Download (BDA) Contribution To Space Weather Investigations

The Brazilian Decimetric Array (BDA)
Contribution to Space Weather
Investigations
H.S. Sawant, J.R. Cecatto, F.C.R. Fernandes, R.R. Rosa, J.E.R. Costa
and BDA team members
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Valley in Chachoeira Paulista selecting “T”array site, Prof. G. Swarup, Director GMRT – India Dr. H.S. Sawant - INPE
and Dr. Hari Om Vats – PRL - India discussing with civil engineer on 13th September 1997.
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PARTICIPATING INSTITUTIONS
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Institutes:
National Institute for Space Research – INPE:
Astrophysics Division (DAS)
Laboratory of Applied Computation (LAC)
Aeroespace Electronic Division (DEA)
Laboratory of Integration and Tests (LIT)
Federal University of São Carlos (UFSCar)
Catholic University of Minas Gerais (PUC-MG)
Center of Radio Astronomy – Mackenzie (CRAAM) – INPE
Tata Institute of Fundamental Research (TIFR) – GMRT – NCRA - India
Indian Institute of Astrophysics (IIA) – Bangalore, India
University of California - Berkeley (UCB), Dept. of Radioastrophysics, USA
New Jersey Institute of Technology (NJIT), USA
Industries/Companies:
Centro de Pesquisa Renato Archer - CENPRA - - Campinas
Intelligent Motion Technology, IMT- LTd. – Pune India
Neuron Ltd. - São José dos Capos - Brazil
UC GRAÇA – São José dos Campos - Brazil.
F4R FIBRA PARA RADIO – Campinas
Two micro-companies Eletronics / Electrical
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SOLAR PHYSICS GROUP
Hanumant Shankar Sawant
José Roberto Cecatto
Francisco C. R. Fernandes
Reinaldo Roberto Rosa
Joaquim E. R. Costa
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CHARACTERISTICS OF BDA PHASE II
Number of antennas
26
Number of baselines
325
Configuration
“T” shape
Frequency bands
1.2 – 1.7, 2.8 and 5.6 GHz
Temporal resolution
~100 ms
Antenna diameter (alt-az mount)
4m
Angular resolution
~2,8’, ~1,4’ e ~0,8’
Maximum baseline
252 m
Minimum baseline
9m
Field of view
40’  40’ of arc
Sensitivity (@ 5.6 GHz with t = 1 s)
~285 Jy/beam (Sun) and ~1,8 Jy/beam (others)
Tracking Coverage
3400 in azimuth and 1800 in elevation
Pointing accuracy
< 3 arcmin
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Methods: The development of BDA phase II involves the participation of several
local companies and national and international institutes.
FAPESP
Fabrication ands test
of the wide-band
feeder (1-6 GHz) - INPE
Mechanical structure
and electronic control
of the tracking system
Feeder – U. C. Berkeley
Amplifier – Neuron (Brazilian company)
1 – 6 GHz
Transport and mounting the
towers on bases – INPE
Receiver
(1-6 GHz)
Mechanical structure – Brazilian company
Electrics/ Electronics
GMRT – IntelteK – INDIA
Digital system of the A/D
Converter
Digital Correlator
Brazilian company - Neuron
Presently, solar
images from other
Observatories are
used
Development and installation by IIA
Donation for the BDA
Japan / India
Fabrication of the RF 70 MHz and
10 MHz cables, with identical
dimensions and linking the cables
from the control room to the antennas
Adjustable
attenuators,
Boxes, Printed
Circuits
INPE
Data acquisition
system
Parallel
machine
Visualization and
analysis of solar
images in
real-time
INPE
FAPESP
FINEP/ CNPq
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DONATION
* (Proc. 97/13374-1)
Astrophysics
research and
Space weather
forecast
UFSCAR / INPE
FINEP
LAC / INPE
NUSASC*
FAPESP
Whole scientific
community
and scientists
from the
participating
institutes
DISTRIBUTION OF RADIOHELIOGRAPHS IN THE WORLD.
