The Gravity waves activities in the Tibetan Plateau are very complex with different effects and natures that are not clear due to the lack of high resolution data from space and also from ground. In this paper,using C...The Gravity waves activities in the Tibetan Plateau are very complex with different effects and natures that are not clear due to the lack of high resolution data from space and also from ground. In this paper,using COSMICGPS radio occultation data from 2006 to 2014, the atmospheric gravity waves activities and climatologic behaviors in Tibetan stratosphere are studied and analyzed, which show different characteristics. Most of the gravity waves with potential energy(Ep) at altitude of 17-24 km are associated with mountain waves. A good correlation between gravity wave activities and zonal wind flow is found. The distribution of gravity wave(GW) activities in Tibet is strongly connected with zonal wind variation and topography. GW activities are enhanced in winter seasons and decreased in summer seasons since strong western winds persist at all heights of the Tibetan troposphere. The gravity waves generated in the Tibetan area are mostly related to the orography of the area. The vertical wavelengths of GWS are shorter.Gravity waves in the Northwest have different vertical wavelengths in the Southeastern part of Tibetan Plateau, and dominant wavelengths are 3-5 km in the Northwest and 2-3 km in the Southeast,respectively. In the summer, the Northwestern part is the main source of wave generation while in the winter the GW is generated almost from all peaks of the Tibetan Plateau. Gravity waves in the region are clearly related to deep convection, which can also be proved by the inverse relation of Outgoing long wave radiation(OLR) and potential energy(Ep).展开更多
As global warming continues,the monitoring of changes in terrestrial water storage becomes increasingly important since it plays a critical role in understanding global change and water resource management.In North Am...As global warming continues,the monitoring of changes in terrestrial water storage becomes increasingly important since it plays a critical role in understanding global change and water resource management.In North America as elsewhere in the world,changes in water resources strongly impact agriculture and animal husbandry.From a combination of Gravity Recovery and Climate Experiment（GRACE） gravity and Global Positioning System（GPS） data,it is recently found that water storage from August,2002 to March,2011 recovered after the extreme Canadian Prairies drought between 1999 and 2005.In this paper,we use GRACE monthly gravity data of Release 5 to track the water storage change from August,2002 to June,2014.In Canadian Prairies and the Great Lakes areas,the total water storage is found to have increased during the last decade by a rate of 73.8 ± 14.5 Gt/a,which is larger than that found in the previous study due to the longer time span of GRACE observations used and the reduction of the leakage error.We also find a long term decrease of water storage at a rate of-12.0 ± 4.2 Gt/a in Ungava Peninsula,possibly due to permafrost degradation and less snow accumulation during the winter in the region.In addition,the effect of total mass gain in the surveyed area,on present-day sea level,amounts to-0.18 mm/a,and thus should be taken into account in studies of global sea level change.展开更多
The Global Geopotential Models (GGMs) of GOCE (Gravity Recovery and steady- state Ocean Circulation Explorer) differ globally as well as regionally in their accuracy and resolution based on the maximum degree and orde...The Global Geopotential Models (GGMs) of GOCE (Gravity Recovery and steady- state Ocean Circulation Explorer) differ globally as well as regionally in their accuracy and resolution based on the maximum degree and order (d/o) of the fully normalized spherical harmonic (SH) coefficients, which express each GGM. The main idea of this study is to compare the free-air gravity anomalies and quasi geoid heights determined from several recent GOCE-based GGMs with the corresponding ones from the Earth Gravitational Model 2008 (EGM2008) over Egypt on the one hand and with ground-based measurements on the other hand. The results regarding to the comparison of GOCE-based GGMs with terrestrial gravity and GPS/levelling data provide better