CN1306276C - Post processing method for observing data of drop-down acoustic Doppler current profile instrument - Google Patents
Post processing method for observing data of drop-down acoustic Doppler current profile instrument Download PDFInfo
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- CN1306276C CN1306276C CNB2004100967478A CN200410096747A CN1306276C CN 1306276 C CN1306276 C CN 1306276C CN B2004100967478 A CNB2004100967478 A CN B2004100967478A CN 200410096747 A CN200410096747 A CN 200410096747A CN 1306276 C CN1306276 C CN 1306276C
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Abstract
The present invention relates to a post processing method for observing data of a drop-down acoustic Doppler ocean current profile instrument. Firstly, original data of LADCP, CTD and GPS are primarily processed to realize the synchronic fusion of the original data; secondly, all observation value of the LADCP is converted to vertical shearing flow speeds of adjacent observation water layers; thirdly, an absolute flow speed profile from the surface to the bottom in an observation water column is taken by a 'bottom tracking method'; fourthly, an absolute flow speed profile from the bottom to the surface in the observation water column is taken by a ' GPS method '; finally, the taken two absolute flow speed profiles are coupled into the ocean current motion absolute speed profile of the whole observation water column through weight. The present invention is characterized in that the ocean current motion absolute speed profile can be obtained according to the original data of LADCP, CTD and GPS obtained by site synchronous observation. A lot of data observed by the drop-down acoustic Doppler ocean current profile instrument of China can be fully utilized.
Description
Technical field
The post-processing approach of acoustic Doppler current profile instrument (Lowered Acoustic Doppler CurrentProfiler, i.e. LADCP) observational data.
Background technology
LADCP is a kind of new observation instrument that international in recent years ocean current monitoring technical field is risen, and domestic each main ocean mechanism also all introduces it.Yet the manufacturer of LADCP can only provide relevant first process software (only can realize the conversion of acoustical signal), and powerless to its data aftertreatment, present basal conditions is as follows:
1) the observation purpose of LADCP instrument is the absolute velocity section that obtains the ocean current motion, but its observation characteristics are the measurements that realize in motion process the ocean current vector, and in observation process the movement velocity of LADCP instrument itself generally all bigger (with the movement velocity of observation water body with a magnitude or a big magnitude), so the direct observed result of LADCP can only be the speed of ocean current with respect to moving instrument.For the data aftertreatment of LADCP, the most direct idea is exactly the speed that records LADCP instrument motion itself earlier, still, under present technical conditions, also is difficult to the LADCP instrument of sub aqua sport is carried out the high-accuracy speed measurement.Has therefore, first problem just produced: the absolute velocity section of how to try to achieve the ocean current motion under the condition of the movement velocity of unknown LADCP instrument own?
2) the multiple instruments simultaneous observation has become the popular trend in oceanographic survey field, in view of this consideration, the LADCP instrument sensor such as leads just not carrying pressure, electricity aspect the inborn hardware design, make and itself can not determine out different observations position constantly in the observation process, so, LADCP observation is actually LADCP, conductivity-temperature-depth system (Conductivity-Temperature-Depth System, be CTD) and a complete LADCP recording geometry constituting of GPS (Global Position System, i.e. GPS).Do therefore, second problem just produced: how to realize the reasonable fusion of LADCP, CTD and three kinds of observational datas of GPS?
The solution of above problem either relate to LADCP instrument itself technical matters, but also relate to the ocean current motion problems of physical oceangraphy research, or with the specific implementation of ocean field investigation confidential relation is arranged, be the key point of LADCP data aftertreatment.Because the difficulty of its solution makes a large amount of LADCP observational datas can not get objective, effective processing, thereby causes the great wasting of resources.
Summary of the invention
The purpose of this invention is to provide a kind of objective, effective LADCP data post-processing approach, to realize LADCP, CTD and GPS source book according to on-the-spot simultaneous observation gained, obtain the absolute velocity section of ocean current motion under the movement velocity condition of unknown LADCP instrument own, a large amount of field datas that LADCP observation station is got can be fully utilized.
