Precipitation meter

Abstract

A precipitation meter (100) is provided with: a receiver (14) that receives water as a substance falling from the air; a water storage tank (15) in which water reaching a predetermined water level is stored; a drain pipe (16) connected to a drain port (15a) of the water storage tank (15); a water discharge device (17) that is attached to the water discharge port (15a) or the water discharge pipe (16) and discharges a prescribed amount of water in the water storage tank (15) by a single operation; a water level gauge (18) for measuring the water level in the water storage tank (15); a detector (21) that detects an increase in the water level in the water storage tank (15); a controller (22) that, on the basis of detection of an increase in the water level in the water storage tank (15), causes the water discharge device (17) to discharge the water in the water storage tank (15) in order to lower the water level in the water storage tank (15) to a prescribed water level; and a calculator (23) that calculates the amount of precipitation and / or the intensity of precipitation using the number of times the water is discharged by the water discharge device (17).

Description

Technical Field

[0001] The present disclosure relates to precipitation meters. Background Art

[0002] A precipitation meter is a device that measures precipitation. The depth of precipitation is the depth to which the water as a substance that falls from the air covers the horizontal ground surface as liquid water within a specified period, assuming that the liquid water does not penetrate into the ground, does not evaporate from the ground surface, and does not drain from the ground surface. "Water as a substance" can also be renamed as "a compound represented by the chemical formula H2O." Based on the International System of Units, this specification uses SI units (including units with SI prefixes), SI combined units, and units using combinations thereof. Other unit systems can also be used. The unit system used will not have any impact on the precipitation meter disclosed in this specification. The Japan Meteorological Agency uses mm (millimetre) as the unit of precipitation, and this specification also uses mm as the unit of precipitation.

[0003] The "prescribed period" can be specified freely. The "prescribed period" is, for example, 10 minutes, 1 hour, 24 hours (to be precise, 24 hours starting from any time), or 1 day (i.e., 24 hours from 0:00 to 24:00). In particular, the precipitation amount D [mm] measured in 1 hour is sometimes referred to as the "measured precipitation intensity", and the unit of "measured precipitation intensity" is mm / h (millimetre per hour). Moreover, the precipitation amount in a period other than 1 hour can also be converted into precipitation per hour. The converted precipitation amount is sometimes also referred to as the "converted precipitation intensity", and the unit of "converted precipitation intensity" is still mm / h. For example, when the precipitation amount in 10 minutes is D [mm], the converted precipitation intensity is 6D [mm / h]. Hereinafter, unless otherwise specified, "converted precipitation intensity" will be referred to as "precipitation intensity".

[0004] "Water as a substance falling from the sky" is roughly divided into liquid water and solid water. The atmospheric phenomenon of liquid water falling from the sky is called rain, and the water droplets that fall are also called rain. An example of an atmospheric phenomenon of solid water falling from the sky is called snow, and in this case, the ice crystals that fall are also called snow. Furthermore, as an example of solid water falling from the sky, ice pellets can be exemplified. The Japan Meteorological Agency calls these ice pellets "hail" (pronounced: hyou) when their diameter is 5 mm or larger, and "graupel" (pronounced: arare) when their diameter is less than 5 mm, and there is a distinction between the two. However, the standard for this distinction is not unified around the world, and there are countries or regions that do not distinguish between the two. Below, unless otherwise specified, "rain", "snow", etc. do not refer to atmospheric phenomena, but to falling objects from the sky. When solid water (such as snow or ice pellets) falls from the air, or when a combination of liquid water (i.e., rain) and solid water falls from the air (the Japan Meteorological Agency calls this atmospheric phenomenon "sleet" (pronounced: mizore)), a precipitation meter uses a heater installed in the meter to convert the solid water into liquid water and then measures the amount of precipitation.

[0005] The volume of liquid water captured in the precipitation meter V [mm 3 ]、Catchment area A[mm 2 There is a relationship between ] and precipitation D [mm] as shown in formula (1). The catchment area is the area of ​​the opening of the precipitation meter that takes in water falling from the sky as a substance.

