Troposphere delays from space geodetic techniques, water vapor radiometers, and numerical weather models over a series of continuous VLBI campaigns
Troposphere delays from space geodetic techniques, water vapor radiometers, and numerical weather models over a series of continuous VLBI campaigns
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DOI：
10.1007/s00190-013-0662-z
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发表时间：
2013-10
影响因子：
4.4
通讯作者：
K. Teke;T. Nilsson;J. Böhm;T. Hobiger;P. Steigenberger;S. García-Espada;R. Haas;P. Willis
中科院分区：
文献类型：
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作者：
K. Teke;T. Nilsson;J. Böhm;T. Hobiger;P. Steigenberger;S. García-Espada;R. Haas;P. Willis
连续的、非常长的基线干涉测量(VLBI)活动已经重复进行了两周多，即2002年10月的CONT02、2005年9月的CONT05、2008年8月的CONT08和2011年9月的CONT11，以证明目前的VLBI当时能够达到的最高精度。在这项研究中，我们比较了参加CONT活动的VLBI站点的天顶总延迟(ZTD)和对流层梯度，这是从VLBI、全球导航卫星系统(GNSS)和卫星集成多普勒轨道和无线电定位(DORIS)的观测中一致估计的。我们使用最先进的软件分析了CONT活动，尽可能遵循常见的处理策略。同时，ZTD和梯度来自数值天气模式，即全球欧洲中期天气预报中心(ECMWF)分析场、高分辨率有限区域模式(欧洲站点)、日本气象厅业务中观分析场(Manal，日本上空)和云解析风暴模拟器(筑波，日本)。最后，根据在CONT会议期间可获得水汽辐射计观测资料的地点的水汽辐射计观测资料，估计了天顶湿延迟。在大多数共址地点和CONT活动中，GNSS和VLBI技术之间的最佳ZTD协议(解释为最小标准偏差)约为5-6毫米。随着时间的推移，除了Doris和Manal之外，我们没有发现各种技术之间的ZTD协议有任何显著的改进。另一方面，对流层参数的一致性和准确性主要取决于大气中的湿度。
Continuous, very long baseline interferometry (VLBI) campaigns over 2 weeks have been carried out repeatedly, i.e., CONT02 in October 2002, CONT05 in September 2005, CONT08 in August 2008, and CONT11 in September 2011, to demonstrate the highest accuracy the current VLBI was capable at that time. In this study, we have compared zenith total delays (ZTD) and troposphere gradients as consistently estimated from the observations of VLBI, Global Navigation Satellite Systems (GNSS), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) at VLBI sites participating in the CONT campaigns. We analyzed the CONT campaigns using the state-of-the-art software following common processing strategies as closely as possible. In parallel, ZTD and gradients were derived from numerical weather models, i.e., from the global European Centre for Medium-Range Weather Forecasts (ECMWF) analysis fields, the High Resolution Limited Area Model (European sites), the Japan Meteorological Agency-Operational Meso-Analysis Field (MANAL, over Japan), and the Cloud Resolving Storm Simulator (Tsukuba, Japan). Finally, zenith wet delays were estimated from the observations of water vapor radiometers (WVR) at sites where the WVR observables are available during the CONT sessions. The best ZTD agreement, interpreted as the smallest standard deviation, was found between GNSS and VLBI techniques to be about 5–6 mm at most of the co-located sites and CONT campaigns. We did not detect any significant improvement in the ZTD agreement between various techniques over time, except for DORIS and MANAL. On the other hand, the agreement and thus the accuracy of the troposphere parameters mainly depend on the amount of humidity in the atmosphere.