Small-scale non-contact evaporation measurement system and method for meteorology

Abstract

The problem to be solved by the present invention is to provide a small-scale non-contact evaporation measurement system and method for meteorological use, capable of measuring evaporation every minute 24 hours a day with accurate measurement results. The small-scale non-contact evaporation measurement system for meteorological use comprises an evaporating dish, a weighing device, a water supply device, and a drainage device. The evaporating dish is placed on the weighing device. A detachable inverted U-shaped siphon is mounted on the side wall of the evaporating dish. The inlet of the siphon is located above the bottom of the evaporating dish and is higher than the outlet. The water supply device's water supply port is located above the dish opening and does not contact the evaporating dish.

Description

Technical Field

[0001] The present invention relates to the technical field of meteorological measurement, and in particular to a non-contact evaporation measurement system and a measurement method for meteorology. Background Art

[0002] Evaporation is a crucial component of both the Earth's surface energy balance and the terrestrial water balance. It is a key factor in determining weather and climate conditions and plays a crucial role in the global water cycle and climate evolution. Evaporation data is also needed in many areas, including water resource assessment, drought assessment, reservoir and lake management and utilization, industrial and agricultural water use, and hydrological forecasting.

[0003] The evaporation measured by the weather station is the evaporation from the water surface. It measures the depth of the water layer lost due to evaporation in a fixed-diameter evaporator within a certain time interval. Commonly used measuring instruments include small evaporators and large evaporators E-601. The large evaporator consists of an evaporation barrel, a water ring, an overflow barrel, and a measuring needle. The evaporation barrel is a 3000cm 2 The evaporator is a cylindrical barrel with a conical bottom. A straight tube is installed in the center of the barrel's bottom. The top of the tube is fitted with a stylus holder and a water level indicator (stylus) made based on the principle of a micrometer screw. The barrel is buried in the ground, with the mouth slightly above the surface. Daily observations are made at 8:00 PM. A stylus is inserted into the holder to read the water level. Evaporation is calculated based on daily water level fluctuations and precipitation. With technological advancements, the stylus has been replaced by a high-precision ultrasonic probe, which continuously monitors the water level changes within the evaporator based on the principle of ultrasonic ranging. The small evaporator is a circular metal basin with a diameter of 20 cm and a height of approximately 10 cm. The rim is inlaid with a knife-shaped copper ring with a straight inner edge and a slanted outer edge. To prevent birds and animals from drinking water, a metal wire mesh ring flared outwards in a trumpet-shaped pattern is placed above the rim. The evaporator is mounted on a cylindrical stand, with the mouth kept level and 70 cm above the ground. A fixed amount of clean water is added daily at 8:00 PM. The remaining water is measured with a measuring cup at 8:00 PM the following day. The amount of water lost is the evaporation rate.

[0004] my country's meteorological departments currently use ultrasonic liquid-level evaporation sensors to automate large-scale evaporation observations. However, standardized, mature automated measurement devices and methods have yet to replace small-scale evaporation observations. The elimination of small-scale evaporation observations during the automation reform of ground-based observations has had a significant impact on both operational and scientific research. Research is urgently needed to develop instruments that can automatically measure small-scale evaporation. Summary of the Invention

[0005] The problem to be solved by the present invention is to provide a small-scale non-contact evaporation measurement system and method for meteorology, which can measure the evaporation per minute for 24 hours a day and the measurement results are accurate.

[0006] The present invention is achieved through the following technical solutions:

[0007] A small-scale non-contact evaporation measurement system for meteorology, comprising an evaporation dish, a weighing device, a water adding device and a drainage device, wherein the evaporation dish is placed on the weighing device;

[0008] A detachable inverted U-shaped siphon is installed on the side wall of the evaporating dish, the inlet of the siphon is located above the bottom of the evaporating dish, and the position of the inlet of the siphon is higher than the outlet;

[0009] The water adding port of the water adding device is located above the dish opening of the evaporating dish and does not contact the evaporating dish.

[0010] Furthermore, the evaporating dish is cylindrical with a diameter of 20-25 cm and a height of 10-15 cm.

