Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01W—METEOROLOGY
  • G01W1/00—Meteorology
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01W—METEOROLOGY
  • G01W1/00—Meteorology
  • G01W1/02—Instruments for indicating weather conditions by measuring two or more variables, e.g. humidity, pressure, temperature, cloud cover or wind speed

Definitions

• the present invention relates to a bioclimatological station intended to allow the in-situ establishment of the energy balance of a plant cover to determine in particular its water needs.
• Certain meteorological stations make it possible to calculate the potential evapotranspiration or FTE of a plant cover from sensors which measure in particular the solar radiation, the temperature and the relative humidity of the air, and the wind speed, knowing that by evapotranspiration one must hear the evaporation of the soil and the transpiration of the plant.
• these stations tend to determine the potential of air to take water from the soil, that is to say the maximum amount of water that could be drawn from the soil / plant system. Concretely, these stations simply aim to limit the waste that can result from intensive watering.
• Some manufacturers of automatic sprinkler systems also supply small stations, essentially equipped with a rain gauge and humidity probes, but they are also intended to avoid wasting water.
• stations were first designed on an experimental basis in laboratories, but these stations then proved to be unusable on an industrial level. Then, thanks to advances in technology, it has been possible to design detection and measurement devices that can be used on an industrial scale in order to be able to achieve bioclimatological stations making it possible to establish an energy balance.
• the stations currently in existence do not allow the actual water requirements of a plant cover to be determined with sufficient precision and at a suitable cost.
• the object of the invention is therefore to design, develop and industrialize a bioclimatological station which makes it possible in particular to calculate the actual evapotranspiration of a plant cover and to provide a set of information to respond in a precise manner to at least two questions: how much water to bring to the plant cover and when to bring this water taking into account in particular the hydric state of the soil.
• the invention proposes a bioclimatological station intended to allow the in-situ establishment of the energy balance of a plant cover to determine in particular its water needs, this energy balance being established on the basis of parameters measured by a set of sensors which equip the station and of processing software executed by a central unit connected to all the sensors and to means for transmitting signals to a control station, this station comprising at least: a pyrradiometer located at a height determined above the plant cover to measure the net solar radiation which is the difference between the incident radiation and the radiation reflected by the ground,
• each device comprising a temperature sensor and a relative humidity sensor placed one next to the other and subjected to the flow of air from a fan, these two devices being carried by movable arms for carrying out measurements at different heights according to the principle of double weighing, and - a rain gauge, said station further comprising autonomous means of supplying electrical energy , consisting of solar panels connected to an energy storage battery, these means being sufficient to ensuring the supply and operation of the station.
• the above anemometer is located at the same height as the pyrradiometer to measure the wind speed and provide a correction factor to the output signal from the pyrradiometer when the wind speed is low.
• the pyrradiometer is located at a height of the order of 1.20 m above the plant cover and with an exposure to the south to obtain good accuracy on the measurements then not influenced by the structure of the station.
• the anemometer comprises fins which are integral with a vertical rotary shaft whose two ends have the shape of a point to limit the frictional forces at the bearings which support the shaft in rotation, and thus have a very low triggering threshold which makes it possible to detect a very low wind speed.
• the station can include three anemometers which are respectively located at heights of the order of 0.40 - 1.20 and 2.00 m above the plant cover to establish a precise curve of the wind profile.
• each air temperature sensor is constituted by a deposit of metal on an insulating substrate to form a resistor whose value varies with the temperature, and the different temperature sensors used are advantageously supplied from the same current source.
• each relative air humidity sensor is constituted by a capacitor whose capacity varies with the humidity of the air, this capacitor being for example connected in series with a resistor fixed value to form an RC circuit whose frequency variations are measured.
• the devices for measuring the temperature and the humidity of the air are used to make various measurements over a height of between 0.20 and 2.00 m above the plant cover.
