青藏高原北部地区长期质量变化研究
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摘要
针对青藏高原内陆地区存在的大范围未被合理解释的正质量变化信号问题,本文利用GRACE卫星观测资料定量研究了青藏高原北部地区2002—2015年间的地表质量变化趋势,并与水文模式和降水资料进行了比较分析。GRACE结果表明青藏高原北部地区存在等效水高为0.41cm/a的长期质量变化,水文模式得到的结果为0.12cm/a。长期信号显示两者虽在空间分布上存在较大差别,但在区域内具有相近极大值,且正信号均向研究区域的东南方向外延,体现出了较好的一致性。GRACE结果的周年振幅是水文模式的23%,这说明在研究区域内呈周期变化的土壤水信号并非是GRACE的优势信号,即水文模式无法给该研究区域质量长期变化以合理解释。此外,青藏高原北部地区的水文模式结果受降水影响较大。
Considering the large range of positive mass variation which has not been reasonably explained in the inner Tibetan Plateau.In this paper,the trend of mass change in the northern Tibetan Plateau during 2 0 0 2-2 0 1 5 is calculated by using GRACE satellite observation data,and the results are compared with hydrological model and precipitation data.GRACE results show that there is a long-term mass change as equivalent water height of 0.4 1 cm/a in the northern Tibetan Plateau,and the result of hydrological model is 0.1 2 cm/a.Long term signal shows that although there is a big difference in spatial distribution between the two signals,they have similar maximum values in the region,and the positive signals are both extended to the southeast direction of the study area,which shows good consistency.The annual amplitude of the GRACE results is 2 3% of the hydrological model,indicating that soil water signals which are periodically changed in the study area are not the superiority dominant signals of GRACE,i.e.,hydrological models can not explain the long-term mass changes of the study area.In addition,the model results in the northern Tibetan Plateau are greatly affected by precipitation.
Considering the large range of positive mass variation which has not been reasonably explained in the inner Tibetan Plateau.In this paper,the trend of mass change in the northern Tibetan Plateau during 2 0 0 2-2 0 1 5 is calculated by using GRACE satellite observation data,and the results are compared with hydrological model and precipitation data.GRACE results show that there is a long-term mass change as equivalent water height of 0.4 1 cm/a in the northern Tibetan Plateau,and the result of hydrological model is 0.1 2 cm/a.Long term signal shows that although there is a big difference in spatial distribution between the two signals,they have similar maximum values in the region,and the positive signals are both extended to the southeast direction of the study area,which shows good consistency.The annual amplitude of the GRACE results is 2 3% of the hydrological model,indicating that soil water signals which are periodically changed in the study area are not the superiority dominant signals of GRACE,i.e.,hydrological models can not explain the long-term mass changes of the study area.In addition,the model results in the northern Tibetan Plateau are greatly affected by precipitation.
引文
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[14]KNUDSEN P.Ocean Tides in GRACE monthly averaged gravity fields[J].Space Science Reviews,2003,108(1/2):261-270.
[15]SWENSON S,WAHR J.Methods for inferring regional surface-mass anomalies from Gravity Recovery and Climate Experiment(GRACE)measurements of time-variable gravity[J].Journal of Geophysical Research:Solid Earth,2002,107:B9.
[2]ZHANG G,YAO T,XIE H,et al.Increased mass over the Tibetan Plateau:from lakes or glaciers?[J].Geophysical Research Letters,2013,40(10):2125-2130.
[3]YI S,SUN W.Evaluation of glacier changes in highmountain Asia based on 10years GRACE RL05 models[J].Journal of Geophysical Research Solid Earth,2014,119(3):2504-2517.
[4]YI S,FREYMUELLER J,SUN W.How fast is the middle-lower crust flowing in eastern Tibet?a constraint from geodetic observations[J].Journal of Geophysical Research(Solid Earth),2016,121(9):6903-6915.
[5]WANG Q,YI S,SUN W.The changing pattern of lake and its contribution to increased mass in the Tibetan Plateau derived from GRACE and ICESat data[J].Geophysical Journal International,2016,207(1):528-541.
[6]CHENG M,TAPLEY B D.Variations in the Earth’s oblateness during the past 28years[J].Journal of Geophysical Research(Solid Earth),2004,109:B09402.
[7]SWENSON S,CHAMBERS D,WAHR J.Estimating geocenter variations from a combination of GRACE and ocean model output[J].Journal of Geophysical Research(Solid Earth)(1978—2012),2008,113:194-205.
[8]SWENSON S,WAHR J.Post-processing removal of correlated errors in GRACE data[J].Geophysical Research Letters,2006,33(8):L08402.
[9]DUAN X,GUO J,SHUM C,et al.On the postprocessing removal of correlated errors in GRACE temporal gravity field solutions[J].Journal of Geodesy,2009,83(11):1095-1106.
[10]WAHR J,MOLENAAR M,BRYAN F.Time variability of the earth’s gravity field:hydrological and oceanic effects and their possible detection using GRACE[J].Journal of Geophysical Research(Solid Earth),1998,103(B12):30205-30229.
[11]GERUO A,WAHR J,ZHONG S.Computations of the viscoelastic response of a 3Dcompressible earth to surface loading:an application to glacial isostatic adjustment in Antarctica and Canada[J].Geophysical Journal International,2013,192(2):557-572.
[12]LANDERER F W,SWENSON S C.Accuracy of scaled GRACE terrestrial water storage estimates[J].Water Resources Research,2012,48(4):4531.
[13]STEFFEN H,PETROVIC S,MLLER J,et al.Significance of secular trends of mass variations determined from GRACE solutions[J].Journal of Geodynamics,2009,48(3/5):157-165.
[14]KNUDSEN P.Ocean Tides in GRACE monthly averaged gravity fields[J].Space Science Reviews,2003,108(1/2):261-270.
[15]SWENSON S,WAHR J.Methods for inferring regional surface-mass anomalies from Gravity Recovery and Climate Experiment(GRACE)measurements of time-variable gravity[J].Journal of Geophysical Research:Solid Earth,2002,107:B9.