CN111695085B - Method, system and electronic equipment for constructing radiometric calibration coefficient sequence - Google Patents
Method, system and electronic equipment for constructing radiometric calibration coefficient sequence Download PDFInfo
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Abstract
The invention provides a method, a system and electronic equipment for constructing a radiometric calibration coefficient sequence. The radiometric calibration coefficient sequence construction method comprises the following steps: acquiring earth observation data of a plurality of single-day remote sensors, and determining an equivalent earth single-day count value sequence according to the earth observation data of the plurality of single-day remote sensors; correcting the equivalent earth single-day count value sequence according to the earth-to-date distance, and determining a trend subsequence according to the corrected equivalent earth single-day count value sequence; and obtaining a radiation calibration correction coefficient for correcting the historical observation data of the remote sensor according to the trend subsequence. The method can solve the problem of tracking the on-orbit change of the radiation response of the remote sensor based on the data observed by the remote sensor on the ground under the condition of not depending on other alternative radiometric calibration sources, and realizes the correction of the radiometric calibration coefficient.
Description
Technical Field
The invention relates to the technical field of satellite remote sensing, in particular to a method, a system and electronic equipment for constructing a radiometric calibration coefficient sequence.
Background
The radiation calibration of the remote sensing data is a precondition of remote sensing quantification application, and the remote sensing data subjected to the radiation calibration has the condition of further man-machine interaction or automatic quantitative inversion. The application of the satellite remote sensing data is developed from a qualitative analysis stage to a quantitative application stage, and higher requirements are put on the calibration precision of the remote sensor. For example, global climate monitoring quantification requirements are becoming more and more clear (temperature changes of a few tenths of a degree per hundred years, fluctuations of one hundredth of an ozone layer per ten years) so that improving the accuracy of satellite remote sensor calibration is facing a great challenge. Radiometric scaling for tracking and evaluating long-term serial data of remote sensors has become an obstacle to further improvement in satellite observations applications.
The solar reflection band is the earliest remote sensing spectrum band, and is widely applied to the aspects of extracting geophysical element information such as cloud, aerosol, liu Biao parameters, ocean water colors and the like. The alternative calibration of the band is an important supplementary and standby means for the remote sensor on-satellite radiometric calibration method. By replacing calibration, a transmission chain from a remote sensor to an SI standard can be perfected in the radiation calibration process, so that the monitoring and tracking of long-term attenuation and short-term fluctuation of the radiation response of the remote sensor are realized. Such as the more typical simultaneous undersea point observation method (Simultaneous Nadir Observation, SNO).
The method for simultaneously observing the points under the satellites simultaneously passes through the orbit intersection point and takes the observation data of the points under the satellites as the calibration data of the common observation target object, so that the method for transmitting the radiation calibration standard of the reference remote sensor to the remote sensor to be calibrated is realized, meanwhile, the observation of the points under the satellites ensures that the observation targets of the two remote sensors are identical, the illumination and the observation geometric conditions are completely consistent, and the difference of the output data of the remote sensors mainly depends on the difference of the spectral response (Spectrum Response Function, SRF) and the difference of the radiation response of the two remote sensors. In the case of SNO, the target object at the satellite's subsurface point is not fixed, for example, SNO between solar synchronous polar satellites often occurs near north-south regions, and the underlying target type may be ice and snow, water, or clouds. The randomness of the underlying surface image of the SNO can lead to errors through SRF differences between remote sensors. On the other hand, the accuracy and stability of the data of the reference remote sensor.
Disclosure of Invention
Based on the problems existing in the prior art, the invention provides a method, a system and electronic equipment for constructing a radiometric calibration coefficient sequence.
In a first aspect, the present invention provides a method for constructing a radiometric calibration coefficient sequence, including:
acquiring earth observation data of a plurality of single-day remote sensors, and determining an equivalent earth single-day count value sequence according to the earth observation data of the plurality of single-day remote sensors;
correcting the equivalent earth single-day count value sequence according to the earth-to-date distance, and determining a trend subsequence according to the corrected equivalent earth single-day count value sequence;
and obtaining a radiation calibration correction coefficient for correcting the historical observation data of the remote sensor according to the trend subsequence.
In some examples, the determining the sequence of equivalent earth single day count values from the observed data of the plurality of single day remote sensors to earth comprises:
carrying out single-day data quality identification on the earth observation data of the single-day remote sensor;
determining extreme data according to the single-day data quality identification, and removing the extreme data from the observed data of the single-day remote sensor to the ground;
calculating the average value of the observed data of the remote sensor to the ground in a single day after the extreme data are removed;
determining a dark current count value and removing the dark current count value from the average value;
and supplementing missing data to the average value of the dark current count value removed by a nearest neighbor method, and taking the supplemented average value as the equivalent earth single-day count value.
