CN101872019B - Quick data processing method of occultation event of parallel asterism - Google Patents
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Abstract
The invention relates to the technical fields of the application and the parallel computation of a navigational satellite, in particular to a quick computation method of an occultation event of a parallel asterism. The method comprises the following steps of: navigating constellations, reading occultation asterism information, distributing satellite pairs according to an obtainable computation core, computing occultation event information accurately and finally, storing as an information file for subsequent occultation data processing. The method provided by the invention is applied to an occultation data processing system, is especially applied to the preprocessing process of a near-real-time (3 to 6h) occultation data processing system for computing the important part of the occultation event information, can enhance the computation efficiency of the process greatly and reduces the computation time greatly, thereby providing quicker data guarantee to the near-real-time application of occultation data applied to weather forecast and space weather forecast.
Description
Technical field
The present invention relates to navigation satellite applications, parallel computing field, relate in particular to a kind of quick data processing method of occultation event of parallel asterism.
Background technology
Radio occultation is used for the atmospheric condition that uranology is surveyed planet at first; In list of references 1 detailed description be applied to the development history (referring to document 1) that planetary scale is surveyed; Nineteen sixty-five, Fischbach proposes this technology is applied to the thought (referring to document 2) that earth atmosphere is surveyed; After this people such as Hardy has carried out a large amount of theoretical researches and analog computation work (referring to document 3); The success of GPS (GPS, Global Positioning System) constellation of the U.S. was built up and was moved and promoted the application in practice of this thought the beginning of the nineties.
Utilize the GPS Radio occultation survey the earth atmosphere state be learn in recent years with the atmospheric science field in one of flourish research direction; Its basic thought is: the GPS receiver that a high frequency sampling is installed on low orbit (LEO, Low Earth Orbit) satellite is observed gps satellite.When signal passed earth ionosphere and troposphere, because respective media vertical refraction index variation, signal path can bend.Along with signal emission and the motion that receives the two ends satellite, crooked signal path can be from high to low or inswept from low to high whole earth atmosphere, and the duration is about about 1min, and this process is known as and once descends or the occultation event that rises.Through mensuration to signal phase and amplitude variations amount in the occultation event, add the Precise Orbit information of GPS and LEO satellite, Vertical Profile that just can the inverting bending angle, and then obtain the atmospheric refraction index profile.When moisture content in the troposphere can be ignored, can directly obtain air pressure and do warm profile based on the perfect-gas atmosphere state equation.When moisture content is big, the ambient temperature field that utilizes other approach (like numerical weather prediction model output or raob (radiosonde observation) data) to provide, and then inverting atmospheric humidity profile.
The generation of this novel air detection means of GPS occultation observation is that the strong of traditional atmospheric exploration means replenished, and its observation data has advantages such as whole world covering, high vertical resolution, high precision, good stability.Its development can remedy the deficiency of radiosonde and weather satellite, promotes the raising of numerical weather forecast precision.For weather forecast; Numerical weather forecast (NWP; Numerical Weather Prediction) pattern must adopt three-dimensional atmospheric parameter data as initial value, provides the radiosondage network of this initial value not enough in the spatial and temporal distributions upper density at present, has greatly limited the precision of pattern.And the vertical resolution of Meteorological Satellites is limited, and is less to the contribution of pattern precision.Occultation observation is because its high vertical resolution and high precision, and what provided enriches the potentiality that data information has further improvement NWP pattern.Because the chronicity of occultation observation and stability, it also has vital role for weather and global change research due.In addition, the GPS occultation is observed ionospheric research advantage also is provided, and it possesses enough spatial and temporal resolutions provides the Global Ionospheric map.
