极移高精度预报对卫星实时定轨、深空探测器导航等应用至关重要.本文提出了一种联合有效角动量(Effective Angular Momentum,EAM)与国际全球卫星导航系统服务组织(International GNSS Service,IGS)提供的超快解数据进行极移预报的方法.该方法基于IGS超快解数据得到的极移第1天预报值,对引入EAM得到的极移预报结果进行校正,获得联合预报值.首先,基于LS(Least Squares)+AR(Auto-Regressive)模型实现了引入EAM的极移预报,相对国际地球自转与参考系统服务组织(International Earth Rotation and Reference Systems Service,IERS)提供的公报A数据,在超短期(第1～10天)预报跨度可以得到更高精度的极移预报结果,其中大气和海洋角动量发挥了主要作用.其次,鉴于IGS超快解数据精度高、更新快的特点,以IGS超快解为基础数据,基于LS+AR模型可以得到极移第1天预报值,其精度显著优于IERS公报A的极移第1天预报值.最后,利用第1天预报值对顾及有效角动量的预报结果进行校正获得了联合预报值,进一步提高了超短期极移预报精度(尤其是第1～5天).2020年7月24日 2022年1月30日间的联合预报结果表明:第1～20天的预报值总体优于IERS公报A的预报值.其中,第1～10天的预报精度显著提升,在预报第1天,X、Y方向预报值相对公报A预报值的精度提升分别可达39.5％～62.3％和24.5％～51.9％;在预报第10天,相对公报A预报值的精度提升分别可达28.0％～28.9％和 21.9％～23.4％.
A hybrid polar motion prediction method combining effective angular momentum and IGS ultra rapid data
Predictions of polar motion is important for geodetic and geophysical applications such as real-time satellite orbit determination and deep space navigation.We propose a hybrid method combining effective angular momentum(EAM)and International GNSS Service(IGS)ultra rapid data for polar motion prediction.In this approach,IGS ultra rapid polar motion are introduced to calibrate the ultra short-term predictions.First,EAM data are combined with LS(Least Squares)+AR(Auto-Regressive)model(EAM+LS+AR)to predict polar motion.Results show that improved ultra short-term forecasts are obtained compared with predictions reported by Bulletin A of the International Earth Rotation and Reference Systems Service(IERS),where atmospheric and oceanic angular momentum are demonstrated to be the major contributors.Second,we introduce the IGS ultra-rapid polar motion with high-accuracy and low-latency to LS+AR model for a further improvement of polar motion prediction on the first day.Finally,the difference between this prediction and that from EAM+LS+AR is caluculated and used to calibrate the predictions from EAM+LS+AR for the following days,which further improves the accuracy of ultra short-term polar motion forecast,especially for 1 5 days.Based on hindcast experiments covering July 24,2020 to January 30,2022,our results perform better than Bulletin A ranging from 1 to 20 days,especially for 1～10 days.On the first day,the predicted polar motion for X and Y poles can be improved by 39.5％62.3％and 24.5％～51.9％respectively;On the 10th day of forecast,the predicted polar motion for X and Y poles can be improved by 28.0％～28.9％and 21.9％～23.4％respectively.
Polar motion forecastEffective angular momentumIGS ultra rapid dataLS+AR model
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