Absolute accuracy of water vapor measurements from six operational radiosonde types launched during AWEX-G and implications for AIRS validation
Absolute accuracy of water vapor measurements from six operational radiosonde types launched during AWEX-G and implications for AIRS validation
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DOI：
10.1029/2005jd006083
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发表时间：
2006-04-07
影响因子：
4.4
通讯作者：
Russo, F
中科院分区：
文献类型：
--
作者：
Miloshevich, LM;Vömel, H;Russo, F
[1]需要对整个对流层柱的无线电探空仪水汽测量精度进行详细评估，以评估观测误差对使用无线电探空仪数据作为输入的应用的影响，例如预报建模、辐射传输计算、遥感器反演验证、气候趋势研究以及气候学和云和辐射参数的发展。在大气红外探测仪(AIRS)水汽实验场(AWEX-G)期间，六种工作无线电探空仪以不同的组合与参考质量湿度计一起飞行，同时从拉曼激光雷达和微波辐射计获得同步测量。这项研究确定了相对于科罗拉多大学(CU)低温霜点湿度计(CFH)同步测量的无线电探空仪水汽测量的平均精度和变异性，CFH是已知绝对精度的参考质量标准。评估了以下类型无线电探空仪的精度和性能特点：Vaisala Rs80-H、RS90和RS92；Sippcan Mark IIa；Modem GL98；以及Meteolabor Snow White湿度计。利用Vaisala探空仪测量对流层上层水汽时，对传感器时滞误差进行了有效的修正，提高了测量精度，降低了可变性。AWEX数据集还用于推导和验证新的经验校正，该校正可根据温度、相对湿度和传感器类型的不同而提高Vaisala测量的平均校准精度。完全校正的Vaisala无线电探空仪测量结果被发现适用于整个对流层的AIRS验证，而其他类型的无线电探空仪仅在对流层条件的子集下适用于准确。虽然这项研究侧重于夜间无线电探空仪测量的准确性，但Vaisala RS90测量与微波辐射计水汽反演的比较表明，白天RS90测量的干偏差为6-8%，这是由传感器的太阳加热引起的。为了完成精度评估，非常需要一组类似AWEX的白天测量数据，理想的情况是从热带地区进行，在那里可以采集对流层温度的全部范围。
[1] A detailed assessment of radiosonde water vapor measurement accuracy throughout the tropospheric column is needed for assessing the impact of observational error on applications that use the radiosonde data as input, such as forecast modeling, radiative transfer calculations, remote sensor retrieval validation, climate trend studies, and development of climatologies and cloud and radiation parameterizations. Six operational radiosonde types were flown together in various combinations with a reference-quality hygrometer during the Atmospheric Infrared Sounder ( AIRS) Water Vapor Experiment-Ground (AWEX-G), while simultaneous measurements were acquired from Raman lidar and microwave radiometers. This study determines the mean accuracy and variability of the radiosonde water vapor measurements relative to simultaneous measurements from the University of Colorado (CU) Cryogenic Frostpoint Hygrometer (CFH), a reference-quality standard of known absolute accuracy. The accuracy and performance characteristics of the following radiosonde types are evaluated: Vaisala RS80-H, RS90, and RS92; Sippican Mark IIa; Modem GL98; and the Meteolabor Snow White hygrometer. A validated correction for sensor time lag error is found to improve the accuracy and reduce the variability of upper tropospheric water vapor measurements from the Vaisala radiosondes. The AWEX data set is also used to derive and validate a new empirical correction that improves the mean calibration accuracy of Vaisala measurements by an amount that depends on the temperature, relative humidity, and sensor type. Fully corrected Vaisala radiosonde measurements are found to be suitably accurate for AIRS validation throughout the troposphere, whereas the other radiosonde types are suitably accurate under only a subset of tropospheric conditions. Although this study focuses on the accuracy of nighttime radiosonde measurements, comparison of Vaisala RS90 measurements to water vapor retrievals from a microwave radiometer reveals a 6 - 8% dry bias in daytime RS90 measurements that is caused by solar heating of the sensor. An AWEX-like data set of daytime measurements is highly desirable to complete the accuracy assessment, ideally from a tropical location where the full range of tropospheric temperatures can be sampled.