15 research outputs found
Recovery phase of magnetic storms induced by different interplanetary drivers
Statistical analysis of Dst behaviour during recovery phase of magnetic
storms induced by different types of interplanetary drivers is made on the
basis of OMNI data in period 1976-2000. We study storms induced by ICMEs
(including magnetic clouds (MC) and Ejecta) and both types of compressed
regions: corotating interaction regions (CIR) and Sheaths. The shortest,
moderate and longest durations of recovery phase are observed in ICME-, CIR-,
and Sheath-induced storms, respectively. Recovery phases of strong ( nT) magnetic storms are well approximated by hyperbolic functions
with constant times for all types of drivers
while for moderate ( nT) storms profile can not
be approximated by hyperbolic function with constant because
hyperbolic time increases with increasing time of recovery phase.
Relation between duration and value for storms induced by ICME and
Sheath has 2 parts: and duration correlate at small durations while
they anticorrelate at large durations.Comment: 18 pages, 4 figures, 2 tables, submitted to JGR special issue
"Response of Geospace to High-Speed Streams
DNA damage profiles induced by sunlight at different latitudes
Despite growing knowledge on the biological effects of ultraviolet (UV) radiation on human health and ecosystems, it is still difficult to predict the negative impacts of the increasing incidence of solar UV radiation in a scenario of global warming and climate changes. Hence, the development and application of DNA-based biological sensors to monitor the solar UV radiation under different environmental conditions is of increasing importance. With a mind to rendering a molecular view-point of the genotoxic impact of sunlight, field experiments were undertaken with a DNA-dosimeter system in parallel with physical photometry of solar UVB/UVA radiation, at various latitudes in South America. Onapplying biochemical and immunological approaches based on specific DNA-repair enzymes and antibodies, for evaluating sunlight-induced DNA damage profiles, it became clear that the genotoxic potential of sunlight does indeed vary according to latitude. Notwithstanding, while induction of oxidized DNA bases is directly dependent on an increase in latitude, the generation of 6-4PPs is inversely so, whereby the latter can be regarded as a biomolecular marker of UVB incidence. This molecular DNA lesion-pattern largely reflects the relative incidence of UVA and UVB energy at any specific latitude. Hereby is demonstrated the applicability of this DNA-based biosensor for additional, continuous field experiments, as a means of registering variations in the genotoxic impact of solar UV radiation. Environ. Mol. Mutagen. 2012. (c) 2012 Wiley Periodicals, Inc.FAPESP (Sao Paulo, Brazil)FAPESP (Sao Paulo, Brazil)CNPq (Brasilia, Brazil)CNPq (Brasilia, Brazil)Ministry of Education, Culture, Sports, Science, and Technology (Japan)Ministry of Education, Culture, Sports, Science, and Technology of JapanLaboratory of Science and Engineering, Takushoku University, JapanLaboratory of Science and Engineering, Takushoku University, Japa
Intense space storms: Critical issues and open disputes
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94671/1/jgra16863.pd
Ring current decay time model during geomagnetic storms: a simple analytical approach
The ring current growth and decay, characterized by the Dst
index, has been studied for thirty years using the Burton et al. (1975) equation. The original formula is based on the restriction
of the DPS (Dessler, Parker, and Schoppke) theorem and assuming a
constant decay time of particles. The decay time scale is
important because the energy injection rate cannot be determined
it without the knowledge of this parameter.
In a previous work, instead of using a constant value, we introduced
the decay time of particles in the energy rate balance equation
as a continuous function of the absolute value of the pressure
corrected Dst index to avoid the reported discontinuities
determining it. Here, based on the DPS restriction,
we extend our previous empirical work to obtain analytically the proposed continuous function considering
losses due to a global resistive force as a product of
viscous-like, and other related dissipation processes. We test our
model predicting Dst for a couple of specific storm events and
also comparing our results with forecasts of a good reference
model appeared in the literature