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Nov 6, 2013 (3 years and 7 months ago)

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Temporal and Frequency Variations of
Flares observed by LYRA onboard of
PROBA2


Joe.Zender@esa.int

(1)


B. Foing (1), D. Vagg(2), M. Dominique(3), I. Dammasch(3),
M. Mierla(3) and the LYRA Team


(1)
Science and Robotic Exploration Directorate, ESA, ESTEC,
Noordwijk, The Netherlands

(2)
Waterford University, Waterford, Ireland

(3) Royal Observatory of Belgium, SIDC, Brussels, Belgium

Outline



INTRODUCTION TO PROBA2


INTRODUCTION TO LYRA


TEMPORAL ANALYSIS OF CX FLARE ON 2010
-
06
-
15T


FREQUENCY ANALYSIS OF SAME FLARE


INTRODUCTION TO WAVELET


WAVELET ANALYSIS OF LYRA DATA


FLARE RESULTS


CONCLUSION AND DISCUSSION


Discussion of Solar activities on 15 June 2010 based on temporal and frequency analysis of
Zirconium (1
-
20nm) and Aluminum (17
-
80nm) channels of the LYRA instrument flown on board of
PROBA

LYRA EUV channels are suitable for flare analysis in time domain. Some flares show oscillations
during initial flare phase, e.g. 0.1Hz and 0.014Hz for the 2010
-
06
-
15 flare


PROBA2


in a nutshell

Technology Demonstrators

17 technological demonstrators:
BepiColombo star tracker (Galileo
Avionica), Digital Sun Sensor
(TNO), GPS Receiver (Alcatel,
DLR), Laser Reflector (ESTEC), …

Built as part of ESA’s
PR
oject for
O
n
B
oard
A
utonomy

Launched on 2
nd

November 2010 into Earth


sun
synchronous
-

orbit


Ground Segment

-

Mission Operations
Centre located at Redu

-

~10 daily passes from
Redu or Svalbard (S
-
band)


Spacecraft

-

Dimension: 80x70x60cm

-

Mass: 120kg, of which 35 for payload

-

Highly autonomous

-

~720km altitude

-

sun
-
pointing

LYRA

SWAP

Flexible commanding at
Science Centre (P2SC)

Data processing at P2SC
within 30
-
45min after data
reception.


Large Yield Radiometer (LYRA)


3 Units, each with 4 channels:
Lyman
-
Alpha 121.6nm, Herzberg
200
-
220nm, Aluminum 17
-
80nm,
Zirconium 1
-
20nm


Unit 2 is operated continuously at 20
Hz (100Hz demonstrated), Unit1 and
Unit3 for calibration purpose and
dedicated campaigns



Spectral Response of LYRA EUV Channels

Measured spectral transmittance of the
Al (157.9 nm thick) and the Zr (141.3
nm thick) filters from Luxel corp.
between 1 and 30 nm

Measured spectral transmittance of the
Acton Research corp. filters: Lyman
-
α
filters (N122, XN122) and 210
-
B
Herzberg filter between 110 nm and
2600 nm

From Astronomy & Astrophysics manuscript no. aa13089
-
09, November 27, 2009

BenMoussa et al, “
Pre
-
Flight calibration of LYRA, the solar VUV radiometer on board
PROBA2”

