Temporal and spatial variability of the bias between TOPEX- and GPS-derived total electron content
Temporal and spatial variability of the bias between TOPEX- and GPS-derived total electron content
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DOI：
10.1007/s00190-005-0448-z
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发表时间：
2005-06
影响因子：
4.4
通讯作者：
C. Brunini;A. Meza;W. Bosch
中科院分区：
文献类型：
--
作者：
C. Brunini;A. Meza;W. Bosch
将使用基于GPS的LaPlata电离层模型(LPIM)和国际参考电离层(IRI95)模型所作的总电子含量(TEC)预测与TOPEX/Poseidon(T/P)卫星上的双频高度计的估计值进行了比较。从1997年1月至1998年12月，对LPIM和IRI95进行了评估，以确定可获得的T/P数据的位置和时间。为了研究T/P和每个模式之间TEC偏差的时空变化，将T/P观测覆盖的区域划分为10个纬度带。对于这两个模式和所有纬度，偏差主要是正的(即T/P值更大)；LPIM偏差比IRI95偏差更低，变化也更小。为了详细分析T/P-LPIM TEC偏差的时间和空间变异性，将地球表面划分为9°边的球面三角形，并对每个三角形拟合一个随时间变化的回归模型。赤道异常上的TEC偏差最大，这归因于LPIM的误差。在40°N纬度有显著的TEC偏差，这归因于T/P海态偏差(SSB)校正的误差。为了将T/P TEC中的系统误差与LPIM引起的系统误差区分开来，分析了其他作者估计的与TEC偏差有关的高度计范围偏差。这表明LPIM低估了TEC，特别是在南半球夏季，而T/P C波段SSB定标在南半球冬季更差。
Total electron content (TEC) predictions made with the GPS-based la plata ionospheric model (LPIM) and the International Reference Ionosphere (IRI95) model were compared to estimates from the dual-frequency altimeter onboard the TOPEX/Poseidon (T/P) satellite. LPIM and IRI95 were evaluated for the location and time of available T/P data, from January 1997 to December 1998. To investigate temporal and spatial variations of the TEC bias between T/P and each model, the region covered by T/P observations was divided into ten latitude bands. For both models and for all latitudes, the bias was mainly positive (i.e. T/P values were larger); the LPIM bias was lower and less variable than the IRI95 bias. To perform a detailed analysis of temporal and spatial variability of the T/P-LPIM TEC bias, the Earth’s surface was divided into spherical triangles with 9°-sides, and a temporally varying regression model was fitted to every triangle. The highest TEC bias was found over the equatorial anomalies, which is attributed to errors in LPIM. A significant TEC bias was found at 40°N latitude, which is attributed to errors in the T/P Sea State Bias (SSB) correction. To separate systematic errors in the T/P TEC from those caused by LPIM, altimeter range biases estimated by other authors were analysed in connection with the TEC bias. This suggested that LPIM underestimates the TEC, particularly during the Southern Hemisphere summer, while T/P C-band SSB calibration is worse during the Southern Hemisphere winter.