In some examples, the correcting the equivalent earth single day count value sequence according to the earth-to-date distance, and determining the trend subsequence according to the corrected equivalent earth single day count value sequence, includes:
acquiring a day-to-ground distance, wherein the day-to-ground distance comprises a day-to-ground distance corresponding to a date and a day average distance;
correcting the equivalent earth single-day count value sequence according to the earth-to-date distance;
and adopting a moving average algorithm to determine a trend subsequence according to the corrected equivalent earth single-day count value sequence.
In some examples, the deriving the radiation calibration correction coefficients for correcting the historical observations of the remote sensor from the trend subsequence includes:
normalizing the trend subsequence by taking the initial element of the trend subsequence as a normalization parameter to obtain a radiation response attenuation coefficient sequence of the remote sensor;
and obtaining a radiation calibration correction coefficient for correcting the historical observation data of the remote sensor according to the radiation response attenuation coefficient sequence.
In a second aspect, the present invention also provides a radiometric calibration coefficient sequence construction system, including:
the system comprises an equivalent earth single-day count value sequence construction module, a data acquisition module and a data processing module, wherein the equivalent earth single-day count value sequence construction module is used for acquiring the earth observation data of a plurality of single-day remote sensors and determining an equivalent earth single-day count value sequence according to the earth observation data of the plurality of single-day remote sensors;
the trend subsequence construction module is used for correcting the equivalent earth single-day count value sequence according to the distance between the sun and the earth, and determining a trend subsequence according to the corrected equivalent earth single-day count value sequence;
and the radiometric calibration coefficient sequence construction module is used for obtaining radiometric calibration coefficients for correcting the historical observation data of the remote sensor according to the trend subsequence.
In some examples, the equivalent earth single day count value sequence construction module includes:
the single-day data quality identification module is used for carrying out single-day data quality identification on the observed data of the remote sensor to the ground in a single day;
the intra-day extreme data removing module is used for determining extreme data according to the single-day data quality identification and removing the extreme data from the observed data of the single-day remote sensor to the ground;
the earth single-day count value calculation module is used for calculating the average value of the observed data of the single-day remote sensor to the earth after the extreme data are removed;
a dark current count value removing module, configured to determine a dark current count value, and remove the dark current count value from the average value;
and the missing date data filling module is used for supplementing missing data to the average value of the dark current count value removed by a nearest neighbor method, and taking the supplemented average value as the equivalent earth single-day count value.
In some examples, the trend subsequence construction module includes:
the sun-earth distance correction module is used for obtaining sun-earth distances, wherein the sun-earth distances comprise sun-earth distances and sun-earth average distances corresponding to dates, and correcting the equivalent earth single-day count value sequence according to the sun-earth distances;
and the trend subsequence extraction module is used for adopting a moving average algorithm to determine a trend subsequence according to the corrected equivalent earth single-day count value sequence.
In some examples, the radiometric correction coefficient sequence construction module comprises:
the radiation response attenuation coefficient sequence calculation module is used for normalizing the trend subsequence by taking the initial element of the trend subsequence as a normalization parameter so as to obtain a radiation response attenuation coefficient sequence of the remote sensor;
and the radiation calibration coefficient correction sequence calculation module is used for obtaining the radiation calibration correction coefficient for correcting the historical observation data of the remote sensor according to the radiation response attenuation coefficient sequence.
In a third aspect, the present invention also provides an electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the radiometric calibration coefficient sequence construction method according to the first aspect when executing the computer program.
In a fourth aspect, the present invention also provides a non-transitory computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the radiometric correction coefficient sequence construction method according to the first aspect.
The above technical solutions in the embodiments of the present invention have at least one of the following technical effects:
according to the embodiment of the invention, the equivalent earth count value is used as a tracking variable for monitoring the radiation response change of the remote sensor, the trend subsequence is extracted by constructing the equivalent earth single-day count value, and the radiation calibration correction coefficient sequence is constructed, so that the correction of the radiation calibration coefficient of the remote sensing historical data is realized. Has the following advantages:
under the condition of not depending on other alternative radiometric calibration sources, the method can solve the problem of tracking the change of the remote sensor radiation response on the track based on the data observed by the remote sensor on the ground, and realize the correction of the radiometric calibration coefficient.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings that are necessary for the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention and that other drawings can be obtained from these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for constructing a radiometric calibration coefficient sequence provided by an embodiment of the present invention;
FIG. 2 is a detailed flow chart of a method for constructing a radiometric calibration coefficient sequence according to an embodiment of the present invention;
FIGS. 3A and 3B are graphs of single day statistics for different dates for a wind cloud, three-size, B star (FY 3B) visible infrared scanning radiometer (VIRR) channel 5;
FIGS. 4A and 4B are graphs of statistical frequency of a wind cloud, three, B star (FY 3B) visible infrared scanning radiometer (VIRR) channel 1;
FIG. 5 is a cumulative probability distribution plot;
FIG. 6 is a schematic diagram of a sequence of raw equivalent earth single day count values;
FIGS. 7A and 7B are schematic diagrams of equivalent Earth's single day count values after removal of the cold air field count value;
FIG. 8 is a schematic diagram of the equivalent earth single day count value sequence population result;
fig. 9A and 9B are schematic diagrams of the corrected equivalent count value of the sun-earth distance correction factor;
FIGS. 10A and 10B are schematic diagrams of trend subsequences and remaining terms;
FIG. 11 is a schematic diagram of a sequence of radiation response attenuation coefficients;
FIG. 12 is a schematic diagram of a radiometric correction coefficient sequence;
FIG. 13 is a block diagram of a system for constructing a radiometric calibration coefficient sequence in accordance with an embodiment of the present invention;
fig. 14 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.
