利用2006—2012年北半球冬季低纬度地区(30°S^30°N)无线电探空站数据及全球大气成分和气候监测再分析数据对1000 h Pa^200 h Pa高度层的气象、电离层与气候星座观测系统全球定位系统掩星反演的比湿廓线进行了精度和可靠性验证。结果表明,水汽对气象、电离层与气候星座观测系统掩星反演影响较大,尤其在中、低对流层及热带地区等水汽含量比较大的地区,且气象、电离层与气候星座观测系统掩星数据在850 hpa以下可能并不太适用于评估其他数据。
On February 12,2014,a large Mw7. 3 earthquake occurred in Yutian of Xijiang Province,China.We processed the global ionosphere maps provided by CODE（ the Center for Orbit Determination in Europe）and the foF2（ the critical frequency of F2-layer） data of Chongqing ionosonde station to analyze the preearthquake ionospheric anomalies. Solar activities and magnetic storm were checked by the sliding inter quartile range method to remove their effects on the ionosphere. A positive ionospheric anomaly with the large amplitude of 20 TECU was observed near the epicenter on February 3（ 10th day before the earthquake）. In addition,the foF2 at Chongqing station had an unusual increase of more than 40% on the day,which was consistent with the TEC（ Total Electron Content） anomaly. The global disturbance represents that the peak of TEC anomaly didn’t coincide with the vertical projection of epicenter. The TEC anomalous area was closer to the equator,and it mainly occurred from local time 16 ∶ 00 to 20 ∶ 00. An enhancement of TEC with the small amplitude also appeared in the magnetically conjugated region.
Based on the concept of Global Position System(GPS)/leveling,the satellite altimetry leveling(SAL) is first proposed to evaluate the marine geoid.SAL is derived by the difference among the mean sea surface(MSS),mean dynamic ocean topography(MDT),and leveling origin.In this study,(1) the original satellite altimetry data are processed to infer the vertical deflection and gravity anomaly,(2) the Chinese coastal marine geoids(CMG) are determined by using the differe nt methods(including Molodensky,least square collocation,Stokes formula,and two-dimensional fast Fourier transformation(FFT) with the vertical deflection and gravity anomaly data),(3) CMG are evaluated by using the results from above different methods,the Gravity field and steady-state Ocean Circulation Explorer(GOCE) gravity potential model(GGPM),and SAL.The results show that(1) CMG from the Molodensky method has the highest precision by using vertical de flection data,(2) the accuracy of CMG indicate good consistency between the SAL and GGPM,(3) SAL can be used as a new method for assessing marine geoid.
