scholarly journals Real-time forecasting of ICME shock arrivals at L1 during the "April Fool’s Day" epoch: 28 March – 21 April 2001

2002 ◽  
Vol 20 (7) ◽  
pp. 937-945 ◽  
Author(s):  
W. Sun ◽  
M. Dryer ◽  
C. D. Fry ◽  
C. S. Deehr ◽  
Z. Smith ◽  
...  
Keyword(s):  
Real Time ◽  
Radio Burst ◽  
Type Ii ◽  
Interplanetary Shocks ◽  
Arrival Times ◽  
Interplanetary Coronal Mass Ejection ◽  
Coronal Shock ◽  
Ex Post ◽  
Interplanetary Physics ◽  
Ex Post Facto

Abstract. The Sun was extremely active during the "April Fool’s Day" epoch of 2001. We chose this period between a solar flare on 28 March 2001 to a final shock arrival at Earth on 21 April 2001. The activity consisted of two presumed helmet-streamer blowouts, seven M-class flares, and nine X-class flares, the last of which was behind the west limb. We have been experimenting since February 1997 with real-time, end-to-end forecasting of interplanetary coronal mass ejection (ICME) shock arrival times. Since August 1998, these forecasts have been distributed in real-time by e-mail to a list of interested scientists and operational USAF and NOAA forecasters. They are made using three different solar wind models. We describe here the solar events observed during the April Fool’s 2001 epoch, along with the predicted and actual shock arrival times, and the ex post facto correction to the real-time coronal shock speed observations. It appears that the initial estimates of coronal shock speeds from Type II radio burst observations and coronal mass ejections were too high by as much as 30%. We conclude that a 3-dimensional coronal density model should be developed for application to observations of solar flares and their Type II radio burst observations.Key words. Interplanetary physics (flare and stream dynamics; interplanetary shocks) – Magnetosheric physics (storms and substorms)

Can Soft X-Rays Be Used as a Proxy for Total Energy Injected by a Flare into the Interplanetary Medium?

1994 ◽  
Vol 144 ◽  
pp. 267-270 ◽  
Author(s):  
Z. K. Smith ◽  
M. Dryer ◽  
M. Armstrong
Keyword(s):  
Numerical Model ◽  
Total Energy ◽  
Interplanetary Medium ◽  
Energy Estimates ◽  
X Rays ◽  
Interplanetary Shocks ◽  
Arrival Times ◽  
X Ray ◽  
Ex Post ◽  
Ex Post Facto

AbstractSolar flares are a source of impulsive energy releases on the Sun that can inject energy into the interplanetary medium. Some of these energy injections drive interplanetary shocks that can, in turn cause disturbances in Earth’s environment. In an attempt to quantify these energy releases using readily available observational data, we explore the possibility of using, as a proxy, the solar flare signatures observed in soft X-ray data. Our motivation has been prompted by the real-time operational requirements of NOAA and U. S. Air Force to provide estimates of arrival times and strengths of shocks that impact Earth’s magnetosphere. The luxury of extensive,ex post factostudies of flare total energy outputs is not possible in an operational context. This study is restricted to flares associated with shocks seen in the corona as metric type II radio bursts. Using GOES data, the energy released in the 1-8Å X-ray wavelength band is computed and then compared to the estimates made from a numerical model based on two-dimensional, time-dependent MHD modeling of flare-initiated interplanetary shocks. We find that the proxy energy estimates computed from the GOES data provideno advantageover the estimates made using the MHD-based numerical model.

scholarly journals Shock location and CME 3D reconstruction of a solar type II radio burst with LOFAR

2018 ◽  
Vol 615 ◽  
pp. A89 ◽  
Author(s):  
P. Zucca ◽  
D. E. Morosan ◽  
A. P. Rouillard ◽  
R. Fallows ◽  
P. T. Gallagher ◽  
...  
Keyword(s):  
Radio Emission ◽  
Radio Burst ◽  
Second Harmonic ◽  
3D Structure ◽  
Large Angle ◽  
Type Ii ◽  
Polytropic Model ◽  
Coronal Shock ◽  
Observational Uncertainty ◽  
Harmonic Source