[0011] Furthermore, a detachable annular protective cover is installed at the mouth of the evaporating dish. The height of the annular protective cover is 7-10 cm and the annular protective cover is made of a transparent material.

[0012] Furthermore, the diameter of the siphon tube is 8-10 mm; the siphon tube is an outer tube and an inner tube installed on the side wall of the evaporating dish in a threaded connection manner.

[0013] Furthermore, the weighing device is an electronic balance or a gravity sensor, the measurement sensitivity of the weighing device is 0.01g, and the measurement time accuracy is 1 second.

[0014] The measurement method using the small-scale non-contact evaporation measurement system for meteorology of the present invention comprises the following steps:

[0015] (1) The mass of the evaporating dish is measured in real time every second, and the mass difference between the previous second and the current second is calculated. When the absolute value of the mass difference exceeds the set threshold, it is determined whether there is interference such as falling rocks or flying birds. If there is interference, it is recorded and the mass of the evaporating dish measured for that minute is corrected at the top of the minute.

[0016] (2) Measure the evaporation rate per minute;

[0017] The mass of the evaporating dish is measured every minute by a weighing device, and the observation results are corrected using precipitation data from the national automatic precipitation station precipitation sensor. The formula for calculating the evaporation rate per minute is as follows:

[0018] E i =(M i-1 -M i ) / (S*ρ)+P i ;

[0019] Among them, M i and M i-1The difference in mass of the evaporating dish after interference correction for minute i and the previous minute i-1, S is the area of ​​the evaporating dish, ρ is the density of water, P i is the minute precipitation at minute i;

[0020] (3) Calculate the evaporation per day;

[0021] There are two methods for calculating hourly evaporation. The calculation formula of one method is the same as the calculation formula of minute evaporation, where M i and M i-1 The difference in mass of the evaporating dish after interference correction at the hour i and the previous hour i-1, P i is the hourly precipitation at time i; one calculation method is to take the sum of all minute evaporations at that time as the hourly evaporation at that time;

[0022] The sum of the hourly evaporation at 24 time points is calculated as the daily evaporation for that day;

[0023] (4) Determine whether the evaporating dish has been replenished with water at regular intervals every day;

[0024] The preset mass value of water to be added to the evaporating dish is M2. When the mass of the evaporating dish actually measured by the weighing device at a fixed time every day is less than M2, the water adding device automatically adds water to the evaporating dish until the mass of the evaporating dish measured by the weighing device reaches M1, at which point the water adding device stops adding water, where M1>M2.

[0025] Furthermore, the method further includes the step of determining whether the evaporating dish has overflowed. Since overflow generally occurs during rain, and the mass of the evaporating dish will suddenly decrease significantly when overflow occurs, the abnormal value of the mass change of the evaporating dish before and after 1 minute can be preset as MM.

[0026] When the weighing device measures M i-1 -M i >MM and Pi>0, it is determined that the evaporating dish overflows at this time. The calculation formula for the evaporation rate per minute is as follows:

[0027] E i =(M i-1 -M i ) / (S*ρ)+P i -h, where h is the height from the highest point of the siphon to the inlet.

[0028] Furthermore, the length of h is 5-6 cm, and the weight of MM is 314-1884 g.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The small-scale non-contact meteorological evaporation measurement system of the present invention includes an evaporating dish, a weighing device, and a water adding device. Using the measurement method of the present invention, the mass of the evaporating dish is measured every minute, and the minute evaporation is converted from the mass difference before and after each minute. The hourly evaporation is converted from the mass difference before and after the hour. The hourly evaporation is corrected based on precipitation data from the national automatic station, water replenishment status, and overflow determination within an hour. The sum of the hourly evaporation at 24 hours per day is the daily evaporation.

[0031] Instead of manually measuring the water level in the evaporation dish to calculate evaporation, the method uses the difference in mass to ensure data accuracy. It can also measure and collect data 24 hours a day. It is suitable for accurately measuring evaporation not only on sunny days but also on rainy days.