The present invention at first carries out just handling to the source book of LADCP, CTD and GPS, realizes that the synchronism of three kinds of data merges; Then, all observed readings of LADCP are converted into the vertical shear flow velocity of each adjacent observation water layer in view of " watt repeatedly formula data " characteristics of LADCP and the characteristic of " difference with the measured value of adjacent two water layers in the section equals the poor of absolute velocity "; Ask for the interior absolute fluid velocity profile of observation water column by " end tracing " then by the table and the end; Ask for the interior absolute fluid velocity profile of observation water column by " GPS method " again by the end and table; At last, the absolute fluid velocity profile of two classes of above-mentioned gained is synthesized by weight, just obtained the ocean current motion absolute velocity section of whole observation water column.
Description of drawings
LADCP watt of formula data synoptic diagram that changes among Fig. 1 the present invention
(wherein every velocity profile that on behalf of LADCP, vertical line measure)
Fig. 2 concrete implementing procedure figure of the present invention
Embodiment
Concrete implementing procedure figure of the present invention such as Fig. 2.
1. data is just handled, comprising the LADCP data just handle, the CTD data just handles and the GPS data is just handled, and realizes that their synchronism merges.Its concrete steps are as follows:
The a.LADCP data is just handled: the LADCP data of utilizing the above version of BBLIST1.0 that instrument producer provides is process software just, the acoustical signal of carrying out observational data transforms, and is processed into 1 section in 1 second sequential data of (all results that LADCP is observed each time are called a section).
The b.CTD data is just handled: the software (every kind of CTD has the Data Processing software of its producer's coupling) that utilizes instrument producer to provide carries out data just to be handled, and be processed into 1 data in 1 second sequential data of (all results that CTD is observed each time are called a sample, and the average result of some samples is called a data).
The c.GPS data is just handled: extract the locating information with LADCP/CTD observation process synchronised from the GPS observational data, be processed into 1 data in 1 second sequential data of (all results that each receives constantly GPS are called a sample, and the average result of some samples is called a data).
D. the synchronism of three kinds of data merges: because the observation process of LADCP and CTD carries out synchronously, so they go out, place of entry are consistent, in view of the above 1 second 1 data CTD sequential data synchronous fusion in the LADCP sequential data of 1 section in 1 second.
2. all observed readings of LADCP are converted into the vertical shear flow velocity of each adjacent observation water layer
A.LADCP " watt repeatedly formula data " characteristics: if the observation effect of acoustic Doppler current profiler (ADCP) is regarded as the effect of a string current meter, just as if in tow this goes here and there current meter and is doing the motion of transferring and rising the actual observation of LADCP so.If the once observation of LADCP is called a section, all observation datas of arbitrary water layer in each section are called a data, the continuous company of section and section and interlocking of data and data will appear in the observed result of LADCP so, in succession velocity profile one by one particularly, just as repeatedly the putting of roof sheet tile, therefore be referred to as " watt repeatedly formula data " (Fig. 1).
The characteristic of b.LADCP observational data: based on " watt repeatedly formula data ", can find the measuring process very of short duration (being generally 0.1s-0.3s) of each section of LADCP, to such an extent as to instrument velocity variable during this period of time itself is very small, thus can be LADCP instrument movement velocity during this period of time as a constant.So in any one identical section of LADCP observation, each observes the length velocity relation of water layer be expressed as follows:
Va1＝VL+V1
Va2＝VL+V2
Va3＝VL+V3
Va4＝VL+V4
……
Wherein: Va1, Va2 etc. is the absolute velocity of each water layer, and VL is the movement velocity of LADCP instrument itself, and V1, V2 etc. is the measured value of each water layer LADCP, then:
Va1-Va2＝V1-V2
Va2-Va3＝V2-V3
Va3-Va4＝V3-V4
……
Find out by these formulas: " just equaling absolute velocity poor of this two water layer with the difference of the LADCP measured value of adjacent two water layers in the section ".This is the most basic characteristic of LADCP observational data, also is that this step is achieved the most key foundation.So, though the direct measured value of LADCP can not reflect the objective attribute of ocean current motion, its difference with the measured value of adjacent two water layers in the section is the real embodiment of ocean current kinetic characteristic.
