All Physics Faculty Publications

All homogeneous pure radiation spacetimes satisfy the Einstein–Maxwell equations

Charles G. Torre — Fri, 14 Dec 2012 13:44:33 PST

It is shown that all homogeneous pure radiation solutions to the Einstein equations admit electromagnetic sources. This corrects an error in the literature.

Comparison of diurnal tide in models and ground-based observations during the 2005 equinox CAWSES tidal campaign

L. C. Chang et al. — Tue, 11 Dec 2012 13:39:26 PST

In this study, ground-based observations of equinox diurnal tide wind fields from the first CAWSES Global Tidal Campaign are compared with results from five commonly used models, in order to identify systematic differences. WACCM3 and Extended CMAM are both self-consistent general circulation models, which resolve general climatological features, while TIME-GCM can be forced to approximate specific conditions using reanalysis fields. GSWM is a linear mechanistic model; while GEWM is an empirical model derived from ground-based and satellite observations. The models resolve diurnal tides consistent in latitudinal structure with observations, dominated by the upward propagating (1,1) mode. There is disagreement in the magnitudes of the tidal amplitudes and vertical wavelengths, while differences in longitudinal tidal variability indicate differences in the nonmigrating tides in the models. These points suggest inconsistencies in model forcing, dissipation, and background winds that must be examined as part of a coordinated effort from the modeling community.

All homogeneous pure radiation spacetimes satisfy the Einstein–Maxwell equations

Charles G. Torre — Thu, 21 Jun 2012 22:43:10 PDT

It is shown that all homogeneous pure radiation solutions to the Einstein equations admit electromagnetic sources. This corrects an error in the literature.

Wind and temperature response of midlatitude mesopause region to the 2009 Sudden Stratospheric Warming

Titus Yuan et al. — Mon, 11 Jun 2012 08:58:15 PDT

In this paper we report winds and temperature in the mesopause region (80–102 km) over full diurnal cycles during the 2009 major Sudden Stratospheric Warming (SSW) at Fort Collins (41°N, 105°W). The measurements were made with the Colorado State University (CSU) sodium Doppler wind-temperature lidar. We deduce the diurnal mean wind and temperature profiles by removing the tidal components from the 24-h continuous observations and present their anomalous behaviors in connection with this event. These mean wind and temperature measurements reveal significant anomalies in the mesopause region: the mean temperature at 80 km was approximately 30 K lower than the climatological mean; the mean zonal wind ranged between ∼ −10 to 0 m/s from 80 to 97 km and then turned eastward in lower thermosphere in a reversal of the climatological mean wind profile. We further use observations from the TIMED/SABER satellite observations and simulations from the WACCM model to investigate the global structure of this dynamical anomaly at Fort Collins. The satellite observations and model reveal that the anomaly is part of a disturbance that extended from the polar region to Fort Collins. These simultaneous wind- and temperature-lidar observations document the direct impact of a major SSW on the dynamic and thermal circulation of the midlatitude mesopause region.

Seasonal variations of midlatitude mesospheric Na layer and their tidal period perturbations based on full diurnal cycle Na lidar observations of 2002–2008

Titus Yuan et al. — Mon, 11 Jun 2012 08:58:08 PDT

The Na lidar facility at Colorado State University (41°N, 105°W) started the full diurnal cycle observations of mesopause region temperature and zonal and meridional winds as well as mesospheric Na density in May 2002. In this paper, monthly means and seasonal variations of the density of mesospheric Na based on lidar observations from May 2002 to December 2008 are reported along with the amplitude and phase of tidal period perturbations. The revealed seasonal behaviors of mesospheric Na layer are generally consistent with published nocturnal climatology, with thick layers and high abundance in winter but thin layers and low abundance near summer. Tidal amplitudes of Na density are large in February–April and August–November with a dominant peak between 85 and 90 km; they are weak in summer months (May–July). The Na density tidal phase profiles, while showing downward progression, show a significant and abrupt phase shift (ideally 180 degrees). The center altitude of this phase shifting (termed switching altitude) is found to coincide with the fractional tidal amplitude (tidal amplitude over diurnal mean) minimum about 2–4 km above the centroid altitude of the associated Na layer. Taking advantage of the established temperature tidal climatology deduced from the same data set, the tidal phase behaviors between temperature and Na density and associated fractional Na density tidal amplitudes are discussed in terms of the theoretical prediction by Gardner and Shelton (1985).

Effect of sudden stratospheric warming on lunar tidal modulation of the equatorial electrojet

J. Park et al. — Thu, 17 May 2012 11:52:45 PDT

Direct comparison on non-tidal signatures in the electrojet, vertical plasma drift and equatorial ionization anomaly

H. Luhr et al. — Thu, 17 May 2012 11:52:25 PDT

Enhanced lunar semidiurnal equatorial vertical plasma drifts during sudden stratospheric warmings

Bela G. Fejer et al. — Thu, 17 May 2012 11:52:02 PDT

Observations of the vertical ion drift in the equatorial ionosphere during the solar minimum period of 2009

R. A. Stoneback et al. — Thu, 17 May 2012 11:51:44 PDT

Equatorial and low latitude ionospheric effects during sudden stratospheric warming events

J. L. Chau et al. — Thu, 17 May 2012 11:51:24 PDT

Low latitude ionospheric electrodynamics

Bela G. Fejer — Thu, 17 May 2012 11:51:06 PDT

Duskside F-region dynamo currents: Its relationship with prereversal enhancement of vertical plasma drift

P. Park et al. — Thu, 17 May 2012 11:50:47 PDT

Lunar dependent equatorial ionospheric effects during sudden stratospheric warmings

Bela G. Fejer et al. — Thu, 17 May 2012 11:50:31 PDT

Climatology of early night equatorial spread F over Jicamarca

N. P. Chapagain et al. — Thu, 17 May 2012 11:50:16 PDT

Quiet variability of equatorial E × B drifts during a sudden stratospheric warning event

J. L. Chau et al. — Thu, 17 May 2012 11:49:57 PDT

Relative effects of electric field and neutral wind on positive ionospheric storms

N. Balan et al. — Thu, 17 May 2012 11:49:39 PDT

The spread F experiment (spread FEx): Program overview and first results

D. C. Fritts et al. — Thu, 17 May 2012 11:49:23 PDT

Overview and summary of the spread F experiment (SpreadFex)

D. C. Fritts et al. — Thu, 17 May 2012 11:49:06 PDT

Seasonal and longitudinal dependence of equatorial disturbance vertical plasma drifts

Bela G. Fejer et al. — Thu, 17 May 2012 11:48:46 PDT

Relation between the occurrence rate of ESF and the vertical plasma drift velocity at sunset derived form global observations

C. Stolle et al. — Thu, 17 May 2012 11:48:30 PDT