[0032] By judging whether the evaporating dish needs to be replenished with water at a specific time every day, it is ensured that there is water in the evaporating dish at all times, thus avoiding the problem of the evaporating dish being out of water after many days;

[0033] 2. Design of the siphon tube. When measuring on rainy days, when the water level in the evaporation dish rises to the highest point of the siphon tube, a siphon phenomenon will occur, and the water will be discharged quickly, so that the water level will drop to the position of the siphon tube inlet. At this time, the calculation formula for the evaporation rate per minute is E i =(M i-1 -M i ) / (S*ρ)+P i -h, so as to accurately record the evaporation amount at that time; avoid the problem of the evaporation dish overflowing due to rainy days and being unable to continue testing the evaporation amount;

[0034] 3. The siphon tube can be detachably installed on the side wall of the evaporating dish, which is convenient for replacing siphon tubes of different lengths according to needs and is more flexible to use;

[0035] 4. The system of the present invention can also be used to observe precipitation, thus achieving diversified functions and uses;

[0036] 5. The meteorological non-contact evaporation measurement system and method of the present invention can accurately measure evaporation without requiring excessive manual intervention, and are suitable for widespread promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic structural diagram of the non-contact evaporation measurement system for meteorology according to the present invention;

[0038] In the figure: 1. Evaporating dish, 2. Weighing device, 3. Water adding device, 4. Siphon, 5. Annular protective cover. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0040] In the description of the invention, it should be understood that the terms "top", "bottom", "up", "down", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention.

[0041] To solve the above problems, Figure 1 As shown, the present application discloses a small-scale non-contact evaporation measurement system for meteorology, which mainly includes four components: an evaporation dish 1, a weighing device 2, a water adding device 3 and a drainage device 4 (siphon).

[0042] The evaporating dish 1 is a cylindrical structure made of copper. In order to standardize the measurement standards, the inner diameter of the evaporating dish 1 is 20 cm and the height is 10 cm. With this design, the inner bottom area S of the evaporating dish 1 is 314 cm. 2 In order to effectively protect the dish opening of the evaporating dish 1, a detachable annular protective cover 5 is installed at the dish opening. The height of the annular protective cover 5 is 7 cm and the annular protective cover 5 is made of transparent lightweight plastic.

[0043] An inverted U-shaped siphon tube 4 is removably mounted on the side wall of the evaporating dish 1. The siphon tube 4 is composed of an outer tube and an inner tube connected by a threaded connection. The lower end of the inner tube serves as the inlet of the siphon tube 4 and is located 2 cm above the bottom of the evaporating dish 1. The lower end of the outer tube serves as the outlet of the siphon tube 4 and is located below the inlet. The height h from the highest point of the siphon tube 4 to the inlet is 5 cm. To ensure a good siphoning effect, the inner diameter of the siphon tube 4 is 8 mm. This design ensures that a siphoning effect occurs when the water level in the evaporating dish 1 reaches the highest point of the siphon tube 4, rapidly draining the water until the water level drops back to the inlet.

[0044] Mount evaporating dish 1 on weighing device 2, which can be an electronic balance with an accuracy of 0.01g. This accurately measures the mass of evaporating dish 1. The water inlet of water supply device 3 is located above the mouth of evaporating dish 1 and does not contact it, thereby preventing it from affecting the measured data of weighing device 2. Water supply device 3 typically consists of a water pipe connected to a water source such as a bucket, equipped with a solenoid valve.

[0045] To achieve automated monitoring and control, the weighing device and water adding device are electrically connected to a PLC controller, which is installed in the weather monitoring room, where staff can observe feedback data at any time. Since a PLC controller is a type of programmable memory used to store programs, execute user-oriented instructions such as logical operations, sequential control, timing, counting, and arithmetic operations, and control various types of machinery or production processes through digital or analog input / output, it can collect signals, organize data, and transmit instructions. Since it is a conventional technology, it can be directly applied to the data transmission in this application and will not be described in detail here.

[0046] The measurement method using the non-contact evaporation measurement system for meteorology of the present invention comprises the following specific steps:

[0047] 1. First, the mass of the evaporating dish is measured in real time every second, and the mass difference between the previous second and the current second is calculated. When the absolute value of the mass difference exceeds the set threshold, it is determined whether there is any interference such as falling rocks or flying birds. If so, it is recorded and the mass of the evaporating dish measured for that minute is corrected at the top of the minute.