Detailed Description
The following describes the embodiments of the present invention further with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical aspects of the present invention, and are not intended to limit the scope of the present invention.
Fig. 1 shows a flowchart of a radiometric calibration coefficient sequence construction method according to an embodiment of the present invention, and as shown in fig. 1, the radiometric calibration coefficient sequence construction method according to the embodiment of the present invention includes the following steps:
s101: and acquiring the earth observation data of a plurality of single-day remote sensors, and determining an equivalent earth single-day count value sequence according to the earth observation data of the plurality of single-day remote sensors.
In one embodiment of the invention, determining a sequence of equivalent earth single day count values from observed data of a plurality of single day remote sensors to earth comprises: carrying out single-day data quality identification on the earth observation data of the single-day remote sensor; determining extreme data according to the single-day data quality identification, and removing the extreme data from the observed data of the single-day remote sensor to the ground; calculating the average value of the observed data of the remote sensor to the ground in a single day after the extreme data are removed; determining a dark current count value and removing the dark current count value from the average value; and supplementing missing data to the average value of the dark current count value removed by a nearest neighbor method, and taking the supplemented average value as the equivalent earth single-day count value.
The manner of the embodiment of the invention is described in detail by taking a visible infrared scanning radiometer (VIRR) as an example of a satellite (such as Fengyun No. three B star (FY-3B)).
Wherein the data processing range is global earth observation data from 11 in 2010 to 5 in 2019. According to the spectrum characteristics of the ground object, selecting an atmospheric window area wave band with higher transmittance from a visible light to long wave infrared spectrum range, continuously observing the earth, and calculating the characteristic parameters of inverting various targets; and meanwhile, a data basis can be provided for the establishment of a long-time sequence satellite climate data set.
The VIRR is a 24-hour continuous earth observation working instrument throughout the day, wherein a channel 1 is a visible near infrared channel, one global jigsaw can be acquired every day, and channels 3, 4 and 5 thermal infrared channels can acquire two global jigsaw every day. The output data quantization level of the VIRR is 10 bits, and in this example, the range of output count values is 0-1023. Taking the channel 1 as an example, the processing manners of other channels are the same, and will not be described again.
The method, as shown in connection with fig. 2, comprises three steps of: and (3) constructing an equivalent earth single-day count value sequence, a trend subsequence and a radiometric calibration coefficient sequence. In the step 1, the construction of the equivalent earth single-day count value sequence comprises 5 steps, namely single-day data quality identification, intra-day extreme data removal, earth single-day count value calculation, dark current count value removal and missing date data filling. The trend subsequence construction in step 2 includes 2 steps, namely, a daily-earth distance correction and trend subsequence extraction. The construction of the radiometric calibration coefficient sequence in the step 3 comprises 2 steps of calculating the radiometric response attenuation coefficient sequence and calculating the radiometric calibration coefficient sequence. As shown in connection with fig. 2.
Equivalent earth single day count value sequence construction:
taking all earth observation data in a VIRR single day as a processing object, and judging whether the data quantity meets the statistical quality requirement; the extreme data are rejected with 0.01% and 99.99% quantiles as references; calculating an equivalent earth single-day count value; removing the dark current count value; filling invalid data values by a nearest neighbor method; and constructing an earth single-day equivalent count value sequence.
1. Single day data quality identification.
When the data is abnormal, the output count value is filled with 0; when the incident energy is too high to saturate the VIRR, the output count value is 1023. Since the output code value 0 or 1023 is an abnormal value, the observation data of 0 and 1023 are not used as daily statistics effective data. And calculating the proportion of the abnormal value to the total observed data, and if the proportion is too large, indicating that the working state of the remote sensor is abnormal on the same day, and the data has quality problems, so that the data is not needed. And taking the effective count value proportion of the 3 infrared channels of the VIRR as an auxiliary judgment quantity, wherein the date with the accumulated product of the effective count value proportion of the 3 channels higher than 0.99 is an effective date, otherwise, the date is an ineffective date, and the date data is not processed.
