Dimitar Danov - Academia.edu (original) (raw)

Papers by Dimitar Danov

Solar Influences on the Magnetosphere, Ionosphere and Atmosphere, Sep 1, 2019

The Catalogues of the solar proton events [Logachev, ed., 1982-2016] provide the homogeneous data... more The Catalogues of the solar proton events [Logachev, ed., 1982-2016] provide the homogeneous data series of events with maximum intensity of > 10 MeV solar protons J ≥ 1 cm-2 s-1 sr-1 beginning from 1970 up to now. The event rates behavior is rather smooth: the total number of such events, relative to accumulated sunspot number, is almost constant in the solar cycles 21-23 and even slightly growing in the solar cycle 24. Contrary, the total number of the most powerful (GLE) events per cycle was constant within statistical errors in the cycles 21-23, and it fell abruptly in cycle 24. Considering the conventional sources of GLEs we found that production of GLEs by X-class bursts was 3 times less in cycle 24 than in cycle 23, while production of GLEs by the >1000 km/s halo-type CMEs was 5 times lower.

Tenth Workshop 'Solar Influences on the Magnetosphere, Aug 16, 2018

Su un n a an nd d S So ol la ar r A Ac ct ti iv vi it ty y I. M. Podgorny, A. I. Podgorny. A seri... more Su un n a an nd d S So ol la ar r A Ac ct ti iv vi it ty y I. M. Podgorny, A. I. Podgorny. A series of powerful solar flares in minimum of solar activity. Proton acceleration on the solar back side

arXiv: Space Physics, 2011

The UNBSSI is a long-term effort for the development of astronomy and space science through regio... more The UNBSSI is a long-term effort for the development of astronomy and space science through regional and international cooperation in this field on a worldwide basis. A series of workshops on BSS was held from 1991 to 2004 (India 1991, Costa Rica and Colombia 1992, Nigeria 1993, Egypt 1994, Sri Lanka 1995, Germany 1996, Honduras 1997, Jordan 1999, France 2000, Mauritius 2001, Argentina 2002, and China 2004; this http URL) and addressed the status of astronomy in Asia and the Pacific, Latin America and the Caribbean, Africa, and Western Asia. One major recommendation that emanated from these workshops was the establishment of astronomical facilities in developing nations for research and education programmes at the university level. Such workshops on BSS emphasized the particular importance of astrophysical data systems and the virtual observatory concept for the development of astronomy on a worldwide basis. Pursuant to resolutions of the United Nations Committee on the Peaceful Use...

The generation of monochromatic Pc4 pulsations by the electron cloud Belehaki A., and TechTIDE EC... more The generation of monochromatic Pc4 pulsations by the electron cloud Belehaki A., and TechTIDE EC consortium, Real-time identification of travelling ionospheric disturbances and validation methodologies Borisenko A.V., Podgorny I.M., Podgorny A.I., Using CUDA supercomputing for acceleration of calculations in study of solar flare mechanism for coronal MHD simulation Brun A.S., Strugarek A., The evolving solar-stellar dynamo Clette F., Lefèvre L., Reconciling the sunspot and group number series Dasso S., State of the art and gaps on the role of interplanetary structures on Sun-Earth coupling

Kosmìčna nauka ì tehnologìâ, 2000

Advances in Space Research, 1985

Single satellite observations allow the correct calculation of the value of field-aligned current... more Single satellite observations allow the correct calculation of the value of field-aligned currents (FAC) only when the scale of field-aligned current band in the latitudinal direction is much smaller then such scale in the longitudinal direction. The analysis shows that the change of the measured on satellite tangential component of the magnetic field in the case of finite current sheet is less than such change when the sheet is infinite (with same current density). This effect leads to underestimation of the value of field-aligned currents. The appeared systematic error of the calculation of field-aligned currents is evaluated. The magnetic field measurements aboard satellite Intercosmos-Bulgaria-1300 in the period August - December 1981 are used. The statistical pictures of the distribution of density and scales of field-aligned current bands are obtained.