[0048] 2. Measure the evaporation rate per minute;

[0049] The mass of the evaporating dish is measured every minute by a weighing device, and the observation results are corrected using precipitation data from the national automatic precipitation station precipitation sensor. The formula for calculating the evaporation rate per minute is as follows:

[0050] E i =(M i-1 -M i ) / (S*ρ)+P i ;

[0051] Among them, M i and M i-1 The difference in mass of the evaporation dish after interference correction for minute i and the previous minute i-1, S is the area of ​​the evaporation dish, and ρ is the density of water. When measuring evaporation, it is rainless weather, then P i Just take 0. If it is rainy, P i is the minute precipitation at minute i;

[0052] On rainy days, the water in the evaporation dish continues to increase due to continuous rain. When the water level reaches the highest point of the siphon tube, a siphon effect occurs, rapidly draining the water until the water level drops back to the inlet. This phenomenon is called siphon overflow, which results in a large difference in the mass measured by the weighing device one minute before and one minute later. To correct the data, the measurement method described in the present invention also includes a step to determine whether the evaporation dish has overflowed, as follows:

[0053] The default value of the abnormal mass change of the evaporating dish before and after 1 minute is MM. Since the thermal evaporation amount in North my country in 1 minute does not exceed 300g, the MM value can be set as 314g;

[0054] When the weighing device measures M i-1 -M i When >MM, it is determined that the evaporating dish overflows at this time. The calculation formula for the minute evaporation amount at this time is as follows:

[0055] E i =(M i-1 -M i ) / (S*ρ)+P i -h, where h is the height from the highest point of the siphon to the inlet.

[0056] 3. Calculate the evaporation rate per day;

[0057] There are two ways to calculate hourly evaporation. One is to convert the hourly evaporation by the mass difference between the previous and next hour, and then correct the hourly evaporation based on the precipitation data from the national automatic station, the water replenishment situation, and the overflow judgment result within one hour. The other is to take the sum of all minute evaporations of the hour as the hourly evaporation. The sum of the hourly evaporations of the 24 hours in a day is the daily evaporation of that day.

[0058] 4. In order to avoid errors in the later data caused by the inability to add water in time after the water in the evaporating dish evaporates completely, it is necessary to regularly check whether the evaporating dish has been refilled with water every day;

[0059] When there is no water in the evaporating dish, the mass of the evaporating dish is measured as M0;

[0060] The preset mass value of water required to replenish the evaporating dish is M2. According to actual application, when the water level of the evaporating dish is lower than 1.5cm, the evaporating dish needs to be replenished. When the water level is 1.5cm, M2 = M0 + 417g;

[0061] The default value of the mass of the evaporating dish when water replenishment stops is M1. According to actual application, when the water level of the evaporating dish reaches 2cm, water addition is stopped. When the water level is 2cm, M1 = M0 + 628g;

[0062] After 20:00 every day, when the weighing device measures the mass of the evaporating dish to be less than M2, the water adding device will add water to the evaporating dish until the weighing device measures the mass of the evaporating dish to be M1, at which time the water adding device will stop adding water.

[0063] The non-contact evaporation measurement system for meteorology described in the present invention can measure not only daily evaporation but also precipitation, thus achieving multiple uses. When measuring precipitation, minute evaporation is generally not considered. The specific steps are as follows:

[0064] 1. Measure the precipitation per minute P i ;

[0065] The mass of the evaporating dish is measured every minute by a weighing device, and the mass change before and after 1 minute is recorded:

[0066] △=M i -M i-1

[0067] When △>0, record the precipitation per minute P i = (M i-1 -M i ) / (S*ρ);

[0068] When △≤0, record the precipitation per minute P i = 0;

[0069] 2. When the weighing device measures M i-1 -M i When >MM, it is determined that the secondary evaporation dish overflows at this time. The calculation formula for the rainfall per minute at this time is as follows:

[0070] P i =(M i-1 -M i ) / (S*ρ)-h, where h is the height from the highest point of the siphon to the inlet.

