Complex principal component analysis of sea-level pressure over the eastern USA

2007 ◽  
Vol 11 (1) ◽  
pp. 27-54 ◽  
Author(s):  
Jerry M. Davis ◽  
Frank L. Estis ◽  
Peter Bloomfield ◽  
John F. Monahan
Keyword(s):  
Principal Component Analysis ◽  
Sea Level ◽  
Principal Component ◽  
Component Analysis ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Eastern Usa

scholarly journals A Reexamination of the Northern Hemisphere Sea Level Pressure Variability by the Independent Component Analysis

SOLA ◽  
2006 ◽  
Vol 2 ◽  
pp. 5-8 ◽  
Author(s):  
Atsushi Mori ◽  
Nobuaki Kawasaki ◽  
Kensuke Yamazaki ◽  
Meiji Honda ◽  
Hisashi Nakamura
Keyword(s):  
Independent Component Analysis ◽  
Sea Level ◽  
Northern Hemisphere ◽  
Component Analysis ◽  
Independent Component ◽  
Sea Level Pressure ◽  
Level Pressure

Climatological Characteristics of Heavy Rainfall in Northern Pakistan and Atmospheric Blocking over Western Russia

2016 ◽  
Vol 29 (21) ◽  
pp. 7743-7754 ◽  
Author(s):  
Tomohito J. Yamada ◽  
Daiki Takeuchi ◽  
M. A. Farukh ◽  
Yoshikazu Kitano
Keyword(s):  
Sea Level ◽  
Heavy Rainfall ◽  
Principal Component ◽  
Heavy Precipitation ◽  
Boreal Summer ◽  
Northern Pakistan ◽  
Atmospheric Blocking ◽  
Sea Level Pressure ◽  
Level Pressure

Abstract Pakistan and northwestern India have frequently experienced severe heavy rainfall events during the boreal summer over the last 50 years including an event in late July and early August 2010 due to a sequence of monsoon surges. This study identified five dominant atmospheric patterns by applying principal component analysis and k-means clustering to a long-term sea level pressure dataset from 1979 to 2014. Two of these five dominant atmospheric patterns corresponded with a high frequency of the persistent atmospheric blocking index and positive sea level pressure over western Russia as well as an adjacent meridional trough ahead of northern Pakistan. In these two groups, a negative sea surface temperature anomaly was apparent over the equatorial mid- to eastern Pacific Ocean. The heavy precipitation periods with high persistent blocking frequency in western Russia as in the 2010 heat wave tended to have 1.2 times larger precipitation intensity compared to the whole of the heavy precipitation periods during the 36 years.

scholarly journals Historical SAM Variability. Part I: Century-Length Seasonal Reconstructions*

2009 ◽  
Vol 22 (20) ◽  
pp. 5319-5345 ◽  
Author(s):  
Julie M. Jones ◽  
Ryan L. Fogt ◽  
Martin Widmann ◽  
Gareth J. Marshall ◽  
Phil D. Jones ◽  
...  
Keyword(s):  
Sea Level ◽  
Southern Hemisphere ◽  
Austral Summer ◽  
Principal Component ◽  
Reanalysis Data ◽  
The Other ◽  
Considerable Variability ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
The Individual

Abstract Seasonal reconstructions of the Southern Hemisphere annular mode (SAM) index are derived to extend the record before the reanalysis period, using station sea level pressure (SLP) data as predictors. Two reconstructions using different predictands are obtained: one [Jones and Widmann (JW)] based on the first principal component (PC) of extratropical SLP and the other (Fogt) on the index of Marshall. A regional-based SAM index (Visbeck) is also considered. These predictands agree well post-1979; correlations decline in all seasons except austral summer for the full series starting in 1958. Predictand agreement is strongest in spring and summer; hence agreement between the reconstructions is highest in these seasons. The less zonally symmetric SAM structure in winter and spring influences the strength of the SAM signal over land areas, hence the number of stations included in the reconstructions. Reconstructions from 1865 were, therefore, derived in summer and autumn and from 1905 in winter and spring. This paper examines the skill of each reconstruction by comparison with observations and reanalysis data. Some of the individual peaks in the reconstructions, such as the most recent in austral summer, represent a full hemispheric SAM pattern, while others are caused by regional SLP anomalies over the locations of the predictors. The JW and Fogt reconstructions are of similar quality in summer and autumn, while in winter and spring the Marshall index is better reconstructed by Fogt than the PC index is by JW. In spring and autumn the SAM shows considerable variability prior to recent decades.