• a third fixed device for measuring the temperature and the humidity of the air is placed in a shelter of the weather type located approximately 2.00 m above the plant cover, this shelter being able to contain the means of transmitting signals to the control station, these means being for example constituted by a radio-modem system.
• the station can also be equipped with a system for determining the hydric state of the soil which comprises a device for measuring the dryness index of the soil and which consists of two electrodes inserted in the ground, an alternating current source and a device for measuring the induced voltage between the two electrodes, and two sensors temperature sunk into the ground at two different depths, these different elements can be associated with a flow meter to also know the energy state of the soil and apprehend energy transfers.
• the station can be equipped with a height sensor to automatically slave the height of the station to the height of the plant cover.
• the station can remain fixed, but by using the height sensor, a correction can be made automatically as a function of the height reached by the plant cover, for example when the latter is turf.
• electric motors are used rather than cylinders to control the position of the arms which carry the devices for measuring the temperature and humidity of the air, and to possibly elevate the station according to the height reached by the plant cover.
• control station which communicates with the station can be used as a decision-aid tool for the user
• this control station can be constituted by a microcomputer which runs software allowing the user to know the parameters that will help him make a decision to program an automatic watering system, for example, and more generally to manage his crops.
• the central unit of the station can modulate the frequency of standby of the station, which limits energy consumption and uses solar panels as an energy source.
• a station according to the invention has numerous advantages, among which we can notably cite:
• FIG. 1 is a perspective view of a bioclimatological station according to the invention
• FIG. 2 is a simplified schematic view of the structure of one of the anemometers which equip the station,
• FIG. 3 is a schematic sectional view of a device for measuring the temperature and the humidity of the air, which equips the station,
• FIG. 4 is an electrical schematic diagram of the measurement carried out by the sensors for measuring the air temperature
• FIG. 5 is a partial view in axial section of a shelter of the weather type intended to contain a device for measuring the temperature and humidity of the air as well as means for transmitting signals to a control station ,
• FIG. 6 is a perspective view of the shelter of FIG. 5 mounted on a mast of the station
• FIG. 7 is a schematic view of a system for determining the hydric and energetic state of the soil
• FIG. 8 is a schematic view in principle of the control means for adjusting the height of the arms which support the devices for measuring the temperature and humidity of the air,
• FIG. 9 graphically represents a curve corresponding to the profile of the air temperature over a certain height and in the ground
• - Figure 10 is a schematic view of the principle of the means for controlling the height of the station relative to the height of the plant cover.
• the bioclimatological station 1 as represented in FIG. 1 is equipped with a set of measurement devices which will make it possible to establish in situ the energy balance of a plant cover.
• the station 1 is equipped with a pyrradiometer 3 which is used to measure the net solar radiation, that is to say the difference between the incident radiation coming from the atmosphere and the radiation reflected by the ground.
• the pyrradiometer 3 is for example constituted, in a manner known per se, of a black body with two opposite main faces which are respectively exposed to incident and reflected radiation, and two networks of thermocouples respectively mounted on said main faces of the black body and which each deliver an output signal proportional to the associated radiation.
• each anemometer 5 includes in particular three fins 7 which are advantageously made of anodized aluminum to increase their rigidity without increasing their weight.
• These three fins 7 are integral with a vertical shaft 9, the two ends of which are machined so as to form a point 9a.
• This shaft 9 is supported in rotation by means of two upper and lower bearings 10. Thanks to the pointed shape of the two ends of the shaft 9, it is possible minimize friction with the bearings 10. It is thus possible to lower the threshold for triggering the rotation of the anemometer and thus measure a wind speed less than 0.2 m / s.
• the speed of rotation of the fins 7 is determined by means of a circular crown 12, coaxial with the shaft 9, integral with the latter and the periphery of which is pierced by several orifices 14 which will pass successively past a counting system optics 16.
• the station 1 is equipped with at least two devices 20 for detecting the temperature and the humidity of the air.