Specifically, the abnormal data proportion is calculated as follows:
wherein Q is the effective data proportion, DN is the VIRR output value, and Count represents the cumulative frequency.
The proportional product of 3 infrared channels was taken as the examined quantity:
Q IR ＝Q B3 Q B4 Q B5 ；
in which Q IR For the channel effective data proportion, Q B3 For the effective data proportion of channel 3, Q B4 For the effective data proportion of channel 4, Q B5 Is the effective data proportion of channel 5.
Data date identification sequence:
in the formula, flag (T) is a quality identifier of date T.
For 12 th 2010 and 4 th, the ratio of the three infrared channels of the VIRR is 0.99896,0.99748,0.99947 and the product is 0.99592, so that the day data is effective data; for data of 12/5 th 2011, the infrared channel ratio is 0.99895,0.99747,0.99062, respectively, and the date Q IR 0.98708, the day data is invalid data because the condition is not satisfied. Fig. 3A and 3B are graphs of the frequency of observation data systems for a single day on different dates of a certain satellite, respectively. Namely: for the single day statistical frequency chart of the star-B VIRR channel 5, fig. 3A is a single day statistical frequency chart of 12 months 4 days of 2010, fig. 3B is a single day statistical frequency chart of 12 months 5 days of 2010, the horizontal axis is an output count value, and the vertical axis is the cumulative occurrence frequency of the output count value on the day.
2. And removing the extreme data in the day.
The extreme anomaly data in the day comprises data points with output count values of 0 and 1023 and other obvious outliers, and the extreme data is removed by adopting a method for counting the frequency of each output count value. For the earth observation data in the day, the frequency of occurrence of each output count value (0-1023) is counted. The frequency corresponding to count values of 0 and 1023 is set to 0. The cumulative probability of each output count value is calculated, and the count value corresponding to a score of less than 0.01% or greater than 99.99% is set to 0.
Specifically, the following formula:
where Hist (DN) is the frequency of occurrences at which the VIRR channel 1 output count value equals DN.
And calculating the accumulated frequency of the code values, wherein the accumulated interval is the frequency of all the code values from the effective initial code value to DN.
Where CumSum (DN) is the cumulative frequency of VIRR channel 1 output count value less than DN.
And finally, calculating to obtain a code value distribution cumulative probability function.
Wherein P is DN The probability that the count value is less than DN is output for VIRR channel 1.
The 0.01% quantile and 99.99% quantile are calculated as:
DN 0.0001 ＝argmax(P i ＜0.0001,i∈0,1023)；
DN 0.9999 ＝argmin(P i ＞0.9999,i∈0,1023)；
in DN 0.0001 At 0.01% quantile count, DN 0.9999 Is 99.99% quantile count.
The statistics frequency of the corrected daily count value is as follows:
where Hist (DN) is the frequency of occurrences of VIRR channel 1 count value of DN.
Taking year 12 and 4 of VIRR as an example, fig. 4A and 4B are statistical frequency charts of the star VIRR channel 1 of the third star of the cloud, wherein fig. 4A is an original cumulative frequency chart, and fig. 4B is a statistical frequency chart after DN is equal to 0 and 1023 is set to 0. Namely: fig. 4A is a graph of the original cumulative frequency, and fig. 4B is a graph of the statistical frequency after DN is equal to 0 and 1023 is set to 0.
FIG. 5 is a cumulative probability distribution plot of VIRR channel 1, and by the consensus described above, the quantiles for this day were calculated as: DN (digital subscriber line) 0.0001 Equal to 10 and DN 0.9999 Equal to 811.
3. And calculating the earth single-day count value.
And calculating a data average value as an equivalent earth single-day count value based on the corrected daily statistical frequency data. The formula is as follows:
in the method, in the process of the invention,
for equivalent earth single day count value, DN' is VIRR output count value, and the value range is 0-1023.
Taking data of 12 th 2010 and 4 th data as an example, the calculated equivalent earth single day count value is equal to 149.56 after the data is removed by the extreme count value. The constructed equivalent earth single day count value sequence is shown in fig. 6, and is a schematic diagram of an original equivalent earth single day count value sequence, wherein the horizontal axis represents the on-orbit working day count of the VIRR, and the vertical axis represents the equivalent earth single day count value with 11 months and 18 days in 2010 as the starting point.
4. The dark current count value is removed.
And counting the average value of the cold air field counting value in the day, and taking the average value as the dark current counting value of the VIRR. The dark current count value is removed from the equivalent earth single day count value. The calculation formula is as follows:
in the method, in the process of the invention,
equivalent earth single day count value for removing intra-day average of cold air field count value, +.>
Is the daily average value of the cold air field count value.
