A medium- and long-term prediction method for ionospheric scintillation in low-latitude areas of my country

Abstract

The present invention discloses a medium- and long-term prediction method for ionospheric scintillation in low-latitude areas of my country, comprising the following steps: Step 1, given a date (month) and a location, reading the solar activity index F10.7 at the same time; Step 2, respectively calculating the changes in the ionospheric scintillation occurrence rate in low-latitude areas of my country with local time, season, geomagnetic latitude and solar activity cycle; Step 3, calculating the occurrence rate of ionospheric scintillation in low-latitude areas of my country; Step 4, calculating the maximum value of the scintillation occurrence rate on the day, and comparing it with the threshold value, and giving a forecast of whether ionospheric scintillation occurs. The low-latitude areas in southern my country are located near the northern hump of the magnetic equatorial anomaly, and ionospheric scintillation occurs frequently and has a relatively serious impact. The method of the present invention is mainly based on long-term GPS ionospheric scintillation observation data to achieve a medium- and long-term forecast of whether ionospheric scintillation occurs in low-latitude areas of my country under a given date and solar activity level.

Description

Technical Field

[0001] The invention belongs to the field of space physics radio waves, and particularly relates to a medium- and long-term forecast modeling method in this field for realizing whether ionospheric scintillation occurs in low-latitude areas of my country based on long-term observation data. Background Art

[0002] Experiments have shown that the ionosphere is often filled with small-scale, constantly moving and changing inhomogeneities. When radio waves propagate through these inhomogeneities and reach the ground, their amplitude, phase, etc. will experience rapid random fluctuations, a phenomenon usually called ionospheric scintillation. Ionospheric scintillation can have an adverse effect on the performance of a variety of aerospace systems. For example, for satellite communications, ionospheric scintillation can cause rapid signal fading. When the signal amplitude rapidly fades to exceed the dynamic range of the receiving system, it will cause communication barriers and increase the bit error rate. In severe cases, it may even cause the communication link to be interrupted.

[0003] The radio scintillation phenomenon is caused by ionospheric inhomogeneities. Existing radio scintillation observation data mainly come from altimeters, on-site measurement equipment carried by satellites and rockets, high-power radars, satellite beacon observations, etc. Based on these observation data, the temporal and spatial variation patterns of ionospheric inhomogeneities and scintillation are revealed. With the accumulation of a large amount of detection data, some regional / global ionospheric scintillation models have been established, typical of which are WBMOD (Wide Band Model) and GISM (Global Ionospheric Scintillation Model). The WBMOD model was established by the Northwest Research Institute of the United States based on the climatological characteristics of irregular bodies and the propagation effects of radio waves passing through the ionosphere. This model is now used in the SCINDA (Scintillation Network Decision Aid) system to provide ionospheric scintillation forecast services to communication and navigation users. The GISM model is mainly based on the multi-phase screen technology and the NeQuick model, and has been adopted by ITU-R after development and improvement. Iyer et al. (2006) developed a regional ionospheric scintillation probability prediction model based on VHF scintillation observation data in India, which can reflect the variation of scintillation occurrence rate with time, season, solar activity and geomagnetic activity. Shi Hao et al. (2014) established an ionospheric scintillation effect model by statistically analyzing the variation of GPS cycle slip occurrence rate with local time, season, solar activity and geomagnetic activity in low-latitude areas of China. This model can reflect the occurrence law of ionospheric scintillation effect with scintillation intensity greater than a certain level. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a medium- and long-term forecast modeling method for ionospheric scintillation in low-latitude areas of my country, which is used to give a medium- and long-term forecast of whether ionospheric scintillation will occur in low-latitude areas of my country under a given date and solar activity level.

