is applied to these three datasets. In the fully coupled CESM1.1 model, with its resolution of $$0.1 \times 0.1$$ 0.1 × 0.1 degrees in the ocean and $$0.25 \times 0.25$$ 0.25 × 0.25 degrees in the atmosphere, the fields analyzed are surface temperatures, sea level pressures and the 200-hPa geopotential. The simulation is 100-year long and the last 66 yr are used in the analysis. The two statistically significant periodicities in this IPCC-class model are 11 and 3.4 year. In the NCEP-NCAR reanalysis, the fields of sea level pressure and of 200-hPa geopotential are analyzed at the available resolution of $$2.5 \times 2.5$$ 2.5 × 2.5 degrees over the 68-years interval 1949–2016. Oscillations with periods of 12 and 3.6 years are found to be statistically significant in this dataset. In the ECMWF ERA5 reanalysis, the 200-hPa geopotential field was analyzed at its resolution of $$0.25 \times 0.25$$ 0.25 × 0.25 degrees over the 71-years interval 1950–2020. Oscillations with periods of 10 and 3.6 years are found to be statistically significant in this third dataset. The spatio-temporal patterns of the oscillations in the three datasets are quite similar. The spatial pattern of these global oscillations over the North Pacific and North Atlantic resemble the Pacific Decadal Oscillation and the LFV found in the Gulf Stream region and Labrador Sea, respectively. We speculate that such regional oscillations are synchronized over the globe, thus yielding the global oscillatory modes found herein, and discuss the potential role of the 11-year solar-irradiance cycle in this synchronization. The robustness of the two global modes, with their 10–12 and 3.4–3.6 years periodicities, also suggests potential contributions to predictability at 1–3 years horizons.

scholarly journals Impacts of Some Climatic Variables on Productivity of Boro rice in South-Western Coastal Regions of Bangladesh

2016 ◽  
Vol 9 (1) ◽  
pp. 95-98
Author(s):  
MM Islam ◽  
MA Farukh ◽  
MA Baten
Keyword(s):  
Climate Change ◽  
Sea Level ◽  
Climatic Variability ◽  
Rice Production ◽  
Maximum Temperature ◽  
Climatic Data ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Average Temperature ◽  
Boro Rice

Climate change is the top most important issue in the modern world. Various aspects of Bangladesh are verily affected by climate change. An agro-climatic study was conducted in Khulna, Satkhira and Bagerhat district in Khulna division as well as the Southwestern coastal part of Bangladesh with last 30 (1981-2011) years of some climatic data of average temperature, maximum temperature, seasonal total rainfall, average humidity and sea level pressure to address the climatic variability and its impacts on Boro rice production in Southwestern coastal part of Bangladesh. The average temperature increased by 0.51°C in Boro season in this area. The sea level pressure was about stable here. The Boro rice production increased by 0.04 and 0.3 tha-1 in Khulna and Bagerhat district. However most of the time the production showed increasing trends except in 2007 and 2009 affected by two devastating natural calamities as “SIDR” and “AILA” occurred in these two year respectively.J. Environ. Sci. & Natural Resources, 9(1): 95-98 2016

scholarly journals Reconstruction of high resolution atmospheric fields for Northern Europe using analog-upscaling

2012 ◽  
Vol 8 (5) ◽  
pp. 1681-1703 ◽  
Author(s):  
F. Schenk ◽  
E. Zorita
Keyword(s):  
High Resolution ◽  
Sea Level ◽  
Climate Model ◽  
Regional Climate ◽  
Low Frequency ◽  
Climate Simulation ◽  
Northern Europe ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Realistic Situation

