Classification of hemispheric monthly mean stratospheric potential vorticity fields

Abstract. Monthly mean NCEP reanalysis potential vorticity fields at the 650 K isentropic level over the Northern and Southern Hemispheres between 1979 and 1997 were studied using multivariate analysis tools. Principal component analysis in the T-mode was applied to demonstrate the validity of such statistical techniques for the study of stratospheric dynamics and climatology. The method, complementarily applied to both the raw and anomaly fields, was useful in determining and classifying the characteristics of winter and summer PV fields on both hemispheres, in particular, the well-known differences in the behaviour and persistence of the polar vortices. It was possible to identify such features as sudden warming events in the Northern Hemisphere and final warming dates in both hemispheres. The stratospheric impact of other atmospheric processes, such as volcanic eruptions, also identified though the results, must be viewed at this stage as tentative. An interesting change in behaviour around 1990 was detected over both hemispheres.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; general circulation; climatology)

Download Full-text

General Characteristics and Classification of Processes in the Earth-Atmosphere System

Computational Techniques for Modeling Atmospheric Processes - Advances in Environmental Engineering and Green Technologies ◽

10.4018/978-1-5225-2636-0.ch002 ◽

2017 ◽

pp. 45-86

Keyword(s):

General Circulation ◽

Outer Space ◽

Radiant Energy ◽

Earth Atmosphere ◽

Heat Flows ◽

Atmospheric Processes ◽

Air Movement ◽

Atmospheric General Circulation ◽

Mass Circulation

Atmospheric processes affect the heat flows coming from above, from space, and from below, from the earth's surface. The solar radiation that comes to Earth from outer space is the main source of energy of atmospheric processes. It is the radiant energy of the Sun that is converted into heat in the atmosphere and at the Earth's surface, kinetic energy, and other forms of energy. But the Sun's rays heat the earth's surface larger than the air directly, so between the earth's surface and the atmosphere, there is lively exchange of heat as well as moisture. The structure of the earth's surface and its relief are very important for these processes. The chapter presents the picture of heat and the moisture circulation in the atmosphere and gives physical basics of atmospheric general circulation including fundamentals of air mass circulation, local physiographic impact on the atmospheric air movement, in-mass atmospheric processes, and basic laws of pollution spreading in the atmosphere.

Download Full-text

Climatological Ertel's potential-vorticity flux and mean meridional circulation in the extratropical troposphere − lower stratosphere

Annales Geophysicae ◽

10.1007/s00585-998-0250-3 ◽

1998 ◽

Vol 16 (2) ◽

pp. 250-265 ◽

Cited By ~ 10

Author(s):

J. Bartels ◽

D. Peters ◽

G. Schmitz

Keyword(s):

Potential Vorticity ◽

Seasonal Cycle ◽

General Circulation ◽

Lower Stratosphere ◽

Climate Model ◽

Middle Atmosphere ◽

Meridional Circulation ◽

Statistical Significance ◽

Baroclinic Wave ◽

Mean Meridional Circulation

Abstract. We investigated to what extent the isentropic, non-geostrophic formulation of zonally averaged circulation derived for stratospheric conditions is applicable to climatological transport in the extratropical troposphere and lower stratosphere. The study is based on 10 years of daily data of ECMWF analysis and on the ECHAM3 climate model of the German Climate Computing Centre. The main result is a scalar isentropic mixing coefficient, Kyy, and a mean meridional transport circulation consistently derived from the same data base. For both data sources, isentropic mean meridional circulation is derived from horizontal mass flow rate for 4 representative months. Alternatively, a mean meridional circulation is calculated from total diabatic heating rates of the ECHAM3 model. It is shown that only the latter is in good agreement with the ECMWF mean meridional circulation. Isentropic analysis also comprises the seasonal cycle of the climatological meridional gradient and flux of Ertel's potential vorticity (PV). Application of Tung's flux-gradient relation yields that for all seasons Kyy is positive in height-latitude regions where statistical significance is reached. Large Kyy values, marking regions of more efficient mixing, have been found in the subtropical vertical band of weak westerly wind and in mid-latitudes in regions of upward-propagating baroclinic wave activity in the middle and upper troposphere. Based on the ECMWF data and results of baroclinic-wave behaviour, strong indications are presented that positive zonally averaged PV flux polewards of the jet core in the NH is strengthened by stationary waves and nonlinear effects. Reduced eddy transport is apparent in winter and spring slightly below the subtropical tropopause jet. The seasonal cycle of Kyy from ECHAM3 data is to a great extent in agreement with the result based on ECMWF analysis. In the model, reduced interannual variability enlarges the height-latitude range where sign of Kyy is significant.Key words. Meteorology and atmospheric dynamics · Climatology · General circulation · Middle atmosphere is significant.

