Troposphere mapping functions for GPS and very long baseline interferometry from European Centre for Medium-Range Weather Forecasts operational analysis data
Troposphere mapping functions for GPS and very long baseline interferometry from European Centre for Medium-Range Weather Forecasts operational analysis data
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DOI：
10.1029/2005jb003629
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发表时间：
2006-02-15
影响因子：
3.9
通讯作者：
Schuh, Harald
中科院分区：
文献类型：
--
作者：
Boehm, Johannes;Werl, Birgit;Schuh, Harald
在大地测量甚长基线干涉测量（VLBI）和GPS数据的分析中，用于绘制从天顶到场地线的大气延迟图的解析形式通常是以1/sin（高程）为单位的三参数连分数。本文利用欧洲中期天气预报中心（CEME-ERA-40）2001年再分析资料，重新确定了流体静力图函数连分式的B、c系数。与以前基于数值天气模型数据的映射函数不同（等压映射函数（Niell，2000）和维也纳映射函数（VMF））（Boehm和Schuh，2004年）），新的c系数取决于一年中的哪一天，并且与Niell映射函数不同（Niell，1996）它们不再相对于赤道对称（除了两个半球的相反相位）。与VMF相比，这对VLBI或GPS站高度的影响是恒定的，在赤道最大为2 mm，在两极季节性变化为4 mm至0 mm。更新后的VMF，基于这些新的系数，并在下文中称为VMF 1，产生稍微更好的VLBI数据的基线长度重复性。在2002年和2003年所有VLBI国际测地和天体测量服务（IVS）-R1和IVS-R4 24小时会议的分析中，采用了不同类型的先验天顶延迟的各种组合的流体静力学和湿制图功能;调查集中在基线长度重复性以及站高的绝对变化上。
In the analyses of geodetic very long baseline interferometry (VLBI) and GPS data the analytic form used for mapping of the atmosphere delay from zenith to the line of site is most often a three-parameter continued fraction in 1/sin(elevation). Using the 40 years reanalysis (ERA-40) data of the European Centre for Medium-Range Weather Forecasts for the year 2001, the b and c coefficients of the continued fraction form for the hydrostatic mapping functions have been redetermined. Unlike previous mapping functions based on data from numerical weather models (isobaric mapping functions (Niell, 2000) and Vienna mapping functions (VMF)(Boehm and Schuh, 2004)), the new c coefficients are dependent on the day of the year, and unlike the Niell mapping functions (Niell, 1996) they are no longer symmetric with respect to the equator (apart from the opposite phase for the two hemispheres). Compared to VMF, this causes an effect on the VLBI or GPS station heights that is constant and as large as 2 mm at the equator and that varies seasonally between 4 mm and 0 mm at the poles. The updated VMF, based on these new coefficients and called VMF1 hereinafter, yields slightly better baseline length repeatabilities for VLBI data. The hydrostatic and wet mapping functions are applied in various combinations with different kinds of a priori zenith delays in the analyses of all VLBI International VLBI Service for Geodesy and Astrometry (IVS)-R1 and IVS-R4 24-hour sessions of 2002 and 2003; the investigations concentrate on baseline length repeatabilities, as well as on absolute changes of station heights.