Fig. 7A and fig. 7B are schematic diagrams of a daily average value sequence of cold-air field counts of the star VIRR channel No. B of the cloud, and an equivalent earth single day count value sequence distribution condition after SV removal. Fig. 7A shows a sequence diagram of the cold air count value, and fig. 7B shows a schematic diagram of the equivalent earth single day count value after the cold air count value is removed.
5. Missing date data fills in.
The missing date data adopts a nearest neighbor method, fills in the equivalent earth single day count value of the date, and constructs an equivalent earth single day count value sequence. And constructing an equivalent earth single day count value sequence by using a nearest neighbor valid data filling method aiming at the condition that the date data identifier is equal to 0 in the sequence due to the overlarge invalid proportion of the date data. The calculation formula is as follows:
in the method, in the process of the invention,
to fill in the equivalent earth single day count value after missing date data.
Fig. 8 is a schematic diagram of a sequence of a third star B VIRR channel 1 filled by a nearest neighbor method, wherein in fig. 8, dots represent original sequence data and triangles represent filled sequence data.
S102: correcting the equivalent earth single-day count value sequence according to the earth-to-date distance, and determining a trend subsequence according to the corrected equivalent earth single-day count value sequence.
In one embodiment of the present invention, the correcting the equivalent earth single day count value sequence according to the earth-to-date distance, and determining the trend subsequence according to the corrected equivalent earth single day count value sequence, includes: acquiring a day-to-ground distance, wherein the day-to-ground distance comprises a day-to-ground average distance corresponding to a date; correcting the equivalent earth single-day count value sequence according to the earth-to-date distance; and adopting a moving average algorithm to determine a trend subsequence according to the corrected equivalent earth single-day count value sequence.
Trend subsequence construction:
the revolution orbit of the earth around the sun is elliptical, and the distance between the sun and the earth shows periodic variation, so that the energy of the sun reaching the earth is influenced. Seasonal variations due to earth-of-day distances should be removed from the equivalent earth single-day count value sequence, namely: and (5) examining the equivalent reflected energy sequence of the earth under the same incident energy state. The earth rotation inclination causes seasonal variation of the earth, and cloud cover and vegetation circulate in units of years, which is a seasonal variation of the equivalent earth single-day count value. Therefore, the equivalent earth single day count value sequence can be synthesized by three subsequences, namely a trend subsequence, a seasonal subsequence and a noise subsequence.
The trend subsequence mainly reflects the attenuation condition of the radiation response of the remote sensor along with time; the seasonal subsequence mainly reflects the periodic change of global reflectivity of the earth caused by the four seasons of the earth; the noise subsequence reflects mainly the global reflectivity day-to-day random variation and the instrument's own noise conditions. In order to obtain the correction of the radiation calibration coefficient of the remote sensor, the trend subsequence is decomposed from the original sequence, so that the calibration correction coefficient can be further obtained.
1. And correcting the distance between the day and the ground.
And correcting the equivalent earth single-day count value sequence based on the day-to-ground distance and the day average distance corresponding to the date. The calculation formula is as follows:
in the method, in the process of the invention,
for the equivalent earth single day count value after correcting the distance between the sun and the earth, d is the distance between the sun and the earth at the time of the date T, < + >>
Average distance for day.
Fig. 9A and 9B are schematic diagrams of an equivalent count value sequence of the wind cloud number three B star VIRR channel 1 and a corresponding daily-ground distance correction factor sequence. Fig. 9A is a schematic diagram of a sequence of the daily distance correction factor, and fig. 9B is a schematic diagram of a sequence of equivalent count values after the daily distance correction.
2. Trend subsequence calculation.
Considering that the period of the seasonal subsequence is the number of years, the average value of the seasonal subsequence in one period is almost equal to 0, and the average value of the noise subsequence in one period is also almost equal to 0 when the noise subsequence is normally distributed, therefore, a moving average algorithm is adopted, the number of years is taken as a smooth calculation period, and the trend subsequence is calculated.
Calculating a trend subsequence of the earth single-day equivalent count value sequence according to the data calculation period of the daily data:
wherein Trend (T) Trend subsequence. The data exceeding the valid range from 183 to 183 before the end of the sequence is set to 0.
The original equivalent earth single-day count value sequence is a residual item after removing the trend subsequence, and the residual item consists of a seasonal subsequence and a noise sequence and is expressed as oscillation distribution with 365 cycles around 0 value. FIGS. 10A and 10B are schematic diagrams of trend subsequences and remaining terms of the wind cloud number three B star VIRR channel 1. Fig. 10A is a schematic diagram of a trend subsequence and an equivalent count value sequence, and fig. 10B is a schematic diagram of the remaining items (seasonal subsequence superimposed noise subsequence).