[0006] [Formula 1]

[0007]

[0008] Precipitation gauges are roughly divided into tipping bucket type precipitation gauges and water storage type precipitation gauges.

[0009] A tipping bucket precipitation meter has the following structure: it consists of two adjacent buckets separated by a central partition. Liquid water drips alternately into each bucket. When a certain amount of liquid water (V1) is stored in one bucket, the bucket's weight causes it to tip over, causing the first bucket to drain the liquid water and the other bucket to begin receiving it. When a certain amount of liquid water (V1) is stored in the other bucket, the bucket's weight causes it to tip over, causing the other bucket to drain the liquid water and the first bucket to begin receiving it. This process of tipping is repeated. The number of tipping times (N) within a predetermined period is counted to measure the amount of precipitation (D [mm]). In precipitation meters commonly used in Japan, V1 is the volume equivalent to 0.5 [mm] of precipitation. Therefore, D = 0.5 × N [mm] holds.

[0010] A water storage type precipitation meter includes a container storing liquid water, and measures the precipitation amount by measuring the amount of stored water using a weight sensor or the like (see Patent Document 1).

[0011] Prior art literature

[0012] Patent Literature

[0013] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-286864 Summary of the Invention

[0014] Technical problem to be solved by the invention

[0015] Tipping bucket dewatering meters utilize the mechanical motion of the bucket (i.e., tilting), making it difficult to ensure long-term operational stability. Furthermore, it is known that the measurement error of tipping bucket dewatering meters increases with increasing rainfall. In particular, the tilting speed of the bucket cannot keep up with rainfall intensities exceeding 100 mm / h, for example.

[0016] A water storage type precipitation meter requires draining water from the container when it is filled with liquid water. Therefore, a water storage type precipitation meter cannot measure precipitation during drainage.

[0017] We disclose a precipitation meter that can continuously measure precipitation amount and / or precipitation intensity even in atmospheric phenomena with precipitation intensity exceeding 100 [mm / h].

[0018] Technical solutions to technical problems

[0019] The technical matters described herein are not intended to explicitly or implicitly limit the invention described in the claims, nor are they intended to enable persons other than those who benefit from the present invention (e.g., the applicant and the right holder) to limit the invention described in the claims. These matters are provided solely to facilitate understanding of the gist of the present invention. A summary of the present invention from other perspectives can be understood, for example, from the claims at the time of filing this patent application.

[0020] The disclosed precipitation meter has: (A) a structure for maintaining a predetermined water volume through drainage; and (B) a structure for discharging a predetermined amount of liquid water during each drainage process. Specifically, the disclosed precipitation meter includes a water storage tank that has previously stored liquid water at a predetermined level H; and a drainage device that discharges a predetermined amount of liquid water from the water storage tank in a single operation. The drainage device discharges the liquid water from the water storage tank in response to the inflow of liquid water into the water storage tank, lowering the water level in the water storage tank to the predetermined level H. The number of drainage operations by the drainage device is used to calculate the amount of precipitation and / or precipitation intensity.

[0021] Effects of the Invention

[0022] According to the disclosed precipitation meter, as will be described in detail later (see description of the embodiments), precipitation amount and / or precipitation intensity can be continuously measured even in atmospheric phenomena with precipitation intensity exceeding 100 [mm / h]. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the configuration of the precipitation meter according to the embodiment.

[0024] Figure 2 This is a flowchart showing the operation of the precipitation meter according to the embodiment. DETAILED DESCRIPTION

[0025] The embodiments are described with reference to the accompanying drawings. Figure 1 The precipitation meter 100 of the illustrated embodiment includes a main body 10 and a processing device 20. The precipitation meter 100 includes a heater (not shown) as needed.