• each device 20 comprises a sensor 22 for measuring the temperature . of the air, and a sensor 24 for measuring the relative humidity of the air.
• a temperature sensor 22 is constituted by the deposit 25 of a metallic material such as platinum on an insulating substrate 26.
• This deposit 25 forms a resistance whose value varies as a function of the temperature, the value of this resistance being for example calibrated to a value of 100 ohms at 0 ° C.
• the two temperature sensors 22 of the two devices 20 are supplied at the time of measurement from the same current source I, so that the two sensors 22 are simultaneously subjected to any variations in current, which will not affect the accuracy of the temperature delta measurements.
• a voltage signal is taken from the terminals of each of the two sensors. 22, voltage which is then amplified by an amplifier A.
• the sensor 24 for measuring the relative humidity of the air is, for example, constituted in a manner known per se, by a capacitor whose capacity will vary as a function of the rate of the relative humidity of the air. This capacitor is connected in series with a resistor of fixed value, and the frequency variations of this RC circuit are measured to then deduce the measurement of the relative humidity of the air.
• a ventilated shelter 27 which consists of two discs 28a and 28b located in a horizontal plane, placed one above the other and spaced from each other by a distance of about 1 cm, the upper disc 28b being pierced with a central passage opening 30. Outside the guide 28 and opposite the opening 30, a fan 32 is mounted to draw the air present in the inlet guide 28.
• Two cups which consists of two discs 28a and 28b located in a horizontal plane, placed one above the other and spaced from each other by a distance of about 1 cm, the upper disc 28b being pierced with a central passage opening 30.
• a fan 32 is mounted to draw the air present in the inlet guide 28.
• the lower cup 34 is pierced with a central passage opening 38 located opposite the fan 32.
• the upper cup 36 also forms a screen against solar radiation for do not influence the measurements of sensors 22 and 24. Shelter 27 thus allows the two sensors 22 and 24 to operate identically regardless of the wind direction.
• the station 1 is also equipped with a weather-type shelter 40 in which at least one other device 20 for measuring the temperature and humidity of the air is housed.
• this shelter 40 is constituted by a set of cups superimposed on each other and regularly spaced between them to allow natural ventilation.
• this shelter 40 is dimensioned so as to be able to also house there a transmission system E of signals to which we will return later.
• the upper part of the shelter 40 is delimited between an upper cup 44a and a central cup 44b. Intermediate cups situated between these two cups 44a and 44b are each pierced with a central opening 46 so as to define a housing for the transmission system E.
• the lower part of the cover 4 0 is defined between the cup 44b and a lower cup 44c with interposition of three intermediate cups 44d, 44e and 44f.
• the device 20 for measuring the temperature and the humidity of the air is mounted between the two intermediate cups 44d and 44e, so that the two cups 44c and 44f form an air inlet guide, then that the cups 44b and 44d form an air outlet guide.
• a shelter 40 which is generally similar, in its lower part, to shelter 27 described with reference to FIG. 3.
• Each cup is removably attached to an upright 50.
• a radial slot f is provided. at the periphery of the cup. This slot f is surmounted by a stirrup 52 pierced with two holes 54 facing each other.
• the amount 50 has a thickness slightly less than the width of the slot f. to be able to engage in the stirrups 52.
• Holes 55 are regularly spaced along the upright 50, and the two holes 54 of a stirrup 52 are placed opposite a hole 55 of the upright 50 to fix the stirrup 52 by means of a bolt for example.
• the longitudinal edge of the upright 50 engaged in the stirrups comprises a succession of regularly spaced legs 58. These tabs 58 serve as a support for the cups, and as a fixing means for the transmission system E and the device 20 for measuring the temperature and humidity of the air.
• Station 1 is also equipped with a system 60 to know the water and energy status of the soil. To determine the hydric state, this system illustrated in FIG.
• the 7 comprises two electrodes 60a and 60b separated from one another by an insulator 62, and two temperature sensors 64 and 65 sunk at two different depths in the ground.