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BDA PROTOTYPE OF 5 ELEMENTS AT INPE-SJC. CAMPUS
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BDA 5 ELEMENTS SHIFTED TO FINAL SITE OF BDA AT CACHOEIRA PAULISTA
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252 m
9m
18m
9m
9m
BDA
CONFIGURATION
36m
N
162m
18m
18m
18m
E
W
S
36m
36m
2268 m
252 m 252 m
252 m
252 m 252 m
1170 m
PHASE II
AND
PHASE III
252 m
252 m
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252 m
252 m
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ANGULAR RESOLUTION OF THE EXISTING SOLAR RADIO-HELIOGRAPHS
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SOLAR IMAGE CAPABILITY
Nobeyama 17 GHz
BDA “Dirty” Image
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BDA “Clean” Image
SCIENTIFIC GOALS
BDA will produce high spatial and time resolution images of
radio sources with high dynamic range.
BDA will provide solar radio images in the lower corona
where flare energy release takes place; flare and CME analysis
will lead to a better understanding of the fundamental problems
in solar physics; spectral tomography technique being developed
for application to space weather forecasting.
BDA will be very useful for galactic and extra-galactic
investigations of the southern sky not accessible to VLA.
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Normally, in observations of optical coronagraphs the solar
disk is occulted and hence only CMEs propagating
perpendicular to the line of sight are observed. However, in
radio observations, there is no occultation of solar disk and
hence CMEs on the disk can also be observed by radio
heliographs such as BDA.
It is the Earth-directed CMEs that are most important for
space weather. Such CMEs can be detected in their initial
stages before they appear in the coronagraphic field of view
and hence help identify the solar sources of Earth-directed
CMEs. CMEs drive shocks, accelerate particles, and
produce geomagnetic storms.
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BDA will image the CME Core
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The observability of CME substructures in microwaves can be assessed using the simple formula for
free‐free optical depth (Gopalswamy, 1999):
tff = α ∫n2f−2T−3/2 dl,
where α ~ 0.2 for T > 104 and ~ 0.08 for T < 104, n = electron density, f = observing frequency and T =
electron temperature. ∫n2 dl is the emission measure of the structure we are interested in, dl being the
elemental length along the line of sight
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CORONAL HOLES
• Coronal holes are important large-scale structures on the Sun, which
produce high-speed solar wind streams (HSS). BDA can readily observe
the coronal holes at all frequencies as depressions.
• When HSS collide with the neighboring slow solar wind, they
produce large-scale magnetized plasma structures known as the
corotating interaction regions (CIRs). CIRs are responsible for a
different type of geomagnetic storms that are known for producing
MeV electrons in Earth’s magnetosphere. These electrons can be
hazardous to satellites in the magnetosphere, and hence important for
space weather prediction. Observing coronal holes in the equatorial
region of the Sun is thus very important.
• In addition, coronal holes will appear as depressions at all the BDA
frequencies, so the structure of coronal holes can also be studied.
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Advanced Data Analysis for BDA:
• Spectral
Analysis for Time Series
Gradient Spectral Analysis and Singularity Spectra for
nonlinear physical processes characterization:
particle acceleration and magnetic reconnections
Lab for Computing and Applied Mathematics (LAC-INPE) (R.R.Rosa)
•Image Wavelet Analysis for characterization of transverse oscillation
propagating slow waves and standing longitudinal waves by using coronal
period mapping, pixelising wavelet filtering (PWF) and spatial decomposition
by using2D Fourier transform along coronal loops
(Institute for Solar-Terrestrial Physics, Irkutsk (R.A. Sych).
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Conclusion
PATCH
ENHA.
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Radio telescopes like the BDA can readily observe the inner
parts of CMEs (the prominence core and cavity) when they
start on the Sun, thus providing advanced warning of
impending adverse space weather at least one day ahead
of time. Similarly, the BDA will be able to observe the
presence of coronal holes on the disk and forecast high
speed streams. Observation of BSS will compliment these
investigations.
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Measurements of the velocity of the type II shock will permit
to predict the interaction of the shock with magnetosphere
in advance by coupe of hours to a day.
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From spectral investigations long duration busts with high
flux also will predict the launch of CME.
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Observed flux of 2.8 GHz by using Messoraty et al’s model
also can predict launch of CME in advance by couple of
hours
ERU.
PRO.
FILAMENT
DEPR.
HV – SW
CIR – MeV
MEGN.
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Acknowledgements
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