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In the present work, the hot-carrier degradation of transistors fabricated by a 0.25- mu m FD SOI CMOS process was investigated.
The direct radiative effects of the build-up of carbon dioxide and other greenhouse gases have led to a gradual cooling of the stratosphere with largest changes in temperature occurring in the upper stratosphere, well above the region of peak ozone concentration.
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Satellite observations of ozone and chlorine monoxide in the Arctic lower stratosphere during winter 1992-1993 are compared with observations during other winters, observations of long-lived tracers and the evolution of the polar vortex. Chlorine in the lower stratospheric vortex during February 1993 was mostly in chemically reactive forms.
The low noise and radiation-hard operation of the SOI Four-Gate transistor (G4-FET) is eperimentally demonstrated.
The Goddard Earth Observing System Chemistry Climate Model (GEOS CCM) has been developed by combining the atmospheric chemistry and transport modules developed over the years at Goddard and the GEOS general circulation model, also developed at Goddard. The first version of the model was used in the CCMVal intercomparison exercises that contributed to the 2006 WMO/UNEP Ozone Assessment. The second version incorporates the updated version of the GCM (GEOS 5) and will be used for the next round of CCMVal evaluations and the 2010 Ozone Assessment. The third version, now under development, incorporates the combined stratosphere and troposphere chemistry package developed under the Global Modeling Initiative (GMI). We will show comparison to past observations that indicate that we represent the ozone trends over the past 30 years. We will also show the basic temperature, composition, and dynamical structure of the simulations. We will further show projections into the future. We will show results from an ensemble of transient and time-slice simulations, including simulations with fixed 1960 chlorine, simulations with a best guess scenario (Al), and simulations with extremely high chlorine loadings. We will discuss planned extensions of the model to include emission-based boundary conditions for both anthropogenic and biogenic compounds.
Studies using all-sky imagers have revealed the presence of various ionospheric irregularities in the night-time mid-latitude F-region. The most prevalent and well known of these are the Medium Scale Traveling Ionospheric Disturbances (MSTIDs) that usually occur when the geomagnetic activity is low, and mid-latitude spread-F plumes that are often observed when the geomagnetic activity is high. The inverse and direct relations between geomagnetic activity (particularly Kp) and the occurrence rate of MSTIDs and midlatitude plumes, respectively, have been observed by several studies using different instruments. In order to understand the underlying causes of these two relations, it is illuminating to better characterize the occurrence of MSTIDs and plumes using multiple magnetospheric state parameters. Here we statistically compare multiple geomagnetic driver and response parameters (such as Kp, AE, Dst, and solar wind parameters) with the occurrence rates of night-time MSTIDs and plumes observed using an all-sky imager at Arecibo Observatory (AO) between 2003 and 2008. The results not only allow us to better distinguish MSTIDs and plumes, but also shed further light on the generation mechanism and electrodynamics of these two different phenomena occurring at night-time in the mid-latitude F-region.
Silicate grains are the most abundant condensate around O-rich evolved stars, including red giants, supernovae (SNe) and binary systems. These grains have been identified in abundance in primitive meteorites and interplanetary dust particles [1,2]. Astronomical observations of the silicate spectroscopic features around circumstellar disks indicate that most silicates are amorphous olivine-like grains, though some sources show a large crystalline portion [3]. Fewer astronomical observations of SN and nova silicates exist, but amorphous Mg-rich grains predominate [4,5]. The laboratory analysis of presolar silicates by transmission electron microscopy (TEM) offers more details on the structure and chemistry of individual grains. These studies provide information on the physical and chemical conditions of the parent stellar atmosphere during grain condensation. Moreover, be-cause silicates are susceptible to secondary alteration, processing events succeeding condensation can be traced. Thus far, similar microstructures have been observed for silicates that condensed in SN outflows and in the envelopes of asymptotic giant branch (AGB) stars, but not as many of the comparatively rare SN grains have been analyzed. Here we examine the mineralogies of two presolar silicate grains having different origins.
Studies using all-sky imagers have revealed the presence of various ionospheric irregularities in the nighttime midlatitude F region. The most prevalent and well known of these are the medium-scale traveling ionospheric disturbances (MSTIDs) that usually occur when the geomagnetic activity is low and midlatitude spread F plumes that are often observed when the geomagnetic activity is high. The inverse and direct relations between geomagnetic activity and the occurrence rate of MSTIDs and midlatitude plumes, respectively, have been observed by several studies using different instruments; however, most of them focus on MSTIDs only and use only Kp to characterize geomagnetic activity. In order to understand the underlying causes of these two relations and to distinguish between MSTIDs and plumes, it is illuminating to better characterize the occurrence of MSTIDs and plumes using multiple magnetospheric state parameters. Here we statistically compare multiple geomagnetic driver and response parameters (such as Kp, AE, Dst, and solar wind parameters) with the occurrence rates of nighttime MSTIDs and plumes observed using an all ]sky imager at Arecibo Observatory (AO) between 2003 and 2008. We also present seasonal and annual variations of MSTIDs and plumes at AO. The results not only allow us to better distinguish MSTIDs and plumes, but also to shed further light on the generation mechanism and electrodynamics of these two different phenomena occurring at nighttime in the midlatitude F region.