[0026] The main body 10 includes a base 11, a housing 12, legs 13, a receiver 14, a water tank 15, a drain pipe 16, a drain device 17, and a water level gauge 18. Attached to the bottom surface of the base 11 are a plurality of legs 13 for fixing the main body 10 to a concrete base (not shown).

[0027] A cylindrical housing 12, mounted on a pedestal 11, houses a receiver 14, a water tank 15, a drain pipe 16, a drain device 17, and a water level gauge 18. The funnel-shaped receiver 14 is fixed to the upper portion of the housing 12. The water tank 15 is located below the receiver 14 and is fixed to the pedestal 11. In this example, the water tank 15 has a rectangular cylindrical shape with a square cross-section and is made of metal such as stainless steel. A net (not shown) is attached to the upper portion of the receiver 14 as needed to prevent the intrusion of debris such as leaves. The water tank 15 is pre-stored with liquid water at a predetermined level. Figure 1 In FIG. 1 , symbol W represents the surface of liquid water previously stored in the water storage tank 15. The surface W of the liquid water previously stored in the water storage tank 15 is covered with the non-volatile oil 19, thereby preventing a change in the water level due to evaporation.

[0028] The receiver 14 receives water as a substance falling from the air. If necessary, the receiver 14 and the net (not shown) are heated by a heater (not shown) to convert the water as a substance falling from the air into liquid water. Hereinafter, unless otherwise specified, "water" means "liquid water". The water flows from the receiver 14 into the water storage tank 15. In this example, Figure 1As shown, the receiver 14 includes a cylindrical water supply pipe 14a that is elongated in the vertical direction (i.e., along the axis of the housing 12). Water flows through the water supply pipe 14a into the water storage tank 15. The outlet (i.e., the lower end) of the water supply pipe 14a is located sufficiently below the water surface W, that is, within the water. This prevents the water surface W from swaying due to the inflow of water.

[0029] The water storage tank 15 has a drain port 15a at its lower portion, and a drain pipe 16 is connected to the drain port 15a. A drain device 17 capable of alternately switching between a draining operation and a water-stopping operation (i.e., alternately switching between an open state and a closed state) is attached to the drain pipe 16. The drain device 17 drains a certain amount of water δ [mm2] from the water storage tank 15 during one draining operation (i.e., one open state). 3 The drainage operation of the drainage device 17 is executed according to the drainage instruction from the controller 22 described later. Examples of the drainage device 17 include metering pumps such as plunger pumps and tube pumps, and normally closed solenoid valves described later. The normally closed solenoid valves discharge water at a certain amount δ [mm 3 ]The principle of drainage will be described later.

[0030] The drain outlet 15a is located sufficiently below the water surface W, preferably near the bottom of the water tank 15. However, to prevent trash passing through the net (not shown) from adversely affecting the drainage operation of the drainage device 17, the drain outlet 15a is preferably spaced upward from the bottom of the water tank 15 to a certain extent. This allows trash to accumulate at the bottom of the water tank 15.

[0031] The water level gauge 18 for measuring the water level is installed in the water tank 15. The base plate 18a of the water level gauge 18 is fixed at a predetermined position by a fixing member (not shown). In this example, the water level gauge 18 is a water level gauge that detects the water level by electrostatic capacitance, such as Figure 1 As shown, the device includes a reference electrode 18b and a water level electrode 18c arranged vertically on a substrate 18a. Reference electrode 18b and water level electrode 18c face the flat sidewall 15b of the rectangular cylindrical water storage tank 15. Sidewall 15b of water storage tank 15 functions as a ground electrode. Reference electrode 18b and sidewall 15b form a parallel plate capacitor, while water level electrode 18c and sidewall 15b also form a parallel plate capacitor.

