A unified framework of semi-volatile partitioning permits models to efficiently treat both semi-volatile primary emissions and secondary organic aerosol production (SOA), and then to treat the chemical evolution (aging) of the aggregate distribution of semi-volatile material. This framework also reveals critical deficiencies in current emissions and SOA formation measurements. The key feature of this treatment is a uniform basis set of saturation vapor pressures spanning the range of ambient organic saturation concentrations, from effectively nonvolatile material at 0.01 microg m(-3) to vapor-phase effluents at 100 mg m(-3). Chemical evolution can be treated by a transformation matrix coupling the various basis vectors. Using this framework, we show that semi-volatile partitioning can be described in a self-consistent way, with realistic behavior with respect to temperature and varying organic aerosol loading. The time evolution strongly suggests that neglected oxidation of numerous "intermediate volatility" vapors (IVOCs, with saturation concentrations above approximately 1 mg m(-3)) may contribute significantly to ambient SOA formation.

/pdf/coupled-partitioning-dilution-and-chemical-aging-of-3eoq4f6ct5.pdf

Coupled partitioning, dilution, and chemical aging of semivolatile organics.

[1] The Naval Research Laboratory three-dimensional simulation code SAMI3/ESF is used to study the response of the postsunset ionosphere to circular gravity waves. We model the coupling of both circular (local) and plane wave (nonlocal) gravity waves to the bottomside F layer as a mechanism for triggering equatorial plasma bubbles. Results support the hypothesis that nonplane gravity waves can more strongly couple to the F layer than plane gravity waves. Results also show that the coupling of the seed wave to the F layer depends on the (nonlocal) growth rate and the local electron density at the position of the seed wave.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2012GL054022

Simulation of the seeding of equatorial spread F by circular gravity waves

We present an overview of solar flares and associated phenomena, drawing upon a wide range of observational data primarily from the RHESSI era Following an introductory discussion and overview of the status of observational capabilities, the article is split into topical sections which deal with different areas of flare phenomena (footpoints and ribbons, coronal sources, relationship to coronal mass ejections) and their interconnections We also discuss flare soft X-ray spectroscopy and the energetics of the process The emphasis is to describe the observations from multiple points of view, while bearing in mind the models that link them to each other and to theory The present theoretical and observational understanding of solar flares is far from complete, so we conclude with a brief discussion of models, and a list of missing but important observations

An Observational Overview of Solar Flares

We use radar observations from the Jicamarca Observatory from 1968 to 1992 to study the effects of the F region vertical plasma drift velocity on the generation and evolution of equatorial spread F The dependence of these irregularities on season, solar cycle, and magnetic activity can be explained as resulting from the corresponding effects on the evening and nighttime vertical drifts In the early night sector, the bottomside of the F layer is almost always unstable The evolution of the unstable layer is controlled by the history of the vertical drift velocity When the drift velocities are large enough, the necessary seeding mechanisms for the generation of strong spread F always appear to be present The threshold drift velocity for the generation of strong early night irregularities increases linearly with solar flux The geomagnetic control on the generation of spread F is season, solar cycle, and longitude dependent These effects can be explained by the response of the equatorial vertical drift velocities to magnetospheric and ionospheric disturbance dynamo electric fields The occurrence of early night spread F decreases significantly during equinox solar maximum magnetically disturbed conditions due to disturbance dynamo electric fields which decrease the upward drift velocities near sunset The generation of late night spread F requires the reversal of the vertical velocity from downward to upward for periods longer than about half an hour These irregularities occur most often at ∼0400 local time when the prompt penetration and disturbance dynamo vertical drifts have largest amplitudes The occurrence of late night spread F is highest near solar minimum and decreases with increasing solar activity probably due to the large increase of the nighttime downward drifts with increasing solar flux

/pdf/effects-of-the-vertical-plasma-drift-velocity-on-the-2m25kbykcc.pdf

Effects of the vertical plasma drift velocity on the generation and evolution of equatorial spread F