Developed countries such as present America and Europe have carried out the science task that spaceborne GPS occultation is observed in succession with the area.From nineteen ninety-five by the American university atmospheric research (UCAR of federation; University Corporation for Atmospheric Research) the notion proof experiment GPS/MET that presides over formally starts, and having launched orbit altitude is the Microlab-1 satellite of 750km.Through processing, proved the feasibility of GPS LEO occultation earth atmosphere state and to improving the potential value (referring to document 4) of NWP pattern to this LEO satellite GPS occultation observational data.The U.S., a plurality of satellites or the satellite constellation of implementing occultation observation launched in Europe, a plurality of countries and regions such as tw Taiwan.Wherein jointly begin to prepare foundation meteorology, ionosphere and weather constellation recording geometry (COSMIC, The Constellation Observing System for Meteorology, Ionosphere, and Climate) with the U.S. and Taiwan.The main science task of COSMIC be utilize GPS occultation data remedy conventional meteorological observation means such as sounding balloon in the ocean, the two poles of the earth sparse deficiency that distributes; For the meteorological research personnel observe, study, forecast high-resolution atmosphere vapour content data is provided storm forms such as hurricane, typhoons; The refine weather forecast pattern in the whole world and zone also provides data information for the research of global climate research, PROGRESS OF IONOSPHERIC RESEARCH IN, earth gravity field simultaneously.The common need that build up of this system cost 100,000,000 dollars, and wherein Taiwan bears 80%.Taiwan always is the typhoon severely afflicated area, and the sounding balloon station, Pacific region that typhoon forms is considerably less, and conventional weather observation data is very limited.The atmospheric exploration data of ambient ocean zone, the Taiwan high-spatial and temporal resolution that COSMIC can provide will play an important role to improving typhoon, rainfall and wind-force prediction precision.After the normal operation of COSMIC, every day, the actual occultation event that provides can reach 2500 times.
The definition of a relevant group of stars (Cluster) has a variety of, and it derives from definition---a series of fixed stars with similar or close characteristic of relevant cluster (Cluster) in the uranology the earliest; Domestic some document also is translated as a group of stars with constellation (Constellation); And often mention the notion of a formation satellite group of stars (Formation-Flying Satellite Cluster) at space industry.So being necessary the notion of with here " group of stars (Cluster or Satellite Cluster) " carries out clearly: the combination of satellite (like CHAMP), constellation (like COSMIC) or the formation satellite group of stars (like GRACE) of fingering row occultation observation is referred to as " a LEO group of stars " of implementing occultation observation.Utilize GNSS group of stars Occultation Technique that the global atmosphere state is monitored, for fields such as the whole world and the weather forecast of local, climate change provide observation data round-the-clock, high-spatial and temporal resolution.
On the other hand, the GPS of USA that continues system, after the Muscovite GLONASS system, Europe (GALILEO) and Chinese (COMPASS) are in research and development of endeavouring navigational satellite system and enforcement.After all moving to these systems, cooperate the group of stars of low orbit occultation cheaply, can produce the tens thousand of even more occultation time every day.This provides unprecedented global cover data for (space) weather forecast on the one hand, has also brought the challenge to the disposal system calculated performance simultaneously.
Since multinuclear, the significantly reduction of multiprocessor computing platform hardware cost, and the MPI's of actual industrial standard level (Message Passing Interface) is widely-used and ripe.For adopting parallel mode to improve the hardware that group of stars occultation disposal system computing velocity provides and the support of system software platform.
Document 1:Fjeldbo, G., A.J.Kliore; And V.R.Eshleman, The neutral atmosphere of Venus asstudied with the Mariner V radio occultation experiments, The Astronomical Journal; 76,123-140,1971.
Document 2:Fischbach, F.F., A satellite method for pressure and temperature below 24km, BulletinofAmerican Meteorological Society, 46,528-532,1965.
Document 3:Hardy, K.R., G.A.Hajj; And E.R.Kursinski, Accuracies of atmospheric profilesobtained from GPS occultations, International Journal of Satellite Communications; 12,463-473,1994
Document 4:Kursinski, E.R., G.A.Hajj; J.T.Schoeld, et.al., Observing Earth ' s atmosphere withradio occultation measurements using the Global Positioning System; Journal of GeophysicalResearch; 102,23429-23465,1997
Summary of the invention
To the technical matters of above-mentioned existence, the purpose of this invention is to provide a kind of quick data processing method of occultation event of parallel asterism, to improve the computing velocity of group of stars occultation event.
