B. Andonov

Bulgarian Academy of Sciences | BAS · Department of Geophysics

A new method for mapping of total electron content (TEC) over Balkan Peninsula (35–46° N, 20–29° E) with a latitudinal and longitudinal step of 1° and a time resolution of one hour is developed. For this purpose 28 ground based GNSS stations are used. The presented method includes: (i) calculations of the slant TEC from the measured time delay of t...

An empirical total electron content (TEC) model response to external forcing over Balkan Peninsula (35°N-50°N; 15°E-30°E) is built by using the Center for Orbit Determination of Europe (CODE) TEC data for full 17 years, January 1999 - December 2015. The external forcing includes geomagnetic activity described by the K p-index and solar activity des...

It is known that both satellite and receiver biases are very important for the accurate estimation of total electron content (TEC). While the satellite biases are regularly calculated by network methods the receiver biases are given only for the reference GPS stations. This study presents the most appropriate procedure for calculation of the single...

This study examines the structure and variability of the ionospheric TEC anomalies driven by geomagnetic storms. For this purpose the CODE global ionospheric TEC data from four geomagnetically disturbed periods (29 October-1 November 2003, 7–10 November 2004, 14-15 December 2006, and 5-6 August 2011) have been considered. By applying the tidal anal...

[1] A global total electron content (TEC) model response to geomagnetic activity described by the Kp index is built by using the Center for Orbit Determination of Europe (CODE) TEC data for a full 13 years, January 1999 to December 2011. The model describes the most probable spatial distribution and temporal variability of the geomagnetically force...

present paper presents a detailed statistical evaluation of the global empirical background TEC model built by using the CODE TEC data for full 13 years, 1999-2011, and described in Part 1. It has been found that the empirical probability density distribution resembles more the Laplace than the Gaussian distribution. A further insight into the natu...

global background total electron content (TEC) model is built by using the Center for Orbit Determination of Europe (CODE) TEC data for full 13 years, 1999-2011. It describes the climatological behavior of the ionosphere under both its primary external driver, i.e., the direct photo-ionization by incident solar radiation, and regular wave particula...

The present paper focuses on planetary wave type responses of the thermosphere/ionosphere system to forcing from above and below during the Arctic winter of 2005/2006. The forcing from above is described by the sunspot numbers, the solar wind speed, the Bz-component of the IMF and the geomagnetic Kp-index, while the forcing from below, i.e. by upwa...

A global empirical model of the rTEC=(TECobs-TECmed)/TECmed depending on the geomagnetic activity (described by the Kp-index) and at a given moment is built by using global TEC data for full 13 years between 1999 and 2011.The data are downloaded from the CODE (Center for Orbit Determination in Europe) database in the Astronomical Institute, Univers...

A global empirical background TEC model is built by using the CODE vertical TEC data for full 13 years, 1999-2011. It represents the state of the ionosphere for a particular epoch of solar activity and can be used for planning radio systems operations. The solar activity is described by both F10.7 and its linear rate of change. In this way we disti...

The paper describes results of the studies devoted to the solar activity impact on the Earth's upper atmosphere and ionosphere, conducted within the frame of COST ES0803 Action. Aim: The aim of the paper is to represent results coming from different research groups in a unified form, aligning their specific topics into the general context of the su...

review is given on solar activity impact on Earth's atmosphere

The paper presents an empirical model of the total electron content (TEC) response to the geomagnetic activity described by the Kp-index. The model is built on the basis of TEC measurements covering the region of North America (50°W–150°W, 10°N–60°N) for the period of time between October 2004 and December 2009. By using a 2D (latitude-time) cross-...

The present paper is focused on the global spatial (altitude and latitude) structure, seasonal and interannual variability of the most stable in amplitude and phase eastward propagating diurnal and semidiurnal tides with zonal wavenumbers 2 and 3 derived from the SABER/TIMED temperatures for full 6 years (January 2002–December 2007). The tidal resu...

The paper focuses on the global spatial structure, seasonal and interannual variability of the stationary planetary waves (SPW) with zonal wavenumber s = 1 (SPW1) and s = 2 (SPW2) derived from the SABER/TIMED temperature measurements for 6 full years (January 2002–December 2007). The monthly mean climatological (multiyear average, 2002–2007) depict...

No abstract available.

