||| |
Dear IGS colleagues, Either because they are decommissioned, dormant or have been affected by discontinuities since 2009.5, a large number of IGS08 stations are now unusable for operational reference frame alignments. In particular, the IGS08 core network has dropped to about 50 usable stations recently, leaving large holes in South America, Africa, and Eastern Asia. This situation led us to propose an update of IGS08, called IGb08. IGb08 mainly includes new sets of coordinates for 33 IGS08 stations having been affected by position discontinuities since 2009.5, and 3 new stations co-located with decommissioned IGS08 stations. (The various changes from IGS08 to IGb08 are described in more details below.) All in all, this update will increase the number of usable Reference Frame stations by about 36 and the number of usable core stations by about 15. IGb08.snx is available with some ancillary files atftp://igs-rf.ign.fr/pub/IGb08 & ftp://igs-rf.ensg.eu/pub/IGb08 : * IGb08.snx : IGb08 SINEX file * IGb08.ssc : IGb08.snx without covariance matrix * IGb08_core.txt : list of IGb08 core stations * IGS08-IGb08.xls : summary table of the IGS08->IGb08 changes * IGS08-IGb08.dat : numerical values of the IGS08->IGb08 changes * IGb08_1701.png : state map of the IGb08 network on week 1701 * IGb08_core_1701.png : state map of the IGb08 core network on week 1701 IGb08 will officially replace IGS08 starting with products of GPS week 1709 (7 October 2012). This switch aims at stabilizing the reference frame alignment of the IGS products and should not lead to any particular inconvenience for users. Paul Rebischung, on behalf of the IGS Reference Frame Working Group 1) Introduction of post-discontinuity coordinates ------------------------------------------------- 38 IGS08 stations with discontinuities since 2009.5 were first identified as "repairable". A special cumulative solution was then formed, based on the igb/igs weekly solutions up to week 1701, in which station annual motions were estimated together with their positions and velocities. Empirical offsets from the pre-break to the post-break station positions were derived from this cumulative solution and used to introduce post-break coordinates for the 38 stations in IGb08. As a validation, IGb08 was used to align the igs weekly solutions of weeks 1632-1701. A check of the alignment residuals for the 38 newly introduced points led us to reject 5 of them from IGb08 (BAN2, DGAR, GUUG, HOLB, OHI3). 2) Intro. of new stations co-located with decommissioned IGS08 stations ----------------------------------------------------------------------- 3 pairs of decommissioned IGS08 stations co-located with currently active stations were identified (CHAT/CHTI, MALI/MAL2, NOUM/NRMD). Empirical "local ties" between these pairs of stations were derived from the same cumulative solution as in 1) and used to introduce the 3 new stations in IGb08. All 3 new stations successfully passed the validation test described in 1). 3) Application of position offsets to account for metadata corrections ---------------------------------------------------------------------- As explained in IGSMAIL-6662, sub-type calibrations will come into use on week 1709 for the JPSREGANT_DD_E and JPSREGANT_SD_E antennas and replace the type mean calibrations used so far. To make IGb08 consistent with the new sub-type calibrations, position offsets were derived from differential PPP tests and applied to the IGS08 positions of the 5 affected IGS08 stations (CAGZ, CONZ, KHAJ, MDVJ, ZIMJ). It was recently discovered that a wrong antenna type had been reported in the sitelogs of 2 IGS08 stations (ALRT, NAIN). To make IGb08 consistent with the right antenna type (now in use), position offsets were derived from differential PPP tests and applied to the IGS08 positions ALRT and NAIN. 4) Discontinuity suppressions ----------------------------- The discontinuities introduced for ALRT and NAIN at the time when their sitelogs were corrected will be removed with the switch to IGb08. Two discontinuities were introduced when the radome of CRO1 was removed and re-installed in 2011. But no significant jump is in fact detectable in CRO1's coordinate time series. Both discontinuities will thus be removed with the switch to IGb08 and CRO1 will become usable again as a Reference Frame station. 5) Station suppression ---------------------- Due to uncertainty about its radome loss (IGSSTATION-4610), BRMU (Bermuda) was removed from IGb08 for the period after 2003.
