Modelling the long-term variations of a coupled—climate model over the past 125,000 Years : A test of the astronomical theory

1988 ◽  
Vol 71 (4) ◽  
pp. 368
Author(s):  
I. Marsita ◽  
A. Berger ◽  
H. Gallee ◽  
Th. Fichefet ◽  
Ch. Tricot
Keyword(s):  
Climate Model ◽  
Coupled Climate Model ◽  
The Past ◽  
Astronomical Theory ◽  
Long Term Variations

Long-term variations in the geomagnetic activity level Part II: Ascending phases of sunspot cycles

1994 ◽  
Vol 12 (10/11) ◽  
pp. 1065-1070 ◽  
Author(s):  
V. Mussino ◽  
O. Borello Filisetti ◽  
M. Storini ◽  
H. Nevanlinna
Keyword(s):  
Correlation Coefficient ◽  
Geomagnetic Activity ◽  
Activity Level ◽  
Activity Levels ◽  
Data Set ◽  
The Past ◽  
Long Term Trends ◽  
A Minor ◽  
Long Term Variations

Abstract. Monthly averages of the Helsinki Ak-values have been reduced to the equivalent aa-indices to extend the aa-data set back to 1844. A periodicity of about five cycles was found for the correlation coefficient (r) between geomagnetic indices and sunspot numbers for the ascending phases of sunspot cycles 9 to 22, confirming previous findings based on a minor number of sunspot cycles. The result is useful to researchers in topics related to solar-terrestrial physics, particularly for the interpretation of long-term trends in geomagnetic activity during the past, and to forecast geomagnetic activity levels in the future.

scholarly journals Flare Stars in the ETA Tauri Fields Significant Long-Term Variations of their Flaring Activity

1989 ◽  
Vol 104 (2) ◽  
pp. 143-146
Author(s):  
G. Szécsényi-Nagy
Keyword(s):  
New Method ◽  
The Past ◽  
Flare Stars ◽  
Frequency Variations ◽  
Flare Frequency ◽  
Long Term Variations

Photographic surveys completed during the past 30 years yielded data of about 600 flare stars in these fields. Although their average flare number is very low 17 of the stars produced 10… 120 flare ups. In order to investigate the possible long-term activity changes of these objects a new method - which is described below -was developed. Making use of it significant flare frequency variations were found at two out of three ‘active’ flare stars.

scholarly journals Errors of Observation in Double-Star Work

1971 ◽  
Vol 5 ◽  
pp. 133-135
Author(s):  
W. D. Heintz
Keyword(s):  
Noise Level ◽  
Double Star ◽  
Astronomical Observation ◽  
Time Interval ◽  
The Past ◽  
Visual Binary ◽  
Long Time ◽  
Observational Errors ◽  
Long Term Variations

Astronomical observation frequently is focused on minute quantities, and on digging information even from below the 'noise level'. In all cases of long-term variations, such as visual binary motions, measurements over a long time interval have to be combined. All of this requires a knowledge of the observational errors in the past and present. We usually are not at liberty to discard old observations since we cannot repeat them at any later time desired. Visual observations leave no re-measurable records, so we have to take the word of the observer, and make the best of it.

scholarly journals A Transient Shock-Wave in the Shell of the Be Star HD 184279

1987 ◽  
Vol 92 ◽  
pp. 95-98
Author(s):  
D. Ballereau ◽  
J. Chauville
Keyword(s):  
Shock Wave ◽  
Radial Velocity ◽  
Emission Spectrum ◽  
Short Term ◽  
Balmer Series ◽  
Spectroscopic Observations ◽  
The Past ◽  
Be Star ◽  
Long Term Variations

HD 184279 (V1294 Aql) has presented in the past an emission spectrum on the first terms of the Balmer series, and shell absorptions on the hydrogen and neutral helium lines. Their variations have been reported by Merrill (1952), Merrill and Lowen (1953) and Svolopoulos (1975). Ballereau and Hubert-Delplace (1982) evidenced long-term V/R variations with an amplitude of ∼100 km s-1. Short-term photometric variations are irregular (Tempesti and Patriarca, 1976), while long-term variations are correlated with radial velocity (RV) of shell lines (Horn et al., 1982). Ballereau and Chauville (in preparation) extended the spectroscopic observations until 1984 and confirmed the pseudo-periodic variations, the last half-period ranging over 3.4 years (April 1, 1980-August 1, 1983).

