Method and apparatus for measuring atmospheric parameters to estimate air quality and climate variables

Abstract

The present invention relates to a method and a device for measuring at least one atmospheric parameter (gas, temperature), which implement the following steps: obtaining a spectral image in the ultraviolet and / or visible and / or infrared range according to the tomography principle and performing a scan. The spectral image is obtained using a network of optical systems (1A to 1D) such as infrared cameras, and is used to estimate the air quality and / or meteorological parameters and / or climate parameters in a geographical area (such as an urban agglomeration).

Description

Technical Field

[0001] The present invention relates to the field of measuring atmospheric parameters, particularly for the purpose of monitoring, predicting, and managing air quality. Background Art

[0002] Techniques for allowing the monitoring of air quality are known for measuring the concentration of pollutants in air samples collected by measurement stations. For example, the French territory is equipped with several hundred stations of this type. However, such measurement stations constitute an expensive infrastructure, and their density is relatively low over the territory.

[0003] Air samples thus collected are generally used to estimate air quality using numerical chemical transport models. These numerical models require a large amount of computing time, which results in a limitation on the number of measurement stations implemented in the geographical area and / or area of interest being studied.

[0004] In doing so, in order to estimate pollution levels at a fine spatial scale, it is necessary to resort to techniques for smoothing and propagating measurement data.

[0005] Such techniques result in an underestimation of pollution levels and more generally lead to a dissatisfactory quality of the analysis and prediction brought about by these techniques. Summary of the Invention

[0006] The object of the present invention is to overcome the above-mentioned drawbacks by proposing a method and device capable of improving the quality of the analysis and prediction of air quality while reducing the cost of the infrastructure and its implementation.

[0007] To this end, according to a first aspect, the present invention relates to a method for measuring at least one atmospheric parameter, comprising an acquisition step and a scanning step as defined below.

[0008] In the acquisition step, a series of spectral images of the Earth's atmosphere are acquired simultaneously using an optical system, particularly a multispectral optical system operating in the wavelength range from ultraviolet to infrared. For example, these optical systems may be imagers and / or radiometers and / or spectral imagers and / or spectral radiometers.

[0009] The term "spectral image" or "spectrometric image" refers to an image that is generally a matrix comprising N*M pixels, where N≥1 and M≥1. For example, in the specific case of acquiring an image using a radiometer, N and M may each be equal to 1, such that this image comprises a single pixel.

[0010] On the one hand, the optical system implemented in the method according to the present invention is located in the Earth's atmosphere and is fixed relative to the Earth coordinate system.

[0011] On the other hand, the optical systems implemented in this method are oriented such that the spectral images they acquire contain measurement data of the at least one atmospheric parameter along the respective lines of sight of the optical systems.

[0012] On the other hand, these optical systems are arranged such that during the acquisition step, there is at least one intersection point between two lines of sight, such that two spectral images acquired simultaneously along these two lines of sight contain mutual measurement data of at least one atmospheric parameter, and these mutual measurement data represent at least one atmospheric parameter at the point of the Earth's atmosphere corresponding to the intersection point.

[0013] According to the present invention, the orientation of the optical systems is changed during the scanning step, and the acquisition and scanning steps are repeated in order to acquire a series of spectral image series, and these spectral image series include a set of mutual measurement data representing at least one atmospheric parameter at a set of points of the Earth's atmosphere.

[0014] This method allows the measurement of atmospheric parameters to be carried out using inexpensive infrastructure and improves the quality of the analysis and prediction of air quality, especially on the scale of relatively small geographical areas (such as urban agglomerations).

[0015] As a non-limiting example, at least one atmospheric parameter may be selected from atmospheric temperature and / or at least one atmospheric gas having characteristics in ultraviolet and / or visible and / or infrared, such as O 3 , NO 2 , SO 2 , CO, PM1, PM2.5, PM10, H 2 O, CO 2 , CH 4 , N 2 O or NH 3 .

[0016] In fact, the optical systems of the present invention allow the measurement of scientific parameters of interest that comply with regulations (such as O 3 , NO 2 , SO 2 , CO; fine particles PM1, PM2.5, PM10) and / or comply with recurring pollution peaks (such as O 3 , NO 2 , PM2.5, PM10), as well as supplementary products (such as meteorological fields (such as T, H 2 O)), greenhouse gases (such as CO 2 , CH 4 , N 2 O), for example, fire markers in forests (such as SO 2 , CO) or even agricultural pollutants (such as NH 3 ).