Events on 13 June 2010

Several flares were observed by LYRA

2010/06/13 00:06:00
-
00:26:00 B8.8 1079

2010/06/13 02:28:00
-
02:35:00 B4.6 1079

2010/06/13 05:30:00
-
05:44:00 M1.0 1079

2010/06/13 06:08:00
-
06:13:00 C1.2 1081

2010/06/13 06:55:00
-
07:00:00 B5.3 1081

2010/06/13 07:05:00
-
07:10:00 C1.2 1080

2010/06/13 07:31:00
-
07:38:00 C1.2 1079

2010/06/13 08:06:00
-
08:16:00 C1.2 1081

2010/06/13 09:41:00
-
09:48:00 C1.7 1081

2010/06/13 10:47:00
-
10:55:00 C1.5 1081

2010/06/13 12:24:00
-
12:29:00 B4.3 1081

2010/06/13 13:20:00
-
13:26:00 B2.5 1081

2010/06/13 14:24:00
-
14:30:00 B2.4 1081

2010/06/13 15:45:00
-
15:59:00 B4.2 1081

2010/06/13 18:10:00
-
18:17:00 B1.8 1081



Events on 13 June 2010

Several flares were observed by LYRA

2010/06/13 00:06:00
-
00:26:00 B8.8 1079

2010/06/13 02:28:0002:35:00 B4.6 1079

2010/06/13 05:30:00
-
05:44:00 M1.0 1079

2010/06/13 06:08:00
-
06:13:00 C1.2 1081

2010/06/13 06:55:00
-
07:00:00 B5.3 1081

2010/06/13 07:05:00
-
07:10:00 C1.2 1080

2010/06/13 07:31:00
-
07:38:00 C1.2 1079

2010/06/13 08:06:00
-
08:16:00 C1.2 1081

2010/06/13 09:41:00
-
09:48:00 C1.7 1081

2010/06/13 10:47:00
-
10:55:00 C1.5 1081

2010/06/13 12:24:00
-
12:29:00 B4.3 1081

2010/06/13 13:20:00
-
13:26:00 B2.5 1081

2010/06/13 14:24:00
-
14:30:00 B2.4 1081

2010/06/13 15:45:00
-
15:59:00 B4.2 1081

2010/06/13 18:10:00
-
18:17:00 B1.8 1081



Events on 13 June 2010
-

Movie

Temporal Analysis of M1.0 Flare

R1: summed average of SWAP 17.4 nm over

AR1079 (also including AR1078 and AR1080)



R2: LYRA Aluminum: 17
-
80nm




R3: LYRA Zirconium: 1
-
20nm





R4: GOES long wavelength 0.1
-
0.8nm





R5: GOES short wavelength 0.05
-
0.4nm

Temporal Analysis of M1.0 Flare

Large Angle
Rotation

Frequency Analysis of Flares using Wavelet

The continuous wavelet transform of a discrete sequence x
n

is defined as the
convolution of x
n

with a scaled and translated version of ψ
o
(η):








By varying the wavelet scale s and translating along the localized time index n, one
can construct a picture showing both the amplitude of any features versus the
scale and how this amplitude varies in time.



Several motherwavelets were analyzed and
for no specific reasons, we selected the Morlet
wavelet for our analysis.


Frequency Analysis of Flares using Wavelet

;; standard IDL parameters

;; motherfunction: MORLET

;; order,w0 6

;; dscale: 0.1

;; pad: no padding

;; start_scale: 2*delta_t

;; nscale: default value, but compute

;;

wv_args = {args, $


family: 'morlet', $


order: 6, $


dscale: 0.1 , $


nscale: 0 , $


pad:0 , $


start_scale: 10 , $


freq_scale: 1.02 $ from Torrence and Compo

}




wv_args.nscale = (ALOG2( ((size(*data))[1]) / wv_args.start_scale )) / wv_args.dscale + 1



The following frequencies are obtained:


9.8039 8.2440 6.9324 5.829 4.901 4.1220 3.4662 2.9147 2.450 2.0610


1.7331 1.4573 1.2254 1.0305 0.866 0.7286 0.61274 0.51525 0.43327 0.36434


0.30637 0.25762 0.2166 0.1821 0.1531 0.1288 0.10831 0.091085 0.076593 0.064406


0.054159 0.04554 0.038296 0.03220 0.02707 0.02277 0.019148 0.01610 0.013539 0.011385


0.009 0.008 0.0067 0.0056 0.0047 0.0040 0.0033 0.0028 0.0023 0.00201 0.00169


Frequency Analysis of Flares using Wavelet



Processing time is long. All the following plots have been based on 10 minutes
intervals.


Scales on all following plots are all identical: xrange=10minutes


Uncertainty area not yet determined

Wavelet of M1.0 flare

Wavelet Training I: Two Frequencies

Linear
scale

frequencies

0.1 Hz

0.014 Hz

Wavelet Training II: noise

Z
-
axis plotted in linear scale

Z
-
axis plotted in log10 scale

Wavelet Training III: frequencies + noise



Frequency Analysis of M1.0 Flare using Wavelet Analysis


Plots in 10 minutes interval

05:10


05:20

05:20


05:30

05:30


05:40

05:40


05:50



All x
-
scales and y
-
scales and z
-
scales are identical over the plots.

05:10


05:20 05:20


05:30

05:30


05:40 05:40


05:50

05:10


05:20 05:20


05:30

05:30


05:40 05:40


05:50

0.002


0.003


0.007


0.014


0.028


0.054


Hz

0.118


0.238


0.477


0.980


1.96

05:10


05:20 05:20


05:30

05:30


05:40 05:40


05:50

Conclusion


LYRA EUV channel time series (Zirconium, Aluminum) suitable for analysis of
solar events


Frequency analysis


No frequencies components/oscillations higher than 0.1/0.2 Hz found so far,
but can not be excluded
-
> more analysis needed


Oscillations found at 0.1 Hz and 0.014 Hz


No indication that these components could be caused by instrumental or spacecraft
effects


Components detected for other flares, but are very seldom


For the observed flare, there were 3 active regions near the limb, so it can not be
excluded that the oscillations are caused by superposition of several events


It’s likely however that the observed oscillations are caused by


Geometry: e.g. energy released in different directions and these are seen as oscillations


Energy: e.g. physical processes at chromosphere


Energy: e.g. energy loss during electron and ion evolution through corona

Next Steps


More systematic analysis


Production of wavelet space as data product


Processing using grid technology


Further development of analysis tools


Combine with modeling efforts

Any comments, suggestions and discussions
are welcome. I am happy to share results and
software with you.