atmospheric circulations
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2022 ◽  
Vol 194 (2) ◽  
Author(s):  
Muhammad Bilal ◽  
Mujtaba Hassan ◽  
Danyal Bin Taufiq Tahir ◽  
Muhammad Shahid Iqbal ◽  
Imran Shahid

2021 ◽  
Vol 9 (12) ◽  
pp. 1386
Author(s):  
Emmanuel OlaOluwa Eresanya ◽  
Yuping Guan

The structure of the equatorial atmospheric circulation, as defined by the zonal mass streamfunction (ZMS), computed using the new fifth-generation ECMWF reanalysis for the global climate and weather (ERA-5) and the National Centers for Environmental Prediction NCEP–US Department of Energy reanalysis (NCEP-2) reanalysis products, is investigated and compared with Coupled Model Intercomparison Project Phase 6 (CMIP 6) ensemble mean. The equatorial atmospheric circulations majorly involve three components: the Indian Ocean cell (IOC), the Pacific Walker cell (POC) and the Atlantic Ocean cell (AOC). The IOC, POC and AOC average monthly or seasonal cycle peaks around March, June and February, respectively. ERA-5 has a higher IOC intensity from February to August, whereas NCEP-2 has a greater IOC intensity from September to December; NCEP-2 indicates greater POC intensity from January to May, whereas ERA-5 shows higher POC intensity from June to October. For the AOC, ERA-5 specifies greater intensity from March to August and NCEP-2 has a higher intensity from September to December. The equatorial atmospheric circulations cells vary in the reanalysis products, the IOC is weak and wider (weaker and smaller) in the ERA-5 (NCEP-2), the POC is more robust and wider (feebler and teensier) in NCEP-2 (ERA-5) and the AOC is weaker and wider (stronger and smaller) in ERA-5 (NCEP-2). ERA-5 revealed a farther westward POC and AOC compared to NCEP-2. In the CMIP 6 model ensemble mean (MME), the equatorial atmospheric circulations mean state indicated generally weaker cells, with the IOC smaller and the POC greater swinging eastward and westward, respectively, while the AOC is more westward. These changes in equatorial circulation correspond to changes in dynamically related heating in the tropics.


Eos ◽  
2021 ◽  
Vol 102 ◽  
Author(s):  
Morgan Rehnberg

The microwave radiometer aboard NASA’s Juno spacecraft reveals the hidden atmospheric circulations at work deep below Jupiter’s colorful clouds.


2021 ◽  
Author(s):  
Matthew H. Rogers ◽  
Jason Furtado ◽  
Bruce Anderson

Abstract Persistent, multi-year shifts in atmospheric circulations and their associated influence on regional climates have profound impacts on physical, biological, and socioeconomic systems. The Pacific Decadal Precession (PDP), an atmospheric mode of variability consisting of a lower tropospheric height dipole which rotates counterclockwise over several years in the North Pacific, describes a series of such shifts in atmospheric circulations. One phase of the PDP, the north-south (N-S) phase, is hypothesized to be partially driven by central tropical Pacific (CP) sea surface temperature (SST) variability, but robust assessment of this dynamical connection in climate models remains to be done. In this study, we investigate this hypothesis with analyses in both reanalysis and selected models from the Coupled Model Intercomparison Project Phase 6 (CMIP6) archive. We show that the emergence of the N-S phase is both related to and influenced by tropical Pacific decadal SST variability, specifically variability associated with CP El Niño-Southern Oscillation (ENSO) events. When examining the CMIP6 model output, we find that most models cannot recover the characteristic cyclonic precession of the dipoles of the PDP, instead featuring only amplitude and sign changes of the N-S phase, Moreover, the models do not replicate the dynamical connections between the tropical Pacific and this North Pacific mode. Our results suggest that primary reasons for this inconsistency are that models inaccurately simulate both the SST pattern associated with the PDP, shared low-frequency power associated with CP ENSO events, and incorrect Rossby wavetrains emanating from the tropical Pacific into the North Pacific on quasi-decadal timescales. Taken together, our analyses offer another benchmark by which to test the fidelity of the climate model simulations in capturing Pacific decadal climate variability in order to improve decadal-to-centennial climate projections.


Atmosphere ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1321
Author(s):  
Larissa de Freitas Ramos de Freitas Ramos Jacinto ◽  
Luiz Claudio Gomes Pimentel ◽  
José Francisco de Oliveira de Oliveira Júnior ◽  
Ian Cunha D’Amato Viana Dragaud ◽  
Corbiniano Silva ◽  
...  

