Long-term changes in Arctic Seas ice extent during the twentieth century

2009 ◽  
pp. 7-27
Author(s):  
Ivan E. Frolov ◽  
Zalman M. Gudkovich ◽  
Valery P. Karklin ◽  
Evgeny G. Kovalev ◽  
Vasily M. Smolyanitsky
Keyword(s):  
Twentieth Century ◽  
Arctic Seas ◽  
Long Term Changes

scholarly journals Changes in the Number of Lightning Deaths in the United States during the Twentieth Century

1998 ◽  
Vol 11 (8) ◽  
pp. 2070-2077 ◽  
Author(s):  
Raúl E. López ◽  
Ronald L. Holle
Keyword(s):  
United States ◽  
Twentieth Century ◽  
Rural Population ◽  
The United States ◽  
Downward Trend ◽  
Average Surface ◽  
Long Term Changes ◽  
Exponential Decrease ◽  
Exponential Trend

Abstract Long-term changes in the number of lightning deaths from 1900 to 1991 have been examined for the contiguous United States. The population-normalized series revealed an exponential decrease in the number of deaths per million people. This exponential trend is also present in the decrease of the rural U.S. population for the period. The two datasets agree remarkably well and this suggests the downward trend in lightning deaths resulted to a large extent from the reduction of the rural population. Superimposed on the overall downward trend in lightning deaths were fluctuations of two or three decades in duration. The patterns of these fluctuations are paralleled by nationwide changes in thunder-day frequencies and average surface temperature values. Thus, it appears that the lightning death fluctuations are climatically induced.

Conclusion and Epilogue

Before HIV ◽  
2013 ◽  
Author(s):  
Shane Doyle
Keyword(s):  
Twentieth Century ◽  
Intimate Relationship ◽  
Adolescent Sexuality ◽  
Perceptions Of Risk ◽  
Long Term Changes ◽  
Control Programmes ◽  
History Of ◽  
And Control

This chapter considers the role of long-term changes in patterns of fertility, mortality, and STDs in the emergence and control of HIV in this region. It emphasizes that in order to explain the rapidity with which HIV became a mass epidemic in a largely rural context, it is necessary to examine the long history of changes in marriage, adolescent sexuality, leisure, materialism, and perceptions of risk. Equally, the remarkable success of AIDS control programmes in both southern Uganda and Buhaya can only be understood through an analysis of the series of campaigns aimed at improving public morality beginning in the early twentieth century, which helped legitimize sex as a topic of serious debate. Finally, the chapter also examines in detail the intimate relationship between fertility and mortality in Africa.

scholarly journals Exploring the long-term changes in the Madden Julian Oscillation using machine learning

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Panini Dasgupta ◽  
Abirlal Metya ◽  
C. V. Naidu ◽  
Manmeet Singh ◽  
M. K. Roxy
Keyword(s):  
Machine Learning ◽  
Twentieth Century ◽  
Machine Learning Techniques ◽  
Support Vector ◽  
Madden Julian Oscillation ◽  
Multilinear Regression ◽  
The Pacific ◽  
Long Term Changes ◽  
Support Vector Regressor

Abstract The Madden Julian Oscillation (MJO), the dominant subseasonal variability in the tropics, is widely represented using the Real-time Multivariate MJO (RMM) index. The index is limited to the satellite era (post-1974) as its calculation relies on satellite-based observations. Oliver and Thompson (J Clim 25:1996–2019, 2012) extended the RMM index for the twentieth century, employing a multilinear regression on the sea level pressure (SLP) from the NOAA twentieth century reanalysis. They obtained an 82.5% correspondence with the index in the satellite era. In this study, we show that the historical MJO index can be successfully reconstructed using machine learning techniques and improved upon. We obtain a significant improvement of up to 4%, using the support vector regressor (SVR) and convolutional neural network (CNN) methods on the same set of predictors used by Oliver and Thompson. Based on the improved RMM indices, we explore the long-term changes in the intensity, phase occurrences, and frequency of the winter MJO events during 1905–2015. We show an increasing trend in MJO intensity (22–27%) during this period. We also find a multidecadal change in MJO phase occurrence and periodicity corresponding to the Pacific Decadal Oscillation (PDO), while the role of anthropogenic warming cannot be ignored.

International interdependence: Some long-term trends and recent changes

1975 ◽  
Vol 29 (4) ◽  
pp. 1021-1034 ◽  
Author(s):  
Peter J. Katzenstein
Keyword(s):  
Twentieth Century ◽  
Time Series ◽  
Time Series Data ◽  
Series Data ◽  
Empirical Measures ◽  
Long Term Changes ◽  
Data Points ◽  
Long Term Trends

This paper provides data on long-term changes in international interdependence. Transactions exchanged between societies and states are one possible means of interdependence. Two decades ago Karl Deutsch collected a substantial amount of data which illustrated a long-term decline in transactions since the beginning of the twentieth century. An extension of his time series data points to a possibly important reversal of that trend in recent years. This conclusion is in agreement with other empirical measures of international interdependence.

Diatoms and aquatic palynomorphs in the sediments of the Eurasian Arctic seas and their significance for paleooceanological investigations in the Arctic

2019 ◽  
pp. 246-251
Author(s):  
Yelena I. Polyakova ◽  
Yekaterina I. Novichkova ◽  
Tatiana S. Klyuvitkina ◽  
Elizaveta A. Agafonova ◽  
Irina M. Kryukova
Keyword(s):  
Bering Sea ◽  
Surface Sediments ◽  
Sea Water ◽  
The Arctic ◽  
Marginal Filter ◽  
Arctic Seas ◽  
Hydrological Parameters ◽  
The Arctic Ocean ◽  
Long Term Studies

Presented the results of long-term studies of diatoms and aquatic palynomorphs in surface sediments of the Arctic seas and the possibility of their use for the reconstructions of paleocirculation water masses, advection of Atlantic and Bering sea water into the Arctic ocean, changes in the river runoff to the seas, sedimentary processes in the marginal filter of the largest rivers, seasonal sea ice cover and other hydrological parameters.

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