A multivariate assessment of climate change projections over South America using CMIP5 models

2020 ◽  
Author(s):  
Paul Loikith ◽  
Valerie Thaler ◽  
Luana Albertani Pampuch ◽  
C. Roberto Mechoso ◽  
Armineh Barkhordarian ◽  
...  
Keyword(s):  
Climate Change ◽  
South America ◽  
Sea Level ◽  
Storm Track ◽  
Northeastern Brazil ◽  
Cmip5 Models ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Poleward Shift ◽  
Model Agreement

<p>A multivariate assessment of climate model projections over South America from the CMIP5 archive is presented. Change in near-surface temperature, precipitation, evapotranspiration, integrated water vapor transport (IVT), sea level pressure, and wind at multiple pressure levels is quantified across the multi-model suite and an assessment of model-to-model agreement on projected change performed. All models project warming by the mid- and late-21<sup>st</sup> century throughout the continent, with the highest magnitude projected over tropical regions. The CMIP5 models are in strong agreement that precipitation will decrease in all seasons over portions of Patagonia, especially along the northern portions of the current-climate mid-latitude storm track. This is consistent with a robustly projected poleward shift of the Pacific extratropical high and mid-latitude storm track indicated by a systematic increase in sea level pressure and decrease in westerly wind over Patagonia. Decreased precipitation for the months of September, October, and November is also projected, with strong model agreement, over portions of northern and northeastern Brazil, coincident with decreases in sea level pressure and increases in evapotranspiration. IVT is broadly projected to decrease over southern South America, coincident with the projected poleward shift of the mid-latitude storm track indicators, with increases projected in the vicinity of the South Atlantic Convergence Zone in austral spring and summer. Further decomposition of the thermodynamic and dynamic components to this change in IVT indicate that the projected decreases in the mid-latitudes are primarily driven by changes in circulation (i.e. dynamic) while the sub-tropical and tropical changes have a predominantly thermodynamic origin. Results provide a comprehensive picture of climate change across South America and highlight where projections should be interpreted with the most confidence.</p>

The North Pacific Oscillation–West Pacific Teleconnection Pattern: Mature-Phase Structure and Winter Impacts

2008 ◽  
Vol 21 (9) ◽  
pp. 1979-1997 ◽  
Author(s):  
Megan E. Linkin ◽  
Sumant Nigam
Keyword(s):  
Sea Level ◽  
Pacific Northwest ◽  
Geopotential Height ◽  
Storm Track ◽  
Teleconnection Pattern ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
The North ◽  
Mature Phase ◽  
The Pacific

Abstract The North Pacific Oscillation (NPO) in sea level pressure and its upper-air geopotential height signature, the west Pacific (WP) teleconnection pattern, constitute a prominent mode of winter midlatitude variability, the NPO/WP. Its mature-phase expression is identified from principal component analysis of monthly sea level pressure variability as the second leading mode just behind the Pacific–North American variability pattern. NPO/WP variability, primarily on subseasonal time scales, is characterized by a large-scale meridional dipole in SLP and geopotential height over the Pacific and is linked to meridional movements of the Asian–Pacific jet and Pacific storm track modulation. The hemispheric height anomalies at upper levels resemble the climatological stationary wave pattern attributed to transient eddy forcing. The NPO/WP divergent circulation is thermal wind restoring, pointing to independent forcing of jet fluctuations. Intercomparison of sea level pressure, geopotential height, and zonal wind anomaly structure reveals that NPO/WP is a basin analog of the NAO, which is not surprising given strong links to storm track variability in both cases. The NPO/WP variability is influential: its impact on Alaskan, Pacific Northwest, Canadian, and U.S. winter surface air temperatures is substantial—more than that of PNA or ENSO. It is likewise more influential on the Pacific Northwest, western Mexico, and south-central Great Plains winter precipitation. Finally, and perhaps, most importantly, NPO/WP is strongly linked to marginal ice zone variability of the Arctic seas with an influence that surpasses that of other Pacific modes. Although NPO/WP variability and impacts have not been as extensively analyzed as its Pacific cousins (PNA, ENSO), it is shown to be more consequential for Arctic sea ice and North American winter hydroclimate.

