scholarly journals Gradient drift instability growth rates from global-scale modeling of the polar ionosphere

Radio Science ◽  
1998 ◽  
Vol 33 (6) ◽  
pp. 1915-1928 ◽  
Author(s):  
J. J. Sojka ◽  
M. V. Subramanium ◽  
L. Zhu ◽  
R. W. Schunk
Keyword(s):  
Growth Rates ◽  
Global Scale ◽  
Polar Ionosphere ◽  
Scale Modeling ◽  
Instability Growth ◽  
Gradient Drift ◽  
Drift Instability

scholarly journals Observation of polar cap patches and calculation of gradient drift instability growth times: A Swarm case study

2015 ◽  
Vol 42 (2) ◽  
pp. 201-206 ◽  
Author(s):  
A. Spicher ◽  
T. Cameron ◽  
E. M. Grono ◽  
K. N. Yakymenko ◽  
S. C. Buchert ◽  
...  
Keyword(s):  
Polar Cap ◽  
Instability Growth ◽  
Gradient Drift ◽  
Drift Instability

Multi-Scale Virtual Reality of Sintering

2007 ◽  
Vol 534-536 ◽  
pp. 573-576
Author(s):  
Eugene Olevsky
Keyword(s):  
Global Scale ◽  
Initial State ◽  
Model Framework ◽  
Time Step ◽  
Computational Framework ◽  
Multi Scale ◽  
Scale Modeling ◽  
History Of ◽  
On Line ◽  
Damage Criteria

The directions of further developments in the modeling of sintering are pointed out, including multi-scale modeling of sintering, on-line sintering damage criteria, particle agglomeration, sintering with phase transformations. A true multi-scale approach is applied for the development of a new meso-macro methodology for modeling of sintering. The developed macroscopic level computational framework envelopes the mesoscopic simulators. No closed forms of constitutive relationships are assumed for the parameters of the material. When a time-step of the calculations is finished for one macroscopic element, the mesostructures of the next element are restored from the initial state according to the history of loading. The model framework is able to predict the final dimensions of the sintered specimen on a global scale and identify the granular structure in any localized area for prediction of the material properties.

scholarly journals E-Region Field-Aligned Irregularities in the Middle of a Solar Eclipse Observed by a Bistatic Radar

2022 ◽  
Vol 14 (2) ◽  
pp. 392
Author(s):  
Lei Qiao ◽  
Gang Chen ◽  
Wanlin Gong ◽  
Xuesi Cai ◽  
Erxiao Liu ◽  
...  
Keyword(s):  
Solar Eclipse ◽  
Recovery Phase ◽  
Bistatic Radar ◽  
Doppler Shifts ◽  
Propagation Parameters ◽  
E Region ◽  
Gradient Drift ◽  
Drift Instability ◽  
Wave Induced ◽  
Field Aligned Irregularities

The Wuhan Ionospheric Oblique Backscatter Sounding System (WIOBSS) was applied as a bistatic radar to record the ionospheric E-region responses to a solar eclipse on 22 July 2009. The transmitter was located in Wuhan and the receiver was located in Huaian. The receiver observed anomalous echoes with larger Doppler shifts at the farther ranges compared with the echoes reflected by Es. According to the simulated ray propagation paths of the reflected and scattered waves, we considered that the anomalous echoes were scattered by E-region field-aligned irregularities (FAIs). The locations of the FAIs recorded by the WIOBSS were estimated with the International Geomagnetic Reference Field (IGRF) and the observed propagation parameters. These irregularities occurred at around the eclipse maximum and lasted for ~20–40 min. The steep plasma density gradient induced by the fast drop photo ionization under the lunar shadow was beneficial to the occurrence of gradient drift instability to generate the FAIs. They were different from the gravity wave-induced irregularities occurring in the recovery phase of the solar eclipse.