S103: and obtaining a radiation calibration correction coefficient for correcting the historical observation data of the remote sensor according to the trend subsequence.
In one embodiment of the invention, obtaining a radiometric calibration correction factor for correcting historical observations of a remote sensor from the trend subsequence comprises: normalizing the trend subsequence by taking the initial element of the trend subsequence as a normalization parameter to obtain a radiation response attenuation coefficient sequence of the remote sensor; and obtaining a radiation calibration correction coefficient for correcting the historical observation data of the remote sensor according to the radiation response attenuation coefficient sequence.
On-orbit radiation response tracking coefficient calculation:
as shown in fig. 2, the valid trend subsequence is normalized by taking the starting element of the trend subsequence as a normalization parameter (denominator), and a remote sensor radiation response attenuation coefficient sequence is obtained. Calculating a radiometric calibration coefficient sequence, and taking the reciprocal of the attenuation coefficient to obtain the radiometric calibration coefficient sequence day by day in the period from 5 months in 2011 to 11 months in 2018.
1. And (5) calculating a radiation response attenuation coefficient sequence.
Taking a trend subsequence initial element as a normalization parameter, normalizing the trend subsequence, and obtaining a remote sensor radiation response attenuation coefficient sequence, wherein the calculation formula is as follows:
where D (T) is the radiation response attenuation coefficient.
FIG. 11 is a schematic representation of the sequence of radiation response decay coefficients for the wind cloud, star B, VIRR, reflecting the decay of radiation response for VIRR channel 1 relative to the trend subsequence, day 183.
Because the radiometric calibration formula of the VIRR solar reflection channel is ρ=coef·dn, where DN is the remote sensor output count value, coef is the radiometric calibration coefficient, and ρ is the corresponding reflectivity. Given that the equivalent reflectivity of the earth corresponding to the trend subsequence has removed seasonal fluctuations and daytime noise fluctuations, the earth reflectivity is constant, and Coef is inversely related to DN. Therefore, the inverse of the attenuation coefficient sequence is the radiation calibration correction coefficient sequence, and the calculation formula is as follows:
where CoefCorr (T) radiation is used to scale the correction coefficient.
Fig. 12 is a schematic diagram of a radiometric calibration coefficient sequence finally obtained in the scheme, and using these data, the radiometric calibration coefficients of the star B VIRR No. three of the wind cloud can be calibrated day by day during the period from 5 months 2011 to 11 months 2018.
According to the method for constructing the radiometric calibration correction coefficient sequence, disclosed by the embodiment of the invention, the equivalent earth count value is used as a tracking variable for monitoring the change of the radiation response of the remote sensor, and the radiometric calibration correction coefficient sequence is constructed by constructing the equivalent earth single-day count value, extracting the trend subsequence and realizing the correction of the radiometric calibration coefficient of the remote sensing historical data. Has the following advantages:
the method can obtain a historical data sequence of remote sensor radiometric calibration correction coefficients, correct the radiometric calibration coefficients day by day, and obtain the result trend consistency through comparing the calibration coefficient attenuation results of the multi-field method, thereby providing effective verification for construction of remote sensing historical data rescaling data sets.
Fig. 13 is a block diagram of a radiometric correction coefficient sequence construction system in accordance with one embodiment of the present invention. As shown in fig. 13, the radiometric correction coefficient sequence construction system according to one embodiment of the present invention comprises: an equivalent earth single day count value sequence construction module 1310, a trend subsequence construction module 1320, and a radiometric calibration coefficient sequence construction module 1330.
The equivalent earth single-day count value sequence construction module 1310 is configured to obtain earth observation data of a plurality of single-day remote sensors, and determine an equivalent earth single-day count value sequence according to the earth observation data of the plurality of single-day remote sensors; the trend subsequence construction module 1320 is configured to correct the equivalent earth single-day count value sequence according to the earth-to-date distance, and determine a trend subsequence according to the corrected equivalent earth single-day count value sequence; the radiometric calibration coefficient sequence construction module 1330 is configured to obtain radiometric calibration coefficients for calibrating historical observations of the remote sensor based on the trend subsequence.
In one embodiment of the present invention, the equivalent earth single day count value sequence construction module 1310 includes: the single-day data quality identification module is used for carrying out single-day data quality identification on the observed data of the remote sensor to the ground in a single day; the intra-day extreme data removing module is used for determining extreme data according to the single-day data quality identification and removing the extreme data from the observed data of the single-day remote sensor to the ground; the earth single-day count value calculation module is used for calculating the average value of the observed data of the single-day remote sensor to the earth after the extreme data are removed; a dark current count value removing module, configured to determine a dark current count value, and remove the dark current count value from the average value; and the missing date data filling module is used for supplementing missing data to the average value of the dark current count value removed by a nearest neighbor method, and taking the supplemented average value as the equivalent earth single-day count value.