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

Climatology and variability of jets in the upper troposphere

2020 ◽  
Author(s):  
Clemens Spensberger ◽  
Thomas Spengler
Keyword(s):  
Sea Level ◽  
Storm Track ◽  
South Pacific ◽  
The South ◽  
Continuous Transition ◽  
Sea Level Pressure ◽  
Upper Troposphere ◽  
Level Pressure ◽  
South Indian ◽  
Jet Variability

<p>Jets in the upper troposphere constitute a cornerstone of both synoptic meteorology and climate dynamics, thus providing a direct link between weather and mid-latitude climate variability. Conventionally, jet variability is mostly inferred indirectly through the variability of geopotential or sea-level pressure. Here we use a feature-based jet detection and present a global climatology of upper tropospheric jets as well as their variability for ocean sectors in both Hemispheres. The jet streams on both hemispheres are found to spiral poleward, featuring a continuous transition from subtropical to eddy-driven jets. Most intrinsic patterns of jet variability represent a changeover from a meridional shifting type variability to a pulsing-type variability, or vice-versa, across each ocean basin.</p><p>For the Southern Hemisphere, we find considerable discrepancies between geopotential and jet-based variability. Specifically, we show that SAM cannot be interpreted in terms of mid-latitude variability, as SAM merely modulates the most poleward part of the cyclone tracks and only marginally influences the distribution of other weather-related features of the storm track (e.g., position of jet axes and Rossby wave breaking). Instead, SAM emerges as the leading pattern of geopotential variability due to strong correlations of sea-level pressure around the Antarctic continent. Considering sector-specific variability pattern, we identify modes of consistent geopotential and jet variability in the South Pacific, and, to a lesser extent, the South Indian Ocean. In the South Pacific the leading mode of variability points towards NAO-like variability.</p>

On the Summertime Strengthening of the Northern Hemisphere Pacific Sea Level Pressure Anticyclone

2009 ◽  
Vol 22 (5) ◽  
pp. 1174-1192 ◽  
Author(s):  
Sumant Nigam ◽  
Steven C. Chan
Keyword(s):  
Sea Level ◽  
Northern Hemisphere ◽  
Asian Monsoon ◽  
Storm Track ◽  
Hadley Cell ◽  
Winter Storm ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Mascarene High ◽  
The Pacific

Abstract This study revisits the question posed by Hoskins on why the Northern Hemisphere Pacific sea level pressure (SLP) anticyclone is strongest and maximally extended in summer when the Hadley cell descent in the northern subtropics is the weakest. The paradoxical evolution is revisited because anticyclone buildup to the majestic summer structure is gradual, spread evenly over the preceding 4–6 months, and not just confined to the monsoon-onset period, which is interesting, as monsoons are posited to be the cause of the summer vigor of the anticyclone. Anticyclone buildup is moreover found focused in the extratropics, not the subtropics, where SLP seasonality is shown to be much weaker, generating a related paradox within the context of the Hadley cell’s striking seasonality. Showing this seasonality to arise from, and thus represent, remarkable descent variations in the Asian monsoon sector, but not over the central-eastern ocean basins, leads to the resolution of this paradox. Evolution of other prominent anticyclones is analyzed to critique the development mechanisms: the Azores high evolves like the Pacific one, but without a monsoon to its immediate west. The Mascarene high evolves differently, peaking in austral winter. Monsoons are not implicated in both cases. Diagnostic modeling of seasonal circulation development in the Pacific sector concludes this inquiry. Of the three forcing regions examined, the Pacific midlatitudes are found to be the most influential, accounting for over two-thirds of the winter-to-summer SLP development in the extratropics (6–8 hPa), with the bulk coming from the abatement of winter storm-track heating and transients. The Asian monsoon contribution (2–3 hPa) is dominant in the Pacific (and Atlantic) subtropics. The modeling results resonate with observational findings and attest to the demise of winter storm tracks as the principal cause of the summer vigor of the Pacific anticyclone.

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 Universal Frequency Spectra of Surface Meteorological Fluctuations

2011 ◽  
Vol 24 (17) ◽  
pp. 4718-4732 ◽  
Author(s):  
Chikara Tsuchiya ◽  
Kaoru Sato ◽  
Tomoe Nasuno ◽  
Akira T. Noda ◽  
Masaki Satoh
Keyword(s):  
Sea Level ◽  
High Frequency ◽  
Storm Track ◽  
High Frequency Range ◽  
Frequency Range ◽  
Frequency Spectra ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Hourly Data ◽  
Physical Quantities