New Methods and Studies, 2011

Large Scale (LS) Field Aligned Currents (FAC) distribution at high latitudes is studied on the ba... more Large Scale (LS) Field Aligned Currents (FAC) distribution at high latitudes is studied on the base of Intercosmos- Bulgaria-1300 satellite observations. It is shown that observed LS-FAC strength and thickness as a whole do not coincide with predictions of well-known empirical LS-FAC models. Possible reasons of this non-coincidence are suggested. Among them are: (a) errors due to identification of FAC regions with respect to satellite position; (b) incorrect selection of model input parameters; (c) smoothing of Magnetic Field (MF) measurements done in models' construction processes. To check some of the reasons mentioned, time intervals of nearly constant or slowly varying Solar Wind (SW) and Interplanetary Magnetic Field (IMF) parameters, when large-scale FACs can be considered in steady-state conditions are selected. We analyze the non-coincidence between the measured and modeled FACs both in magnitude and position and conclude that the smoothing of the MF measurements during ...

The generation of monochromatic Pc4 pulsations by the electron cloud Belehaki A., and TechTIDE EC... more The generation of monochromatic Pc4 pulsations by the electron cloud Belehaki A., and TechTIDE EC consortium, Real-time identification of travelling ionospheric disturbances and validation methodologies Borisenko A.V., Podgorny I.M., Podgorny A.I., Using CUDA supercomputing for acceleration of calculations in study of solar flare mechanism for coronal MHD simulation Brun A.S., Strugarek A., The evolving solar-stellar dynamo Clette F., Lefèvre L., Reconciling the sunspot and group number series Dasso S., State of the art and gaps on the role of interplanetary structures on Sun-Earth coupling

Aerospace Research in Bulgaria

The UV-index (UVI) is a measure of the erythemally effective solar radiation reaching the Earth s... more The UV-index (UVI) is a measure of the erythemally effective solar radiation reaching the Earth surface and it was introduced to alert people about the need of Sun protection. The present study applies a model that estimates the UVI over the high Bulgarian mountains for clear sky conditions considering the Total Ozone Content (TOC), which was taken from satellite measurements. The results show that during the periods from May to August at altitudes above 2 000 m a.s.l. very high UVI's (greater than 8) were observed for more than 18 days per month. The UVI values were very high practically for every day of July at altitudes higher than 1 500 m. Extremely high UVI result from episodes with TOC lower than 290 DU during June and July at the highest mountain parts with elevations greater than 2 500 m. High radiation risks were observed during April, especially when the preceding polar vortex was strong and the mountains were snow covered.

Su un n a an nd d S So ol la ar r A Ac ct ti iv vi it ty y I. M. Podgorny, A. I. Podgorny. A seri... more Su un n a an nd d S So ol la ar r A Ac ct ti iv vi it ty y I. M. Podgorny, A. I. Podgorny. A series of powerful solar flares in minimum of solar activity. Proton acceleration on the solar back side

The Catalogues of the solar proton events [Logachev, ed., 1982-2016] provide the homogeneous data... more The Catalogues of the solar proton events [Logachev, ed., 1982-2016] provide the homogeneous data series of events with maximum intensity of > 10 MeV solar protons J ≥ 1 cm-2 s-1 sr-1 beginning from 1970 up to now. The event rates behavior is rather smooth: the total number of such events, relative to accumulated sunspot number, is almost constant in the solar cycles 21-23 and even slightly growing in the solar cycle 24. Contrary, the total number of the most powerful (GLE) events per cycle was constant within statistical errors in the cycles 21-23, and it fell abruptly in cycle 24. Considering the conventional sources of GLEs we found that production of GLEs by X-class bursts was 3 times less in cycle 24 than in cycle 23, while production of GLEs by the >1000 km/s halo-type CMEs was 5 times lower.