In this study, we use observations from the Gravity Recovery and Climate Experiment (GRACE) satellite mission to evaluate freshwater storage trends in the north-central Middle East, including portions of the Tigris and Euphrates River Basins and western Iran, from January 2003 to December 2009. GRACE data show an alarming rate of decrease in total water storage of approximately -27.2 plus or minus 0.6 mm per yr equivalent water height, equal to a volume of 143.6 cubic kilometers during the course of the study period. Additional remote-sensing information and output from land surface models were used to identify that groundwater losses are the major source of this trend. The approach used in this study provides an example of ''best current capabilities'' in regions like the Middle East, where data access can be severely limited. Results indicate that the region lost 17.3 plus or minus 2.1 mm per yr equivalent water height of groundwater during the study period, or 91.3 plus or minus 10.9 cubic kilometers in volume. Furthermore, results raise important issues regarding water use in transboundary river basins and aquifers, including the necessity of international water use treaties and resolving discrepancies in international water law, while amplifying the need for increased monitoring for core components of the water budget
In this study, we use observations from the Gravity Recovery and Climate Experiment (GRACE) satellite mission to evaluate freshwater storage trends in the north-central Middle East, including portions of the Tigris and Euphrates River Basins and western Iran, from January 2003 to December 2009. GRACE data show an alarming rate of decrease in total water storage of approximately -27.2 plus or minus 0.6 millimeters per year equivalent water height, equal to a volume of 143.6 cubic kimometers during the course of the study period. Additional remote-sensing information and output from land surface models were used to identify that groundwater losses are the major source of this trend. The approach used in this study provides an example of ''best current capabilities'' in regions like the Middle East, where data access can be severely limited. Results indicate that the region lost 17.3 plus or minus 2.1 millimeters per year equivalent water height of groundwater during the study period, or 91.3 plus or minus 10.9 cubic kilometers in volume. Furthermore, results raise important issues regarding water use in transboundary river basins and aquifers, including the necessity of international water use treaties and resolving discrepancies in international water law, while amplifying the need for increased monitoring for core components of the water budget.
The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft collected data that provided important insights into the structure, chemical makeup, and compositional diversity of Mercury. The X-Ray Spectrometer (XRS) and Gamma-Ray Spectrometer (GRS) onboard MESSENGER provided the first detailed chemical analyses of Mercury's surface. Among the many discoveries included several surprising characteristics about the surface of Mercury, including elevated S abundances (up to 4 percent by weight), low Fe abundances (less than 4 percent by weight), and relatively low O abundances (O/Si ratio of 1.40 plus or minus 0.03). The surface chemistry as determined by MESSENGER has been used to identify up to nine distinct geochemical terranes on Mercury. Numerous modeling and experimental efforts have been undertaken to infer the mineralogy and petrology of mercurian lavas and surface materials. However, all of these efforts have presumed valence states for each of the elements according to the following: Si4+, Ti4+, Al3+, Cr2+, Fe2+, Mn2+, Mg2+, Ca2+, Na+, K+, S2-, Cl-. Based on these valence assignments, cations are charged balanced with the anions O2-, S2-, and Cl- and the compositions are recast in terms of oxides, sulfides, and chlorides. Based on these assumptions, the geochemical terranes that have been identified on Mercury yield O/Si wt. ratios ranging from 1.61 to 1.84, which is substantially higher than the preliminary O/Si ratio of 1.40 plus or minus 0.03 determined by the MESSENGER GRS]. We have re-evaluated the O/Si ratio using the entire MESSENGER dataset to reassess its implications for the geochemistry of Mercury.
