Flare Irradiance Studies with the EUV Variability Experiment on SDO

Flare Irradiance Studies with the EUV Variability Experiment

on SDO

R. A. Hock, F. G. Eparvier, T. N. Woods, A. R. Jones, University of Colorado at Boulder

L. DidkovskyUniversity of Southern California

B. J. ThompsonNASA Goddard Space Flight Center

ILWS-2011 Workshop "Towards the Next Solar Maximum" 30 August 2011 Beijing, China

PI: Tom Woods, Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder CO

All about EVE

SCIENCE THEMES:

1. Specify the solar EUV spectral irradiance and its variability on multiple time scales

2. Advance current understanding of how and why the solar EUV spectral irradiance varies

3. Improve the capability to predict the EUV spectral irradiance variability

4. Understand the response of the geospace environment to variations in the solar EUV spectral irradiance and the impact on human endeavors


• Multiple EUV Grating Spectrograph (MEGS) At 0.1 nm resolution

MEGS-A: 5-36 nm MEGS-B: 35-105 nm

At 1 nm resolution MEGS-SAM: 0-7 nm

At 10 nm resolution MEGS-Photometers: @ 122 nm

Ly-a Proxy for other H I emissions at 80-102 nm and He I emissions at 45-58 nm

• EUV Spectrophotometer (ESP) At 4 nm resolution

17.5, 25.6, 30.4, 36 nm At 7 nm resolution

0.1 - 7 nm (zeroth order)• Solar Aspect Monitor (SAM)

.1 - 7 nm image

All about EVE


All about EVE

First light EVE spectrum with AIA & ESP bandpasses. EVE measures the spectral EUV irradiance from 5-105 nm with

0.1 nm spectral resolution a 10-second time cadence.


Temperature Coverage of EVE

Peak formation temperature from CHIANTI vs. wavelength

for bright lines in a EVE spectrum (quiet Sun)


Active Region Evolution

Sub-daily variations in EUV lines are associated with AR evolution and small flares

5%

3%


Solar Activity during Year 1

Levels of solar activity during the first year of SDO observations


Space Weather & Flare Location

Space Weather products are available from http://lasp.colorado.edu/eve/data_access/


...not just flares anymore

EVE is proving to be a remarkable instrument for understanding the global nature of EUV irradiance variability

Future work will focus on moving from qualitative study of the EUV irradiance variability to quantitative study

2048 pixels

10

24

pix

els


Coronal Dimmings

Coronal dimming seen in both AIA 171 channel and EVE 17.1 nm line


Radiative Output of Solar Flares

Four M1.0 flares have significantly different light curves in the EUV. EVE allows us to quantify how the corona

cools after a flare.


Flare Classification


Compact FlaresC2.2 on 25 October 2010

Non-eruptive

Cohesive group of loops brighten concurrently


Localized Eruptive FlaresC4.6 on 12 November 2010

Localized brightening associated with EUV surges

Occurs at the edge of an AR at the footpoint of a loop that connects to a different part of the AR or to another AR entirely.

Possibly the Skylab point flares previously categorized with compact flares


Arcade FlaresC2.3 on 14 December 2010

Long(ish) duration events with EUV emission lasting hours

Generally associated with filament eruptions & coronal dimmings

Arcade of post-flare loops in corona and 2-ribbon footpoints in chromosphere


Late Phase FlaresC8.8 on 5 May 2010

Two spatially-distinct but related enhancements in 2-3 MK emission tens of minutes to hours apart

Previously observed but EVE has shown that these flares have a strong and unique irradiance signature that can account for up to 40-80% of the energy radiated in the EUV


Example of a Late Phase Flare

Comparison of AIA and EVE lightcurves & a cartoon of the evolution of the 5 May 2010 C8.8 flare


Distribution of Flare Types


Distribution of Flare Types


Future Work

Continue to update the flare catalog including

Adding ~150 flares from March 2011

Adding association with CMEs

Validating impulsive phase using RHESSI data

Validating extracted parameters from EVE data

Start to associate flare parameters with physical quantities:

Loop length

Arcade length

Magnetic field strength


Arcade Flare Irradiances

Correlations of rise time in SXR with

(1) flare duration, (2) delay in EUV peak

irradiances, and (3) GOES magnitude


Irradiance Flare Peak Width


Impulsive PhaseMeasured by He II 30.4 nm

C1.0+ C4.0+

Documents

Flare Irradiance Studies with the EUV Variability Experiment on SDO