A portable instrument for the measurement of salinity of rainwater using FET's     

Rao  A. M. 《Pure and Applied Geophysics》1985,123(2):344-347

A portable salinity meter with field effect transistors for the continuous recording of salinity of rainwater is described. The variations in salinity are converted into current variations by using a D.C. differential amplifier and is recorded on an Esterline Angus Recorder. The Meter enables us to measure rainfall intensity as well as salinity simultaneously. The chief advantages of the present instrument are that it is portable and has a range of measurement from 1×10^–4 to 1×10^–1 ppm on a linear scale.  相似文献   

Evaluating precipitation products for hydrologic modeling over a large river basin in the Midwestern USA     

Jingrui Wang  Ganming Liu 《水文科学杂志》2020,65(7):1221-1238

ABSTRACT

We evaluated precipitation estimates, TRMM (Tropical Rainfall Measuring Mission 3B42V7), CFSR (Climate Forecast System Reanalysis), GHCN-D (Global Historical Climatology Network-Daily Version 3.24), and Daymet, using the Soil and Water Assessment Tool (SWAT). The suitability and quality of TRMM, CFSR and Daymet in forcing the SWAT-based hydrological model was examined by means of model calibration. A calibrated TRMM-driven model slightly overestimated streamflow, while a calibrated CFSR-driven model performed worst. The Daymet-driven model performance was as good as the GHCN-D-driven model in reproducing observations. In addition, the temperature was far less sensitive compared with precipitation in driving SWAT. TRMM 3B42V7 showed great potential in streamflow simulation. The results and findings from this study provide new insights into the suitability of precipitation products for hydrological and climate impact studies in large basins, particularly those in typical climates and physiographic settings similar to the Midwestern USA.  相似文献   

精密测距三角水准测量的研究   总被引：1，自引：0，他引：1  

徐正扬  林广元  郭木根  王克宽 《测绘学院学报》1991,(4)

本文从理论上分析了T2000测距三角高程的各项误差,提出了按跳点法观测的垂线偏差影响公式和精度达0.2毫米的量高方法,讨论了减弱大气垂直折光影响的措施。通过150公里的比较试验,得出了S≤500米,α≤10°按跳点法观测或S≤1公里、α≤8°按对向测距三角高程均能达到二等水准精度要求的结论。  相似文献   

延寿跨断层短水准测量误差性质及其来源的讨论     

王成志  李希文 《东北地震研究》2000,16(3):51-55

本文应用数理统计的理论,方法对延寿跨断层短水准１９８８年至１９９４年计４６期观测成果进行了数理统计处理（ｔ分布检验）,对其检验结果结合测线的布设、场地情况,干扰情况以及施测条件等因素加以综合分析,认为观测成果中系统误差是客观存在的,据此采取相应的改进措施,利用改进措施后的观测成果进一步做ｔ分布检验系统误差得以减小。  相似文献   

TRMM卫星降水数据在天山山区的校正方法研究   总被引：4，自引：3，他引：1  

金晓龙  邵华  邱源  杜浩阳 《气象》2018,44(7):882-891

本文基于全球降水观测(Global Precipitation Measurement,GPM)及天山山区40个气象站点数据,提出了一种新的热带降水测量任务(Tropical Rainfall Measuring Mission,TRMM)卫星数据误差校正方法(MERGE),并与广泛使用的地理差异分析(Geographical Different Analysis,GDA)方法进行对比,通过交叉验证来评价两种方法对山区年/月降水的校正效果。结果表明,MERGE方法不仅能提高TRMM的空间分辨率(0.05°),且在年(平均Bias降低了21%)、月(平均Bias降低了37%)尺度上的校正结果都优于GDA方法;校正后TRMM降水的误差在不同月份存在很大差异,即在降水较多的雨季(4—10月)误差较大(MAE3mm),而在干季(11月至次年3月)误差较小(MAE3mm)。MERGE方法不仅能有效改善高海拔地区的降水误差(平均误差降低了59%),且对原始TRMM数据的依赖性较小(R2=0.47),即使在原始TRMM数据表现不佳的局部区域,也能有效降低其误差。  相似文献   

数字式雹雨分测仪的研制     

董晓波  孟宪罗  甄树勇  石安英  吕峰  胡向峰 《干旱气象》2014,(3):465-468,480

重点介绍了数字式雹雨分测仪的工作原理:通过过滤的方式成功将冰雹和雨滴分离,再利用阿基米德定律测算出降雹量。该仪器充分利用了雨量测量、GPRS数据传输、太阳能供电等先进技术,具有全自动、数字化特点及良好的组网能力。经实际野外试验观测表明,该仪器性能稳定,使用便捷。通过野外试验观测数据分析,数字式雹雨分测仪观测的雨量与其他仪器观测的雨量相比,误差在可接受范围内。由于该仪器能够实时观测到降雹量,为冰雹的观测研究提供了仪器支持。  相似文献