Download Full-text

Stratosphere-troposphere exchange in an extratropical cyclone, calculated with a Lagrangian method

Annales Geophysicae ◽

10.1007/s00585-000-0573-1 ◽

2000 ◽

Vol 18 (5) ◽

pp. 573-582 ◽

Cited By ~ 14

Author(s):

M. Sigmond ◽

J. Meloen ◽

P. C. Siegmund

Keyword(s):

Wind Shear ◽

Total Ozone ◽

General Circulation ◽

Middle Atmosphere ◽

Statistical Significance ◽

Atmospheric Dynamics ◽

Extratropical Cyclone ◽

Northwest Coast ◽

Mesoscale Meteorology ◽

Meteorology And Atmospheric Dynamics

Abstract. A Lagrangian technique is developed and applied to calculate stratosphere-troposphere exchange in an extratropical cyclone. This exchange is computed from the potential vorticity or PV along trajectories, calculated from ECMWF circulation data. Special emphasis is put on the statistical significance of the results. The computed field of the cross-tropopause flux is dominated by elongated patterns of statistically significant large downward and small upward fluxes. The downward fluxes mainly occur in the lower part of the considered tropopause folds. The upward fluxes are found near the entrance of the folds, in the tropopause ridges. The ratio between the area averaged downward and upward cross-tropopause fluxes increases with increasing strength of the cyclone. Since the largest fluxes are shown to occur in the regions with the largest wind shear, where PV-mixing is thought to cause large cross-tropopause fluxes, the results are expected to be reliable, at least in a qualitative sense. The position of a tropopause fold along the northwest coast of Africa is confirmed by total ozone observations. The results indicate that the applied Lagrangian technique is an appropriate tool for diagnosing stratosphere-troposphere exchange.Key words: Meteorology and atmospheric dynamics (general circulation; mesoscale meteorology; middle atmosphere dynamics)

Download Full-text

Stratospheric SO<sub>2</sub> and sulphate aerosol, model simulations and satellite observations

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-11395-2013 ◽

2013 ◽

Vol 13 (4) ◽

pp. 11395-11425 ◽

Cited By ~ 8

Author(s):

C. Brühl ◽

J. Lelieveld ◽

M. Höpfner ◽

H. Tost

Keyword(s):

Atmospheric Chemistry ◽

Radiative Forcing ◽

General Circulation ◽

Middle Atmosphere ◽

Lower Boundary ◽

Circulation Model ◽

Volcanic Eruptions ◽

Satellite Observations ◽

Quasi Biennial Oscillation ◽

Tropospheric Aerosol

Abstract. A multiyear study with the atmospheric chemistry general circulation model EMAC with the aerosol module GMXe at high altitude resolution demonstrates that the sulfur gases COS and SO2, the latter from low-latitude volcanic eruptions, predominantly control the formation of stratospheric aerosol. The model consistently uses the same parameters in the troposphere and stratosphere for 7 aerosol modes applied. Lower boundary conditions for COS and other long-lived trace gases are taken from measurement networks, while estimates of volcanic SO2 emissions are based on satellite observations. We show comparisons with satellite data for aerosol extinction (e.g. SAGE) and SO2 in the middle atmosphere (MIPAS on ENVISAT). This corroborates the interannual variability induced by the Quasi-Biennial Oscillation, which is internally generated by the model. The model also realistically simulates the radiative effects of stratospheric and tropospheric aerosol including the effects on the model dynamics. The medium strength volcanic eruptions of 2005 and 2006 exerted a nonnegligible radiative forcing of up to −0.6 W m−2 in the tropics, while the large Pinatubo eruption caused a maximum though short term tropical forcing of about −10 W m−2. The study also shows that observed upper stratospheric SO2 can be simulated accurately only when a sulphur sink on meteoritic dust is included and the photolysis of gaseous H2SO4 in the near infrared is higher than assumed previously.

Download Full-text

Results of an interactively coupled atmospheric chemistry – general circulation model: Comparison with observations

Annales Geophysicae ◽

10.5194/angeo-19-435-2001 ◽

2001 ◽

Vol 19 (4) ◽

pp. 435-457 ◽

Cited By ~ 56

Author(s):

R. Hein ◽

M. Dameris ◽

C. Schnadt ◽

C. Land ◽

V. Grewe ◽

...

