This paper analyzed the existing methods of wave measurement, and described the advantages of GPS applied in measuring the wave. The equations of absolute velocity estimation were discussed, focusing on two methods wi...This paper analyzed the existing methods of wave measurement, and described the advantages of GPS applied in measuring the wave. The equations of absolute velocity estimation were discussed, focusing on two methods with Doppler shill. The error sources and their effect on velocity estimation were analyzed. Then, some tests were carried on to simulate dynamic velocity determination using static data Based on the high-frequency carrier-phase derived Doppler observations, the velocity has been estimated to the precision of 1 cm/s or so, even to the mm/s level. And with the receiver generated Doppler measurements, the precision can reach 3 - 15 cm/s.展开更多
This study examined wintertime (November-April) cold wave frequency (CWF) in northern China during the last 42 years and its association with Arctic Oscillation (AO) through analysis of daily mean surface temperature ...This study examined wintertime (November-April) cold wave frequency (CWF) in northern China during the last 42 years and its association with Arctic Oscillation (AO) through analysis of daily mean surface temperature from 280 stations across northern China and European Centre for Medium-Range Weather Forecasts (ECMWF) 40-Year Re-analysis ERA-40 data. The leading empirical orthogonal function EOF mode of wintertime CWF (CWF-EOF1) indicates an identical signal over most northern China, with the characteristic trend of linear decline for the leading principal component (CWF-PC1). After the linear trend is removed, remarkable inter-annual variability is found to be the dominant feature of the CWF-PC1. The regression map for sea level pressure based on CWF-PC1 corresponds to the negative phase of AO. Correlation analysis further proves that CWF-PC1 has a significant negative correlation with AO at the inter-annual time scale. The relationship between AO and global surface air temperature is also investigated in order to understand its association with cold air activity over East Asia, and it is suggested that the anomalies of atmospheric circulation in Siberia may serve as a bridge for interaction between AO and CWF in northern China during wintertime.展开更多
基金supported by the Key Laboratory of Marine Hydrocarbon Resources and Environmental Geology(MRE201233)Key Laboratory of Surveying and Mapping Technology on Island and ReefState Bureau of Surveying and Mapping(2012B04)
文摘This paper analyzed the existing methods of wave measurement, and described the advantages of GPS applied in measuring the wave. The equations of absolute velocity estimation were discussed, focusing on two methods with Doppler shill. The error sources and their effect on velocity estimation were analyzed. Then, some tests were carried on to simulate dynamic velocity determination using static data Based on the high-frequency carrier-phase derived Doppler observations, the velocity has been estimated to the precision of 1 cm/s or so, even to the mm/s level. And with the receiver generated Doppler measurements, the precision can reach 3 - 15 cm/s.
基金supported by the National Basic Research Program of China (973 Program) (Grant No.2009CB421406)the National Key Technologies R&D Program of China (Grant No.2007BAC29B03)the The National Natural Science Foundation of China Project (Grant No.40821092)
文摘This study examined wintertime (November-April) cold wave frequency (CWF) in northern China during the last 42 years and its association with Arctic Oscillation (AO) through analysis of daily mean surface temperature from 280 stations across northern China and European Centre for Medium-Range Weather Forecasts (ECMWF) 40-Year Re-analysis ERA-40 data. The leading empirical orthogonal function EOF mode of wintertime CWF (CWF-EOF1) indicates an identical signal over most northern China, with the characteristic trend of linear decline for the leading principal component (CWF-PC1). After the linear trend is removed, remarkable inter-annual variability is found to be the dominant feature of the CWF-PC1. The regression map for sea level pressure based on CWF-PC1 corresponds to the negative phase of AO. Correlation analysis further proves that CWF-PC1 has a significant negative correlation with AO at the inter-annual time scale. The relationship between AO and global surface air temperature is also investigated in order to understand its association with cold air activity over East Asia, and it is suggested that the anomalies of atmospheric circulation in Siberia may serve as a bridge for interaction between AO and CWF in northern China during wintertime.