The magnetic storm that commenced on June 22, 2015 was one of the largest storms in the current solar cycle, resulting from an active region on the Sun that produced numerous coronal mass ejections (CMEs) and associated interplanetary shock waves. On June 22 at 18:36 UT the magnetosphere was impacted by the leading-edge shock wave and a sheath carrying a large and highly variable interplanetary magnetic field (IMF) Bz with values ranging from +25 to -40 nT. During the subsequent interval from 0000 to 0800 UT, there was a second intensification of the geomagnetic storm resulting from the impact of the CME. We present dramatic responses of simultaneous particle measurements from the high-altitude Magnetospheric Multiscale Mission (MMS) at high altitudes in the magnetosphere (approx. 9-12 Re) and from the low-altitude (F-region) Floating Potential Measurement Unit (FPMU) on board the International Space Station (ISS). We analyze potential causes of these dramatic particle flux dropouts by putting them in the context of storm-time electrodynamics, and support our results with numerical simulations of the global magnetosphere and ionosphere. During the sheath phase of the storm, the MMS spacecraft in the near-earth equatorial plane observed a rapid reconfiguration of the magnetic field near 1923 UT. Initially in the warm plasmasheet, particle flux dropouts were observed as they tracked the plasma-sheet to lobe transitions with the stretching and thinning of the plasmasheet. Anti-sunward flowing O+ ions of ionospheric origin were also measured during this period, confirming that the MMS spacecraft temporarily was in a lobe.
The magnetic storm that commenced on June 22, 2015 was one of the largest storms in the current solar cycle, resulting from an active region on the Sun that produced numerous coronal mass ejections (CMEs) and associated interplanetary shock waves. On June 22 at 18:36 UT the magnetosphere was impacted by the leading-edge shock wave and a sheath carrying a large and highly variable interplanetary magnetic field (IMF) Bz with values ranging from +25 to -40 nT. During the subsequent interval from 0000 to 0800 UT, there was a second intensification of the geomagnetic storm resulting from the impact of the CME. We present dramatic responses of simultaneous particle measurements from the high-altitude Magnetospheric Multiscale Mission (MMS) at high altitudes in the magnetosphere (approx. 9-12 Re) and from the low-altitude (F-region) Floating Potential Measurement Unit (FPMU) on board the International Space Station (ISS). We analyze potential causes of these dramatic particle flux dropouts by putting them in the context of storm-time electrodynamics, and support our results with numerical simulations of the global magnetosphere and ionosphere. During the sheath phase of the storm, the MMS spacecraft in the near-earth equatorial plane observed a rapid reconfiguration of the magnetic field near 1923 UT. Initially in the warm plasma sheet, particle flux dropouts were observed as they tracked the plasma-sheet to lobe transitions with the stretching and thinning of the plasma sheet. Anti-sunward flowing O+ ions of ionospheric origin were also measured during this period, confirming that the MMS spacecraft temporarily was in a lobe.
We have diagnosed the lifetimes of long-lived source gases emitted at the surface and removed in the stratosphere using six three-dimensional chemistry-climate models and a two-dimensional model. The models all used the same standard photochemical data. We investigate the effect of different definitions of lifetimes, including running the models with both mixing ratio (MBC) and flux (FBC) boundary conditions. Within the same model, the lifetimes diagnosed by different methods agree very well. Using FBCs versus MBCs leads to a different tracer burden as the implied lifetime contained in theMBC value does not necessarilymatch a model's own calculated lifetime. In general, there are much larger differences in the lifetimes calculated by different models, the main causes of which are variations in the modeled rates of ascent and horizontal mixing in the tropical midlower stratosphere. The model runs have been used to compute instantaneous and steady state lifetimes. For chlorofluorocarbons (CFCs) their atmospheric distribution was far from steady state in their growth phase through to the 1980s, and the diagnosed instantaneous lifetime is accordingly much longer. Following the cessation of emissions, the resulting decay of CFCs is much closer to steady state. For 2100 conditions the model circulation speeds generally increase, but a thicker ozone layer due to recovery and climate change reduces photolysis rates. These effects compensate so the net impact on modeled lifetimes is small. For future assessments of stratospheric ozone, use of FBCs would allow a consistent balance between rate of CFC removal and model circulation rate.
We report on a set of clear and abrupt decreases in the high-frequency boundary of whistlerode emissions detected by Cassini at high latitudes (about ±40°) during the low-altitude proximal flybys f Saturn . These abrupt decreases or dropouts have start and stop locations that correspond to L shells at the dges of the A and B rings. Langmuir probe measurements can confirm, in some cases, that the abrupt decrease in the high-frequency whistler mode boundary is associated with a corresponding abrupt electron density dropout over evacuated field lines connected to the A and B rings. Wideband data also reveal electron plasma oscillations and whistler mode cutoffs consistent with a low-density plasma in the region. he observation of the electron density dropout along ring-connecting field lines suggests that strong ambipolar forces are operating, drawing cold ionospheric ions outward to fill the flux tubes. There is an analog with the refilling of flux tubes in the terrestrial plasmasphere. We suggest that the ring-connected electron density dropouts observed between 1.1 and 1.3 R(sub s) are connected to the low-density ring plasma cavity observed overtop the A and B rings during the 2004 Saturn orbital insertion pass.
We have obtained high and medium resolution images of the SiO J=2-1 (V=0) emission from the circumstellar envelopes of three oxygen-rich Mira variables, XXyg, RX Boo, and IK Tau.