For achieving the above object, the present invention adopts following technical scheme:
1. read satellite numbering, information such as precision positions by GNSS ephemeris file;
2. read each satellite numbering of a group of stars, information such as precision positions by LEO occultation group of stars ephemeris file;
3. based on open free MPI platform, calculate the quantity of navigation constellation and per two combinations of satellites of an occultation group of stars, distribute according to the quantity that can obtain computation core;
4. based on the MPI platform, each GNSS-LEO satellite of parallel computation is to formed occultation event precise information, and said occultation event precise information comprises the moment, precision positions, height etc.;
5. it is right to form satellite after all satellites finish to calculating, occultation information information table according to time sequence, and save as file.
Step is 3. middle distributes according to the quantity that can obtain computation core, adopts following method to realize:
Computation core according to the user can use is counted nk, and the GNSS satellite of participating in calculating counts n1 and LEO group of stars satellite is counted n2, gives each computation core with distribution of computation tasks.For k computation core, the span of k is 1-nk, distributes n1/nk GNSS satellite, and (n1, nk) a GNSS satellite distributes since the 1st computation core remaining MOD successively.The span of nk is 1-128, and actual maximum nk depends on the hardware system platform.The span of n1 and n2 is 1-256, and the GNSS satellite and the occultation LEO group of stars satellite of real work at present all are no more than 100.
The present invention has the following advantages and good effect:
1, to the satellite that produces occultation event to independence, adopt the fine granularity parallel mode to carry out occultation event fully and calculate, have high-efficiency characteristics;
2, method is simple, to carry out efficient high, is applicable to the multinuclear heart and multiprocessor computer system, can effectively improves the work efficiency of group of stars occultation data system;
3, construction cost is low, and can realize the robotization batch processing, can satisfy nearly requirement of using in real time.
Description of drawings
Fig. 1 is occultation event moment geometric relationship figure in the prior art.
Fig. 2 is the process flow diagram of the occultation event of parallel asterism quick calculation method that proposes of the present invention.
Fig. 3 is ephemeris reading flow journey figure in the prior art.
Fig. 4 is a resources allocation process flow diagram among the present invention.
Fig. 5 is an occultation event information parallel computation process flow diagram among the present invention.
Fig. 6 is the traditional classical way and the method realization completion occultation event information calculations time comparison diagram of the present invention's proposition.
Embodiment
Because when calculate constituting the right occultation event information of high orbit (GNSS) and low orbit (LEO) satellite, satellite between on calculating, do not have the logical relation of priority.So the right calculating of each satellite is independently.Based on this basis, can realize parallel computation efficiently.
Then adopt the classical way in occultation field during concrete calculating occultation event position; As shown in Figure 1; The GPS of GNSS system to have realized is an example: the exact position of gps satellite and LEO satellite is known, and the earth's core very judges whether to produce the standard of occultation signal to the vertical line segment distance with GPS and LEO instantaneous vector.If adding occultation event this judgement of threshold value of face height superlatively greater than earth radius, this distance can not constitute occultation observation.
Fig. 1 is certain synoptic diagram of geometric relationship in a flash of occultation event.The raypath in a certain moment of gps signal and gps satellite and LEO satellite coexist in the plane, and this plane is called the occultation plane.The O point is the refraction center.When regarding the earth as sphere, the refraction center overlaps with the earth's core.Because the influence of earth atmosphere, raypath can be crooked to the big direction of refractive index, and the point that height is minimum apart from the face of land on the raypath is called the perigee.The implication of each parameter is among the figure:
The projection of speed on the occultation plane of
LEO satellite and gps satellite;
Raypath influence parameter, promptly the refraction center is to outgoing and incoming signal path gradually
a：
Any one vertical range in the near line;
χ: the angle of signal exit direction with
;
α: the total refraction angle of atmosphere;
ζ:
and
angle between;
η:
and
angle between;
θ: GPS and LEO satellite are with respect to the angle between the position vector at refraction center;
θ
L:
And the angle between the signal incident direction;
θ
G:
And the angle between the signal exit direction;
R
LG: the geometric distance between LEO satellite and the gps satellite;
r
t: the perigee radius vector, promptly the raypath perigee is with respect to the geometric distance at refraction center.
