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en:about [2016/04/12 17:58] vojtiken:about [2018/08/14 13:26] (current) kaklik
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 ====== How do we measure the ionosphere? ====== ====== How do we measure the ionosphere? ======
-Our measuring network focuses on the Earth's ionosphere. It's an upper atmospheric layer which is located approximately in the heights from 60 km to 1000 km. Thanks to the solar activity, the neutral gas is ionized in the ionosphere so the low temperature plasma is created there. Except the Sun, the ionospheric plasma can be influenced by the Jupiter magnetic storms, meteors or some strong gamma ray bursts. In accordance with the height where the plasma is located in, we can devide the ionosphere into three basic regions, D, E and F. Their location depends significantly on the day time and on the season. For example, the D region is nearly completely recombined at night. As a typical summer phenomenon, then, the F region is possibly split into the F1 and F2 regions and so-called sporadic layer can be formed in the E region. \\ + 
-The ionospheric regions are shown in Figure 1. The diagram compares their height with the notoriously-known atmospheric layers. \\+Our measuring network focuses on the Earth's ionosphere. It's an upper atmospheric layer which is located approximately in the heights from 60 km to 1000 km. Thanks to the solar activity, the neutral gas is ionized in the ionosphere so the low temperature plasma is created there. Except the Sun, the ionospheric plasma can be influenced by the Jupiter magnetic storms, meteors or some strong gamma ray bursts. In accordance with the height where the plasma is located in, we can devide the ionosphere into three basic regions, D, E and F. Their location depends significantly on the day time and on the season. For example, the D region is nearly completely recombined at night. As a typical summer phenomenon, then, the F region is possibly split into the F1 and F2 regions and so-called sporadic layer can be formed in the E region. 
 + 
 +{{ youtube>5opUZO7FMLw?medium }} 
 + 
 +The ionospheric regions are shown in Figure 1. The diagram compares their height with the notoriously-known atmospheric layers.  
 + 
 [[http://www.sws.bom.gov.au/Images/Educational/Space%20Weather/What%20is%20Space%20Weather/ionosphere.jpg|Figure 1]] [[http://www.sws.bom.gov.au/Images/Educational/Space%20Weather/What%20is%20Space%20Weather/ionosphere.jpg|Figure 1]]
 {{:en:ionosphere.jpg?500|The diagram showing appropriate ionospheric region is given.}} \\ {{:en:ionosphere.jpg?500|The diagram showing appropriate ionospheric region is given.}} \\
 +
 We can see that the ionospheric regions are also compared using the electron density. This quantity is one of the most important physical diagnostics of any plasma. It shows the amount of charge particles found in unit volume. The electron density is specific for the current time and height and is also strongly influenced by a high-energy impacts reaching the atmosphere. \\ We can see that the ionospheric regions are also compared using the electron density. This quantity is one of the most important physical diagnostics of any plasma. It shows the amount of charge particles found in unit volume. The electron density is specific for the current time and height and is also strongly influenced by a high-energy impacts reaching the atmosphere. \\
 This phenomenon, which we measure, is called ionospheric response. But how can the ionosphere be measured, indeed? \\ This phenomenon, which we measure, is called ionospheric response. But how can the ionosphere be measured, indeed? \\
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 [[http://www.rfcafe.com/references/qst/images2/ionosphere-radio-transmission-qst-march-1940-5.jpg|Figure 2]] [[http://www.rfcafe.com/references/qst/images2/ionosphere-radio-transmission-qst-march-1940-5.jpg|Figure 2]]
 {{:en:ionosphere-radio-transmission-qst-march-1940-5.jpg?400|The scheme of radio signal reflection is shown.}} \\ {{:en:ionosphere-radio-transmission-qst-march-1940-5.jpg?400|The scheme of radio signal reflection is shown.}} \\
-The frequency of measured radio signal differs in dependence on the appropriate ionospheric region. The D ionospheric region is monitored by the VLF (Very Low Frequency) measurement within the SID monitors, see [[en:vlf_data|VLF Data Analysis]]. Good results were achieved on the frequency of 23.4 kHz where the [[https://en.wikipedia.org/wiki/VLF_transmitter_DHO38|DHO 38 transmitter]]  can be tuned in. \\+The frequency of measured radio signal differs in dependence on the appropriate ionospheric region. The D ionospheric region is monitored by the VLF (Very Low Frequency) measurement within the SID monitors, see [[en:vlf_data|VLF Data Analysis]]. Good results were achieved on the frequency of 23.4 kHz where the [[https://en.wikipedia.org/wiki/VLF_transmitter_DHO38|DHO 38 transmitter]] can be tuned in. \\
 [[https://upload.wikimedia.org/wikipedia/commons/9/94/Marinesender_DHO38_L%C3%A4ngstwellensender_der_Marine.jpg|Figure 3]] [[https://upload.wikimedia.org/wikipedia/commons/9/94/Marinesender_DHO38_L%C3%A4ngstwellensender_der_Marine.jpg|Figure 3]]
 {{:en:dho38.jpg?400|The VLF transmitter DHO 38.}} \\ {{:en:dho38.jpg?400|The VLF transmitter DHO 38.}} \\
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 However, no ionospheric region is a homogenous layer. The plasma drifts strongly in horizontal and vertical direction as well. For example, the focusion and defocusion of charge particles can be discussed, see Figure 6. \\ However, no ionospheric region is a homogenous layer. The plasma drifts strongly in horizontal and vertical direction as well. For example, the focusion and defocusion of charge particles can be discussed, see Figure 6. \\
 [[https://raw.githubusercontent.com/Ionozor/data-processing/master/Octave/data/Sample%20data/Vertical_distribution_date.jpg|Figure 6]] [[https://raw.githubusercontent.com/Ionozor/data-processing/master/Octave/data/Sample%20data/Vertical_distribution_date.jpg|Figure 6]]
-{{:en:vertical_distribution_date.jpg?400 \\+{{:en:vertical_distribution_date.jpg?400|Vertical distribution of the ionospheric plasma in the D region is shown.}} \\ 
 +To get the exact data of this plasma flow, the Doppler measurement has been designed. The method is based on the Doppler Effect, which can be described as a frequency change induced by some locomotion. It is known that if the measured plasma approaches us, the frequency escalates and if it recedes, the frequency is tapered off. Because of these phenomena, the blue and red shift can be recognized and measured. It provides us to have the exact specification of the ionospheric drift. \\ 
 +[[http://imagine.gsfc.nasa.gov/features/yba/M31-velocity/images/doppler3.gif|Figure 7]] 
 +{{:en:doppler3.gif?450|A very simplified scheme of the Doppler shift is given.}}
en/about.1460483922.txt.gz · Last modified: 2016/04/12 17:58 (external edit)