improvement with respect to EGM2008. The 4th release GOCE-based GGM developed with the use of space-wise solution strategy (SPW_R4) approximates the gravity field well over the Egyptian region. The SPW_R4 model is accordingly suggested as a reference model for recovering the long wavelength (up to SH d/o 200) components of quasi geoid heights when modelling the gravimetric quasi-geoid over the Egypt. Finally, three types of transformation models: Four-, Five- and Seven-parameter transformations have been applied to reduce the data biases and to provide a better fitting of quasi geoid heights obtained from the studied GOCE-based GGMs to those from GPS/levelling data. These models reveal that the standard deviation of vertical datum over Egypt is at the level of about 32 cm.展开更多
Through calculating and analyzing of GPS continuous observation data and mobile gravity data,the study results from the data are as follows.( 1) The different movement rate of the fault ends provides conditions for st...Through calculating and analyzing of GPS continuous observation data and mobile gravity data,the study results from the data are as follows.( 1) The different movement rate of the fault ends provides conditions for stress accumulation.( 2) The high value zone of gravity anomaly appeared in the monitoring area before the earthquake,and gravity variation contour lines are parallel to the strike of fault; and the process of enhancingweakening-enhancing appeared in the regional gravity field before earthquake.展开更多
This work presents the results of complex gravity observation performed at Shults Cape, Gamov peninsula (42.58°N, 131.15°E), Russia. Absolute laser gravimeter GABL type and Scintrex type relative gravimeter ...This work presents the results of complex gravity observation performed at Shults Cape, Gamov peninsula (42.58°N, 131.15°E), Russia. Absolute laser gravimeter GABL type and Scintrex type relative gravimeter were used for measurement. To investigate the accuracy of tidal corrections we compared the observed tidal parameters of the main tidal waves O1 and M2 with modeled ones computed from 6 different ocean tidal models: CSR4, FES02, FES04, GOT00, NAO99 and TPX06. After discussion a theoretical model based on TPX06 ocean tides model and DDW99 non hydrostatic body tides model was used for tidal correction of absolute gravity data. Preliminary estimate of gravity effect induced by the Tohoku-Oki earthquake of11 March 2011Mw = 9.0 at Primorye territory (Russia) was found to be 5.1 ± 2.0 μGal. Co-seismic crustal displacements revealed by GPS data at Far EastRussiacontinental coast are also investigated. Volumetric dilatation of this area is observed at +1.7 × 10-8 level.展开更多
基金supported by the National Natural Science Foundation of China Project(Grant No.11573052)
文摘The Gravity waves activities in the Tibetan Plateau are very complex with different effects and natures that are not clear due to the lack of high resolution data from space and also from ground. In this paper,using COSMICGPS radio occultation data from 2006 to 2014, the atmospheric gravity waves activities and climatologic behaviors in Tibetan stratosphere are studied and analyzed, which show different characteristics. Most of the gravity waves with potential energy(Ep) at altitude of 17-24 km are associated with mountain waves. A good correlation between gravity wave activities and zonal wind flow is found. The distribution of gravity wave(GW) activities in Tibet is strongly connected with zonal wind variation and topography. GW activities are enhanced in winter seasons and decreased in summer seasons since strong western winds persist at all heights of the Tibetan troposphere. The gravity waves generated in the Tibetan area are mostly related to the orography of the area. The vertical wavelengths of GWS are shorter.Gravity waves in the Northwest have different vertical wavelengths in the Southeastern part of Tibetan Plateau, and dominant wavelengths are 3-5 km in the Northwest and 2-3 km in the Southeast,respectively. In the summer, the Northwestern part is the main source of wave generation while in the winter the GW is generated almost from all peaks of the Tibetan Plateau. Gravity waves in the region are clearly related to deep convection, which can also be proved by the inverse relation of Outgoing long wave radiation(OLR) and potential energy(Ep).