[0032] like Figure 1 As shown, the reference electrode 18b is located in the water, and the water level electrode 18c vertically crosses the water surface W (i.e., vertically intersects the water surface W). The water level gauge 18 has an electrostatic capacitance C measured by the reference electrode 18b when the water storage tank 15 stores water reaching a predetermined water level H. s [F] and the electrostatic capacitance C measured by the water level electrode 18c w[F] are equal to each other. Since the dielectric constant of water is greater than the dielectric constant of air, when the water level in the water tank 15 is higher than the predetermined water level H, the electrostatic capacitance C of the water level electrode 18c is w [F] is greater than the electrostatic capacitance C of the reference electrode 18b s [F] Since the water surface W is covered with the non-volatile oil 19, the electrostatic capacitance C of the water level electrode 18c w [F] represents the combined electrostatic capacitance of three dielectrics (ie, water, oil, and air) having different dielectric constants. By using the electrostatic capacitance C of the reference electrode 18b, the electrostatic capacitance C of the reference electrode 18b is calculated. s [F] and the electrostatic capacitance C of the water level electrode 18c w The structure of [F] can reduce the influence of changes in electrostatic capacitance caused by changes in water temperature, etc.

[0033] The processing device 20 includes a detector 21 , a controller 22 , and a calculator 23 .

[0034] The detector 21 detects the rise in the water level in the water tank 15 caused by the inflow of water based on the measurement of the water level meter 18. Specifically, when the capacitance C of the water level electrode 18c w [F], capacitance C of the reference electrode 18b s When the equation (2) between [F] and the threshold value ξ[F] holds, the detector 21 detects a rise in the water level in the water storage tank 15. The threshold value ξ[F] is equivalent to the amount δ[mm 3 ]The same amount δ[mm 3 ] into the water tank 15. In other words, the water level rise ΔH [mm] detected by the detector 21 is expressed by the formula (3). In the formula (3), B [mm 2 ] is the cross-sectional area of ​​the water storage tank 15. When the water storage tank 15 stores water reaching a predetermined water level H, the vertical length of the portion of the water level electrode 18c in contact with air must be greater than ΔH [mm].

[0035] [Formula 2]

[0036]

[0037] When the detector 21 detects a rise in the water level, the controller 22 outputs a drainage command to the drainage device 17 in order to lower the water level in the water storage tank 15 to a predetermined water level H.

[0038] The calculator 23 calculates the precipitation amount D [mm] and / or precipitation intensity D [mm] using the number N of drainage instructions output by the controller 22 within the predetermined period P [h]. P[mm / h]. As mentioned above, the amount of water discharged by the drainage device 17 in one drainage operation is determined as δ [mm 3 Therefore, the amount of precipitation D[mm] within the specified period P[h] can be calculated by formula (4), and the precipitation intensity D can be calculated by formula (5). P [mm / h]. A[mm 2 ] is the water collection area, specifically the area of ​​the opening of the receiver 14.

[0039] [Formula 3]

[0040]

[0041] If water flows into the water storage tank 15 exceeding the drainage capacity of the drainage device 17, the precipitation amount and precipitation intensity cannot be accurately measured. P,max [mm / h], the maximum number of drainage operations that the drainage device 17 can perform per second is n max [1 / s], formula (6) must hold.

[0042] [Formula 4]

[0043]

[0044] When detector 21 performs detection processing every Δt [s], water tank 15 must have a void area (i.e., an area filled with air within water tank 15) that can accommodate the maximum volume of water flowing into water tank 15 during the period Δt. Therefore, equation (7) must hold. In equation (7), L [mm] is the height of the void area of ​​water tank 15.

[0045] [Formula 5]

[0046]

[0047] Hereinafter, calculation of the precipitation amount and / or precipitation intensity using the precipitation meter 100 including the drainage device 17 including the normally closed electromagnetic valve will be described.

