Repository of University of Nova Gorica

Search the repository
A+ | A- | Help | SLO | ENG

Query: search in
search in
search in
search in
* old and bolonia study programme

Options:
  Reset


1 - 8 / 8
First pagePrevious page1Next pageLast page
1.
Influence of very large spatial heterogeneity on estimates of sea-level trends
M. Shnirman, Vincent Courtillot, Alexander Shapoval, Jean-Louis Le Mouël, 2020, original scientific article

Abstract: We propose a new method to estimate sub-decadal to centennial time scales of sea-level change. Since the coastal data exhibit large spatial heterogeneity and temporal variability, the global sea-level rate is estimated as an appropriate average of the rates observed at available locations and computed with sliding windows. We claim that under such heterogeneity the median serves as a better representative of an adequate average than the mean. With this approach, the sea-level rate in 60 to 70 yr windows over the past century is found to be smaller than 1.7-1.9 mm/yr. These upper estimates are in line with those obtained with a scarce list of available long quasi-gapless series
Found in: osebi
Keywords: sea-level rise, median, sliding window, statistically significant trend
Published: 16.03.2021; Views: 452; Downloads: 0
.pdf Fulltext (1,62 MB)

2.
Observational evidence in favor of scale-free evolution of sunspot groups
Alexander Shapoval, Jean-Louis Le Mouël, M. Shnirman, Vincent Courtillot, 2018, original scientific article

Found in: osebi
Keywords: sunspots, sun, magnetic fields, data analysis
Published: 23.03.2021; Views: 557; Downloads: 19
.pdf Fulltext (451,74 KB)
This document has many files! More...

3.
Dynamics of sunspot series on time scales from days to years
Jean-Louis Le Mouël, M. Shnirman, Vincent Courtillot, Alexander Shapoval, 2017, original scientific article

Found in: osebi
Keywords: sunspots series, average lifetime, average birthrate, data analysis
Published: 30.03.2021; Views: 504; Downloads: 18
.pdf Fulltext (1,52 MB)
This document has many files! More...

4.
Stochastic description of the high-frequency content of daily sunspots and evidence for regime changes
Vincent Courtillot, Alexander Shapoval, Jean-Louis Le Mouël, M. Shnirman, 2015, original scientific article

Found in: osebi
Keywords: chaos, solar activity, sunspots
Published: 19.04.2021; Views: 365; Downloads: 19
URL Fulltext (0,00 KB)
This document has many files! More...

5.
6.
When daily sunspot births become positively correlated
Alexander Shapoval, Jean-Louis Le Mouël, M. Shnirman, Vincent Courtillot, 2015, original scientific article

Found in: osebi
Keywords: solar cycle, sunspots, auto regressive process
Published: 19.04.2021; Views: 384; Downloads: 0
.pdf Fulltext (1,13 MB)

7.
Is a sudden increase of irregularity of sunspot numbers a precursor of a return to low solar activity?
M. Shnirman, Alexander Shapoval, Jean-Louis Le Mouël, Vincent Courtillot, 2014, original scientific article

Found in: osebi
Keywords: solar cycle, sunspots, lifetime
Published: 19.04.2021; Views: 362; Downloads: 3
URL Fulltext (0,00 KB)
This document has many files! More...

8.
Two regimes in the regularity of sunspot number
M. Shnirman, Vincent Courtillot, Alexander Shapoval, Jean-Louis Le Mouël, 2013, original scientific article

Abstract: Sunspot numbers WN display quasi-periodical variations that undergo regime changes. These irregularities could indicate a chaotic system and be measured by Lyapunov exponents. We define a functional λ (an "irregularity index") that is close to the (maximal) Lyapunov exponent for dynamical systems and well defined for series with a random component: this allows one to work with sunspot numbers. We compute λ for the daily WN from 1850 to 2012 within 4 yr sliding windows: λ exhibit sharp maxima at solar minima and secondary maxima at solar maxima. This pattern is reflected in the ratio R of the amplitudes of the main versus secondary peaks. Two regimes have alternated in the past 150 yr, R1 from 1850 to 1915 (large λ and R values) and R2 from 1935 to 2005 (shrinking difference between main and secondary maxima, R values between 1 and 2). We build an autoregressive model consisting of Poisson noise plus an 11 yr cycle and compute its irregularity index. The transition from R1 to R2 can be reproduced by strengthening the autocorrelation a of the model series. The features of the two regimes are stable for model and WN with respect to embedding dimension and delay. Near the time of the last solar minimum (~2008), the irregularity index exhibits a peak similar to the peaks observed before 1915. This might signal a regime change back from R2 to R1 and the onset of a significant decrease of solar activity.
Found in: osebi
Keywords: Lyapunov exponent, solar activity, solar cycle
Published: 19.04.2021; Views: 416; Downloads: 16
URL Fulltext (0,00 KB)
This document has many files! More...

Search done in 0 sec.
Back to top