This data set is the meteorological observation data of Nanxiaohegou basin from 1954 to 1980, including the daily water surface evaporation of Yangjiagou, dongzhuanggou and 18 Mu stations. During the freezing period, the small dish was observed once every day at 8:00. The evaporation capacity of evaporating dish is observed by rainfall cup of the same specification or special platform scale. The original water in the evaporating dish is 20 mm. At 8:00 a.m. of the previous day, the water in the cup is filled with 20 mm. After 24 hours, the remaining water in the dish is returned to the measuring cup, and the amount of reduction is the evaporation of the day.
After observation, change water to keep the water volume of 20 mm in the dish. When there is rain falling into the dish, the actual evaporation is obtained by subtracting the precipitation during the observation and recording. When there is ice in the dish, use the weighing method to observe. Pour 20 mm clear water into the dish, weigh the weight (g) on the platform scale, and set the scale at the weight of 20 mm water. On the observation day, put the evaporation pan (containing ice) on the platform scale, and add water to the pan with a rainfall cup until the scale is flat. The water added is the accumulated evaporation.
1) If the calculated evaporation is negative, it will be recorded as "0.0 +". 2) Since the evaporating dish freezes in the specified observation time, and the observation is carried out at a non icing time, a "B" symbol should be added to the right side of the evaporation value. 3) During the icing period, if the total amount of evaporation is observed once a few days, the total amount should be recorded in the grid of the observation day, and the symbol "↓ B" should be filled in the grid of each day when the observation is stopped. However, for those who cross the month, the evaporation allocated to the previous month should be calculated according to the proportion of the number of days, and recorded in the doomsday grid of the month. Then, the total evaporation amount minus the evaporation amount of the previous month is used to calculate the evaporation allocated to the next month. When it is recorded in the observation day grid, the two values are added with the column symbol "Φ", and the rest days are filled with "↓ B". 4) If the observation data is missing, interpolation can be carried out, but the time of interpolation shall not exceed 3 days within 10 days. 5) During the non icing period, if the evaporation of all the missing days is included in the observation value of the subsequent observation day, no icing sign is added. 6) If there are combined and broken down values in a month, they are still regarded as complete data, and monthly evaporation is not bracketed. 7) In this period, the total number of the selected days is divided by the total number of the combined days in a month. If it is selected as the maximum and minimum, brackets shall be added; if other values are selected as the maximum and minimum instead of the average value, brackets shall be added generally; only if it can be determined that they are the maximum and minimum of a month, they shall not be bracketed. 8) The dates of the first and last ice in the evaporating dish during the period from July 1 of the previous year to June 30 of this year are recorded in the columns of the first and last ice formation in the pan. The date of the first freezing in the pan from July 1 to the end of this year is recorded in the ice date column at the beginning of this winter.
In the process of compilation and input of observation data, there are four levels of manual verification, including tabulation, primary calibration, recheck and audit, so as to ensure the data quality.
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