solar soft x-rays data p eriodic analysis

Solar Soft X-Rays Data PSolar Soft X-Rays Data Periodiceriodic AnalysisAnalysis

Pu WangPu WangDepartment of AstronomyDepartment of Astronomy , Nanjing University, Nanjing University

July 9, 2005July 9, 2005Pwang@nju.edu.cnPwang@nju.edu.cn

The First Chinese-Korean Solar Physics WorkshopThe First Chinese-Korean Solar Physics Workshop

Outline of Presentation

1. Introduction

5. Future Works

2. Data and Analysis Methods

3. Periodicity Analysis Results

4. Discussion and Summary

1. Introduction

As a long-term periodicity, the Sun exhibits the 11-year sunspot cycle, which ha

s been known for a long time. For short terms, the Sun often exhibits 27-d and 1

3.5-d periodicities, which tell more about spatial organization of the solar activity

than its temporal organization. The regime between these extremes of time scal

es (between 27 d and 11 y) is called the “mid range.”

Periodicities in this mid range have been explored, starting with the discovery of

a 153-d periodicity in -ray flare occurrence (Rieger et al. 1984). Since then, man

y researchers investigated mid-range periodicities, using various solar activity in

dicators.

Many researchers studied periodicities in sunspot areas and numbers.

Analysis of flare data of different solar cycles found other periodicities.

1. Introduction

51-d period in flares selected by CFI (comprehensive flare index) during cycle 19

(Bai 1987)

The 77 day periodicity in the flare rate of cycle 22 (Astrophysical Journal)

78-d period in flares selected by microwave-peak flux during cycle 20 (Bogart &

Bai 1985)

84-d period in CFI-selected flares during cycle 20 (Bai 1992b)

127-d period in flares selected by CFI and flares selected by 10-cm radio peak fl

ux

The ~150 day quasi-periodicity in interplanetary and solar phenomena during cyc

le 23

Evidence for a fundamental period of the sun and its relation to the 154 day com

plex of periodicities

On the 24- and 155-day periodicity observed in solar Hα flares

1. Introduction

It is important to detect mid-range flare periodicities and to calculate accurately

their statistical significances because flare periodicities can provide information

on properties of the Sun.

Flare periodicities can provide information on properties of the Sun.

Using X-ray flux to analyze the Flare periodicities can provide accurate

information on properties of the Sun.

Flare periodicities in earlier cycles (19–22) have been studied by many authors,

but it seems necessary reanalyze them with the different methods so that we

can compare statistical significances of several periodicities analyzed

previously with different methods.

2. Data and Analysis Methods

GOES SPACE ENVIRONMENT MONITOR 1-Minute & 5-

Minute Averages Data

1986.01.01-2005.05.31

XL 1 - 8 Å X-rays (Watts/m2)

XS 0.5 - 3 Å X-rays, or 0.5 – 4 Å prior to GOES-8 (Watts/m2)

The GOES X-ray Sensor (XRS) data have recently been used

in new ways for forecasting and specifying conditions.

The Wavelet Transform

txx dt

s

ttx

sssCWT

1),(),(

Continuous wavelet transform of the signal x(t) using the analysis wavelet (.)

Translation parameter, measure of time

Scale parameter, measure of frequency

The mother wavelet. All kernels are obtained by translating (shifting) and/or scaling the mother wavelet

A normalization constant Signal to be

analyzed

Scale = 1/frequency

2. Data and Analysis Methods

24-hours integrated soft x-ray flux.

Using Morlet mother wavelet function

This wavelet has no scaling function, but i

s explicit.

2 / 2( ) cos(5 )xx Ce x

1986.01.01-1996.12.31 XL Day

3. Periodicity Analysis Results

Confirmed periodicity: 25.5,77

New periodicity:

230

1986.01.01-1996.12.31 XS day

3. Periodicity Analysis Results

Confirmed periodicity: 25.5,77,127

3. Periodicity Analysis Results

Confirmed periodicity: 25.5,77,152

New periodicity:230

1999.02.05-2003.02.10 XL day

1999.02.05-2003.02.10 XS day

3. Periodicity Analysis Results

Confirmed periodicity: 25.5,77,127

New periodicity:230

3. Periodicity Analysis Results

Confirmed periodicity: 25.5,77,152

New periodicity:

230

1997.01.01-2005.05.31 XL day

1997.01.01-2005.05.31 XS day

3. Periodicity Analysis Results

Confirmed periodicity: 25.5,77,152

1986.01.01-2005.05.31 XL day

3. Periodicity Analysis Results

Confirmed periodicity: 25.5,77

New periodicity:230

1986.01.01-2005.05.31 XS day

3. Periodicity Analysis Results

Confirmed periodicity: 25.5,77,127,152

New periodicity:230

4. Discussion and Summary

• By using soft x-ray flux data, we can also find 25.5, 77, 127,

152-d Periodicities.

• Interesting probably 230-d Periodicity have been found by a

nalyzing soft x-ray flux data.

• Different time scale show different Periodicity .

• Using soft x-ray flux data also can accurately describe the so

lar activity Periodicity

• The results presented may provide useful information for the

space weather forecast

5. Future Works

• The results may provide useful information for the space wea

ther forecast, and the validity needs to be verified by observat

ions.

• The observational examples and statistical results will be dev

oted to our Future works.

• Some solar flare occurrence periodicities should be confirme

d by other ideas.

Thank you!

The First Chinese-Korean Solar Physics The First Chinese-Korean Solar Physics WorkshopWorkshop

Thank you!

The First Chinese-Korean Solar Physics The First Chinese-Korean Solar Physics WorkshopWorkshop