C. according to this above, all observed readings of LADCP are converted into the vertical shear flow velocity of each adjacent observation water layer: respectively at each section of LADCP observation, the LADCP measured value of each adjacent water layer is subtracted each other, obtain the velocity shear amount between them, and then obtain corresponding shear rate divided by bed thickness.So, just on each water layer of observation water column, obtain some shear rate values.It is worthy of note, because the catenary motion speed of seawater is generally all very little, this metering system of LADCP almost is difficult to be differentiated, so mentioned speed is meant the tangential movement speed of seawater in this instructions, shear rate is meant the vertical shear rate of horizontal velocity.
3. " end tracing " asks for the interior absolute fluid velocity profile by the end and table of water column, and its concrete steps are as follows:
A. extract the data that has end trace information the LADCP data sequences after merging;
B. selecting near-bottom is reference layer, ask for the relative velocity of interior each water layer of observation water column: at first all shear rate values of each water layer are carried out the Gaussian distribution check with respect to it, be that 0.95 fiducial interval is carried out data arithmetic mean or other statistical average to degree of confidence then, thereby try to achieve the flow velocity degree shear rate of this water layer; Continue according to this, obtain the flow velocity shear rate of all water layers; From reference layer, the shear rate value is carried out degree of depth stepping type integration according to the order from the bottom to the top layer, obtain the relative velocity of each water layer with respect to reference layer;
C. ask for the absolute flow velocity of reference layer of the nearly end based on end trace information data: near the end trace information of LADCP (only near-bottom time just can obtain) is meant seabed that LADCP observation station the gets speed V with respect to the LADCP instrument
Follow the tracks of at the end, and for earth coordinates, the seabed is actionless, so the reverse value of this class observed reading is exactly the speed V of LADCP instrument displacement in fact
Survey, just can obtain it and LADCP measured value direct interaction the absolute velocity V of reference layer
Reference layer:
V
Reference layer=V
Survey-V
Follow the tracks of at the end(1)
D. ask in the observation water column by the absolute fluid velocity profile of the end and table: more than obtained the absolute flow velocity of reference layer and each water layer relative velocity, the simple formula below the absolute fluid velocity profile of asking for whole water column only needs each water layer used with respect to reference layer:
V
N-is absolute=V
Reference+ V
N-is with respect to reference layer(2)
Wherein each water layer in the water column is observed in the n representative.
4. " GPS method " asks for the interior absolute flow velocity profile by the table and the end of water column, and its concrete steps are as follows:
A. extract the data that has GPS information the LADCP data sequences after merging;
B. selecting nearly top layer is reference layer, ask for the relative velocity of interior each water layer of observation water column: at first all shear rate values of each water layer are carried out the Gaussian distribution check with respect to it, be that 0.95 fiducial interval is carried out data arithmetic mean or other statistical average to degree of confidence then, thereby try to achieve the flow velocity shear rate of this water layer; Continue according to this, obtain the flow velocity degree shear rate of all water layers; From reference layer, the shear rate value is carried out degree of depth stepping type integration according to the order from the top layer to the bottom, obtain the relative velocity of each water layer with respect to reference layer;
C. ask for the absolute flow velocity of nearly table reference layer based on the GPS information material: aspect the utilizing of GPS information, the most direct idea is on the speed that the locating information of GPS directly applies to LADCP instrument itself is determined.But not only the bearing accuracy of GPS does not reach the requirement of this use, and also exists the relative motion of highly significant between LADCP instrument itself and the gps antenna, so the locating information of GPS can not directly apply on the determining of LADCP instrument self speed.Yet, in the measuring process of LADCP, always can accomplish to make LADCP from surveying a certain position entry of ship, again from identical position water outlet, also be " LADCP and the relative position of surveying ship remain unchanged when entry and during water outlet ".So, in whole measuring process, the speed V of LADCP instrument own
LADCPThe time integral horizontal shift that just equals to survey ship, its equation expression is as follows:
X wherein
Ship TThe reckoning that is meant EXIT POINT is put, X
Ship 0The reckoning that is meant place of entry is put, DX
ShipBe meant the horizontal shift of surveying ship in the whole measuring process.