Context. Type II radio bursts are evidence of shocks in the solar atmosphere and inner heliosphere that emit radio waves ranging from sub-meter to kilometer lengths. These shocks may be associated with coronal mass ejections (CMEs) and reach speeds higher than the local magnetosonic speed. Radio imaging of decameter wavelengths (20–90 MHz) is now possible with the Low Frequency Array (LOFAR), opening a new radio window in which to study coronal shocks that leave the inner solar corona and enter the interplanetary medium and to understand their association with CMEs. Aims. To this end, we study a coronal shock associated with a CME and type II radio burst to determine the locations at which the radio emission is generated, and we investigate the origin of the band-splitting phenomenon. Methods. Thetype II shock source-positions and spectra were obtained using 91 simultaneous tied-array beams of LOFAR, and the CME was observed by the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO) and by the COR2A coronagraph of the SECCHI instruments on board the Solar Terrestrial Relation Observatory(STEREO). The 3D structure was inferred using triangulation of the coronographic observations. Coronal magnetic fields were obtained from a 3D magnetohydrodynamics (MHD) polytropic model using the photospheric fields measured by the Heliospheric Imager (HMI) on board the Solar Dynamic Observatory (SDO) as lower boundary. Results. The type II radio source of the coronal shock observed between 50 and 70 MHz was found to be located at the expanding flank of the CME, where the shock geometry is quasi-perpendicular with θBn ~ 70°. The type II radio burst showed first and second harmonic emission; the second harmonic source was cospatial with the first harmonic source to within the observational uncertainty. This suggests that radio wave propagation does not alter the apparent location of the harmonic source. The sources of the two split bands were also found to be cospatial within the observational uncertainty, in agreement with the interpretation that split bands are simultaneous radio emission from upstream and downstream of the shock front. The fast magnetosonic Mach number derived from this interpretation was found to lie in the range 1.3–1.5. The fast magnetosonic Mach numbers derived from modelling the CME and the coronal magnetic field around the type II source were found to lie in the range 1.4–1.6.

scholarly journals Real-Time In Vitro Fluorescence Anisotropy of the Cyanobacterial Circadian Clock

2019 ◽  
Vol 2 (2) ◽  
pp. 42 ◽  
Author(s):  
Joel Heisler ◽  
Archana Chavan ◽  
Yong-Gang Chang ◽  
Andy LiWang
Keyword(s):  
Circadian Clock ◽  
Real Time ◽  
Fluorescence Anisotropy ◽  
Polyacrylamide Gel Electrophoresis ◽  
Live Cells ◽  
Ex Post ◽  
Clock Proteins ◽  
Ex Post Facto ◽  
Clock Reaction

Uniquely, the circadian clock of cyanobacteria can be reconstructed outside the complex milieu of live cells, greatly simplifying the investigation of a functioning biological chronometer. The core oscillator component is composed of only three proteins, KaiA, KaiB, and KaiC, and together with ATP they undergo waves of assembly and disassembly that drive phosphorylation rhythms in KaiC. Typically, the time points of these reactions are analyzed ex post facto by denaturing polyacrylamide gel electrophoresis, because this technique resolves the different states of phosphorylation of KaiC. Here, we describe a more sensitive method that allows real-time monitoring of the clock reaction. By labeling one of the clock proteins with a fluorophore, in this case KaiB, the in vitro clock reaction can be monitored by fluorescence anisotropy on the minutes time scale for weeks.

Real-Time On-Line Performance Diagnostics of Heavy-Duty Industrial Gas Turbines

2002 ◽  
Vol 124 (4) ◽  
pp. 910-921 ◽  
Author(s):  
S. C. Gu¨len ◽  
P. R. Griffin ◽  
S. Paolucci
Keyword(s):  
Real Time ◽  
Gas Turbines ◽  
Performance Monitoring ◽  
Engine Performance ◽  
Combined Cycle ◽  
Ex Post ◽  
Ex Post Facto ◽  
Industrial Gas Turbines ◽  
On Line ◽  
And Performance

This paper describes the results of real-time, on-line performance monitoring of two gas turbines over a period of five months in 1997. A commercially available software system is installed to monitor, analyze and store measurements obtained from the plant’s distributed control system. The software is installed in a combined-cycle, cogeneration power plant, located in Massachusetts, USA, with two Frame 7EA gas turbines in Apr. 1997. Vendor’s information such as correction and part load performance curves are utilized to calculate expected engine performance and compare it with measurements. In addition to monitoring the general condition and performance of the gas turbines, user-specified financial data is used to determine schedules for compressor washing and inlet filter replacement by balancing the associated costs with lost revenue. All measurements and calculated information are stored in databases for real-time and historical trending and tabulating. The data is analyzed ex post facto to identify salient performance and maintenance issues.

scholarly journals A BROKEN SOLAR TYPE II RADIO BURST INDUCED BY A CORONAL SHOCK PROPAGATING ACROSS THE STREAMER BOUNDARY

2012 ◽  
Vol 750 (2) ◽  
pp. 158 ◽  
Author(s):  
X. L. Kong ◽  
Y. Chen ◽  
G. Li ◽  
S. W. Feng ◽  
H. Q. Song ◽  
...  
Keyword(s):  
Radio Burst ◽  
Type Ii ◽  
Coronal Shock ◽  
Solar Type