We present a series of models for the plasma properties along open magnetic flux tubes rooted in solar coronal holes, streamers, and active regions. These models represent the first self-consistent solutions that combine (1) chromospheric heating driven by an empirically guided acoustic wave spectrum; (2) coronal heating from Alfven waves that have been partially reflected, then damped by anisotropic turbulent cascade; and (3) solar wind acceleration from gradients of gas pressure, acoustic wave pressure, and Alfven wave pressure. The only input parameters are the photospheric lower boundary conditions for the waves and the radial dependence of the background magnetic field along the flux tube. We have not included multifluid or collisionless effects (e.g., preferential ion heating), which are not yet fully understood. For a single choice for the photospheric wave properties, our models produce a realistic range of slow and fast solar wind conditions by varying only the coronal magnetic field. Specifically, a two-dimensional model of coronal holes and streamers at solar minimum reproduces the latitudinal bifurcation of slow and fast streams seen by Ulysses. The radial gradient of the Alfven speed affects where the waves are reflected and damped, and thus whether energy is deposited below or above the Parker critical point. As predicted by earlier studies, a larger coronal "expansion factor" gives rise to a slower and denser wind, higher temperature at the coronal base, less intense Alfven waves at 1 AU, and correlative trends for commonly measured ratios of ion charge states and FIP-sensitive abundances that are in general agreement with observations. These models offer supporting evidence for the idea that coronal heating and solar wind acceleration (in open magnetic flux tubes) can occur as a result of wave dissipation and turbulent cascade.

http://iopscience.iop.org/article/10.1086/518001/pdf

Self-consistent Coronal Heating and Solar Wind Acceleration from Anisotropic Magnetohydrodynamic Turbulence

Coupling parameterizations in magnetosphere-ionosphere-thermosphere modeling

Disturbed time observations of the temporal dependence and dynamics of TEC, scintillation, and ionospheric irregularity zonal drifts

We use OI 630 nm airglow images obtained with the All‐sky imager installed at São João do Cariri (7.4°S, 36.5°W) to report the very rare phenomenon of disconnection and reconnection between adjacent plasma bubbles. We report here for the first time observations of the phenomenon at Cariri. These observations show that the phenomenon is independent of the solar flux and occurs between September and December in the Brazilian sector. The phenomenon consists first in separating a part of the bubble followed by its capture by other adjacent bubbles via electrostatic potential fields. Statistically, the phenomenon is of very low occurrence and its probability varies between 1/120 and 1/165 per year, and on certain occasions it is zero.

Disconnection and Reconnection in Plasma Bubbles Observed by OI 630 nm Airglow Images From Cariri Observatory

Font: Arial Bold, 9) Radio communication community has great interest to know the daily behavior of the maximum usable frequency (MUF) for its applications. The MUF is obviously dependent of the ionospheric F-layer critical frequency (foF2) and its corresponding altitude (hmF2). In this work, the parameters foF2 and hmF2 and a spherical geometry are used to calculate MUF considering and not considering the ionospheric refraction effects in the electromagnetic wave propagation. The values of foF2 and hmF2 were obtained from ionograms and from a Parameterized Regional Ionospheric Model (PARIM). We have also compared our calculated MUF values with experimental data for different solar flux levels and for different locations over the Brazilian sector. In general, the results present very good agreement with data recorded by digisondes-ionosondes. Maps of MUFs constructed using ionospheric peak parameters given by PARIM show coherent results.

/pdf/a-simple-method-to-calculate-the-maximum-usable-frequency-21lq7wkrc1.pdf

Inez S. Batista

Papers

Coupling parameterizations in magnetosphere-ionosphere-thermosphere modeling

Disturbed time observations of the temporal dependence and dynamics of TEC, scintillation, and ionospheric irregularity zonal drifts

Disconnection and Reconnection in Plasma Bubbles Observed by OI 630 nm Airglow Images From Cariri Observatory

A Simple Method to Calculate the Maximum Usable Frequency

GPS scintillations, TEC and zonal plasma drifts observed during the COPEX 2002 campaign: Preliminary results