Evaluation of precipitation distribution at different altitude by the development of weight type precipitation gauge

重量式降水仪研制评价不同海拔降水分布

• 批准号: 14595005
• 负责人: UENO Kenichi
• 金额: $ 1.66万
• 依托单位: The University of Shiga Prefecture
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14595005/
• 关键词: Precipitation; Weight type; Warm winter; Gauge; Snowfall; Shiga prefecture; 降水量計

Small weight type precipitation gauge was developed trough three trial stages, to measure the winter precipitation at different altitude and to evaluate the water equivalent of snow Dover (WES) in case of temperature change in recent warm winters, At a first stage, "Trial gauge 1 (T1)" was developed to measure min and to understand the basic behavior of water level variability in the field. Transparent water tanks was used as a unique point to observe the behavior of antifreeze liquid Anti-evaporation oil and wind fence were important items to reduce the noise of water level. "Trial gauge 2 (T2)" was developed as an improved version of Ti equipped with a double wall for water tank with solar panel heating and automatic draining functions. Heat budget analysis of radiate cooling and melting of solid precipitation was done, and was verified by the experiment by using G2. The results showed that a 10W heater was enough to keep the water temperature at 0C and could be conducted only by a s … More olar panel with 24Wh battery in case of winter climate at Hikone. To test at colder air temperature with heavier snowfall condition, "Trial gauge 3 (T3)" was developed with fundamental reconstruction of body shape with a function of automatic supplement system of antifreeze, as a original model of "new small type weight type precipitation gauge". The T3 has a small orifice size as 5cm radiance to reduce the heating energy of antifreeze. Field campaign was conducted at Surumi observatory, northern Shiga prefecture, on January and February in 2004. The T3 was successfully measured snow and rain for two months with automatic heating and drain/supply system of antifreeze by self measurement of water level and water temperature. Hourly precipitation amount was consistent well with heating type rain gauge, except that two cases of continuous heavy snowfall and delay of melting snow on the standard gauge caud data discrepancy. One serious problem was found, such as that separated precipitation water on the antifreeze frozen in the tank due. to strong radiative cooling and caused snowcap at the next snowfall event. Separation of pressure sensor from the bottom of gauge is another issue to prevent pressure noise due to temperature change.Unfortunately, precipitation observation at different altitude by using multiple T3 was not conducted because of the delay of gauge development and extra-ordinal warm winter in January 2004. On the other hand, seasonal change of WES was diagnosed by using simple experimental model with precipitation and temperature data measured at Surunii main and satellite station. The model was consisted with a discrimination function between solid and liquid precipitation and degree-hour wefcient to estimate melting rate as a function of temperature. Digital elevation map (DEM) was also constructed at 7m interval based on local topography map. The estimated WES well coincided with intra-seasonal variation of snow depth. In case of 2℃ temperature increase (decrease) caused anomalous increase (decrease) of WES at Surumi. Beside, temperature at satellite station, locating 200m higher than that at main station, was not always lower than that at the main station. A reason is speculated as development of inversion layer in the night due to snow cover in the small valley. Therefore, speculated WES was not increased as a function of elevation. To reveal the area averaged WES changes, we need to consider the temperature variation in the valley as well as difference of precipitation amount at different altitudes. Less

为了测量不同海拔高度的冬季降水，评估近年暖冬气温变化情况下雪多佛（WES）的水当量，通过三个试验阶段研制了小重量式降水计。第一阶段研制了“1号试验计（T1）”，用于测量最小值并了解野外水位变化的基本行为。采用透明水箱作为观察防冻液行为的独特点，防蒸发油和风栅是降低水位噪声的重要项目。“试验仪表2 （T2）”是Ti的改进版本，配备了带有太阳能板加热和自动排水功能的双壁水箱。对固体析出物的辐射冷却和熔化过程进行了热收支分析，并用G2进行了实验验证。结果表明，在冬季气候条件下，一个10W的加热器足以使水温保持在0℃，并且仅需要一个5w以上的太阳能电池板和24Wh电池就可以实现。为了在更冷的气温和更强的降雪条件下进行试验，研制了具有防冻液自动补充系统功能的“三号试验计（T3）”，作为“新型小重量式雨量计”的原创型号。T3具有5cm辐射的小孔口尺寸，以减少防冻液的加热能量。2004年1月和2月在滋贺县北部的Surumi天文台进行了实地活动。T3通过自动测量水位和水温，采用防冻液自动加热和排水/供应系统，成功测量了两个月的雨雪。逐时降水量与加热式雨量计吻合较好，但标准雨量计连续降雪量和融雪延迟两次出现数据偏差。一个严重的问题被发现，如分离沉淀水在防冻液罐中冻结所致。以强辐射冷却而造成下一次降雪时的积雪。压力传感器与压力表底部的分离是防止温度变化引起的压力噪声的另一个问题。遗憾的是，由于2004年1月异常暖冬和量具发展滞后，未能利用多个T3进行不同高度的降水观测。另一方面，利用苏里尼主站和卫星站实测的降水和温度资料，利用简单的实验模型对WES的季节变化进行诊断。该模型由固液析出判别函数和度时系数组成，以估计熔化速率作为温度的函数。在当地地形图的基础上，以7m为间隔构建数字高程图（DEM）。估算的WES与雪深的季节内变化吻合较好。当气温升高（降低）2℃时，泗水WES异常升高（降低）。此外，比主站高200m的卫星站温度并不总是低于主站温度。推测其原因是由于小山谷积雪，夜间逆温层形成。因此，推测WES不随海拔升高而增加。为了揭示区域平均WES变化，我们需要考虑河谷的温度变化以及不同海拔的降水量差异。少