In one embodiment of the present invention, the trend subsequence construction module 1320 includes: the sun-earth distance correction module is used for obtaining sun-earth distances, wherein the sun-earth distances comprise sun-earth distances and sun-earth average distances corresponding to dates, and correcting the equivalent earth single-day count value sequence according to the sun-earth distances; and the trend subsequence extraction module is used for adopting a moving average algorithm to determine a trend subsequence according to the corrected equivalent earth single-day count value sequence.
In one embodiment of the present invention, the radiometric correction coefficient sequence construction module 1330 includes: the radiation response attenuation coefficient sequence calculation module is used for normalizing the trend subsequence by taking the initial element of the trend subsequence as a normalization parameter so as to obtain a radiation response attenuation coefficient sequence of the remote sensor; and the radiation calibration coefficient correction sequence calculation module is used for obtaining the radiation calibration correction coefficient for correcting the historical observation data of the remote sensor according to the radiation response attenuation coefficient sequence.
The system for constructing the radiometric calibration coefficient sequence in the embodiment of the invention utilizes the equivalent earth count value as a tracking variable for monitoring the change of the radiation response of the remote sensor, and extracts a trend subsequence to construct the radiometric calibration coefficient sequence by constructing the equivalent earth single-day count value, thereby realizing the calibration of the radiometric calibration coefficient of the remote sensing historical data. Has the following advantages:
the method can obtain a historical data sequence of remote sensor radiometric calibration correction coefficients, correct the radiometric calibration coefficients day by day, and obtain the result trend consistency through comparing the calibration coefficient attenuation results of the multi-field method, thereby providing effective verification for construction of remote sensing historical data rescaling data sets.
It should be noted that, a specific implementation manner of the radiometric calibration correction coefficient sequence construction system according to the embodiment of the present invention is similar to a specific implementation manner of the radiometric calibration correction coefficient sequence construction method according to the embodiment of the present invention, and specific please refer to the description of the method section, so that redundancy is reduced, and redundant description is omitted.
Based on the same inventive concept, a further embodiment of the present invention discloses an electronic device, see fig. 14, comprising in particular: a processor 1401, a memory 1402, a communication interface 1403, and a communication bus 1404;
wherein the processor 1401, the memory 1402, and the communication interface 1403 perform communication with each other through the communication bus 1404; the communication interface 1403 is used for implementing information transmission between devices;
the processor 1401 is configured to invoke a computer program in the memory 1402, where the processor implements all the steps of the radiometric correction coefficient sequence construction method described above when executing the computer program, for example, where the processor implements the following steps when executing the computer program: acquiring earth observation data of a plurality of single-day remote sensors, and determining an equivalent earth single-day count value sequence according to the earth observation data of the plurality of single-day remote sensors; correcting the equivalent earth single-day count value sequence according to the earth-to-date distance, and determining a trend subsequence according to the corrected equivalent earth single-day count value sequence; and obtaining a radiation calibration correction coefficient for correcting the historical observation data of the remote sensor according to the trend subsequence.
Based on the same inventive concept, a further embodiment of the present invention provides a non-transitory computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements all the steps of the radiometric calibration coefficient sequence construction method described above, for example, the processor implementing the following steps when executing the computer program: acquiring earth observation data of a plurality of single-day remote sensors, and determining an equivalent earth single-day count value sequence according to the earth observation data of the plurality of single-day remote sensors; correcting the equivalent earth single-day count value sequence according to the earth-to-date distance, and determining a trend subsequence according to the corrected equivalent earth single-day count value sequence; and obtaining a radiation calibration correction coefficient for correcting the historical observation data of the remote sensor according to the trend subsequence.
Further, the logic instructions in the memory described above may be implemented in the form of software functional units and stored in a computer-readable storage medium when sold or used as a stand-alone product. Based on this understanding, the technical solution of the present invention may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution, in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a personal computer, a server, a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
The apparatus embodiments described above are merely illustrative, wherein the elements illustrated as separate elements may or may not be physically separate, and the elements shown as elements may or may not be physical elements, may be located in one place, or may be distributed over a plurality of network elements. Some or all of the modules can be selected according to actual needs to achieve the purpose of the embodiment of the invention. Those of ordinary skill in the art will understand and implement the present invention without undue burden.
From the above description of the embodiments, it will be apparent to those skilled in the art that the embodiments may be implemented by means of software plus necessary general hardware platforms, or of course may be implemented by means of hardware. Based on such understanding, the foregoing technical solution may be embodied essentially or in a part contributing to the prior art in the form of a software product, which may be stored in a computer readable storage medium, such as a ROM/RAM, a magnetic disk, an optical disk, etc., and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the index monitoring method described in the respective embodiments or some parts of the embodiments.