scholarly journals Multidecadal variability in seasonal mean sea level along the North Sea coast

2018 ◽  
Author(s):  
Thomas Frederikse ◽  
Theo Gerkema
Keyword(s):  
Sea Level ◽  
North Sea ◽  
Large Scale ◽  
Low Frequency ◽  
Principal Component ◽  
Sea Level Pressure ◽  
Mean Sea Level ◽  
Level Pressure ◽  
The North ◽  
The North Sea

Abstract. Seasonal deviations from annual-mean sea level in the North Sea region show a large low-frequency component with substantial variability at decadal and multi-decadal time scales. In this study, we quantify low-frequency seasonal variations from annual-mean sea level and look for drivers of this variability. The amplitude, as well as the temporal evolution of this multi-decadal variability shows substantial variations over the North Sea region, and this spatial pattern is similar to the well-known pattern of the influence of winds and pressure changes on sea level on higher frequencies. The largest low-frequency signals are found in the German Bight and along the Norwegian coast. We find that the variability is much stronger in winter and autumn than in other seasons, and that this winter and autumn variability is predominantly driven by wind and sea-level pressure anomalies which have their cause in large-scale atmospheric patterns. For the spring and summer seasons, only a small fraction of the observed variability can be explained by local and large-scale atmospheric changes. Large-scale atmospheric patterns have been derived from a principal component analysis of sea-level pressure. The first principal component of sea-level pressure over the North Atlantic Ocean, which is linked to the North Atlantic Oscillation (NAO), explains the largest fraction of winter-mean variability for most stations, while for some stations, the variability consists of a combination of multiple principal components. The low-frequency variability in season-mean sea level can manifest itself as trends in short records of seasonal sea level. For multiple stations around the North Sea, running-mean 40-year trends for autumn and winter sea level often exceed the long-term trends in annual mean sea level, while for spring and summer, the seasonal trends have a similar order of magnitude as the annual-mean trends. Removing the variability explained by atmospheric variability vastly reduces the seasonal trends, especially in winter and autumn.

A German version of the Intermittent Claudication Questionnaire (ICQ): cultural adaptation and validation

VASA ◽  
2012 ◽  
Vol 41 (5) ◽  
pp. 333-342 ◽  
Author(s):  
Kirchberger ◽  
Finger ◽  
Müller-Bühl
Keyword(s):  
Principal Component Analysis ◽  
Intermittent Claudication ◽  
Completion Time ◽  
Short Form ◽  
Principal Component ◽  
Component Analysis ◽  
German Version ◽  
Average Completion Time ◽  
Sf 36 ◽  
Related Quality

Background: The Intermittent Claudication Questionnaire (ICQ) is a short questionnaire for the assessment of health-related quality of life (HRQOL) in patients with intermittent claudication (IC). The objective of this study was to translate the ICQ into German and to investigate the psychometric properties of the German ICQ version in patients with IC. Patients and methods: The original English version was translated using a forward-backward method. The resulting German version was reviewed by the author of the original version and an experienced clinician. Finally, it was tested for clarity with 5 German patients with IC. A sample of 81 patients were administered the German ICQ. The sample consisted of 58.0 % male patients with a median age of 71 years and a median IC duration of 36 months. Test of feasibility included completeness of questionnaires, completion time, and ratings of clarity, length and relevance. Reliability was assessed through a retest in 13 patients at 14 days, and analysis of Cronbach’s alpha for internal consistency. Construct validity was investigated using principal component analysis. Concurrent validity was assessed by correlating the ICQ scores with the Short Form 36 Health Survey (SF-36) as well as clinical measures. Results: The ICQ was completely filled in by 73 subjects (90.1 %) with an average completion time of 6.3 minutes. Cronbach’s alpha coefficient reached 0.75. Intra-class correlation for test-retest reliability was r = 0.88. Principal component analysis resulted in a 3 factor solution. The first factor explained 51.5 of the total variation and all items had loadings of at least 0.65 on it. The ICQ was significantly associated with the SF-36 and treadmill-walking distances whereas no association was found for resting ABPI. Conclusions: The German version of the ICQ demonstrated good feasibility, satisfactory reliability and good validity. Responsiveness should be investigated in further validation studies.

Sign in / Sign up

Export Citation Format

Share Document