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MURI:NADIR Progress on Area 6

solar atmospheric models and spectra

October 2010

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Radius (~1. arc sec)

Current Results (3)Using SDO/AIA Images

Active region

Network+internetwork

Active region

Active regions and network have a large contrast in this band so these images are much better than Ca II PSPT images but essentially show the same shape as any other UV/EUV emission

Histogram of a quadrant of one of the rings

Intensity tracings along radial directions

Coronal vs chromospheric & photospheric features

There is a general relationship but a lot of dispersion. In partbecause of time difference but mostly because of coronal vertical extent. Layering is needed to account for this.

Current 1-dimensional Models of the Solar Atmospheric Features

Photosphere & Chromosphere Lower transition-region

Upper transition-region Corona

Features designation:B-internetworkE-networkF-active networkH-normal plageP-bright plage

S-sunspot umbraR-sunspot penumbra

A-coronal hole Q-hot facula, post-flare

Solar Atmospheric Features UV spectra Comparison SRPM and SOHO/SUMER

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B D F H P

SRPM features disk center

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SUMER slit position

Active region observed by SUMER

The solar atmospheric features modelswere originally tailored to match SUMERradiance observations and a large number of other observations including very detailed line profiles in the visible. The data above was published in 2009 but better agreement in UV lines is now achieved with the updated transition-region shown in this presentation but not yet published.

UV SSI variations

Ly α is significant because although its relative variation, over the cycle and rotational, is only of ~0.15 in absolute terms it is close to a mW m-2 (all over the dayside hemisphere) and is absorbed by the Schuman-Runge lines and continuum at ~80 km and higher altitude in the Earth atmosphere (i.e. mesosphere).These variations are likely to perturb the thermosphere lower boundary.Other UV variations are comparable or larger in relative terms but much smaller in absolute values.

Comparison of EUV spectra with SDO/EVE and SOLSTICE observations

SRPM at 1 nm resolution

black-SRPM at 1Agreen-SOLSTICEviolet-SDO/EVEblue-Thuiller et all.

Detail of EUV comparison

Black-SRPM at 1 A (for 2008); brown-SDO/EVE 2008; violet-SDO/EVE 2010; blue-Thuillier et al.Agreement is good but there are some differences between SRPM and SDO/EVE as well as some between the two EVE rocket flights. Thuillier et al. is much lower and not defined resolution and too high.

Mid resolution (1 A) “lines” and temperature assignment

It is important to be aware that the apparent “lines” in the 1 A resolution data are not really individual spectral lines of a species. Although it is true that sometimes one spectral line dominates the mid-resolution “line”, this is not always the case and often there are important contributions from several spectral lines and these contributions weight differently for various solar features.Examples of this are shown above where the “normalized” full-resolution and mid-resolution spectra for inter-network (B) and facula (P) show that high-temperature species are nearly absent in B but appear strong in P.

Time variation of absorption convolved SSI

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These calculations used the photoionization cross-sections from the NRLUV model and the SRPM photon-flux spectra.(Note that at lower resolution photon-flux and irradiance are not directly and simply related, but either can be easily evaluated by SRPM.)

Future improvements• Publication of current models and results.• Further models in progress:

– Coronal hole feature (A)– High temperature facular region (Q), post-flare– Coronal portion of penumbra and umbra (R & S

respectively)• Consideration of filling factor, variable with height in coronal

models• Mixed temperature regions allowing several features mix into

unresolved patch• Better handling of near-limb features• Estimates of solar cycle variations and more comparisons

with AIA and EIT images over variable activity.