Ilha Grande Bay is located in Angra dos Reis, Rio de Janeiro State, Brazil. The area is characterized by different land cover, complex topography and proximity to the Atlantic Ocean. These aspects make it susceptible to thermally and dynamically induced atmospheric circulations such as those associated with valley/mountain and land/sea breeze systems, among others. The Almirante Álvaro Alberto Nuclear Complex (CNAAA) is located in this region, with a total of two nuclear power plants (NPPs) in operation in the Brazilian territory, Angra I and Angra II. Therefore, knowledge of local atmospheric circulation has become a matter of national and international security. Considering the importance of the meteorological security tool as a support for licensing, installation, routine operation and nuclear accident mitigation, the main aim of this study is the development of combined strategies of environmental statistical modeling in the analysis of thermally and dynamically driven atmospheric circulations over mountainous and coastal environments. We identified and hierarchized the influence of the thermally and mechanically driven forcing on the wind regime and stability conditions in the coastal atmospheric boundary layer over the complex topography region. A meteorological network of ground-based instruments was used along with physiographic information for the observational characterization of the atmospheric patterns in the spatial and time–frequency domain. The predominant wind directions and intensity are attributed to the combined action of multiscale weather systems, notably, the valley/mountain and continent/ocean breeze circulations, the forced channeling due to valley axis orientation, the influence of the synoptic scale systems and atmospheric thermal tide. The observational investigation of the combined influence of terrain effects and meteorological systems aimed to understand the local atmospheric circulation serves as support for safety protocols of the NPPs, contemplating operation and environmental management. The importance of the study for the adequacy and skill evaluation of computational modeling systems for atmospheric dispersion of pollutants such as radionuclide and conventional contaminants can be also highlighted, in order that such systems are used as tools for environmental planning and managing nuclear operations, particularly those located in regions over mountainous and coastal environments with a heterogeneous atmospheric boundary layer.


Author(s):  
Mohamed Abdallah Ahmed Alriah ◽  
Shuoben Bi ◽  
Shamsuddin Shahid ◽  
Athanase Nkunzimana ◽  
Brian Ayugi ◽  
...  

2021 ◽  
Author(s):  
Abolfazl Rezaei

Abstract The ability to predict future variability of groundwater resources in time and space is of critical
importance in society’s adaptation to climate variability and change. Periodic control of large scale ocean-atmospheric circulations on groundwater levels proposes a potentially effective source of longer term forecasting capability. In this study, as a first national-scale assessment, we use the continues wavelet transform, global power spectrum, and wavelet coherence analyses to quantify the controls of the Atlantic Multidecadal Oscillation (AMO), Pacific Decadal Oscillation (PDO), North Atlantic Oscillation (NAO), and El Niño Southern Oscillation (ENSO) over the representative groundwater levels of the 24 principal aquifers, scattered across different 14 climate zones of Iran. The results demonstrate that aquifer storage variations are partially controlled by annual to interdecadal climate variability and are not solely a function of pumping variations. Moreover, teleconnections are observed to be both frequency and time specific. The significant coherence patterns between the climate indices and groundwater levels are observed at five frequency bands of the annual (~1-yr), interannual (2-4- and 4-6-yr), decadal (8-12-yr), and interdecadal (14-18yr), consistent with the dominant modes of climate indices. AMO’s strong footprint is observed at interdecadal and annual modes of groundwater levels while PDO’s highest imprint is seen in interannual, decadal, and interdecadal modes. The highest controlling influence of ENSO is observed across the decadal and interannual modes whereas the NAO’s footprint is marked at annual and interdecadal frequency bands. Further, it is observed that the groundwater variability being higher modulated by a combination of large-scale atmospheric circulations rather than each individual index. The decadal and interdecadal oscillation modes constitute the dominant modes in Iranian aquifers. Findings also mark the unsaturated zone contribution in damping and lagging of the climate variability modes, particularly for the higher frequency indices of ENSO and NAO where the groundwater variability is observed to be more correlated with lower frequent climate circulations such as PDO and AMO, rather than ENSO and NAO. Finally, it is found that the data length can significantly affect the teleconnections if the time series are not contemporaneous and only one value of coherence/correlation is computed for each particular series instead of separate computations for different frequency bands and different time spans.


2021 ◽  
Author(s):  
Wenqin zhuo ◽  
Fei Huang ◽  
Ruichang Ding ◽  
Jin Luo

Abstract This work examines precursory atmospheric circulations with various wave trains contributing to extreme cooling over central Eurasia in boreal winter from 1979-2016 based on the ERA-Interim dataset. The empirical orthogonal function (EOF) method is used to classify the anomalous sea level pressure field averaged in two weeks prior to extreme cooling. Based on the classification, three types of precursory atmospheric circulation patterns are named according to the origins of wave trains, and their formation mechanisms are revealed as well . Type1: Baffin Bay-origin pattern, which forms in the downstream development of Rossby wave packets generated from the downward stratospheric energy transmission over the Baffin Bay. Type2: Pacific-origin pattern, similar to a Eurasian (EU) teleconnection pattern, arises at the exit area of the westerly jet in the central North Pacific where cyclonic shear exists; then it develops along the northerly westerly jet over the North Atlantic, which may act as a waveguide to the Eurasian continent. Type 3: Atlantic-origin, manifests as the negative phase of type 2, consistent with the Scandinavian (SCAND) pattern, which may results from the air-sea interaction induced by the warm anomaly of sea surface temperature in the middle of North Atlantic. In conclusion, the three types of precursory atmospheric wave train patterns that bring extreme cooling to Eurasia possess diverse disturbing sources and development mechanisms. The results, which are investigated based on a quasi-biweekly time scale , deepen our understanding of the atmospheric genesis of extreme weather and have specific indicative significance to improve the technique of extended forecast.


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