As the design considerations of this part, it is as follows with reference to the concrete steps of absolute fluid velocity profile to utilize the GPS information material to ask for nearly top layer:
I. at first, for the absolute velocity V of arbitrary specific water layer
Definitely, both can use the speed V of LADCP instrument own
LADCPWith LADCP measured value V
SurveyAnd characterize:
V
Definitely=V
LADCP+ V
Survey(4)
Also can use reference layer speed V
DefinitelyWith with respect to reference layer speed V
Relatively for reference layerAnd characterize:
V
Definitely=V
Reference layer+ V
Relatively for reference layer(5)
So can get:
V
Reference layer=V
LADCP+ V
Survey-V
With respect to reference layer(6)
Ii. following formula is carried out integration to the time interval T of whole measuring process, and in conjunction with (3) formula,
Can get:
First on following formula the right determined by the GPS information material, and second and the 3rd are then by directly obtaining in the measured value of LADCP and the aforementioned processing step.So, can not directly apply under the situation that LADCP instrument self speed determines, consider whole measuring process, utilize LADCP when entry and during water outlet and survey the unchangeability of ship relative position, obtain the speed of nearly table reference layer in the GPS locating information.
D. ask in the observation water column by the table and the absolute fluid velocity profile at the end: will more than the absolute flow velocity of reference layer that obtains and each water layer be synthesized together with respect to the relative velocity of reference layer, just obtain the absolute flow velocity of each water layer in the whole water column, its equation expression is:
V
N-is absolute=V
Reference+ V
N-is with respect to reference layer(8)
Wherein each water layer in the water column is observed in the n representative.
5. obtain the ocean current motion absolute velocity section of whole observation water column by the weight coupling: no matter be " end tracing ", still " GPS method ", in the process of asking for observation water column ocean current motion absolute velocity section, all relate to corresponding integral process, just must cause the cumulative effect of measuring error like this along with the prolongation of integral process.Yet, " end tracing " be by bottom to the top layer integration, error accumulation upwards increases; " GPS method " then be by the top layer to the bottom integration, error accumulation increases downwards.So, can be according to the reverse order of their this error accumulations, the processing that is coupled accordingly realizes the process control that error becomes little, its concrete steps are as follows:
A. the ocean current motion absolute velocity section of the whole observation water column that is obtained by " end tracing " is called " end tracking section "; The ocean current motion absolute velocity section of the whole observation water column that is obtained by " GPS method " is called " GPS section "; They are carried out the uniform format processing, realize that promptly the material point position of each water layer is unified mutually, the interval of whole data sequences is unified mutually with length.
B. the coupling of " benchmark data section ": comparative analysis " end tracking section " and " GPS section ", ask for the most approaching data section (generally being positioned at the stage casing) of speed between them, be called " benchmark data section ".During this section data is coupled separately weight all be taken as 50%, the synthetic absolute flow velocity that obtains each water layer of this section.
C. from " benchmark data section " down up to the coupling of near-bottom: determine " end tracking section " from " benchmark data section " down up to the weight coefficient of each water layer of near-bottom from 50% linear increment to 100%; Determine " GPS section " from " benchmark data section " down up to the weight coefficient of each water layer of near-bottom from 50% linear decrease to 0%; Each water layer is synthetic respectively then, obtains the absolute flow velocity of each water layer of this section.
D. from " benchmark data section " up up to the coupling on nearly top layer: determine " end tracking section " from " benchmark data section " up up to the weight coefficient of each water layer on nearly top layer from 50% linear decrease to 0%; Determine " GPS section " from " benchmark data section " up up to the weight coefficient of each water layer on nearly top layer from 50% linear increment to 100%; Each water layer is synthetic respectively then, obtains the absolute flow velocity of each water layer of this section.
In sum, the present invention who constructs thus can obtain the absolute velocity section of ocean current motion according to LADCP, CTD and the GPS source book of on-the-spot simultaneous observation gained under the condition of the movement velocity of unknown LADCP instrument own.Make the great mass of data of China's acoustic Doppler current profile instrument observation be expected to be fully utilized.
