GRACE/GRACE-FO mascons and satellite laser ranging: Updates from GSFC

2020 ◽  
Author(s):  
Bryant Loomis ◽  
Michael Croteau ◽  
Terry Sabaka ◽  
Scott Luthcke ◽  
Kenny Rachlin
Keyword(s):  
Computational Cost ◽  
Technical Note ◽  
Satellite Laser Ranging ◽  
Laser Ranging ◽  
Normal Equations ◽  
Low Degree ◽  
Damping Parameter ◽  
Variable Gravity ◽  
Trade Study ◽  
Comparable Quality

<p>We present a summary of our recent work on time-variable gravity estimates derived from GRACE/GRACE-FO and satellite laser ranging (SLR). We show the latest results of our monthly mascon solution, with special attention paid to the selection and impact of the damping parameter applied to the regularization matrices. Additionally, we present a new method of regularized mascon estimation from spherical harmonics. Provided that the full normal equations for these coefficients are available, this method allows for a mathematically equivalent mascon estimate to those determined from a single iteration solution from Level-1B observations, but at a fraction of the computational cost. For this we use the ITSG-Grace2018 solution and full normal equations to produce a new mascon solution of comparable quality to current mascon products, and we are in the process of using this rapid approach to perform a trade study of various regularization strategies. Lastly, we present low degree SLR solutions that form the basis of the C20 and C30 solutions provided in Technical Note 14, and present preliminary results of large SLR-derived mascons from 1993 – Present.</p>

scholarly journals Technical note: an interannual inversion method forcontinuous CO<sub>2</sub> data

2004 ◽  
Vol 4 (2) ◽  
pp. 477-484 ◽  
Author(s):  
R. M. Law
Keyword(s):  
Computational Cost ◽  
Technical Note ◽  
Inversion Method ◽  
Seasonal Cycles ◽  
Concentration Data ◽  
Sequential Method ◽  
Monthly Data ◽  
Hourly Data ◽  
Atmospheric Data ◽  
Comparable Quality

Abstract. A sequential synthesis inversion method is described to estimate CO2 sources from continuous atmospheric data. The sequential method makes the problem computationally feasible. The method is assessed using four-hourly synthetic concentration data generated from known sources. Multi-year mean sources and seasonal cycles are estimated with comparable quality as those from a traditional inversion of monthly mean data. Interannual variations in the estimated sources are closer to those of the known sources using the four-hourly data rather than monthly data. The computational cost of the basis function simulations can be reduced by generating responses that are only six months long. This does not significantly degrade the inversion results compared to using responses that are 12 months in length.

scholarly journals Technical note: an interannual inversion method for continuous CO<sub>2</sub> data

2003 ◽  
Vol 3 (6) ◽  
pp. 5977-6000
Author(s):  
R. M. Law
Keyword(s):  
Computational Cost ◽  
Technical Note ◽  
Inversion Method ◽  
Seasonal Cycles ◽  
Concentration Data ◽  
Sequential Method ◽  
Monthly Data ◽  
Hourly Data ◽  
Atmospheric Data ◽  
Comparable Quality

Abstract. A sequential synthesis inversion method is described to estimate CO2 sources from continuous atmospheric data. The sequential method makes the problem computationally feasible. The method is assessed using four-hourly synthetic concentration data generated from known sources. Multi-year mean sources and seasonal cycles are estimated with comparable quality as those from a traditional inversion of monthly mean data. Interannual variations in the estimated sources are closer to those of the known sources using the four-hourly data rather than monthly data. The computational cost of the basis function simulations can be reduced by generating responses that are only six months long. This does not significantly degrade the inversion results compared to using responses that are 12 months in length.

scholarly journals Accelerated ice mass depletion revealed by low-degree gravity field from satellite laser ranging: Greenland, 1991-2011

2013 ◽  
Vol 40 (17) ◽  
pp. 4662-4667 ◽  
Author(s):  
Koji Matsuo ◽  
Benjamin F. Chao ◽  
Toshimichi Otsubo ◽  
Kosuke Heki
Keyword(s):  
Gravity Field ◽  
Satellite Laser Ranging ◽  
Laser Ranging ◽  
Low Degree ◽  
Mass Depletion

scholarly journals Accelerated ice-sheet mass loss in Antarctica from 18-year satellite laser ranging measurements

2016 ◽  
Vol 59 (1) ◽  
Author(s):  
Shuanggen Jin ◽  
Mosta Abd-Elbaky ◽  
Guping Feng
Keyword(s):  
Ice Sheet ◽  
Accurate Estimate ◽  
East Antarctica ◽  
Satellite Laser Ranging ◽  
Laser Ranging ◽  
West Antarctica ◽  
Low Degree ◽  
Ice Sheet Mass Balance ◽  
Good Agreement

<p>Accurate estimate of the ice-sheet mass balance in Antarctic is very difficult due to complex ice sheet condition and sparse in situ measurements. In this paper, the low-degree gravity field coefficients of up to degree and order 5 derived from Satellite Laser Ranging (SLR) measurements are used to determine the ice mass variations in Antarctica for the period 1993–2011. Results show that the ice mass is losing with -36±13 Gt/y in Antarctica, -42±11 Gt/y in the West Antarctica and 6±10 Gt/y in the East Antarctica from 1993 to 2011. The ice mass variations from the SLR 5×5 have a good agreement with the GRACE 5×5, GRACE 5×5 (1&amp;2) and GRACE (60×60) for the entire continent since 2003, but degree 5 from SLR is not sufficient to quantify ice losses in West and East Antarctica, respectively. The rate of ice loss in Antarctica is -28±17 Gt/y for 1993-2002 and -55±17 Gt/y for 2003-2011, indicating significant accelerated ice mass losses since 2003. Furthermore, the results from SLR are comparable with GRACE measurements.</p>

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