[0017] In one embodiment, during the scanning step, the orientation of the optical system can be changed such that between the acquisition step before this scanning step and the acquisition step after this scanning step, the at least one intersection point passes from a first geographical coordinate to a second geographical coordinate, which is different from the first geographical coordinate in terms of longitude and / or latitude and / or altitude.

[0018] According to a second aspect, the invention also relates to a method for studying at least one atmospheric parameter implementing the measurement method described above.

[0019] Preferably, such a method for studying at least one atmospheric parameter can further include a step of analyzing the acquired spectral images. This analysis step preferably includes a step of inverting the spectral images using at least a part of a set of mutually measured data included in these spectral images.

[0020] According to a third aspect, the invention also relates to a device for measuring at least one atmospheric parameter. This device includes a network of optical systems, which are arranged to implement the method for measuring at least one atmospheric parameter as described above.

[0021] As described above, the optical system can be an imager and / or a radiometer and / or a spectral imager and / or a spectral radiometer. In other words, the optical system can be an infrared camera.

[0022] The distance between two adjacent optical systems can generally be included between 10 m and 20 km, preferably between 2 km and 5 km, and more preferably equal to 3 km.

[0023] According to a first variant, the optical system can be fastened to a corresponding support fixed to the ground, such as a tower, a building, a water tower or even a tethered balloon.

[0024] Thus, the existing infrastructure can be utilized.

[0025] According to a second variant, the optical system can be loaded on one or more stationary aircraft, such as drones or atmospheric balloons.

[0026] According to a fourth aspect, the invention also relates to using the method and / or device described above for estimating the air quality and / or meteorological parameters and / or climate parameters of a geographical area, the range of which preferably includes between 100 m and 100 km. Without limitation, this geographical area can be an urban agglomeration, an industrial site, a forest or an agricultural site.

[0027] Thus, the present invention allows for the construction of a ground-based remote sensing tomography network capable of measuring the quality of urban air at the residential scale. For example, such a solution allows users or residents to know their personal exposure to air pollutants due to reliable and continuous measurements carried out at the local scale. Description of the Drawings

[0028] Other features and advantages of the present invention will become apparent upon reading the following non-limiting description and the drawings, in which:

[0029] Figure 1 The network of optical systems in a first configuration according to the present invention is schematically represented;

[0030] Figure 2 The network of optical systems in a second configuration is shown. Figure 1 of the optical system.

[0031] In all the drawings, the same elements are identified by the same reference numerals. Detailed Description

[0032] The present invention relates to a device and a method for measuring at least one atmospheric parameter, which implement the step of simultaneously acquiring a series of spectral images of the Earth's atmosphere using an optical system.

[0033] (Multiple) atmospheric parameters can be composed, for example, of any combination of atmospheric gases having characteristics in the ultraviolet and / or infrared (such as O 3 , NO 2 , SO 2 , CO, PM1, PM2.5, PM10, H 2 O, CO 2 , CH 4 , N 2 O, NH 3 ). Another example of an atmospheric parameter is atmospheric temperature.

[0034] The acquisition step is schematically shown in Figure 1 .

[0035] Figure 1 A network of four optical systems 1A to 1D is shown. These optical systems 1A to 1D are generally cameras (such as imagers, radiometers, spectral imagers or spectral radiometers) capable of acquiring spectral images in the wavelength range from ultraviolet to infrared.

[0036] Optical systems 1A to 1D are located in the Earth's atmosphere and are fixed relative to the Earth coordinate system R1. The term "fixed optical system" refers to an optical system having a relative position with respect to the Earth coordinate system R1, which is invariant during the implementation of the method of the present invention, regardless of the orientation of these optical systems that can change during the implementation of the method of the present invention.

[0037] For this purpose, optical systems 1A to 1D can be mounted on corresponding supports fixed to the ground, such as towers, buildings, water towers or even moorings. Preferably, these supports have power and / or Internet in order to supply power to the optical systems. The device can also include a power supply device of the solar cell type and / or a wifi connection device (such as 3G or 4G), and / or any other type of remote connection device.