[0048] The amount of water δ[mm 3 ] is expressed by formula (8). In formula (8), S[mm 2 ] is the cross-sectional area of ​​the drainage pipe 16, K vis the flow coefficient, and v(t) [mm / s] is the velocity of water flowing out of the drain pipe 16. t is the time elapsed from the start of the drainage operation. When water is considered to be an incompressible fluid with negligible viscosity, the velocity v(t) is expressed by equation (9) (Bernoulli's principle). In equation (9), g is the acceleration due to gravity (approximately 9.8 [m / s 2 ]), H(t) [mm] is the water level (ie, the height from the drain port 15a to the water surface W), and B is sufficiently greater than S. Therefore, the i-th drainage period T i The j-th (i≠j) drainage period T j are equal to each other, and the water level H(0) at the start of the i-th drainage i The water level H(0) at the start of the j-th drainage j When they are equal, the drainage volume δ in the i-th drainage process i The amount of drainage δ in the jth drainage treatment j Equal to each other.

[0049] [Formula 6]

[0050]

[0051] By using the discharge volume δ calculated by formula (8) and formula (4), the precipitation volume D [mm] can be calculated. By using the discharge volume δ calculated by formula (8) and formula (5), the precipitation intensity D can be calculated. P [mm / h].

[0052] According to Equation (8), it is necessary to calculate the integral and accurately measure the water level H. By sufficiently suppressing fluctuations in the water level H, these calculation and measurement costs can be reduced. Specifically, by setting the period T to a small value (e.g., less than 1 second) and making the cross-sectional area B of the water storage tank 15 sufficiently larger than the cross-sectional area S of the drainage pipe 16 (e.g., B > 100 × S), water level fluctuations caused by inflow and outflow can be sufficiently suppressed. As a result, the discharge volume δ is expressed by Equation (10) (Torricelli's theorem).

[0053] [Formula 7]

[0054]

[0055] For example, when P=1[h], A=π×50[mm]×50[mm], S=π×2[mm]×2[mm], K v =0.14, T=0.5[s], H=75[mm], according to formula (5) and formula (10), the precipitation intensity D P,max[mm / h] is expressed by formula (11). When water level detection is performed at 0.5 second intervals (Δt=0.5), the maximum value of N is 7200. Therefore, the maximum precipitation intensity D that can be measured by the precipitation meter 100 is P,max [mm / h] is 978[mm / h].

[0056] [Formula 8]

[0057]

[0058] Figure 2 The flowchart shown shows the operation flow of the processing device 20 for measuring the precipitation amount and precipitation intensity every predetermined period P[h]. Figure 2 In , the symbol "=" is a substitution operator, which means to substitute the value on the right into the symbol on the left. Figure 2 In , the symbols ">" and "≧" are comparison operators, and the comparison results on the left and right are represented by true and false values.

[0059] As an initial setting, the controller 22 sets the control variable n to 0 (step S1 ) and sets the variable T n The current time is set (step S2). The controller 22 increments the control variable n (step S3), sets the count value N indicating the number of times the water discharge command is output to 0 (step S4), and sets the variable T n The current time is set (step S5).

[0060] The water level gauge 18 measures the water level H in the water storage tank 15. n (Step S6). Detector 21 detects a rise in the water level (Step S7). In the above example, detector 21 detects changes in the water level based on changes in capacitance measured by water level gauge 18. If there is no precipitation, detector 21 will not detect a rise in the water level.

[0061] If a water level rise is detected in step S7, the controller 22 outputs a drainage command (specifically, a 1-pulse signal) to the drainage device 17 (step S8), causing the drainage device 17 to perform drainage and incrementing the count value N (step S9), thereby calculating the elapsed time T. n -T n-1 (Step S10).

[0062] If the water level rise is not detected in the process of step S7, the controller 22 calculates the elapsed time T n -T n-1 (Step S10).

[0063] If the time T has passed in the process of step S10 n -T n-1If the time T is less than the period P, the process after step S5 is executed. n -T n-1 When the period P is reached, the calculator 23 calculates the drainage volume δ [mm 3 ], the count value N indicating the number of drainage instructions, the area A of the opening of the receiver 14 [mm 2 ], and period P[h], calculate the precipitation amount and precipitation intensity (step S11), and output the calculated precipitation amount and precipitation intensity (step S12). The precipitation amount D[mm] is calculated by formula (4), and the precipitation intensity D P [mm / h] is calculated using formula (5).