Evidence of in-situ Type II radio bursts in interplanetary shocks

2016 ◽  
Vol 12 (S327) ◽  
pp. 134-139
Author(s):  
S. M. Díaz-Castillo ◽  
J. C. Martínez Oliveros ◽  
B. Calvo-Mozo
Keyword(s):  
Radio Burst ◽  
Radio Bursts ◽  
Type Ii ◽  
Geometrical Configuration ◽  
Interplanetary Shocks ◽  
Principal Characteristics ◽  
Magnetic Structures ◽  
Show Evidence ◽  
Type Ii Radio Bursts

AbstractWe present a database of 11 interplanetary shocks associated to coronal mass ejections (CMEs) observed by STEREO and Wind missions between 2006 and 2011 that show evidence of Type II radio burst. For all events, we calculated the principal characteristics of the shock driver, the intensity and geometrical configuration of the in-situ shock and checked for the existence of in-situ type II radio burst. We made a comparative analysis of two CME events (on 18 August 2010 and 4 June 2011), which are apparently associated to two or more magnetic structures which interact in space (i.e. CMEs, SIRs, CIRs). These events show varied shock configurations and intensities. We found evidence of in-situ type II radio bursts in one of the events studied, suggesting that the geometry of the shock (quasi-perpendicularity) is also critical for the generation and/or detection of radio emission in-situ.

scholarly journals The Broken Lane of a Type II Radio Burst Caused by Collision of a Coronal Shock with a Flare Current Sheet

Solar Physics ◽  
2016 ◽  
Vol 291 (11) ◽  
pp. 3369-3384 ◽  
Author(s):  
Guannan Gao ◽  
Min Wang ◽  
Ning Wu ◽  
Jun Lin ◽  
E. Ebenezer ◽  
...  
Keyword(s):  
Current Sheet ◽  
Radio Burst ◽  
Type Ii ◽  
Coronal Shock

Real-Time On-Line Performance Diagnostics of Heavy-Duty Industrial Gas Turbines

2000 ◽  
Author(s):  
S. Can Gülen ◽  
Patrick R. Griffin ◽  
Sal Paolucci
Keyword(s):  
Real Time ◽  
Gas Turbines ◽  
Performance Monitoring ◽  
Engine Performance ◽  
Combined Cycle ◽  
Ex Post ◽  
Ex Post Facto ◽  
Industrial Gas Turbines ◽  
On Line ◽  
And Performance

This paper describes the results of real-time, on-line performance monitoring of two gas turbines over a period of five months in 1997. A commercially available software system is installed to monitor, analyze and store measurements obtained from the plant’s distributed control system. The software is installed in a combined-cycle, cogeneration power plant, located in Mass., USA, with two Frame 7EA gas turbines in April 1997. Vendor’s information such as correction and part load performance curves are utilized to calculate expected engine performance and compare it with measurements. In addition to monitoring the general condition and performance of the gas turbines, user-specified financial data is used to determine schedules for compressor washing and inlet filter replacement by balancing the associated costs with lost revenue. All measurements and calculated information are stored in databases for real-time and historical trending and tabulating. The data is analyzed ex post facto to identify salient performance and maintenance issues.

scholarly journals Real-Time Radar Reflectivity Calibration from Differential Phase Measurements

2014 ◽  
Vol 31 (5) ◽  
pp. 1089-1097 ◽  
Author(s):  
Aldo Bellon ◽  
Frédéric Fabry
Keyword(s):  
Real Time ◽  
Heavy Precipitation ◽  
Phase Measurements ◽  
Differential Phase ◽  
Ex Post ◽  
Ex Post Facto ◽  
Strong Convection ◽  
The Stability ◽  
Light Precipitation ◽  
Self Consistency

AbstractAn algorithm based on the self-consistency between the horizontal reflectivity ZH and the specific differential phase KDP has been devised for the calibration of the reflectivity measurements of the McGill S-band dual-polarization radar and implemented in real time in the fall of 2012. By combining pairs of measured and theoretical differential propagation phases (ΦDP) along rain paths from several azimuths, elevation angles, and radar cycles, a robust calibration estimate is obtained even in relatively light precipitation, provided the number of pairs is of the order of at least 103. It confirmed the stability of the radar system as further corroborated by disdrometer and ground echo comparisons. However, the two-parameter ZH–KDP technique proved to be inadequate in convective situations because it overestimates ΦDP differences of paths with heavy precipitation. An ex post facto analysis has revealed that a three-parameter (ZH–KDP–ZDR) relationship provides a much better agreement with the measured ΦDP differences regardless of the intensity of the precipitation along the rain paths. The main usefulness of the technique remains its ability to derive a reliable calibration correction factor even in light precipitation; thus, it is readily applicable in climate regimes and/or at times of the year characterized by the absence of strong convection capable of providing the large ΦDP differences previously thought necessary for such a technique to be successful.

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