PowerPoint - ISLA

cursefarmΔίκτυα και Επικοινωνίες

24 Οκτ 2013 (πριν από 4 χρόνια και 18 μέρες)

229 εμφανίσεις

July 2003

1

July 2003

Australian Infrasound Resources

and

Projects


David Brown

Geoscience Australia

ph: +61
-
2
-
6249
-
9024

Email: David.Brown@ga.gov.au


July 2003

Australian Resources


Geoscience Australia


Australian National University


Australian Projects


Nuclear Monitoring


Volcano Monitoring


Bird Migration


GA’s Projected Capability (12
-
18 months)


Possible NSF Funded Infrasound Projects

2

Outline


July 2003

3

July 2003

Resources

Geoscience Australia


Operating 4 of the 5
Australian

IMS infrasound stations

»
I06AU Cocos. Is, operational Sept. 2005

»
I05AU Bucklands, Tas currently operational, sending data to Vienna

»
I04AU Shannon, WA, operational Mar. 2005

»
I03AU Davis, Antarctica, operational Dec. 2006



Likely to provide assistance/advice on the

Rabaul

installation


Cocos Is.

Shannon

Bucklands

Tennant Creek

Davis

Rabaul

July 2003

4

July 2003

Resources

Geoscience Australia


Responsible for processing data from all 5 Australian IMS infrasound stations


Recently (3 months ago) initiated processing of IMS infrasound data (I07AU)



Automatic signal detection (INFER)



Analyst review


High
-
speed numerical modeling of fluid flow and wave propagation problems


Beowulf cluster (coming)


July 2003

5

July 2003

Resources

Australian National University


Operating 1 of 5 Australian IMS infrasound stations

»

I07AU Tennant Creek, NT currently operational, sending data to Vienna

»

2 years of archived data

»

27 years of (largely inaccessible) archived data from earlier WRAI array



July 2003

0

30

60

90

120

minutes

75 microbar

[after Christie]

Gravity

Acoustic

Acoustic

Acoustic

1980 Chinese Nuclear Detonation, Lop Nor, 4 Mt

July 2003

7

July 2003

Resources

Australian National University




World class supercomputer facility



Developed INFER automatic infrasonic detection algorithm



July 2003

INFER: Motivation

STS
-
96

[DLIAR, Los Alamos]


Acoustic signal from shuttle launch
STS
-
96 recorded at DLIAR, Los
Alamos


a significant signal


Distinct lack of



correlation


amplitude


Signal presence is obvious to the
human eye due to the dominant
azimuth and trace velocity


July 2003

INFER: the Hough Transform

Image Space
,
S

Parameter Space
,
P

Hough Transform

Pairs of points (
x
i
,
y
i
) get mapped to the point (
,
) where

July 2003

INFER: the Hough Transform

Image Space
,
S

Parameter Space
,
P

Hough Transform

STS
-
96

[DLIAR, Los Alamos]

July 2003

INFER: 3D array geometry

-
3

-
2

-
1

0

1

2

3

2

3

1

0

-
1

-
2

-
3

1

3.5

3

2.5

2

1.5

Sx (s/km)

Sz (s/km)

Sy (s/km)

radius = acoustic slowness

July 2003

INFER: detection results



July 2003



INFER: detection results

July 2003



INFER


makes a single detection per phase



Fortran code complete (minor bugs)



C
-
code ready for testing



dynamically populates various CSS database tables



arrival



detection



infra_features



lastid



wfdisc



psd_frequency



infra_psd



infra_noise_models



determines PSD for every 1/2 hour for every channel

July 2003

INFER: PSD measurement

July 2003

I10CA high noise model

I10CA low noise model

INFER: PSD noise models

July 2003

I33MG high noise model

I33MG low noise model

INFER: PSD measurement

July 2003

18

July 2003

Projects

Nuclear Monitoring



Satisfying Australian Government’s obligations to monitor compliance of the
CTBT



near
-
real time processing of data from 5 IMS infrasound stations


Automatic signal detection

»

INFER
detection algorithm

currently operational at Geoscience Australia



Automatic source location

»

operational by the end of 2003



Analyst review

»

recently initiated, ongoing development of analyst procedures



Source characterisation and discrimination analyses

»

localised large
-
scale open
-
cut mining activity

»

Tripartite sub
-
net: I04AU, I05AU, I07AU uniquely positioned to do source
location analyses

July 2003

19

July 2003

Projects


Volcano Monitoring



Prompted by a call by the Airlines to develop a multi
-
technology ‘early warning’
system for volcanic ash.




‘Consortium’ of Australian companies and government organisations formed to
determine if it is possible to create a multi
-
technology volcanic ash monitoring
system for aircraft



Vulcan
-
AUS

group:



Bureau of Meteorology



Qantas



Geoscience Australia



CSIRO



Airservices Australia




Formed in mid
-
1980’s in response to a volcanic ash encounter of a British Airways
747 over Indonesia.

July 2003

20

July 2003

Projects


Volcano Monitoring



GA’s role:



Perform usual near
-
real time automatic signal detection of IMS infrasound array data



‘Siphon’ off detections from a near
-
real time event list that are within a few degrees of
known volcanic activity



email event list to interested persons



microbarom false alarms may be significant



seasonal erosion of propagation ducts will also occur

July 2003

21

July 2003

Projects


Bird Migration



does infrasound have a role to play in the migration of birds to wetland areas
during major flooding events ?



GA’s role:



systematically process data during periods of known flooding and search for
anomalous infrasonic signals


July 2003

22

July 2003

GA’s Projected Capability
12 to 18 months


Real
-
time processing of data from several infrasound arrays:


Tennant Creek, Northern Territory



Hobart, Tasmania



Shannon, Western Australia


Generation of an automatic detection list



various CSS database tables dynamically populated


Rudimentary source location of GT events



use crossing azimuths, time used to preserve causality



use observed departures from great
-
circle to refine source location procedure

July 2003

23

July 2003

Volcano Early Infrasound Warning System (VEIWS)



need to perform research that will determine if a significant early warning for
volcanic ash can be reliably given via a precursory infrasound signal



do magma chamber rumbles generate atmospheric acoustic signals prior to venting ?



What instrumentation is required to measure the signal ?



What are the signal chracteristics ?




Will require near
-
real time infrasound data processing




May require development of a sophisticated real
-
time numerical microbarom filter



A starting point may be Olson’s Analytical signal technique



Possible NSF funded infrasound projects

July 2003

24

July 2003


Grand
-
Challenge’ numerical infrasound algorithm



Will:


solve the basic Navier
-
Stokes equations on an ellipsoid



be fully non
-
linear



be non
-
hydrostatic



include acoustic
-
gravity modes



use as input NRL climatological and environmental data



accurately model physics from a highly
-
nonlinear source region to the completely
linear far
-
field



Suitable for operation on the:



‘Earth Simulator’ supercomputer



A Beowulf cluster


Will include



topography



acoustic radiation from the ocean surface



solar tides

Possible NSF funded infrasound projects

July 2003

25

July 2003


Grand
-
Challenge’ numerical infrasound algorithm



Purpose:



Infrasound can ‘catch up’ with all other geophysical modelling efforts.



assess the validity of other modelling procedures:



ray tracing



modal calculations



parabolic approximation



Better understand:



Microbarom radiation and to what extent it heats the atmosphere



The phenomenon of Mountain Associated waves



Acoustic scattering and diffraction



Accurate source location



Possible NSF funded infrasound projects