[0064] After the process of step S12, the processes of step S3 and subsequent steps are implemented to measure the precipitation amount and precipitation intensity in the next period P.

[0065] You can also Figure 2 The flowchart shown is changed so that the calculator 23 only calculates the precipitation amount D [mm] or the precipitation intensity D P Flowchart of either side of [mm / h].

[0066] According to the precipitation meter of the present disclosure, as described above, even in an atmospheric phenomenon where the precipitation intensity exceeds 100 [mm / h], it is possible to continuously measure the precipitation amount and / or precipitation intensity.

[0067] The water level gauge 18 may measure the water level based on changes in the electrostatic capacitance of an electrode extending in the direction of water level measurement. The water level gauge 18 may also directly measure the water level using ultrasound or infrared rays. The water level gauge 18 may also convert the weight measured by a load cell into the water level.

[0068] The drainage device 17 may be provided in the drainage port 15 a instead of the drainage pipe 16 .

[0069] The water surface W may be covered not with the non-volatile oil 19 but with a material having a specific gravity lighter than water, such as foamed polystyrene.

[0070] In the case where the drain pipe 16 is long, the measurement accuracy can be further improved by taking into account the viscosity coefficient of the drain pipe 16 and / or the slope of the drain pipe 16 .

[0071] <Supplement>

[0072] The present invention has been described with reference to exemplary embodiments, but it will be understood by those skilled in the art that various changes can be made without departing from the scope of the present invention, and that elements thereof can be replaced with equivalents. Furthermore, without departing from the essential scope of the present invention, more modifications can be applied to adapt a particular system, device, or component thereof to the teachings of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed for the purpose of practicing the present invention, but includes all embodiments contained in the appended claims.

[0073] Furthermore, the use of terms such as "first" and "second" when used in this specification and / or claims does not indicate order or importance, and terms such as "first" and "second" are used to distinguish elements. The terms used in this specification are used to illustrate the embodiments and are not intended to limit the present invention. The term "comprising" and its variations when used in this specification and / or claims clarify the presence of the features, steps, operations, elements and / or components mentioned, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components and / or groups thereof. If there is the term "and / or", one or more and all combinations of the elements in the associated list are included. In the claims and the specification, unless otherwise expressly stated, "connected", "coupled", "joined", "linked", or their synonyms, and all their forms do not necessarily deny the existence of one or more intermediate elements between two elements that are, for example, "connected" or "coupled" or "linked" to each other. In the claims and the specification, if there is the term "any", unless otherwise expressly stated, it should be understood to mean the same as the full name symbol. For example, the expression "with respect to any X" has the same meaning as "with respect to all X" or "with respect to each X". If there is an expression such as "at least one of A, B, C" (for example, in English, "at least one of A, B and C", "at least one of A, B or C", "at least one of A, B and / or C"), unless otherwise specified, it means selecting an element from the set P that is the power set 2 of the set S that contains all the listed elements as a base. S The set obtained by removing the empty set φ from . In this example, S = {A, B, C}, 2 S ={φ,{A},{B},{C},{A,B},{A,C},{B,C},{A,B,C}},P={{A},{B},{C},{A,B},{A,C},{B,C},{A,B,C}}, which means selecting an element from the set P (e.g., {A,C}).

[0074] Unless otherwise specified, all terms used in this specification (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which this invention belongs. Furthermore, terms such as those defined in commonly used dictionaries should be interpreted as having the same meaning as they do in the context of the relevant art and this disclosure, and should not be interpreted in an idealized or excessively formal manner unless explicitly defined.

[0075] It should be understood that many techniques and steps are disclosed in the description of the present invention. Each of these techniques and steps has its own advantages and can be used in combination with one or more of the other disclosed techniques, or with all of them, as appropriate. Therefore, to avoid complexity, this description avoids describing all possible combinations of individual techniques or steps. Nevertheless, the description and claims should be interpreted as if such combinations are fully within the scope of the present invention and the claims.