中文翻译:
亲爱的IGS同事,
要么因为退役,休眠或受到影响
自2009年以来的不连续性,现在有大量的IGS08站
无法用于操作参考帧对齐。特别是
最近,IGS08核心网已降至约50个可用站点,
在南美洲,非洲和东亚留下大洞。这个
情况促使我们提出IGS08的更新,称为IGb08。
IGb08主要包括33个IGS08台站的新坐标集
自2009年以来已经受到位置不连续性的影响.5和3个新站点
与退役的IGS08站同处一地。 (各种变化来自
IGS08至IGb08将在下面详细描述。)总而言之,这一点
更新将增加可用参考帧站的数量
大约36个可用核心站的数量约为15个。
IGb08.snx可用于一些辅助文件
ftp://igs-rf.ign.fr/pub/IGb08&ftp://igs-rf.ensg.eu/pub/IGb08:
* IGb08.snx:IGb08 SINEX文件
* IGb08.ssc:没有协方差矩阵的IGb08.snx
* IGb08_core.txt:IGb08核心站列表
* IGS08-IGb08.xls:IGS08-> IGb08变更汇总表
* IGS08-IGb08.dat:IGS08-> IGb08变化的数值
* IGb08_1701.png:第1701周IGb08网络的状态图
* IGb08_core_1701.png:第1701周IGb08核心网的状态图
IGb08将从GPS周产品开始正式取代IGS08
1709(2012年10月7日)。该开关旨在稳定参考系
IGS产品的对齐并不应导致任何特定的
给用户带来不便。
Paul Rebischung代表IGS参考框架工作组
1)引入不连续后坐标
-------------------------------------------------
自2009年以来已确定38个IGS08站点,这些站点已不连续
作为“可修复的”。然后在此基础上形成了一种特殊的累积解决方案
igb / igs每周解决方案,直至1701年,其中每年一次
运动与他们的位置和速度一起估计。
从破发前到破发后站位的经验抵消
来自这个累积的解决方案并用于介绍
IGb08中38个站的断续后坐标。
作为验证,IGb08用于对齐每周一周的解决方案
1632年至1701年。检查新引入的38的对齐残差
积分让我们拒绝其中的5个来自IGb08(BAN2,DGAR,GUUG,HOLB,
OHI3)。
2)简介新的电台与退役的IGS08电台共址
-------------------------------------------------- ---------------------
3对退役的IGS08站与当前活动的站位于同一地点
确定了台站(CHAT / CHTI,MALI / MAL2,NOUM / NRMD)。经验
这些电台对之间的“本地联系”来源于此
累积解决方案如1)并用于介绍3个新站
IGb08。所有3个新站成功通过了验证测试
在1)中描述。
3)应用位置偏移来考虑元数据校正
-------------------------------------------------- --------------------
如IGSMAIL-6662中所述,子类型校准将开始使用
第1709周为JPSREGANT_DD_E和JPSREGANT_SD_E天线并更换
到目前为止使用的类型平均校准。使IGb08符合
新的子类型校准,位置偏移来自差分
PPP测试并应用于5个受影响的IGS08的IGS08位置
站(CAGZ,CONZ,KHAJ,MDVJ,ZIMJ)。
最近发现了一种错误的天线类型
2个IGS08站(ALRT,NAIN)的坐标。使IGb08保持一致
使用正确的天线类型(现在使用),导出位置偏移
从差分PPP测试,并应用于IGS08位置ALRT和
NAIN。
4)不连续抑制
-----------------------------
ALRT和NAIN在他们的时候引入了不连续性
通过切换到IGb08,将删除纠正的sitelogs。
当去除CRO1的天线罩时引入两个不连续性
并且在2011年重新安装。但实际上没有明显的跳跃
CRO1的坐标时间序列。因此将消除两个不连续性
切换到IGb08和CRO1将再次作为参考使用
帧站。
5)站抑制
----------------------
由于其天线罩损失的不确定性(IGSSTATION-4610),BRMU(百慕大)
在2003年之后的一段时间内被从IGb08中删除。
以上转载。
注:理论上:你可以把IGB08当成ITRF08来用。
Archiver|手机版|科学网 ( 京ICP备07017567号-12 )
GMT+8, 2024-9-1 08:19
Powered by ScienceNet.cn
Copyright © 2007- 中国科学报社