[0071] 3. Calculate the amount of rainfall in a day;

[0072] After collecting minute-by-minute rainfall data and minute-by-minute evaporation data for 24 hours a day, the sum of the minute-by-minute rainfall is the daily precipitation for that day, and the sum of the minute-by-minute evaporation is the daily evaporation for that day.

Claims

1. A measurement method using a small-scale meteorological non-contact evaporation measurement system, characterized in that: It includes an evaporating dish, a weighing device, a water adding device and a draining device, wherein the evaporating dish is placed on the weighing device; A detachable inverted U-shaped siphon is installed on the side wall of the evaporating dish, the inlet of the siphon is located above the bottom of the evaporating dish, and the position of the inlet of the siphon is higher than the outlet; The water adding port of the water adding device is located above the opening of the evaporating dish and does not contact the evaporating dish; The following steps are involved: (1) The mass of the evaporating dish is measured in real time every second, and the mass difference between the previous second and the current second is calculated. When the absolute value of the mass difference exceeds the set threshold, it is determined whether there is interference such as falling rocks or flying birds. If there is interference, it is recorded and the mass of the evaporating dish measured for that minute is corrected at the top of the minute. (2) Measure the evaporation rate per minute; The mass of the evaporating dish is measured every minute by a weighing device, and the observation results are corrected using precipitation data from the national automatic precipitation station precipitation sensor. The formula for calculating the evaporation rate per minute is as follows: E i =(M i-1 -M i ) / (S*ρ)+P i ; Among them, M i and M i-1 The difference in mass of the evaporating dish after interference correction for minute i and the previous minute i-1, S is the area of ​​the evaporating dish, ρ is the density of water, P i is the minute precipitation at minute i; (3) Calculate the evaporation per day; There are two methods for calculating hourly evaporation. The calculation formula of one method is the same as the calculation formula of minute evaporation, where M i and M i-1 The difference in mass of the evaporating dish after interference correction at the hour i and the previous hour i-1, P i is the hourly precipitation at time i; one calculation method is to take the sum of all minute evaporations at that time as the hourly evaporation at that time; The sum of the hourly evaporation at 24 time points is calculated as the daily evaporation for that day; (4) Determine whether the evaporating dish has been replenished with water at regular intervals every day; The preset mass value of water required to replenish the evaporating dish is M2; When the mass of the evaporating dish actually measured by the weighing device at a fixed time every day is less than M2, the water adding device automatically adds water to the evaporating dish until the mass of the evaporating dish measured by the weighing device is M1, at which point the water adding device stops adding water. Among them, M1>M2; The process also includes determining whether the evaporating dish has overflowed. Since overflow usually occurs during rain, and the mass of the evaporating dish will suddenly decrease significantly when overflow occurs, the abnormal value of the mass change of the evaporating dish before and after 1 minute can be preset as MM. When the weighing device measures M i-1 -M i >MM and P i When >0, it is determined that the evaporating dish has overflowed. The calculation formula for the evaporation rate per minute is as follows: E i =(M i-1 -M i ) / (S*ρ)+P i -h, where h is the height from the highest point of the siphon to the inlet.

2. The measuring method according to claim 1, wherein The evaporating dish is cylindrical with a diameter of 20-25 cm and a height of 10-15 cm.

3. The measuring method according to claim 2, characterized in that The mouth of the evaporating dish is provided with a detachable annular protective cover, the height of the annular protective cover is 7-10 cm, and the annular protective cover is made of a transparent material.

4. The measuring method according to claim 1, wherein The diameter of the siphon tube is 8-10 mm; the siphon tube is installed on the side wall of the evaporating dish in a threaded connection manner with an outer tube and an inner tube.

5. The measuring method according to claim 1, wherein: The weighing device is an electronic balance or a gravity sensor, and the measurement sensitivity of the weighing device is 0.01g and the measurement time accuracy is 1 second.

6. The measuring method according to claim 1, characterized in that The length of h is 5-6 cm, and the weight of MM is 314-1884 g.

Images