Furthermore, in the description herein, reference to the terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (6)
1. A method of radiometric calibration coefficient sequence construction comprising:
acquiring earth observation data of a plurality of single-day remote sensors, and determining an equivalent earth single-day count value sequence according to the earth observation data of the plurality of single-day remote sensors; the determining the equivalent earth single-day count value sequence according to the observed data of the plurality of single-day remote sensors to the earth comprises the following steps:
carrying out single-day data quality identification on the earth observation data of the single-day remote sensor;
determining extreme data according to the single-day data quality identification, and removing the extreme data from the observed data of the single-day remote sensor to the ground;
calculating the average value of the observed data of the remote sensor to the ground in a single day after the extreme data are removed;
determining a dark current count value and removing the dark current count value from the average value;
supplementing missing data to the average value of the dark current count value removed by a nearest neighbor method, and taking the supplemented average value as the equivalent earth single-day count value sequence;
correcting the equivalent earth single-day count value sequence according to the earth-to-date distance, and determining a trend subsequence according to the corrected equivalent earth single-day count value sequence; the correcting the equivalent earth single-day count value sequence according to the earth-to-date distance, and determining a trend subsequence according to the corrected equivalent earth single-day count value sequence, comprising: acquiring a day-to-ground distance, wherein the day-to-ground distance comprises a day-to-ground distance corresponding to a date and a day average distance;
correcting the equivalent earth single-day count value sequence according to the earth-to-date distance; adopting a moving average algorithm to determine a trend subsequence according to the corrected equivalent earth single-day count value sequence;
and obtaining a radiation calibration correction coefficient for correcting the historical observation data of the remote sensor according to the trend subsequence.
2. The method of claim 1, wherein the obtaining the radiometric calibration correction coefficients for correcting the historical observations of the remote sensor from the trend subsequence comprises:
normalizing the trend subsequence by taking the initial element of the trend subsequence as a normalization parameter to obtain a radiation response attenuation coefficient sequence of the remote sensor;
and obtaining a radiation calibration correction coefficient for correcting the historical observation data of the remote sensor according to the radiation response attenuation coefficient sequence.
3. A radiometric correction coefficient sequence construction system comprising:
the system comprises an equivalent earth single-day count value sequence construction module, a data acquisition module and a data processing module, wherein the equivalent earth single-day count value sequence construction module is used for acquiring the earth observation data of a plurality of single-day remote sensors and determining an equivalent earth single-day count value sequence according to the earth observation data of the plurality of single-day remote sensors; the equivalent earth single-day count value sequence construction module comprises:
the single-day data quality identification module is used for carrying out single-day data quality identification on the observed data of the remote sensor to the ground in a single day;
the intra-day extreme data removing module is used for determining extreme data according to the single-day data quality identification and removing the extreme data from the observed data of the single-day remote sensor to the ground;
the earth single-day count value calculation module is used for calculating the average value of the observed data of the single-day remote sensor to the earth after the extreme data are removed;
a dark current count value removing module, configured to determine a dark current count value, and remove the dark current count value from the average value;
the missing date data filling module is used for supplementing missing data to the average value of the dark current count value removed by a nearest neighbor method, and taking the supplemented average value as the equivalent earth single-day count value sequence;
the trend subsequence construction module is used for correcting the equivalent earth single-day count value sequence according to the distance between the sun and the earth, and determining a trend subsequence according to the corrected equivalent earth single-day count value sequence; the trend subsequence construction module comprises:
the sun-earth distance correction module is used for obtaining sun-earth distances, wherein the sun-earth distances comprise sun-earth distances and sun-earth average distances corresponding to dates, and correcting the equivalent earth single-day count value sequence according to the sun-earth distances;
the trend subsequence extraction module is used for adopting a moving average algorithm to determine a trend subsequence according to the corrected equivalent earth single-day count value sequence;
and the radiometric calibration coefficient sequence construction module is used for obtaining radiometric calibration coefficients for correcting the historical observation data of the remote sensor according to the trend subsequence.
4. A radiometric correction coefficient sequence construction system as claimed in claim 3 wherein said radiometric correction coefficient sequence construction module comprises:
the radiation response attenuation coefficient sequence calculation module is used for normalizing the trend subsequence by taking the initial element of the trend subsequence as a normalization parameter so as to obtain a radiation response attenuation coefficient sequence of the remote sensor;
and the radiation calibration coefficient correction sequence calculation module is used for obtaining the radiation calibration correction coefficient for correcting the historical observation data of the remote sensor according to the radiation response attenuation coefficient sequence.
5. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the radiometric correction coefficient sequence construction method according to any one of claims 1 to 2 when executing the computer program.
6. A non-transitory computer readable storage medium having stored thereon a computer program, characterized in that the computer program, when executed by a processor, implements a radiometric correction coefficient sequence construction method according to any of claims 1 to 2.
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