[0038] Alternatively, optical systems 1A to 1D can be loaded on one or more stationary aircraft, such as drones or atmospheric balloons.

[0039] As a non-limiting example, the distance between two adjacent optical systems can be about 3 km. More generally, depending on the geographical area to be studied, this distance can be included between 10 m and 20 km. Of course, the distance between each pair of adjacent optical systems can be the same or different. In Figure 1 the example, the distance between optical systems 1A and 1B is the same as the distance between optical systems 1B and 1C and the distance between optical systems 1C and 1D.

[0040] Reference Figure 1 , optical systems 1A to 1D are oriented such that the spectral images they acquire contain measurement data of at least one atmospheric parameter along the corresponding lines of sight 2A1 to 2D1 of these optical systems 1A to 1D.

[0041] In other words, each of optical systems 1A to 1D corresponds to a corresponding line of sight 2A1 to 2D1, along which each of these optical systems 1A to 1D obtains a spectral image or a series of spectral images. In particular, optical system 1A acquires a spectral image or a series of spectral images along line of sight 2A1, optical system 1B acquires a spectral image or a series of spectral images along line of sight 2B1, etc. (see Figure 1 ).

[0042] During the acquisition step, in the Figure 1 configuration shown, optical systems 1A to 1D are arranged such that there is at least one intersection between two lines of sight. In this example, there is at least one intersection I1 between lines of sight 2A1 and 2B1, and there is at least one intersection I2 between lines of sight 2C1 and 2D1.

[0043] This arrangement allows the optical systems 1A and 1B to simultaneously acquire two spectral images along the lines of sight 2A1 and 2B1. These two spectral images contain mutual measurement data of at least one atmospheric parameter. These mutual measurement data represent at least one atmospheric parameter at a point in the Earth's atmosphere (in this case corresponding to the intersection point I1).

[0044] Similarly, this arrangement allows the optical systems 1C and 1D to simultaneously acquire two spectral images along the lines of sight 2C1 and 2D1. These two spectral images contain mutual measurement data of at least one atmospheric parameter. These mutual measurement data represent at least one atmospheric parameter at a point in the Earth's atmosphere (in this case corresponding to the intersection point I2).

[0045] Thus, during the acquisition step in the configuration shown in Figure 1 an acquisition includes a first series of two spectral images, this series of spectral images including a set of mutual measurement data representing at least one atmospheric parameter at a set of two points in the Earth's atmosphere corresponding to the intersection points I1 and I2.

[0046] According to the tomography principle, due to the implementation of the scanning step, the present invention allows the acquisition of a succession of series of spectral images.

[0047] The scanning step includes changing the orientation of the optical systems 1A to 1D shown by changing the orientation of the lines of sight associated with these optical systems between the configuration of Figure 1 and the configuration of Figure 2 According to the present invention, this acquisition and scanning step is continuously repeated in order to acquire a succession of series of spectral images, these series of spectral images including a set of mutual measurement data representing at least one atmospheric parameter at a set of points in the Earth's atmosphere.

[0048] In the example of

[0049] and Figure 1 and Figure 2 after acquiring two spectral images in the configuration shown in Figure 1 and then changing the orientation of the optical systems 1A to 1D to achieve the configuration shown in Figure 2 the acquisition step is carried out in the configuration of Figure 2 More precisely, in the configuration of

[0050] the optical systems 1A to 1D are arranged such that there is an intersection point I3 between the lines of sight 2A2 and 2B2, there is an intersection point I4 between the lines of sight 2C2 and 2D2, and there is an intersection point I5 between the lines of sight 2A2 and 2D2. In the configuration of Figure 2 the lines of sight 2A2, 2B2, 2C2 and 2D2 respectively correspond to the optical systems 1A, 1B, 1C and 1D. Figure 2 ​

[0051] In this arrangement, two spectral images can thus be acquired simultaneously along the lines of sight 2A2 and 2B2 containing mutual measurement data of at least one atmospheric parameter. These mutual measurement data represent at least one atmospheric parameter at a point corresponding to the intersection point I3 of the Earth's atmosphere.

