| Oceans play a central role in the global climate system,and the variations of the sea level is an important manifestation of the impact of anthropogenic climate change on society and the environment.In the past few decades,the analysis of data from the tide stations showed that from 1950 to 2009,the average rising speed of sea level was1.7±0.3 mm/yr.The analysis of satellite altimetry data showed that from 1993 to 2009,The ascending speed of the plane is 3.3±0.3 mm/yr.It can be seen that the rate of sea level rise has accelerated in the past three decades,and the mass imbalance of polar ice caps and major mountain glaciers is one of the main factors of sea level rise today.Accurately monitoring the changes in the quality of polar ice caps and mountain glaciers can not only provide reliable basic data for us to understand and predict global climate and sea-level changes,but also provide an important scientific basis for safeguarding the human living environment.The Gravity Recovery and Climate Experiment(GRACE)mission has provided an all-weather,high-precision,efficient and fast technical method for monitoring the variations of the global surface mass,and has achieved a series of significant results since its launch in March 2002.This paper considers that the leakage error caused by GRACE spherical harmonic coefficients after expansion and spatial smoothing filtering has a greater impact.Therefore,the global land area is used as the research area.The effects of the scale factor method and the iterative recovery method on the correction of leakage errors are compared and analyzed.The comparison found that in the middle and low latitude regions where precipitation is abundant all year round and the water storage changes have obvious periodicity,both methods can effectively correct the leakage error;in high latitude or high altitude glacier signal areas,the iterative recovery method is applied to the leakage The error correction effect is better than the scale factor method,and the iterative recovery method can also effectively recover the signal leakage at the land-ocean junction.At present,a large part of the quality change signals from climate and hydrological changes depend on the GIA(Glacial Isostatic Adjustment)model,and at this stage,it is impossible to determine which GIA model is more realistic.Based on this,this paper uses other prediction results and uncertainties of the GIA model to compare and analyze each GIA model,that is,eight GIA models are used to study its impact on the inversion of global surface quality changes using GRACE data.In the terrestrial area,the GRACE results before and after the GIA deduction are compared with the results of the terrestrial hydrological model and the ice surface monitoring;in the marine area,by analyzing the contribution of terrestrial water and polar ice caps to changes in seawater quality and combining satellite altimetry and Argo Ocean The temperature and salinity data set is used for further comparative analysis of seawater quality changes.The model ICE-6G?D is more suitable for adjusting the global quality change trend by integrating the entire land and ocean assessment.Based on the time-varying gravity field information,the characteristics of the contribution of changes in the mass of polar ice caps and mountain glaciers to changes in global average sea level can be separated indirectly.This article uses the RL06 data provided by CSR to invert the global ocean mass change rate is about 2.22 mm/a;the inversion of the Antarctic ice cap mass change rate is-114.48 Gt/a,contribution to sea level is about 0.31 mm/a;inversely,the Greenland ice sheet mass change rate is-246.00 Gt/a,and contribution to sea level is about 0.68 mm/a;The total mass change rate of land mountain glaciers and ice caps is-151.70 Gt/a,and its contribution to sea level is about 0.42 mm/a.The total contribution of the melting of polar ice caps and mountain glaciers to sea level is about 1.41 mm/a,accounting for 65% of the total ocean mass changes. |
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