Keyword(s):

General Circulation Model ◽

Atmospheric Chemistry ◽

General Circulation ◽

Middle Atmosphere ◽

Stratospheric Ozone ◽

Circulation Model ◽

Ozone Layer ◽

The Arctic ◽

Time Step ◽

Stratospheric Dynamics

Abstract. The coupled climate-chemistry model ECHAM4.L39(DLR)/CHEM is presented which enables a simultaneous treatment of meteorology and atmospheric chemistry and their feedbacks. This is the first model which interactively combines a general circulation model with a chemical model, employing most of the important reactions and species necessary to describe the stratospheric and upper tropospheric ozone chemistry, and which is computationally fast enough to allow long-term integrations with currently available computer resources. This is possible as the model time-step used for the chemistry can be chosen as large as the integration time-step for the dynamics. Vertically the atmosphere is discretized by 39 levels from the surface up to the top layer which is centred at 10 hPa, with a relatively high vertical resolution of approximately 700 m near the extra-tropical tropopause. We present the results of a control simulation representing recent conditions (1990) and compare it to available observations. The focus is on investigations of stratospheric dynamics and chemistry relevant to describe the stratospheric ozone layer. ECHAM4.L39(DLR)/CHEM reproduces main features of stratospheric dynamics in the arctic vortex region, including stratospheric warming events. This constitutes a major improvement compared to earlier model versions. However, apparent shortcomings in Antarctic circulation and temperatures persist. The seasonal and interannual variability of the ozone layer is simulated in accordance with observations. Activation and deactivation of chlorine in the polar stratospheric vortices and their inter-hemispheric differences are reproduced. Considering methane oxidation as part of the dynamic-chemistry feedback results in an improved representation of the spatial distribution of stratospheric water vapour concentrations. The current model constitutes a powerful tool to investigate, for instance, the combined direct and indirect effects of anthropogenic trace gas emissions.Key words. Atmospheric composition and structure (middle atmosphere – composition and chemistry) – Meteorology and atmospheric dynamics (general circulation; middle atmosphere dynamics)

Download Full-text

Classification of Observations through Combination of the Dimension Reduction and the Cluster Analysis

International Journal of Advanced Research in Computer Science and Software Engineering ◽

10.23956/ijarcsse.v7i8.13 ◽

2017 ◽

Vol 7 (8) ◽

pp. 30

Author(s):

Hyeuk Kim

Keyword(s):

Machine Learning ◽

Principal Component Analysis ◽

Cluster Analysis ◽

Unsupervised Learning ◽

Principal Component ◽

Component Analysis ◽

Baseball Players ◽

Partitioning Around Medoids ◽

Different Characteristics

Unsupervised learning in machine learning divides data into several groups. The observations in the same group have similar characteristics and the observations in the different groups have the different characteristics. In the paper, we classify data by partitioning around medoids which have some advantages over the k-means clustering. We apply it to baseball players in Korea Baseball League. We also apply the principal component analysis to data and draw the graph using two components for axis. We interpret the meaning of the clustering graphically through the procedure. The combination of the partitioning around medoids and the principal component analysis can be used to any other data and the approach makes us to figure out the characteristics easily.

Download Full-text

Pemanfaatan CFSRv2 untuk Statistical Downscaling menggunakan Principal Component Regression dan Partial Least Square

Xplore Journal of Statistics ◽

10.29244/xplore.v8i1.275 ◽

2019 ◽

Vol 8 (1) ◽

Author(s):

Khairunnisa Khairunnisa ◽

Rizka Pitri ◽

Victor P Butar-Butar ◽

Agus M Soleh

Keyword(s):

Statistical Downscaling ◽

General Circulation ◽

Principal Component Regression ◽

Circulation Model ◽

Principal Component ◽

Meteorological Station ◽

Grid Size ◽

Partial Least Square ◽

Least Square ◽

Output Data

This research used CFSRv2 data as output data general circulation model. CFSRv2 involves some variables data with high correlation, so in this research is using principal component regression (PCR) and partial least square (PLS) to solve the multicollinearity occurring in CFSRv2 data. This research aims to determine the best model between PCR and PLS to estimate rainfall at Bandung geophysical station, Bogor climatology station, Citeko meteorological station, and Jatiwangi meteorological station by comparing RMSEP value and correlation value. Size used was 3×3, 4×4, 5×5, 6×6, 7×7, 8×8, 9×9, and 11×11 that was located between (-40) N - (-90) S and 1050 E -1100 E with a grid size of 0.5×0.5 The PLS model was the best model used in stastistical downscaling in this research than PCR model because of the PLS model obtained the lower RMSEP value and the higher correlation value. The best domain and RMSEP value for Bandung geophysical station, Bogor climatology station, Citeko meteorological station, and Jatiwangi meteorological station is 9 × 9 with 100.06, 6 × 6 with 194.3, 8 × 8 with 117.6, and 6 × 6 with 108.2, respectively.

