438 research outputs found
How Secondary Mathematics Teachers Are Incorporating Literacy In Their Classrooms And To What Extent?
A New Record of Deepwater Sculpin, Myoxocephalus thompsonii, in Northeastern Alberta
We present the first documented records of Deepwater Sculpin, Myoxocephalus thompsonii, from northern Alberta, and the second record for the province. Three specimens of Deepwater Sculpin were taken in gill nets set at 17 to 20 m depth in Colin Lake, Alberta, on 15 September 2001. Colin Lake, located in the Canadian Shield region of northeastern Alberta about 125 km northeast of Fort Chipewyan, drains into Lake Athabasca via the Colin River. The only other known Alberta population of Deepwater Sculpin inhabits Upper Waterton Lake in the southwestern corner of the province. This record is approximately 300 km SSE of the nearest verified record in the Northwest Territories and 400 km NW of the nearest verified record in Saskatchewan
Sun and planets from a climate point of view
The Sun plays a dominant role as the gravity centre and the energy source of a planetary system. A simple estimate shows that it is mainly the distance from the Sun that determines the climate of a planet. The solar electromagnetic radiation received by a planet is very unevenly distributed on the dayside of the planet. The climate tries to equilibrate the system by transporting energy through the atmosphere and the oceans provided they exist. These quasi steady state conditions are continuously disturbed by a variety of processes and effects. Potential causes of disturbance on the Sun are the energy generation in the core, the energy transport trough the convection zone, and the energy emission from the photosphere. Well understood are the effects of the orbital parameters responsible for the total amount of solar power received by a planet and its relative distribution on the planet's surface. On a planet, many factors determine how much of the arriving energy enters the climate system and how it is distributed and ultimately reemitted back into space. On Earth, there is growing evidence that in the past solar variability played a significant role in climate chang
Solar modulation during the Holocene
International audienceWe built a composite of three reconstructions of the solar modulation function over the Holocene. The reconstructions until 1950 are based on data from cosmogenic radionuclides and the present time (1951?2004) on neutron monitor data. Interpreting our composite as an index of solar activity, we were able to compare the current solar activity with the last 9300 years. During this time span 25 periods with similar high activity than the current period were found. That corresponds to about 15% of the time which lead to the conclusion that currently the Sun is very but not exceptionally active. Our composite has a large potential for studies dealing with solar activity like the understanding of the solar dynamo and the reconstruction of solar forcing
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Predicting space climate change
The recent decline in the open magnetic flux of the Sun heralds the end of the Grand Solar Maximum (GSM) that has persisted throughout the space age, during which the largestâfluence Solar Energetic Particle (SEP) events have been rare and Galactic Cosmic Ray (GCR) fluxes have been relatively low. In the absence of a predictive model of the solar dynamo, we here make analogue forecasts by studying past variations of solar activity in order to evaluate how longâterm change in space climate may influence the hazardous energetic particle environment of the Earth in the future. We predict the probable future variations in GCR flux, nearâEarth interplanetary magnetic field (IMF), sunspot number, and the probability of large SEP events, all deduced from cosmogenic isotope abundance changes following 24 GSMs in a 9300âyear record
The chaotic solar cycle II. Analysis of cosmogenic 10Be data
Context. The variations of solar activity over long time intervals using a
solar activity reconstruction based on the cosmogenic radionuclide 10Be
measured in polar ice cores are studied. Methods. By applying methods of
nonlinear dynamics, the solar activity cycle is studied using solar activity
proxies that have been reaching into the past for over 9300 years. The
complexity of the system is expressed by several parameters of nonlinear
dynamics, such as embedding dimension or false nearest neighbors, and the
method of delay coordinates is applied to the time series. We also fit a damped
random walk model, which accurately describes the variability of quasars, to
the solar 10Be data and investigate the corresponding power spectral
distribution. The periods in the data series were searched by the Fourier and
wavelet analyses. The solar activity on the long-term scale is found to be on
the edge of chaotic behavior. This can explain the observed intermittent period
of longer lasting solar activity minima. Filtering the data by eliminating
variations below a certain period (the periods of 380 yr and 57 yr were used)
yields a far more regular behavior of solar activity. A comparison between the
results for the 10Be data with the 14C data shows many similarities. Both
cosmogenic isotopes are strongly correlated mutually and with solar activity.