[0005] The present invention adopts the following technical solution:

[0006] A method for medium- and long-term prediction of ionospheric scintillation in low-latitude areas of my country, the improvement of which is that it comprises the following steps:

[0007] Step 1, given a date (month) and location, read the solar activity index F10.7 at the same time;

[0008] Step 2, calculate the changes of ionospheric scintillation occurrence rate in low-latitude areas of my country with local time, season, geomagnetic latitude and solar activity cycle:

[0009] The variation of flicker occurrence rate with local time f t (t) is calculated using the following formula:

[0010]

[0011] In the above formula, t is the local time;

[0012] Seasonal variation of scintillation rate s (t) is calculated using the following formula:

[0013]

[0014] In the above formula, τ is the accumulated days per year;

[0015] Variation of scintillation rate with geomagnetic latitude l (m):

[0016]

[0017] In the above formula, m is the geomagnetic latitude;

[0018] The variation of scintillation rate with the solar activity cycle r (R) is calculated using the following formula:

[0019] When R>63,

[0020]

[0021] When R≤63,

[0022] f r (R)=0 (4b)

[0023] In the above formula, R is F10.7, τ is the annual accumulation day;

[0024] Step 3, calculate the occurrence rate F of ionospheric scintillation in my country's low-latitude areas according to the following formula:

[0025] F=Af s (τ)f r (R)f t (t)f l (m) (5)

[0026] In the above formula, A is a constant;

[0027] Step 4: Calculate the maximum value of the scintillation occurrence rate on the day based on the scintillation occurrence rate calculated in step 3, and compare it with the threshold value to give a forecast of whether ionospheric scintillation occurs. The specific method is as follows:

[0028] If the maximum value of the scintillation occurrence rate is greater than 4%, ionospheric scintillation is predicted to occur; if the maximum value of the scintillation occurrence rate is less than 2%, ionospheric scintillation is predicted not to occur.

[0029] The beneficial effects of the present invention are:

[0030] The low-latitude areas in southern my country are located near the northern hump of the magnetic equatorial anomaly, where ionospheric scintillation occurs frequently and has a relatively serious impact. The method of the present invention is mainly based on long-term GPS ionospheric scintillation observation data to achieve medium- and long-term forecasts of whether ionospheric scintillation will occur in my country's low-latitude areas under given dates and solar activity levels.

[0031] The method of the invention can provide guidance for the planning and design of various space activities, and can be used to support the analysis of ionospheric scintillation effects on Beidou navigation, satellite communication and other systems in the region, and can also be extended to other regions after appropriate modification. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic flow diagram of the method of the present invention;

[0033] Figure 2 is the ionospheric scintillation occurrence rate of embodiment 1 of the present invention;

[0034] Figure 3 It is the ionospheric scintillation occurrence rate of embodiment 2 of the present invention. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0036] Embodiment 1, as Figure 1 As shown, this embodiment discloses a forecasting method, which can predict the occurrence rate of ionospheric scintillation activity in low-latitude areas of my country on a given date, including the following steps:

[0037] Step 1: Given the date: January 1st to December 31st, 2012, time: 00-24LT, location: Haikou Station (geographic longitude: 20.00°, geographic latitude 110.34°, geomagnetic latitude: 10.02°), read the solar activity index F10.7 during the same period;

[0038] Step 2, calculate the variation of ionospheric scintillation occurrence rate at a given location with local time, season, geomagnetic latitude and solar activity cycle:

[0039] The variation of flicker occurrence rate with local time f t (t) is calculated using the following formula:

[0040]

[0041] In the above formula, t is the local time;

[0042] Seasonal variation of scintillation rate s (τ) is calculated using the following formula:

[0043]

[0044] In the above formula, τ is the accumulated days per year;

[0045] Variation of scintillation rate with geomagnetic latitude l (m):

[0046]

[0047] In the above formula, m is the geomagnetic latitude;

[0048] The variation of scintillation rate with the solar activity cycle r (R) is calculated using the following formula:

[0049] When R>63,

[0050]

[0051] When R≤63,

[0052] f r (R)=0 (4b)

[0053] In the above formula, R is F10.7, τ is the annual accumulation day;

[0054] Step 3: Calculate the occurrence rate F of ionospheric scintillation at a given location according to the following formula:

[0055] F=Af s (τ)f r (R)f t (t)fl (m) (5)

[0056] In the above formula, f s (τ), f r (R), f t (t) and f l (m) are the seasonal variation, solar activity week variation, diurnal variation and spatial variation described in step 2, A is a constant, and the result is as follows: Figure 2 As shown;

[0057] Step 4: Calculate the maximum value of the scintillation occurrence rate on the day based on the scintillation occurrence rate calculated in step 3, and compare it with the threshold value to give a forecast of whether ionospheric scintillation occurs. The specific method is as follows:

[0058] If the maximum value of the scintillation occurrence rate is greater than 4%, the probability of ionospheric scintillation is relatively high, and the occurrence of ionospheric scintillation can be predicted; if the maximum value of the scintillation occurrence rate is less than 2%, the probability of ionospheric scintillation is relatively low, and the non-occurrence of ionospheric scintillation can be predicted.