Download Full-text

Chemometric Analysis for the Classification of some Groups of Drugs with Divergent Pharmacological Activity on the Basis of some Chromatographic and Molecular Modeling Parameters

Combinatorial Chemistry & High Throughput Screening ◽

10.2174/1386207321666180129102149 ◽

2018 ◽

Vol 21 (2) ◽

pp. 125-137

Author(s):

Jolanta Stasiak ◽

Marcin Koba ◽

Marcin Gackowski ◽

Tomasz Baczek

Keyword(s):

Correlation Analysis ◽

Pharmacological Activity ◽

Correlation Coefficients ◽

Principal Component ◽

Cardiovascular Drugs ◽

New Drugs ◽

Analgesic Drugs ◽

Starting Point ◽

Chromatographic Parameters

Aim and Objective: In this study, chemometric methods as correlation analysis, cluster analysis (CA), principal component analysis (PCA), and factor analysis (FA) have been used to reduce the number of chromatographic parameters (logk/logkw) and various (e.g., 0D, 1D, 2D, 3D) structural descriptors for three different groups of drugs, such as 12 analgesic drugs, 11 cardiovascular drugs and 36 “other” compounds and especially to choose the most important data of them. Material and Methods: All chemometric analyses have been carried out, graphically presented and also discussed for each group of drugs. At first, compounds’ structural and chromatographic parameters were correlated. The best results of correlation analysis were as follows: correlation coefficients like R = 0.93, R = 0.88, R = 0.91 for cardiac medications, analgesic drugs, and 36 “other” compounds, respectively. Next, part of molecular and HPLC experimental data from each group of drugs were submitted to FA/PCA and CA techniques. Results: Almost all results obtained by FA or PCA, and total data variance, from all analyzed parameters (experimental and calculated) were explained by first two/three factors: 84.28%, 76.38 %, 69.71% for cardiovascular drugs, for analgesic drugs and for 36 “other” compounds, respectively. Compounds clustering by CA method had similar characteristic as those obtained by FA/PCA. In our paper, statistical classification of mentioned drugs performed has been widely characterized and discussed in case of their molecular structure and pharmacological activity. Conclusion: Proposed QSAR strategy of reduced number of parameters could be useful starting point for further statistical analysis as well as support for designing new drugs and predicting their possible activity.

Download Full-text

Fingerprint of PGI Mantova Cucumis melo by ICP-MS and Chemometric Analysis

Current Nutrition & Food Science ◽

10.2174/1573401316999200504094207 ◽

2020 ◽

Vol 17 (1) ◽

pp. 94-104

Author(s):

Antonio F. Mottese ◽

Maria R. Fede ◽

Francesco Caridi ◽

Giuseppe Sabatino ◽

Giuseppe Marcianò ◽

...

Keyword(s):

Cucumis Melo ◽

Principal Component ◽

Inorganic Elements ◽

Discrimination Power ◽

Icp Ms ◽

High Discrimination ◽

Strong Relation ◽

Trace Element Contents ◽

Safe Food

Background and Objectives: In this work, yellow and green varieties of Cucumis melo fruits belonging to different cultivars were studied. In detail, three Sicilian cultivars of winter melons tutelated by TAP (Traditional agro-alimentary products) labels were considered, whereas asun protected the Calabrian winter melon was studied too. With the aim to compare the selective uptakes of inorganic elements among winter and summer fruits, the “PGI Melone Mantovano” was investigated. The purpose of this work was to apply the obtained results i) to guarantee the quality and healthiness of fruits, ii) to producers defend, iii) to help the customers in safe food purchase. Method: All samples were analyzed by ICP-MS and the obtained results, subsequently, were subjected to Cluster analysis (CA), Principal component analysis (PCA) and Canonical discriminant analysis (CDA). Results: CA results were generally in agreement with samples origin, whereas the PCA elaboration has confirmed the presence of a strong relation between fruit origins and trace element contents. In particular, two principal components justified the 57.32% of the total variance (PC1= 40.95%, PC2= 16.37%). Finally, the CDA approach has provided several functions with high discrimination power, confirmed by the correct classification of all samples (100%). Conclusions: CA, PCA and CDA could represent an integrated to label to discriminate the origin of agri-food products and, thus, protect and guarantee their healthiness.

Download Full-text