• the electrodes 60a and 60b are supplied from an alternating current source, and the voltage across the terminals of the two electrodes is measured to obtain a dryness index.
• the two electrodes 60a and 60b form the rigid end of a cane 68 in which the two temperature sensors 64 and 65 are also housed. This cane 68 can carry external graduations to easily adjust the degree of insertion into the ground. This also makes it possible to maintain a constant distance between the two temperature sensors 64 and 65.
• the flow meter 69 is located at the same depth as the first temperature sensor 64.
• the station 1 also includes a rain gauge 70 and a wind vane 72.
• the station 1 also includes autonomous means for supplying electrical energy, constituted by solar panels 75 which are connected to an energy storage battery. These means are sufficient to supply the entire station. Indeed, the measurements carried out by the various sensors are not made continuously, so that the station 1 is most often in standby state, which notably limits the energy consumption.
• the station 1 comprises a support architecture which is constituted by a frame 80 which is supported by means of at least three vertical masts Ml, M2 and M3, which rest on the ground by feet which can be adjusted in height.
• the chassis 80 supports the rain gauge 70 which is mounted substantially in the extension of the mast Ml.
• the chassis 80 supports, via an arm 82, the pyrradiometer 3 which is advantageously exposed to the south and at a height situated approximately 1.20 m above the plant cover.
• the two masts M2 and M3 extend over a height greater than that of the mast Ml.
• the three anemometers 5 are supported by lateral arms 83 which are connected to the two masts M2 and M3.
• the three anemometers 5 are respectively located at heights corresponding respectively to 0.40 - 1.20 and 2.00 m, the intermediate anemometer 5 being located at the same height as the pyrradiometer 3.
• the weather-type shelter 40 is for example mounted at the end of the mast M2, while the wind vane 72 is mounted at the end of the mast M3.
• the chassis 80 also comprises a substantially horizontal beam 84 mounted across the two masts M2 and M3.
• This beam 84 is advantageously hollow and with a substantially triangular cross section for example.
• the ends of two arms 85 are articulated, the other ends of which each support a device 20 for measuring the temperature and humidity of the air.
• each arm 85 can pivot to adjust the height of the device 20 relative to the plant cover.
• each arm 85 is for example constituted by a parallelogram deformable, the deformation of which during the pivoting movement of the arm 85 keeps the device 20 in a substantially horizontal position.
• the deformable parallelogram includes two parallel upper arms 87 and lower arms 89 which are located in the same vertical plane. At one end, the upper arm 87 is secured to an upper horizontal shaft 91 supported in rotation by two bearings 93 carried by the beam 84. At one end, the lower arm 89 is secured to a lower horizontal shaft 95 supported in rotation by two bearings 96 carried by the beam 84. The other two ends of the upper 87 and lower 89 arms are connected to each other by an articulated link 97 which is integral with a device 20 for measuring the temperature and humidity.
• the deformable parallelogram is completed by two parallel arms 101 and 103 which are respectively articulated, at one end, to the two arms 87 and 89 by articulation axes 105.
• the two other ends of the two arms 101 and 103 are integral with the two shafts 91 and 95, respectively.
• the lower shaft 95 is controlled in rotation by an eccentric device 107 which is actuated from an electric motor 108 housed inside the beam 84.
• the lower shaft 95 can not support a mechanical part located in the vicinity eccentric 107 and which passes in front of several position detectors, each detector defining an adjustment height for the device 20.
• the eccentric device 107 is controlled as a function of the position of this mechanical part.
• a station 1 which can be raised depending on the height of the plant cover.
• the three masts Ml, M2 and M3 of station 1 are then supported by a base 110 adjustable in height, the base 110 is secured to an arm 112 which is mounted articulated at 114 on a base 116 resting on the ground.
• One end of a lever 118 is articulated on the arm 112, while its other end cooperates with a control device 120 actuated by an electric motor to adjust the inclination of the arm 112 relative to the ground and therefore adjust the height of the station relative to the top of the plant cover V.