Claims (2)
1. the post-processing approach of observing data of drop-down acoustic Doppler current profile instrument is characterized in that at first the source book of LADCP, CTD and GPS is carried out just handling, and realizes that the synchronism of three kinds of data merges; Then, all observed readings of LADCP are converted into the vertical shear flow velocity of each adjacent observation water layer in view of " watt repeatedly formula data " characteristics of LADCP and the characteristic of " difference with the measured value of adjacent two water layers in the section equals the poor of absolute velocity "; Ask for the interior absolute fluid velocity profile of observation water column by " end tracing " then by the table and the end; Ask for the interior absolute fluid velocity profile of observation water column by " GPS method " again by the end and table; At last, the absolute fluid velocity profile of two classes of above-mentioned gained is synthesized by weight, just obtained the ocean current motion absolute velocity section of whole observation water column, the step of the above-mentioned ocean current motion absolute velocity section that passes through the whole observation water column of weight coupling acquisition is:
A. the ocean current motion absolute velocity section of the whole observation water column that is obtained by " end tracing " is called " end tracking section "; The ocean current motion absolute velocity section of the whole observation water column that is obtained by " GPS method " is called " GPS section "; They are carried out the uniform format processing, realize that promptly the material point position of each water layer is unified mutually, the interval of whole data sequences is unified mutually with length;
B. the coupling of " benchmark data section ": comparative analysis " end tracking section " and " GPS section ", ask for the most approaching data section of speed between them, be called " benchmark data section ", during this section data is coupled separately weight all be taken as 50%, the synthetic absolute flow velocity that obtains each water layer of this section;
C. from " benchmark data section " down up to the coupling of near-bottom: determine " end tracking section " from " benchmark data section " down up to the weight coefficient of each water layer of near-bottom from 50% linear increment to 100%; Determine " GPS section " from " benchmark data section " down up to the weight coefficient of each water layer of near-bottom from 50% linear decrease to 0%; Each water layer is synthetic respectively then, obtains the absolute flow velocity of each water layer of this section;
D. from " benchmark data section " up up to the coupling on nearly top layer: determine " end tracking section " from " benchmark data section " up up to the weight coefficient of each water layer on nearly top layer from 50% linear decrease to 0%; Determine " GPS section " from " benchmark data section " up up to the weight coefficient of each water layer on nearly top layer from 50% linear increment to 100%; Each water layer is synthetic respectively then, obtains the absolute flow velocity of each water layer of this section.
2. the post-processing approach of observational data as claimed in claim 1, it is characterized in that it is at first all shear rate values of each water layer to be carried out the Gaussian distribution check with respect to the step of the relative velocity of reference layer that interior each water layer of water column is observed in above-mentioned asking for, be that 0.95 fiducial interval is carried out data arithmetic mean or other statistical average to degree of confidence then, thereby try to achieve the flow velocity shear rate of this water layer; Continue according to this, obtain the flow velocity degree shear rate of all water layers; From reference layer, the shear rate value is carried out degree of depth stepping type integration according to the order from the bottom to the top layer, obtain the relative velocity of each water layer with respect to reference layer.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101726734B (en) * | 2009-12-20 | 2011-12-14 | 中国海洋大学 | Posture balancing self-control device of lowered acoustic Doppler current profiler |
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| US8474474B2 (en) * | 2009-07-10 | 2013-07-02 | Fisher Controls International Llc | Control valve having pressure boundary integrity diagnostic capabilities, method of making the control valve, and method of using the control valve |
| CN101891008B (en) * | 2010-05-07 | 2013-03-13 | 上海劳雷仪器系统有限公司 | Ship speed-compensating electric winch |
| CN109297530B (en) * | 2018-08-06 | 2019-08-23 | 广州海洋地质调查局 | A kind of multi-environment element information fusion method of the full water column in deep-sea and processing terminal |
| CN115184638B (en) * | 2022-07-05 | 2023-08-18 | 浙江大学 | Post-processing method and processing terminal for deep sea LADCP observation data |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5077700A (en) * | 1990-12-21 | 1991-12-31 | The United States Of America As Represented By The Secretary Of The Navy | Doppler velocity profiler |
| US6820008B1 (en) * | 2001-07-24 | 2004-11-16 | Fugro Global Environmental & Ocean Sciences, Inc. | System and method for measuring deep sea currents |
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2004
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5077700A (en) * | 1990-12-21 | 1991-12-31 | The United States Of America As Represented By The Secretary Of The Navy | Doppler velocity profiler |
| US6820008B1 (en) * | 2001-07-24 | 2004-11-16 | Fugro Global Environmental & Ocean Sciences, Inc. | System and method for measuring deep sea currents |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101726734B (en) * | 2009-12-20 | 2011-12-14 | 中国海洋大学 | Posture balancing self-control device of lowered acoustic Doppler current profiler |
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