New versions of the BDS/GNSS zenith tropospheric d

Authors: Wei Li Yunbin Yuan Jikun Ou Yanju Chai Zishen Li YueiAn Liou Ningbo Wang

Publish Date: 2014/09/24

Volume: 89, Issue: 1, Pages: 73-80

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Abstract

The initial IGGtrop model proposed for Chinese BDS BeiDou System is not very suitable for BDS/GNSS research and application due to its large data volume while it shows a global mean accuracy of 4 cm New versions of the global zenith tropospheric delay ZTD model IGGtrop are developed through further investigation on the spatial and temporal characteristics of global ZTD From global GNSS ZTD observations and weather reanalysis data new ZTD characteristics are found and discussed in this study including small and inconsistent seasonal variation in ZTD between 10circ hbox S mathrmand 10circ hbox N and stable seasonal variation outside weak zonal variation in ZTD at higher latitudes north of 60circ hbox N and south of 40circ hbox S and at heights above 6 km etc Based on these analyses new versions of IGGtrop named hbox IGGtrop r i i=1 2 3 are established through employing corresponding strategies using a simple algorithm for equatorial ZTD generating an adaptive spatial grid with lower resolutions in regions where ZTD varies little and creating a method for optimized storage of model parameters Thus the hbox IGGtrop r ii=1 2 3 models require much less parameters than the IGGtrop model nearly 31–212  of that for the IGGtrop model The three new versions are validated  by five years of GNSSderived ZTDs at 125 IGS sites and it shows that hbox IGGtrop r 1 demonstrates the highest ZTD correction performance similar to IGGtrop hbox IGGtrop r 3 requires the least model parameters hbox IGGtrop r 2 is moderate in both zenith delay prediction performance and number of model parameters For the hbox IGGtrop r 3 model the biases at those IGS sites are between 64 and 43 cm with a mean value of 08~cm and RMS errors are between 21 and 85 cm with a mean value of 40 cm Different BDS and other GNSS users can choose a suitable model according to their application and research requirementsThe authors are grateful to the IGS for providing GNSS ZTD data and NOAA for providing NCEP reanalysis data This work was supported by the National Basic Research Program of China 2012CB825604 the National Natural Science Foundation of China 41231064 41104103 41021003 the CAS Knowledge Innovation Program KGCXZEW4072 the 863 program 2012AA121803 and the National Science Council NSC of Taiwan 1012111M008018

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