基金supported by National Natural Science Foundation of China(Grant Nos.41431070,41174016,41274026,41274024,41321063)National Key Basic Research Program of China(973 Program,2012CB957703)+1 种基金CAS/SAFEA International Partnership Program for Creative Research Teams(KZZD-EW-TZ-05)The Chinese Academy of Sciences
文摘As global warming continues,the monitoring of changes in terrestrial water storage becomes increasingly important since it plays a critical role in understanding global change and water resource management.In North America as elsewhere in the world,changes in water resources strongly impact agriculture and animal husbandry.From a combination of Gravity Recovery and Climate Experiment（GRACE） gravity and Global Positioning System（GPS） data,it is recently found that water storage from August,2002 to March,2011 recovered after the extreme Canadian Prairies drought between 1999 and 2005.In this paper,we use GRACE monthly gravity data of Release 5 to track the water storage change from August,2002 to June,2014.In Canadian Prairies and the Great Lakes areas,the total water storage is found to have increased during the last decade by a rate of 73.8 ± 14.5 Gt/a,which is larger than that found in the previous study due to the longer time span of GRACE observations used and the reduction of the leakage error.We also find a long term decrease of water storage at a rate of-12.0 ± 4.2 Gt/a in Ungava Peninsula,possibly due to permafrost degradation and less snow accumulation during the winter in the region.In addition,the effect of total mass gain in the surveyed area,on present-day sea level,amounts to-0.18 mm/a,and thus should be taken into account in studies of global sea level change.
文摘The Global Geopotential Models (GGMs) of GOCE (Gravity Recovery and steady- state Ocean Circulation Explorer) differ globally as well as regionally in their accuracy and resolution based on the maximum degree and order (d/o) of the fully normalized spherical harmonic (SH) coefficients, which express each GGM. The main idea of this study is to compare the free-air gravity anomalies and quasi geoid heights determined from several recent GOCE-based GGMs with the corresponding ones from the Earth Gravitational Model 2008 (EGM2008) over Egypt on the one hand and with ground-based measurements on the other hand. The results regarding to the comparison of GOCE-based GGMs with terrestrial gravity and GPS/levelling data provide better improvement with respect to EGM2008. The 4th release GOCE-based GGM developed with the use of space-wise solution strategy (SPW_R4) approximates the gravity field well over the Egyptian region. The SPW_R4 model is accordingly suggested as a reference model for recovering the long wavelength (up to SH d/o 200) components of quasi geoid heights when modelling the gravimetric quasi-geoid over the Egypt. Finally, three types of transformation models: Four-, Five- and Seven-parameter transformations have been applied to reduce the data biases and to provide a better fitting of quasi geoid heights obtained from the studied GOCE-based GGMs to those from GPS/levelling data. These models reveal that the standard deviation of vertical datum over Egypt is at the level of about 32 cm.
基金funded by the Xinjiang Earthquake Science Foundation,China(201211)
文摘Through calculating and analyzing of GPS continuous observation data and mobile gravity data,the study results from the data are as follows.( 1) The different movement rate of the fault ends provides conditions for stress accumulation.( 2) The high value zone of gravity anomaly appeared in the monitoring area before the earthquake,and gravity variation contour lines are parallel to the strike of fault; and the process of enhancingweakening-enhancing appeared in the regional gravity field before earthquake.
文摘This work presents the results of complex gravity observation performed at Shults Cape, Gamov peninsula (42.58°N, 131.15°E), Russia. Absolute laser gravimeter GABL type and Scintrex type relative gravimeter were used for measurement. To investigate the accuracy of tidal corrections we compared the observed tidal parameters of the main tidal waves O1 and M2 with modeled ones computed from 6 different ocean tidal models: CSR4, FES02, FES04, GOT00, NAO99 and TPX06. After discussion a theoretical model based on TPX06 ocean tides model and DDW99 non hydrostatic body tides model was used for tidal correction of absolute gravity data. Preliminary estimate of gravity effect induced by the Tohoku-Oki earthquake of11 March 2011Mw = 9.0 at Primorye territory (Russia) was found to be 5.1 ± 2.0 μGal. Co-seismic crustal displacements revealed by GPS data at Far EastRussiacontinental coast are also investigated. Volumetric dilatation of this area is observed at +1.7 × 10-8 level.