[0059] Embodiment 2, this embodiment discloses a forecasting method, which can predict the occurrence rate of ionospheric scintillation activity in low-latitude areas of my country on a given date, including the following steps:

[0060] Step 1: Given the date: January 1st to December 31st, 2010, time: 00-24LT, location: Guangzhou Station (geographic longitude: 23.14°, geographic latitude 113.36°, geomagnetic latitude: 19.53°), read the solar activity index F10.7 during the same period;

[0061] Step 2, calculate the variation of ionospheric scintillation occurrence rate at a given location with local time, season, geomagnetic latitude and solar activity cycle:

[0062] The variation of flicker occurrence rate with local time f t (t) is calculated using the following formula:

[0063]

[0064] In the above formula, t is the local time;

[0065] Seasonal variation of scintillation rate s (τ) is calculated using the following formula:

[0066]

[0067] In the above formula, τ is the accumulated days per year;

[0068] Variation of scintillation rate with geomagnetic latitude l (m):

[0069]

[0070] In the above formula, m is the geomagnetic latitude;

[0071] The variation of scintillation rate with the solar activity cycle r (R) is calculated using the following formula:

[0072] When R>63,

[0073]

[0074] When R≤63,

[0075] f r (R)=0 (4b)

[0076] In the above formula, R is F10.7, τ is the annual accumulation day;

[0077] Step 3: Calculate the occurrence rate F of ionospheric scintillation at a given location according to the following formula:

[0078] F=Af s (τ)f r (R)f t (t)f l (m) (5)

[0079] In the above formula, f s (τ), f r (R), f t (t) and f l (m) are the seasonal variation, solar activity week variation, diurnal variation and spatial variation described in step 2, A is a constant, and the result is as follows: Figure 3 As shown;

[0080] Step 4: Calculate the maximum value of the scintillation occurrence rate on the day based on the scintillation occurrence rate calculated in step 3, and compare it with the threshold value to give a forecast of whether ionospheric scintillation occurs. The specific method is as follows:

[0081] If the maximum value of the scintillation occurrence rate is greater than 4%, the probability of ionospheric scintillation is relatively high, and the occurrence of ionospheric scintillation can be predicted; if the maximum value of the scintillation occurrence rate is less than 2%, the probability of ionospheric scintillation is relatively low, and the non-occurrence of ionospheric scintillation can be predicted.

Claims

1. A medium- and long-term prediction method for ionospheric scintillation in low-latitude areas of my country, characterized in that: The steps include: Step 1, given a date and location, read the solar activity index F10.7 at the same time; Step 2, calculate the changes of ionospheric scintillation occurrence rate in low-latitude areas of my country with local time, season, geomagnetic latitude and solar activity cycle: The variation of flicker occurrence rate with local time f t (t) is calculated using the following formula: In the above formula, t is the local time; Seasonal variation of scintillation rate s (τ) is calculated using the following formula: In the above formula, τ is the accumulated days per year; Variation of scintillation rate with geomagnetic latitude l (m): In the above formula, m is the geomagnetic latitude; The variation of scintillation rate with the solar activity cycle r (R) is calculated using the following formula: When R>63, When R≤63, f r (R)=0 (4b) In the above formula, R is F10.7, τ is the annual accumulation day; Step 3, calculate the occurrence rate F of ionospheric scintillation in my country's low-latitude areas according to the following formula: F=Off s (τ)f r (R)f t (t)f l (m) (5) In the above formula, A is a constant; Step 4: Calculate the maximum value of the scintillation occurrence rate on the day based on the scintillation occurrence rate calculated in step 3, and compare it with the threshold value to give a forecast of whether ionospheric scintillation occurs. The specific method is as follows: If the maximum value of the scintillation occurrence rate is greater than 4%, ionospheric scintillation is predicted to occur; if the maximum value of the scintillation occurrence rate is less than 2%, ionospheric scintillation is predicted not to occur.

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