The quick data processing method of occultation event of parallel asterism that the present invention proposes specifically may further comprise the steps:
1, reads satellite numbering, information such as precision positions by GNSS ephemeris file;
2, read each satellite numbering of a group of stars, information such as precision positions by LEO occultation group of stars ephemeris file;
3, based on open free MPI platform, calculate the quantity of navigation constellation and per two combinations of satellites of an occultation group of stars, distribute according to the quantity that can obtain computation core;
4, based on the MPI platform, each GNSS-LEO satellite of parallel computation comprises formed occultation event precise information: constantly, and precision positions, height etc.;
5, all satellite finishes to calculating, and to form satellite right in the back, occultation information information table according to time sequence, and save as file.
Combine accompanying drawing that the present invention is described further with specific embodiment below:
The enforcement environment of present embodiment is following:
Multinuclear or multiprocessor computer hardware platform.Operating system is selected Linux for use, and the concurrent software platform is selected MPICH-2 for use; Be ready to the scheme file of specified format, as the setting of control program operation principal parameter.The path that comprises precise ephemeris, the title of spanned file etc.
Fig. 2 is a general flow chart, Fig. 3 be " read GNSS Navsat and LEO low orbit satellite " among Fig. 2 the part detail flowchart.Fig. 4 is the detail flowchart of " resources allocation " part among Fig. 2.Fig. 5 is the detail flowchart that " is the criterion distributes calculation resources and carries out parallel computation and storage " part among Fig. 2 with the GNSS satellite.
(1) control information of the interior setting of read schemes file;
In control information storage and the self-defining scheme file.Content comprises the GNSS number of satellite of participating in calculating, numbering and ephemeris file path, LEO number of satellite, numbering and ephemeris file path, information such as destination file path.
(2) according to control information, the precise ephemeris data (like Fig. 4) of GNSS and LEO are read in circulation;
Specialty read the general procedure process of these type of data under this process adopted, and belonged to technology well known in the art.
(3), distribute calculative GNSS satellite numbering of every kernel and number of satellites, and set up relevant resource allocation information table (like Fig. 5) according to obtainable calculating inner core (CPU) number;
Concrete resource allocation methods is: the computation core that program can be used according to the user (CPU) number nk (1～nk); The GNSS satellite of participating in calculating counts n1 and LEO group of stars satellite is counted n2; The computation core is distributed n1/nk GNSS satellite; (n1, nk) a GNSS satellite distributes from the 1st computation core remaining MOD.Set up the resource allocation information table of CPU number-GNSS satellite numbering, i.e. the GNSS number of satellite and the numbering of the required calculating of each computation core; Get into the described data handling procedure of Fig. 4 after accomplishing.
The span of nk is 1-128, and actual maximum nk depends on the hardware system platform.The span of n1 and n2 is 1-256, and the GNSS satellite and the occultation LEO group of stars satellite of real work at present all are no more than 100.
(4) according to resource allocation information, start available calculating inner core simultaneously, every computation core is installed the GNSS satellite of distribution and the occultation event information calculations that all LEO satellites match, and deposits the result in specified file (like Fig. 6);
Fig. 6 can be divided into 7 layers from top to bottom.Resource allocation information table (layer 1) according to step that Fig. 5 describes generates comprising: GNSS satellite number that every computation core (CPU) is distributed and numbering and corresponding LEO satellite number information, parallel data processing of carrying out the occultation event information calculations on all CPU.For k computation core (CPU), the GNSS satellite index i that outermost circulation distributes for this CPU, to the last one on the 1st the GNSS satellite (layer 2 is to layer 6) that circulation distributes from this CPU; For every GNSS satellite; LEO group of stars satellite index j is also from the 1st to n2 circulate (layer 3 is to layer 5); Unpaired message through every GNSS and every LEO group of stars satellite reads corresponding GNSS satellite ephemeris and LEO satellite; And calculate by constantly judging whether to constitute occultation event, if constitute then the position of calculating occultation event the duration.Store the relevant information (layer 4) of occultation event then.When all GNSS satellites that this CPU distributed all dispose, then (layer 7) accomplished in the calculating of this CPU.
After all calculating completion, form statistical information and report messages.
