1 MURI:NADIR Progress on Area 6 solar atmospheric models and spectra October 2010

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 part because 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 & ChromosphereLower transition-region Upper transition-regionCorona Features designation: B-internetwork E-network F-active network H-normal plage P-bright plage S-sunspot umbra R-sunspot penumbra A-coronal hole Q-hot facula, post-flare

Solar Atmospheric Features UV spectra Comparison SRPM and SOHO/SUMER SRPM features disk center P H SUMER slit position Active region observed by SUMER The solar atmospheric features models were originally tailored to match SUMER radiance 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 1A green-SOLSTICE violet-SDO/EVE blue-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 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.