[0052] Figure 2 The arrangement shown in also allows two spectral images to be acquired simultaneously along the lines of sight 2C2 and 2D2 containing mutual measurement data of at least one atmospheric parameter. These mutual measurement data represent at least one atmospheric parameter at a point corresponding to the intersection point I4 of the Earth's atmosphere.

[0053] Furthermore, in this configuration, the two spectral images acquired by the optical systems 1A and 1D along the lines of sight 2A2 and 2D2 also contain mutual measurement data representing at least one atmospheric parameter at a point corresponding to the intersection point I5 of the Earth's atmosphere.

[0054] Thus, in Figure 2 The acquisition step carried out under the configuration shown in allows the acquisition of a second series of two spectral images, the two spectral images of this second series including a set of mutual measurement data representing at least one atmospheric parameter at a set of three points corresponding to the intersection points I3, I4, and I5 of the Earth's atmosphere.

[0055] This continuous repetition of the acquisition and scanning steps can be implemented such that the set of mutual measurement data represents at least one atmospheric parameter at a set of points of the Earth's atmosphere located in a substantially horizontal plane and / or a substantially vertical plane and / or the volume of the Earth's atmosphere.

[0056] To this end, the orientation of the optical systems 1A to 1D during the scanning step can be changed such that from the acquisition step before this scanning step to the acquisition step after this scanning step, one or more intersection points each pass from a first geographical coordinate to a second geographical coordinate, this second geographical coordinate being different from the first geographical coordinate in terms of longitude and / or latitude and / or altitude.

[0057] The density of the lines of sight and intersection points (that is, the number of repetitions of the acquisition and scanning steps and the spacing or increment of the orientation angles of the optical systems) can be adjusted according to the topology of the region of interest, the desired horizontal and vertical resolutions, the density of the optical systems, and / or the optical level of each spectral band or channel of each optical system.

[0058] The optical systems are preferably arranged in an elevated position, that is, in a configuration that maximizes the geometric level.

[0059] In an exemplary embodiment, the optical systems 1A to 1D are mounted on a robotic turntable (not shown), allowing these optical systems to be oriented at angles including between -180° and +180° in the longitude direction and including between 0° and +90° in the latitude direction. The latitude angle is counted positively towards the zenith relative to the horizontal line on the ground. Such an embodiment allows scanning of the upper hemisphere.

[0060] In another embodiment, the latitude angle may include between -90° and +90° so as to also scan the lower hemisphere, and thus evaluate the possible contribution of the measured values of surface reflectance and its incidence in radiative transfer (direct modeling) and inversion (see below).

[0061] Any type of scan may be considered without departing from the scope of the present invention, and the foregoing exemplary embodiments are in no way restrictive.

[0062] The present invention allows the study of atmospheric parameters by analyzing spectral images acquired according to the principles described above.

[0063] To this end, a preferred analysis step is implemented, including a step of inverting the spectral image by using at least a part of the mutual measurement data sets included in these spectral images.

[0064] The analysis may be implemented using Bayesian multi-line-of-sight inversion software.

[0065] To take into account the temporal evolution of at least one atmospheric parameter, the analysis may be implemented sequentially by operating abnormally between time t and time t - 1h. For example, a prediction may be provided by the field calculated for the gas at t - 1h and the estimation performed for complementary products of the meteorological field type (such as T and H 2 O) at t. The initial prediction may be derived from the analysis or prediction performed by a meteorological center for the geographical area under study.

[0066] Sequential time processing allows elimination of a part of the evolution of geophysical variables (atmospheric variables or characteristics of the reflecting surface), and thus maintains a linear direct model. It also allows a significant acceleration of the calculation time.

[0067] Of course, the present invention is not limited to the specific examples just described, and those skilled in the art will be able to make any adjustments or implement additional steps or features without departing from the scope of the present invention.

[0068] Thus, a camera calibration step may be implemented, for example, using a light emitter whose spectrum is well characterized (radiometric calibration), or even using a black and white target with a predetermined geometric pattern (geometric calibration).

[0069] Among other advantages, the present invention allows:

[0070] - Estimate air quality with a residential spatio-temporal measurement resolution of less than 250 m / h,

[0071] - Generate research results in real time through direct measurement rather than digital models, with an accuracy in the range of 15 to 25%,

[0072] - Completely cover the urban agglomeration with a network of measurement stations that is 400 times denser than the existing network density,

[0073] - Implement a three-dimensional characterization of the atmosphere,

[0074] - Obtain complementary products (such as meteorological fields (e.g., T, H 2 O)), greenhouse gases (e.g., CO 2 , CH 4 , N 2 O), fire markers in forests (e.g., SO 2 , CO) or even agricultural pollutants (e.g., NH 3 ).