[0076] In the following claims, if there are corresponding structures, materials, acts, and equivalents of all functional elements that combine a means or step, the structures, materials, or acts for performing the function in combination with the other elements are intended to be included.

[0077] While the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Various changes and modifications are permitted without departing from the spirit of the present invention. The selected and described embodiments are used to illustrate the principles of the present invention and its practical application. The present invention may be used as various embodiments with various changes or modifications, each of which is determined according to the intended use. Such changes and modifications are all intended to be included within the scope of the present invention as defined by the appended claims, and are intended to be given the same protection when interpreted in accordance with the extent of fairness, legality, and justice.

[0078] Description of Reference Numerals

[0079] 10 Main Body

[0080] 11 pedestal

[0081] 12 Housing

[0082] 13 Legs

[0083] 14 Receiver

[0084] 14a Water supply pipe

[0085] 15 Water tank

[0086] 15a Drain

[0087] 15b Sidewall

[0088] 16 Drain pipe

[0089] 17 Drainage device

[0090] 18 Water level gauge

[0091] 18a base plate

[0092] 18b Reference electrode

[0093] 18c Water level electrode

[0094] 19 Fixed oil

[0095] 20 Processing device

[0096] 21 Detector

[0097] 22 Controller

[0098] 23 Calculator

[0099] 100 Precipitation Meter

Claims

1. A precipitation meter, characterized in that: include: a receiver that receives the water as a substance falling from the air; a water storage tank into which the water in the receiver flows as liquid water, wherein the water storage tank has a drain outlet and stores water reaching a predetermined water level higher than the position of the drain outlet; a drain pipe connected to the drain outlet; a drainage device, which is installed at the drain port or the drain pipe and discharges a certain amount of the water in the water tank in one operation; a water level gauge for measuring the water level in the water storage tank; a detector for detecting a rise in the water level in the water storage tank based on a measurement result of the water level gauge; a controller configured to cause the drainage device to drain the water in the water storage tank so as to lower the water level in the water storage tank to the predetermined water level based on detection of a rise in the water level in the water storage tank; as well as A calculator calculates the amount of precipitation and / or the intensity of precipitation using the number of times the drainage device drains water.

2. The precipitation meter according to claim 1, characterized in that The water level gauge includes a reference electrode and a water level electrode disposed in the water tank, wherein the reference electrode is located in the water in the water tank, and the water level electrode intersects the surface of the water in the water tank. The water level meter measures the water level by comparing the electrostatic capacitance measured by the reference electrode and the electrostatic capacitance measured by the water level electrode.

3. The precipitation meter according to claim 2, characterized in that The detector is when the electrostatic capacitance C of the water level electrode w Not less than the electrostatic capacitance C of the reference electrode s and a threshold value ξ, the rise of the water level in the water tank is detected, wherein the threshold value ξ is an electrostatic capacitance increment value corresponding to the rise in water level caused by the same amount of water as the amount discharged by the drainage device through one operation flowing into the water tank.

4. The precipitation meter according to any one of claims 1 to 3, characterized in that [Formula 9] Established, where A[mm 2 ] is the area of ​​the opening of the receiver, D P,max [mm / h] is the maximum value of precipitation intensity that can be measured by the precipitation meter, n max [1 / s] is the maximum number of drainage operations that the drainage device can perform per second, δ[mm 3 ] is the amount of water discharged by the drainage device through one drainage operation.

5. The precipitation meter according to any one of claims 1 to 4, characterized in that The receiver includes a water supply pipe, The water in the receiver flows into the water storage tank through the water supply pipe. The outlet of the water supply pipe is located below the predetermined water level.

6. The precipitation meter according to any one of claims 1 to 5, characterized in that The surface of the water in the water storage tank is covered with non-volatile oil.

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