Instant determination of polar motion with tri-static common view lunar laser ranging 后印本

摘要: A method is presented for determining instant values of Earth’s polar motion (PM) using a set of lunar laser ranging  (LLR)  measurements  acquired  simultaneously  by  tri-static  common  view  (TCV)  at  three  LLR stations  in Europe.  We  developed  a  model  of  the  LLR  TCV  measurements,  then  formulated  the  linear  equation  for  solving  PM. Although  there  was  no  actual  TCV  event  in  the  data,  we  conducted  a  two-phase  study  to  test  our  method  using  actual LLR  normal  points  (NPs)  acquired  by  the  European  stations  during  2012–2022.  In  the  first  phase,  we  simulated  TCV events  and  PM  solutions.  The  robustness  of our  method  was  assessed  by  introducing  Universal  Time  (UT1)  errors  and per-station  range  errors  in  this  phase.  In  the  second  phase,  we  augmented  the  actual  LLR  NPs  with  simulated  data  to generate realistic  TCV  events  and  solutions,  using  the ‘1+2’ and ‘2+1’ strategies,  which  differed  in  terms  of  data composition.  Results  indicated  that  a  UT1  error  of  0.1  ms  caused  PM  errors  of  <18  mas,  while  a uniform  range  error of  50  mm  resulted  in  PM  errors  of  <180  mas.  In  the  augmentation  phase,  the  maximum  solution  errors  were  752  and 899  mas,  and  88.5%  and  91.2%  of  the  solutions  were  better  than the  predictions  for  the ‘1+2’ and ‘2+1’ strategies, respectively.  The  presented  approach  relies  on  precise  geodetic  data,  and  therefore,  it  is  not  intended  to  replace  the traditional  method.  However,  this study  demonstrated  that  instant  determination  of  PM  is  feasible  and  robust,  although the accuracy requires further enhancement.