[0075] The application fields of the present invention are numerous and particularly include local and continuous monitoring of the air quality in cities, such as monitoring industrial sites by targeting greenhouse gases, monitoring the safety of residents through detecting forest fires, agriculture, infrared thermal imaging of buildings, land development, and monitoring health by studying the correlation between pollution and disease prevalence, etc.

Claims

1. A method for measuring at least one atmospheric parameter selected from atmospheric temperature and / or at least one atmospheric gas having characteristics in the ultraviolet and / or visible and / or infrared ranges, characterized in that the method comprises: an acquisition step, in which a series of spectral images of the Earth's atmosphere are simultaneously acquired using a plurality of multispectral optical systems operating in a wavelength range from ultraviolet to infrared, the multispectral optical systems: being located in the Earth's atmosphere, being fixed relative to the Earth coordinate system, being oriented such that the spectral images acquired by the multispectral optical systems contain measurement data of the at least one atmospheric parameter along the respective lines of sight of the multispectral optical systems, being arranged such that during this acquisition step, there is at least one intersection point between two lines of sight, such that two spectral images acquired simultaneously along these two lines of sight contain mutual measurement data of the at least one atmospheric parameter, and these mutual measurement data represent the at least one atmospheric parameter at the point of the Earth's atmosphere corresponding to the intersection point, a scanning step, in which the orientation of the multispectral optical systems is changed, and in which the acquisition step and the scanning step are repeated in order to acquire a series of spectral image series, which includes a set of mutual measurement data representing the at least one atmospheric parameter at a set of points in the Earth's atmosphere.

2. The method according to claim 1, characterized in that At least one atmospheric gas is O 3 , NO 2 , SO 2 , CO, PM1, PM2.5, PM10, H 2 O, CO 2 , CH 4 , N 2 O or NH 3 .

3. The method according to claim 1 or 2, characterized in that during the scanning step, the orientation of the multispectral optical systems is changed such that between the acquisition step before this scanning step and the acquisition step after this scanning step, the at least one intersection point is transferred from a first geographical coordinate to a second geographical coordinate, and this second geographical coordinate is different from the first geographical coordinate in terms of longitude and / or latitude and / or altitude.

4. A method for studying at least one atmospheric parameter, characterized in that the method implements the measurement method according to any one of claims 1 - 3, and in which the method for studying at least one atmospheric parameter further comprises a step of analyzing the acquired spectral images, and this analysis step includes a step of inverting the spectral images using at least a part of the set of mutual measurement data contained in these spectral images.

5. A device for measuring at least one atmospheric parameter, characterized in that the device comprises a network of multispectral optical systems arranged to implement the method according to any one of claims 1 to 3, wherein the multispectral optical systems are adapted to operate in a wavelength range from ultraviolet to infrared, and wherein the network of multispectral optical systems includes a plurality of multispectral optical systems, the multispectral optical systems: being located in the Earth's atmosphere, being fixed relative to the Earth coordinate system, being oriented such that the spectral images acquired by the multispectral optical systems contain measurement data of the at least one atmospheric parameter along the respective lines of sight of the multispectral optical systems.

6. The device according to claim 5, characterized in that the distance between two adjacent multispectral optical systems is between 10 m and 20 km.

7. The device according to claim 5 or 6, characterized in that the multispectral optical system is fastened to a corresponding support fixed to the ground.

8. The device according to claim 5 or 6, characterized in that the multispectral optical system is mounted on one or more stationary aircraft.

9. The device according to claim 5 or 6, characterized in that the multispectral optical system is an imager and / or a radiometer.

10. The device according to claim 5, characterized in that the distance between two adjacent multispectral optical systems is between 2 km and 5 km.

11. Use of a method according to any one of claims 1 to 4 or a device according to any one of claims 5 to 9 for estimating the air quality and / or meteorological parameters and / or climate parameters of a geographical area having a range between 100 m and 100 km.

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