Abstract. The analog method (AM) has found application to reconstruct gridded climate fields from the information provided by proxy data and climate model simulations. Here, we test the skill of different setups of the AM, in a controlled but realistic situation, by analysing several statistical properties of reconstructed daily high-resolution atmospheric fields for Northern Europe for a 50-yr period. In this application, station observations of sea-level pressure and air temperature are combined with atmospheric fields from a 50-yr high-resolution regional climate simulation. This reconstruction aims at providing homogeneous and physically consistent atmospheric fields with daily resolution suitable to drive high resolution ocean and ecosystem models. Different settings of the AM are evaluated in this study for the period 1958–2007 to estimate the robustness of the reconstruction and its ability to replicate high and low-frequency variability, realistic probability distributions and extremes of different meteorological variables. It is shown that the AM can realistically reconstruct variables with a strong physical link to daily sea-level pressure on both a daily and monthly scale. However, to reconstruct low-frequency decadal and longer temperature variations, additional monthly mean station temperature as predictor is required. Our results suggest that the AM is a suitable upscaling tool to predict daily fields taken from regional climate simulations based on sparse historical station data.

scholarly journals Caracterização de Mudanças Climáticas na Antártica a partir da Segunda Metade do Século XX

2019 ◽  
Vol 12 (6) ◽  
pp. 2091
Author(s):  
Natália Silva ◽  
Ilana Elazari Klein Coaracy Wainer ◽  
Marcos Henrique Maruch Tonelli
Keyword(s):  
Climate Change ◽  
Wind Speed ◽  
Sea Level ◽  
Southern Hemisphere ◽  
Sea Level Pressure ◽  
Annular Mode ◽  
Level Pressure ◽  
British Antarctic Survey ◽  
Southern Hemisphere Annular Mode ◽  
San Martín

A Antártica é uma região do planeta extremamente sensível às mudanças globais do clima. Para quantificar essas mudanças, é possível estudar a variação de algumas propriedades atmosféricas como temperatura (T), pressão no nível do mar (PNM) e velocidade de ventos (v). Dados de estações meteorológicas espalhadas pela Antártica distribuídos pelo British Antarctic Survey são analisados. Os resultados mostram que as tendências de temperatura apresentam uma distribuição peculiar, visto que na porção oeste do continente há um intenso aquecimento (e.g.,0.55°C/década em San Martin), enquanto que o lado leste observa um resfriamento (-0.06°C/década em Zhongshan). O índice Intervalo de Temperatura Diária (ITD) também é utilizado para caracterizar mudanças climáticas e é consistente com as variações obtidas para a temperatura, caracterizando, portanto, o chamado Padrão de Dipolo na temperatura. Com relação à PNM, 19 estações meteorológicas das 20 estudadas, apresentam tendências negativas e na grande maioria dessas observa-se também intensificação da velocidade dos ventos. Essas mudanças estão associadas principalmente aos modos de variabilidade natural do planeta, sendo que o maior determinante das características climáticas nas regiões extratropicais do Hemisfério Sul é o Modo Anular do Hemisfério Sul (SAM). Characterization of climate change in Antarctica from the second half of 20th CenturyA B S T R A C TAntarctica is a region of the planet extremely sensitive to global climate change. To quantify these changes, it is possible to study the variation of some atmospheric properties such as Temperature, Sea Level Pressure and Wind Speed. Data from meteorological stations in Antarctica provided by the British Antarctic Survey are analyzed. The results show that Temperature trends have a peculiar distribution, since on the western side of the continent there is intense heating (e.g., 0.55°C/decade in San Martin), while the east side observes cooling trends (-0.06°C/decade  in Zhongshan). The Daily Temperature Range index is also used to characterize climatic changes and agrees with the variations obtained for the Temperature, thus characterizing the so-called Dipole Pattern in temperature. About the Sea Level Pressure, 19 meteorological stations of the 20 studied, present negative trends and in the great majority of these it is also observed intensification on the wind speed. These changes are mainly associated with the natural modes of variability of the planet, and the Southern Hemisphere Annular Mode (SAM) is the major determinant of the climatic characteristics in the extratropical regions of the Southern Hemisphere.Keywords: Antarctica, Climate Change, Temperature Dipole, Southern Hemisphere Annular Mode.

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