Finally, we find that a series of damped random walk models provides a good fit
to the 10Be data with a fixed characteristic time scale of 1000 years, which is
roughly consistent with the quasi-periods found by the Fourier and wavelet
analyses.Comment: 8 pages, 11 figure
Geology and ground-water resources of Clayton County, Iowa
https://ir.uiowa.edu/igs_wsb/1006/thumbnail.jp
Evolution of the solar irradiance during the Holocene
Aims. We present a physically consistent reconstruction of the total solar
irradiance for the Holocene. Methods. We extend the SATIRE models to estimate
the evolution of the total (and partly spectral) solar irradiance over the
Holocene. The basic assumption is that the variations of the solar irradiance
are due to the evolution of the dark and bright magnetic features on the solar
surface. The evolution of the decadally averaged magnetic flux is computed from
decadal values of cosmogenic isotope concentrations recorded in natural
archives employing a series of physics-based models connecting the processes
from the modulation of the cosmic ray flux in the heliosphere to their record
in natural archives. We then compute the total solar irradiance (TSI) as a
linear combination of the jth and jth + 1 decadal values of the open magnetic
flux. Results. Reconstructions of the TSI over the Holocene, each valid for a
di_erent paleomagnetic time series, are presented. Our analysis suggests that
major sources of uncertainty in the TSI in this model are the heritage of the
uncertainty of the TSI since 1610 reconstructed from sunspot data and the
uncertainty of the evolution of the Earth's magnetic dipole moment. The
analysis of the distribution functions of the reconstructed irradiance for the
last 3000 years indicates that the estimates based on the virtual axial dipole
moment are significantly lower at earlier times than the reconstructions based
on the virtual dipole moment. Conclusions. We present the first physics-based
reconstruction of the total solar irradiance over the Holocene, which will be
of interest for studies of climate change over the last 11500 years. The
reconstruction indicates that the decadally averaged total solar irradiance
ranges over approximately 1.5 W/m2 from grand maxima to grand minima
A new approach to long-term reconstruction of the solar irradiance leads to large historical solar forcing
The variable Sun is the most likely candidate for natural forcing of past
climate change on time scales of 50 to 1000 years. Evidence for this
understanding is that the terrestrial climate correlates positively with solar
activity. During the past 10,000 years, the Sun has experienced substantial
variations in activity and there have been numerous attempts to reconstruct
solar irradiance. While there is general agreement on how solar forcing varied
during the last several hundred years --- all reconstructions are proportional
to the solar activity --- there is scientific controversy on the magnitude of
solar forcing. We present a reconstruction of the Total and Spectral Solar
Irradiance covering 130 nm--10 m from 1610 to the present with annual
resolution and for the Holocene with 22-year resolution. We assume that the
minimum state of the quiet Sun in time corresponds to the observed quietest
area on the present Sun. Then we use available long-term proxies of the solar
activity, which are Be isotope concentrations in ice cores and 22-year
smoothed neutron monitor data, to interpolate between the present quiet Sun and
the minimum state of the quiet Sun. This determines the long-term trend in the
solar variability which is then superposed with the 11-year activity cycle
calculated from the sunspot number. The time-dependent solar spectral
irradiance from about 7000 BC to the present is then derived using a
state-of-the-art radiation code. We derive a total and spectral solar
irradiance that was substantially lower during the Maunder minimum than
observed today. The difference is remarkably larger than other estimations
published in the recent literature. The magnitude of the solar UV variability,
which indirectly affects climate is also found to exceed previous estimates. We
discuss in details the assumptions which leaded us to this conclusion.Comment: 9 pages, 5 figures, accepted for publication in
Astronomy&Astrophysic
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The solar influence on the probability of relatively cold UK winters in the future
Recent research has suggested that relatively cold UK winters are more common when solar activity is low (Lockwood et al 2010 Environ. Res. Lett. 5 024001). Solar activity during the current sunspot minimum has fallen to levels unknown since the start of the 20th century (Lockwood 2010 Proc. R. Soc. A 466 303â29) and records of past solar variations inferred from cosmogenic isotopes (Abreu et al 2008 Geophys. Res. Lett. 35 L20109) and geomagnetic activity data (Lockwood et al 2009 Astrophys. J. 700 937â44) suggest that the current grand solar maximum is coming to an end and hence that solar activity can be expected to continue to decline. Combining cosmogenic isotope data with the long record of temperatures measured in central England, we estimate how solar change could influence the probability in the future of further UK winters that are cold, relative to the hemispheric mean temperature, if all other factors remain constant. Global warming is taken into account only through the detrending using mean hemispheric temperatures. We show that some predictive skill may be obtained by including the solar effect
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