Fig. 6 has provided and has calculated 1 day gps satellite and 1-6 low-orbit satellite adopts the classical single CPU and the comparison that expends time in of this method parallel computation occultation event information.Can find out, for single CPU calculates,, calculate the linear increase that is consuming time along with the increase of the LEO number of satellite that calculates.Adopting walks abreast then calculates nothing consuming time obviously increases.Certainly,, LEO satellite number calculates the corresponding increase of meeting consuming time later on when surpassing 8 because this instance is in the system with 8 CPU, to carry out.
Above-mentioned instance is used for the present invention that explains, rather than limits the invention, and in the protection domain of spirit of the present invention and claim, the present invention is made any modification and change, all falls into protection scope of the present invention.
Claims (2)
1. an occultation event of parallel asterism quick calculation method is characterized in that, may further comprise the steps:
1. read satellite numbering and precision positions information by GNSS ephemeris file;
2. read a group of stars each satellite numbering and precision positions information by LEO occultation group of stars ephemeris file;
3. based on open free MPI platform, calculate the quantity of navigation constellation and per two combinations of satellites of an occultation group of stars, distribute according to the quantity that can obtain computation core;
4. based on the MPI platform, each GNSS-LEO satellite of parallel computation is to formed occultation event precise information, and said occultation event precise information comprises the moment, precision positions and height;
5. all satellites form the information table of occultation information according to time sequence after calculating is finished, and save as file.
2. occultation event of parallel asterism quick calculation method according to claim 1 is characterized in that:
Step is 3. middle distributes according to the quantity that can obtain computation core, adopts following substep:
Computation core according to the user can use is counted nk, and the GNSS satellite of participating in calculating counts n1 and LEO group of stars satellite is counted n2, gives each computation core with distribution of computation tasks;
For k computation core, distribute n1/nk GNSS satellite, remaining MOD (n1; Nk) a GNSS satellite distributes since the 1st computation core successively; Wherein, the span of k is 1-nk, and the span of nk is 1-128; Actual maximum nk depends on the hardware system platform, and the span of n1 and n2 is 1-256.
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| CN102288974B (en) * | 2011-05-10 | 2012-11-14 | 航天恒星科技有限公司 | System for generating satellite navigation occultation signal |
| CN102426369B (en) * | 2011-11-22 | 2013-10-16 | 航天恒星科技有限公司 | L2C obscuration signal open loop tracking processing method |
| CN103852812B (en) * | 2012-12-07 | 2016-06-08 | 深圳航天东方红海特卫星有限公司 | A kind of forward simulation occultation method |
| CN104216031B (en) * | 2014-09-15 | 2017-05-24 | 航天东方红卫星有限公司 | Variable-step-size obscuration forecasting method |
| CN107561557B (en) * | 2017-08-18 | 2020-04-28 | 中国科学院遥感与数字地球研究所 | Atmospheric composition retrieval method for occultation detector |
| CN109100763A (en) * | 2018-07-12 | 2018-12-28 | 国家卫星海洋应用中心 | Spaceborne pencil beam microwave scatterometer geometry location method based on optimization GPS data |
| CN109270558B (en) * | 2018-09-30 | 2021-04-13 | 中国气象局气象探测中心 | Shelter forecasting method for mountain base |
| CN109059916B (en) * | 2018-09-30 | 2021-05-18 | 中国气象局气象探测中心 | Aerostat occultation forecasting method based on inertial navigation |
| CN111596328B (en) * | 2020-06-30 | 2023-06-20 | 天津云遥宇航科技有限公司 | Time sequence control method for data of GNSS occultation receiver |
| CN115826007B (en) * | 2023-02-17 | 2023-05-12 | 天津云遥宇航科技有限公司 | Method for forecasting neutral atmosphere occultation event of satellite-based global navigation satellite system |
| CN117809161A (en) * | 2023-12-19 | 2024-04-02 | 航天天目(重庆)卫星科技有限公司 | Star-masking refractive index profile data quality evaluation system based on multi-source data |
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| US7912422B2 (en) * | 2006-07-31 | 2011-03-22 | University Corporation For Atmospheric Research | Method and system for demodulation of open-loop GPS radio occultation signals |
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