scholarly journals Sensitivities in global scale modeling of isoprene

2004 ◽  
Vol 4 (1) ◽  
pp. 1-17 ◽  
Author(s):  
R. von Kuhlmann ◽  
M. G. Lawrence ◽  
U. Pöschl ◽  
P. J. Crutzen
Keyword(s):  
Sensitivity Study ◽  
Global Scale ◽  
Tropospheric Chemistry ◽  
Order Estimate ◽  
Chemical Mechanisms ◽  
Intermediate Products ◽  
Scale Modeling ◽  
Reference Simulation ◽  
Isoprene Oxidation ◽  
Future Work

Abstract. A sensitivity study of the treatment of isoprene and related parameters in 3D atmospheric models was conducted using the global model of tropospheric chemistry MATCH-MPIC. A total of twelve sensitivity scenarios which can be grouped into four thematic categories were performed. These four categories consist of simulations with different chemical mechanisms, different assumptions concerning the deposition characteristics of intermediate products, assumptions concerning the nitrates from the oxidation of isoprene and variations of the source strengths. The largest differences in ozone compared to the reference simulation occured when a different isoprene oxidation scheme was used (up to 30-60% or about 10 nmol/mol). The largest differences in the abundance of peroxyacetylnitrate (PAN) were found when the isoprene emission strength was reduced by 50% and in tests with increased or decreased efficiency of the deposition of intermediates. The deposition assumptions were also found to have a significant effect on the upper tropospheric HOx production. Different implicit assumptions about the loss of intermediate products were identified as a major reason for the deviations among the tested isoprene oxidation schemes. The total tropospheric burden of O3 calculated in the sensitivity runs is increased compared to the background methane chemistry by 26±9  Tg( O3) from 273 to an average from the sensitivity runs of 299 Tg(O3). % revised Thus, there is a spread of ± 35% of the overall effect of isoprene in the model among the tested scenarios. This range of uncertainty and the much larger local deviations found in the test runs suggest that the treatment of isoprene in global models can only be seen as a first order estimate at present, and points towards specific processes in need of focused future work.

scholarly journals Simultaneous VHF radar backscatter and ionosonde observations of low-latitude E region

2005 ◽  
Vol 23 (3) ◽  
pp. 773-779 ◽  
Author(s):  
A. K. Patra ◽  
S. Sripathi ◽  
P. B. Rao ◽  
K. S. V. Subbarao
Keyword(s):  
Low Latitude ◽  
Vhf Radar ◽  
Radar Echoes ◽  
First Results ◽  
E Region ◽  
Gradient Drift ◽  
Drift Instability ◽  
Relationship Of ◽  
The Relationship ◽  
Field Aligned Irregularities

Abstract. The first results of simultaneous observations made on the low-latitude field-aligned irregularities (FAI) using the MST radar located at Gadanki (13.5° N, 79.2° E, dip 12.5°) and the Es parameters using an ionosonde at a nearby station Sriharikota (13.7° N, 80.1° E, dip 12.6°) are presented. The observations show that while the height of the most intense radar echoes is below the virtual height of Es (h'Es) during daytime, it is found to be either below or above during nighttime. The strength of the FAI is better correlated with the top penetration frequency (ftEs) and the blanketing frequency (fbEs) during the night (r=0.4 in both cases) as compared to the day (r=0.35 and -0.04, respectively). Furthermore, the signal strength of FAI is reasonably correlated with (ftEs-fbEs) during daytime (r=0.59) while very poorly correlated during nighttime (r=0.18). While the radar observations in general appear to have characteristics close to that of mid-latitudes, the relationship of these with the Es parameters are poorer than that of mid-latitudes. The observations reported here, nevertheless, are quite consistent with the expectations based on the gradient drift instability mechanism.

Likelihood of gradient drift instability development during the August 21, 2017 solar eclipse

2020 ◽  
Vol 175 (1-2) ◽  
pp. 136-140
Author(s):  
Chirag Rathod ◽  
Lee Kordella ◽  
Wayne Scales ◽  
Greg Earle ◽  
Bhuvana Srinivasan
Keyword(s):  
Solar Eclipse ◽  
Instability Development ◽  
Gradient Drift ◽  
Drift Instability
Sign in / Sign up

Export Citation Format

Share Document