The paper is focused on the global spatial structure, seasonal and interannual variability of the ∼5-day Rossby (W1) and ∼6-day Kelvin (E1) waves derived from the SABER/TIMED temperature measurements for 6 full years (January 2002–December 2007). The latitude structure of the ∼5-day W1 wave is related to the gravest symmetric wave number 1 Rossby w...

The conventional sources of ionospheric structure and variability are changes in solar radiative output and geomagnetic activity, together with the subsequent response of the thermosphere and ionosphere system and interaction between the components. Most of the time, particularly recently when the level of solar activity is very low, there is not a...

A new empirical model nowcasting and predicting a proxy to the geomagnetic K index is developed, which is based on the combined use of solar wind parameters and ground-based magnetic data. The present approach implements the previously developed solar wind-based MAK model, calibrating its values with magnetogram-derived K index. The new model is na...

This paper is focused on the nonmigrating tidal activity seen in the SABER/TIMED temperatures that is related to the major sudden stratospheric warming (SSW) taking place in the Arctic winter of 2003/2004. The emphasis is on the nonmigrating diurnal tides observed in the stratosphere and lower mesosphere which is usually accepted to be insignifican...

The present paper is focused on the global spatial (altitude and latitude) structure and seasonal and interannual variability of the migrating diurnal tide derived from the Sounding of the Atmosphere using Broadband Emission Radiometry/Thermosphere-Ionosphere-Mesosphere-Energetics and Dynamics (SABER/TIMED) temperature measurements for 6 full years...

The present paper is focused on the global spatial (altitude and latitude) structure, seasonal and interannual variability of the migrating semidiurnal tide derived from the SABER/TIMED temperature measurements for 6 years (January 2002-December 2007). The tidal results are obtained by a new analysis method where the tides (migrating and nonmigrati...

This short-communication presents a new method for assessing the amplitude modulation of the stationary planetary waves (SPWs). The suggested procedure allows estimating the contribution of the amplitude modulated SPWs to the field of the zonally travelling planetary waves. The root of the method consists in calculating of a quantity that is analog...

Part 1 of the present paper is focused on the types of planetary wave seen in the TIMED/SABER and UK Met Office (UKMO) temperature data in the Northern Hemisphere (NH) (0–50°N) stratosphere (30–60 km) during the Arctic winter of 2003/2004, as the emphasis is on their spatial structure (latitude and altitude) and temporal evolution particularly in r...

Part 2 of the present paper is focused on the planetary wave coupling from the stratosphere to the lower thermosphere (30–120 km) during the Arctic winter of 2003/2004. The planetary waves seen in the TIMED/SABER temperature data in the latitudinal range 50°N–50°S are studied in detail. The altitude and latitude structures of the planetary wave (st...

The vertical coupling of the stratosphere-mesosphere system through quasi-stationary and traveling planetary waves during the major sudden stratospheric warming (SSW) in the Arctic winter of 2003/2004 has been studied using three types of data. The UK Met Office (UKMO) assimilated data set was used to examine the features of the global-scale planet...

The coupling of the dynamical regimes in the high- and low-latitude stratosphere and mesosphere during the major SSW in the Arctic winter of 2003/2004 has been studied. The UKMO zonal wind data were used to explore the latitudinal coupling in the stratosphere, while the coupling in the mesosphere was investigated by neutral wind measurements from e...

The stratosphere–mesosphere response to the major sudden stratospheric warming (SSW) in the winter of 2003/2004 has been studied. The UKMO (UK Meteorological Office) data set was used to examine the features of the large-scale thermodynamic anomalies present in the stratosphere of the Northern Hemisphere. The vertical and latitudinal structure of t...

The paper presents clear evidence of zonally symmetric planetary waves with very large amplitudes present in the UK Met Office zonal wind data of the Northern Hemisphere stratosphere in the winter of 2003–2004. The spectral analysis reveals that three prevailing periods of ∼23, 17 and 11 days contribute to the observed zonally symmetric oscillation...

In a previous work the authors have developed a model, providing Kp as a function of the interplanetary magnetic ÿeld Bz component. They introduced a modiÿed Bz function (denoted as Bzm), exhibiting a delayed reaction to Bz changes. The modiÿed function Bzm was deÿned by using the analogy with a damping RC-circuit output voltage. The delaying react...

The influence of the ionospheric parameters on the polarization characteristics of magnetosonic or ULF compressional wave disturbances is modeled. The parameters that have a significant impact on the polarization signature of the ULF compressional disturbances are the maximum height (hmE) and maximum concentration (NmE) of the E-region. The polariz...