Statistical characteristics of surface meteorology are examined in terms of frequency spectra. According to a recent work using hourly data over 50 yr in the Antarctic, the frequency spectra have a characteristic shape proportional to two different powers of the frequency in the frequency ranges lower and higher than a transition frequency of (several days)−1. To confirm the universality of the characteristic spectra, hourly data—including surface temperature, sea level pressure, and zonal and meridional winds—collected over 45 yr at 138 stations in Japan were analyzed. Similar spectral shapes are obtained for any physical quantities at all stations. The spectral slopes clearly depend on the latitude, particularly for sea level pressure, which in the high-frequency range are steeper at higher latitudes. Next, the analysis was extended using realistic simulation data over one month with a nonhydrostatic model to examine the global characteristics of the spectra in the high-frequency range. The model spectra accord well with the observations in Japan. The spectral slopes are largely dependent on the latitude—that is, shallow in the low latitudes, and steep in the middle and high latitudes for all the physical quantities. The latitudinal change of the spectral slope is severe around 30°, which may be due to the dynamical transition from nongeostrophy to geostrophy. The longitudinal variations are also observed according to the geography. The variance is large in the storm-track region for surface pressure, on the continents for temperature and over the ocean for winds.

scholarly journals A Weather-Pattern-Based Evaluation of the Performance of CMIP5 Models over Mexico

Climate ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 5 ◽  
Author(s):  
Yanet Díaz-Esteban ◽  
Graciela B. Raga ◽  
Oscar Onoe Díaz Rodríguez
Keyword(s):  
Sea Level ◽  
Climate Models ◽  
Weather Type ◽  
Specific Humidity ◽  
Cmip5 Models ◽  
Model Errors ◽  
Sea Level Pressure ◽  
Low Level ◽  
Level Pressure ◽  
Synoptic Conditions

The fifth phase of the Coupled Model Inter-Comparison Project (CMIP5) is frequently used to force regional climate models for dynamic downscaling and projections, which decision makers in turn use for future plans in different sectors. It is, therefore, highly important to assess their performance in order to use them as reliable tools. A weather-type approach for the evaluation of the performance of CMIP5 models is employed in this study, with the objective of providing insight into model errors under a set of distinct synoptic conditions and circulation types associated with the rainy season over Mexico and Central America. The Self-Organizing Maps algorithm is used to identify the main weather regimes (constructed from sea level pressure, specific humidity, and low-level winds at a daily time-scale), which are then evaluated against reanalysis. The results show that model performance depends on the weather type in all of the variables except for sea level pressure, which confirms the usefulness of this approach. The models simulate better the humidity patterns that show weak deviations from the climatological norm. In addition, the wind pattern representing the Caribbean Low Level Jet is well reproduced by all the models. The results show the capacity of this methodology for determining the extent to which climate models represent the main circulation patterns that characterize the climate and local weather in Mexico.

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 Projected Significant Increase in the Number of Extreme Extratropical Cyclones in the Southern Hemisphere

2017 ◽  
Vol 30 (13) ◽  
pp. 4915-4935 ◽  
Author(s):  
Edmund K. M. Chang
Keyword(s):  
Sea Level ◽  
Southern Hemisphere ◽  
Cmip5 Models ◽  
General Interest ◽  
Extratropical Cyclones ◽  
The South ◽  
Sea Level Pressure ◽  
Near Surface ◽  
Level Pressure ◽  
South Indian

Extratropical cyclones are responsible for much of the extreme weather in the midlatitudes; thus, how these cyclones may change under increasing greenhouse gas forcing is of much general interest. Previous studies have suggested a poleward shift in the location of these cyclones, but how the intensity may change remains uncertain, especially in terms of maximum wind speed. In this study, projected changes in extreme cyclones in the Southern Hemisphere, based on 26 models participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5), are presented. Multiple definitions of extreme cyclones have been examined, including intensity exceeding constant thresholds of sea level pressure perturbations, 850-hPa vorticity, and 850-hPa winds, as well as variable thresholds corresponding to a top-5 or top-1 cyclone per winter month in these three parameters and the near-surface winds. Results presented show that CMIP5 models project a significant increase in the frequency of extreme cyclones in all four seasons regardless of the definition, with over 88% of the models projecting an increase. Spatial patterns of increase are also consistent, with the largest increase projected between 45° and 60°S, extending from the South Atlantic across the south Indian Ocean into the Pacific. The projected increases in cyclone statistics are consistent with those in Eulerian statistics, such as sea level pressure (SLP) variance. However, while the projected increase in SLP variance can be linked to increase in the mean available potential energy (MAPE), the increases in cyclone statistics are not well correlated with those in MAPE.

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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