• the frame 80 supports a height detector 125 which will make it possible to automatically control the height of the station relative to the top of the plant cover V which constitutes the reference height.
• the bioclimatological station 1 is not elevated as a function of the height of the plant cover V, but the height detector 125 is nevertheless used to automatically provide a correction factor to the measurements made by the various sensors as a function of the height plant cover.
• This variant can be applied in particular when the plant cover is grass, for example.
• all the sensors which equip the station 1 are electrically connected to a central unit U housed in the chassis 80 and supplied with power. by battery B which is itself powered by solar panels.
• This central unit U notably comprises a memory in which software and processing circuits are recorded.
• the central unit U is connected for example to the radio-modem system E housed in the shelter 40 of the weather type and which, via the antenna An, can transmit information to a control station Pc which will communicate with the central unit U.
• This Pc control station is for example constituted by a microcomputer equipped with a display screen, and this Pc station will be used as a decision-making aid tool for the 'user.
• the station 1 is in a standby state as often as possible, which avoids any unnecessary or excessive energy consumption.
• the user will decide when to take cognizance of the energy balance or at the very least to take cognizance of certain parameters measured by station 1 for interpretation and decision-making.
• the user then activates the station 1 from the control station Pc and orders are then transmitted to the central unit U.
• the intermediate anemometer 5 which is located at the same height as the pyrradiometer 3, has the particular function of providing a correction factor to the output signals of the pyrradiometer 3. This correction is
• the measurements made by the three anemometers 5 make it possible to carry out an average of the wind speed at each of the heights of 0.40 - 1.20 and 2 m above the plant cover to obtain the wind profile.
• the two arms 85 are movable in opposite directions to each other according to the principle of a double weighing measurement.
• the two arms 85 are at the same height for the measurement of the intermediate temperature. This measurement makes it possible to detect any drifts at the level of each device 20 for measuring the air temperature and humidity, which makes it possible to ensure preventive maintenance at the level of these devices 20.
• a temperature profile C can be determined graphically, as illustrated in FIG. 9.
• the two temperature sensors 64 and 65 housed in the ground also make it possible, in combination with the flow meter 69, to ensure, for example, a frost prediction. Indeed, if the temperature T measured by the sensor 64 approaches 0 ° C, the direction of power flow sensed by the flow meter 69, that is to say, positive flow if the ground will as it warms or negative flux if the soil is cooling, the temperature differences Tl and T2 between the two sensors 64 and 65, the dryness index determined from the two electrodes 60a and 60b, will make it possible to determine whether the temperature of the soil will continue to descend or, on the contrary, will start to rise again. 21
• the intensity and duration of which are detected by the rain gauge it is useful to know the effect of humidification of the soil by rainwater, in other words to assess runoff.
• the drought index does not change, we can deduce that the amount of rainwater has not penetrated into the soil, hence runoff.
• the measurements made by the two temperature sensors 64 and 65 vary abnormally, it will be possible to assess the depth of humidification of the soil by rain.
• the masts M2 and M3 are constituted by tubular elements which are used to ensure the passage of the electrical connections between the sensors and the central unit U.

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• Environmental & Geological Engineering (AREA)
• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Atmospheric Sciences (AREA)
• Biodiversity & Conservation Biology (AREA)
• Ecology (AREA)
• Environmental Sciences (AREA)
• Testing Or Calibration Of Command Recording Devices (AREA)

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• 1996
  • 1996-07-08 FR FR9608466A patent/FR2750771B1/fr not_active Expired - Fee Related
• 1997
  • 1997-07-01 EP EP97931837A patent/EP0910808A1/de not_active Withdrawn
  • 1997-07-01 AU AU35451/97A patent/AU3545197A/en not_active Abandoned
  • 1997-07-01 WO PCT/FR1997/001168 patent/WO1998001773A1/fr not_active Application Discontinuation

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