Long Term Variations in Jupiter’s 11 cm Radio Emission

1975 ◽  
Vol 2 (6) ◽  
pp. 340-342
Author(s):  
P.M. McCulloch
Keyword(s):  
Radio Emission ◽  
Orbital Period ◽  
Full Range ◽  
Rotational Axis ◽  
The Past ◽  
Range Of Values ◽  
Long Term Variations

During the past twelve years five series of observations have been made of the polarization of Jupiter’s radio emission at a wavelength of 11 cm. This data shows characteristics which have been stable over a period of years as well as some unexplained variations. The observations were made during one complete orbital period of Jupiter and hence were obtained over the full range of values of DE, the angle between Jupiter’s rotational axis and the plane of the sky. These are summarized in Table 1. The 1967 observations have been reported previously (Komesaroff and McCulloch 1967) and the 1963 data is from Roberts and Komesaroff (1965).

Errors of Observation in Double-Star Work

1965 ◽  
Vol 5 ◽  
pp. 132-135
Author(s):  
W. D. Heintz
Keyword(s):  
Noise Level ◽  
Double Star ◽  
Astronomical Observation ◽  
Time Interval ◽  
The Past ◽  
Visual Binary ◽  
Long Time ◽  
Observational Errors ◽  
Long Term Variations

Astronomical observation frequently is focused on minute quantities, and on digging information even from below the ‘noise level’. In all cases of long-term variations, such as visual binary motions, measurements over a long time interval have to be combined. All of this requires a knowledge of the observational errors in the past and present. We usually are not at liberty to discard old observations since we cannot repeat them at any later time desired. Visual observations leave no re-measurable records, so we have to take the word of the observer, and make the best of it.

TESTING A PARTICLE FILTER TO RECONSTRUCT CLIMATE CHANGES OVER THE PAST CENTURIES

2011 ◽  
Vol 21 (12) ◽  
pp. 3611-3618 ◽  
Author(s):  
SVETLANA DUBINKINA ◽  
HUGUES GOOSSE ◽  
YOANN SALLAZ-DAMAZ ◽  
ELISABETH CRESPIN ◽  
MICHEL CRUCIFIX
Keyword(s):  
Particle Filter ◽  
Particle Filtering ◽  
Large Scale ◽  
Climate Changes ◽  
Climate Model ◽  
Real Data ◽  
Model Output ◽  
Coupled Climate Model ◽  
The Past ◽  
Reasonable Cost

We implement a data-assimilation method based on a particle filter in the coupled climate model LOVECLIM focusing on decadal to centennial time scales. Several tests are performed with particle filtering using pseudo-observations obtained from a twin experiment with the model, as well as using real-data observations over the last century. These tests demonstrate that it is possible to obtain a model output well correlated with the observations at the large scale at a reasonable cost.

scholarly journals Adding a dynamical cryosphere into <i>i</i>LOVECLIM (version 1.0) – Part 1: Coupling with the GRISLI ice-sheet model

2013 ◽  
Vol 6 (4) ◽  
pp. 5215-5249 ◽  
Author(s):  
D. M. Roche ◽  
C. Dumas ◽  
M. Bügelmayer ◽  
S. Charbit ◽  
C. Ritz
Keyword(s):  
Climate Model ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
System Model ◽  
Coupled Climate Model ◽  
Climate Conditions ◽  
Coupling Procedure ◽  
First Results ◽  
Coupling Approach

Abstract. We present the coupling approach and the first results of the GRISLI ice-sheet model within the iLOVECLIM coupled climate model. The climate component is a relatively low resolution Earth System Model of Intermediate complexity, well suited for long-term integrations and thus for coupled climate–cryosphere studies. We describe the coupling procedure with emphasise on the downscaling scheme and the methods to compute the snow fraction from total precipitation fields. We then present results for the Northern Hemisphere ice sheet (Greenland) under pre-industrial climate conditions at the end of a 14 000 yr-long integration. The obtained simulated ice sheet presents a too large thickness in central Greenland owing to the overestimation of precipitation in the atmospheric component. We find that including downscaling procedures for temperature improves the temperature distributions over Greenland for both summer and annual mean temperatures. Overall, we find an ice-sheet areal extent in reasonnable agreement with the observed Greenland ice sheet given the simplicity of the chosen climate model.

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