Advances in Space Research, 2015

Solar Influences on the Magnetosphere, Ionosphere and Atmosphere, Sep 1, 2019

The Catalogues of the solar proton events [Logachev, ed., 1982-2016] provide the homogeneous data... more The Catalogues of the solar proton events [Logachev, ed., 1982-2016] provide the homogeneous data series of events with maximum intensity of > 10 MeV solar protons J ≥ 1 cm-2 s-1 sr-1 beginning from 1970 up to now. The event rates behavior is rather smooth: the total number of such events, relative to accumulated sunspot number, is almost constant in the solar cycles 21-23 and even slightly growing in the solar cycle 24. Contrary, the total number of the most powerful (GLE) events per cycle was constant within statistical errors in the cycles 21-23, and it fell abruptly in cycle 24. Considering the conventional sources of GLEs we found that production of GLEs by X-class bursts was 3 times less in cycle 24 than in cycle 23, while production of GLEs by the >1000 km/s halo-type CMEs was 5 times lower.

Tenth Workshop 'Solar Influences on the Magnetosphere, Aug 16, 2018

Su un n a an nd d S So ol la ar r A Ac ct ti iv vi it ty y I. M. Podgorny, A. I. Podgorny. A seri... more Su un n a an nd d S So ol la ar r A Ac ct ti iv vi it ty y I. M. Podgorny, A. I. Podgorny. A series of powerful solar flares in minimum of solar activity. Proton acceleration on the solar back side

arXiv: Space Physics, 2011

The UNBSSI is a long-term effort for the development of astronomy and space science through regio... more The UNBSSI is a long-term effort for the development of astronomy and space science through regional and international cooperation in this field on a worldwide basis. A series of workshops on BSS was held from 1991 to 2004 (India 1991, Costa Rica and Colombia 1992, Nigeria 1993, Egypt 1994, Sri Lanka 1995, Germany 1996, Honduras 1997, Jordan 1999, France 2000, Mauritius 2001, Argentina 2002, and China 2004; this http URL) and addressed the status of astronomy in Asia and the Pacific, Latin America and the Caribbean, Africa, and Western Asia. One major recommendation that emanated from these workshops was the establishment of astronomical facilities in developing nations for research and education programmes at the university level. Such workshops on BSS emphasized the particular importance of astrophysical data systems and the virtual observatory concept for the development of astronomy on a worldwide basis. Pursuant to resolutions of the United Nations Committee on the Peaceful Use...

The generation of monochromatic Pc4 pulsations by the electron cloud Belehaki A., and TechTIDE EC... more The generation of monochromatic Pc4 pulsations by the electron cloud Belehaki A., and TechTIDE EC consortium, Real-time identification of travelling ionospheric disturbances and validation methodologies Borisenko A.V., Podgorny I.M., Podgorny A.I., Using CUDA supercomputing for acceleration of calculations in study of solar flare mechanism for coronal MHD simulation Brun A.S., Strugarek A., The evolving solar-stellar dynamo Clette F., Lefèvre L., Reconciling the sunspot and group number series Dasso S., State of the art and gaps on the role of interplanetary structures on Sun-Earth coupling

Kosmìčna nauka ì tehnologìâ, 2000

Advances in Space Research, 1985

Single satellite observations allow the correct calculation of the value of field-aligned current... more Single satellite observations allow the correct calculation of the value of field-aligned currents (FAC) only when the scale of field-aligned current band in the latitudinal direction is much smaller then such scale in the longitudinal direction. The analysis shows that the change of the measured on satellite tangential component of the magnetic field in the case of finite current sheet is less than such change when the sheet is infinite (with same current density). This effect leads to underestimation of the value of field-aligned currents. The appeared systematic error of the calculation of field-aligned currents is evaluated. The magnetic field measurements aboard satellite Intercosmos-Bulgaria-1300 in the period August - December 1981 are used. The statistical pictures of the distribution of density and scales of field-aligned current bands are obtained.

New Methods and Studies, 2011

Large Scale (LS) Field Aligned Currents (FAC) distribution at high latitudes is studied on the ba... more Large Scale (LS) Field Aligned Currents (FAC) distribution at high latitudes is studied on the base of Intercosmos- Bulgaria-1300 satellite observations. It is shown that observed LS-FAC strength and thickness as a whole do not coincide with predictions of well-known empirical LS-FAC models. Possible reasons of this non-coincidence are suggested. Among them are: (a) errors due to identification of FAC regions with respect to satellite position; (b) incorrect selection of model input parameters; (c) smoothing of Magnetic Field (MF) measurements done in models' construction processes. To check some of the reasons mentioned, time intervals of nearly constant or slowly varying Solar Wind (SW) and Interplanetary Magnetic Field (IMF) parameters, when large-scale FACs can be considered in steady-state conditions are selected. We analyze the non-coincidence between the measured and modeled FACs both in magnitude and position and conclude that the smoothing of the MF measurements during ...

The generation of monochromatic Pc4 pulsations by the electron cloud Belehaki A., and TechTIDE EC... more The generation of monochromatic Pc4 pulsations by the electron cloud Belehaki A., and TechTIDE EC consortium, Real-time identification of travelling ionospheric disturbances and validation methodologies Borisenko A.V., Podgorny I.M., Podgorny A.I., Using CUDA supercomputing for acceleration of calculations in study of solar flare mechanism for coronal MHD simulation Brun A.S., Strugarek A., The evolving solar-stellar dynamo Clette F., Lefèvre L., Reconciling the sunspot and group number series Dasso S., State of the art and gaps on the role of interplanetary structures on Sun-Earth coupling

Aerospace Research in Bulgaria

The UV-index (UVI) is a measure of the erythemally effective solar radiation reaching the Earth s... more The UV-index (UVI) is a measure of the erythemally effective solar radiation reaching the Earth surface and it was introduced to alert people about the need of Sun protection. The present study applies a model that estimates the UVI over the high Bulgarian mountains for clear sky conditions considering the Total Ozone Content (TOC), which was taken from satellite measurements. The results show that during the periods from May to August at altitudes above 2 000 m a.s.l. very high UVI's (greater than 8) were observed for more than 18 days per month. The UVI values were very high practically for every day of July at altitudes higher than 1 500 m. Extremely high UVI result from episodes with TOC lower than 290 DU during June and July at the highest mountain parts with elevations greater than 2 500 m. High radiation risks were observed during April, especially when the preceding polar vortex was strong and the mountains were snow covered.

Su un n a an nd d S So ol la ar r A Ac ct ti iv vi it ty y I. M. Podgorny, A. I. Podgorny. A seri... more Su un n a an nd d S So ol la ar r A Ac ct ti iv vi it ty y I. M. Podgorny, A. I. Podgorny. A series of powerful solar flares in minimum of solar activity. Proton acceleration on the solar back side

The Catalogues of the solar proton events [Logachev, ed., 1982-2016] provide the homogeneous data... more The Catalogues of the solar proton events [Logachev, ed., 1982-2016] provide the homogeneous data series of events with maximum intensity of > 10 MeV solar protons J ≥ 1 cm-2 s-1 sr-1 beginning from 1970 up to now. The event rates behavior is rather smooth: the total number of such events, relative to accumulated sunspot number, is almost constant in the solar cycles 21-23 and even slightly growing in the solar cycle 24. Contrary, the total number of the most powerful (GLE) events per cycle was constant within statistical errors in the cycles 21-23, and it fell abruptly in cycle 24. Considering the conventional sources of GLEs we found that production of GLEs by X-class bursts was 3 times less in cycle 24 than in cycle 23, while production of GLEs by the >1000 km/s halo-type CMEs was 5 times lower.

Advances in Space Research, 2015