Browsing by Author "Wiese, David N."

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    Along-Orbit Analysis of GRACE Follow-On Inter-Satellite Laser Ranging Measurements for Sub-Monthly Surface Mass Variations
    Ghobadi-Far, Khosro; Han, Shin-Chan; McCullough, Christopher M.; Wiese, David N.; Ray, Richard D.; Sauber, Jeanne; Shihora, Linus; Dobslaw, Henryk (American Geophysical Union, 2022-02)
    We examined the sensitivity of GRACE Follow-On (GRACE-FO) laser ranging interferometer (LRI) measurements to sub-monthly time-variable gravity (TVG) signals caused by transient, high-frequency mass changes in the Earth system. GRACE-FO LRI provides complementary inter-satellite ranging measurements with higher precision over a wider range of frequencies than the baseline K-band microwave ranging system. The common approach for studying mass variation relies on the inverted TVG or mascon solutions over a period of, for example, one month or 10 days which are adversely affected by temporal aliasing and/or smoothing. In this article, we present the alternative along-orbit analysis methodology in terms of line-of-sight gravity difference (LGD) to fully exploit the higher precision LRI measurements for examination of sub-monthly mass changes. The discrepancy between "instantaneous" LGD LRI observations and monthly-mean LGD (from Level-2 data) at satellite altitude indicates the sub-monthly gravitational variability not captured by monthly-mean solutions. In conjunction with the satellite ocean altimetry observations, high-frequency non-tidal atmosphere and ocean models, and hydrology models, we show that the LGD LRI observations detect the high-frequency oceanic mass variability in the Argentine Basin and the Gulf of Carpentaria, and sub-monthly variations in surface (river) water in the Amazon Basin. We demonstrate the benefits gained from repeat ground track analysis of GRACE-FO LRI data in the case of the Amazon surface water flow. The along-orbit analysis methodology based on LGD LRI time series presented here is especially suitable for quantifying temporal and spatial evolution of extreme, rapidly changing mass variations.
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    Understanding of Contemporary Regional Sea-Level Change and the Implications for the Future
    Hamlington, Benjamin D.; Gardner, Alex S.; Ivins, Erik; Lenaerts, Jan T. M.; Reager, J. T.; Trossman, David S.; Zaron, Edward D.; Adhikari, Surendra; Arendt, Anthony; Aschwanden, Andy; Beckley, Brian D.; Bekaert, David PS S.; Blewitt, Geoffrey; Caron, Lambert; Chambers, Don P.; Chandanpurkar, Hrishikesh A.; Christianson, Knut; Csatho, Beata; Cullather, Richard; DeConto, Robert M.; Fasullo, John T.; Frederikse, Thomas; Freymueller, Jeffrey T.; Gilford, Daniel M.; Girotto, Manuela; Hammond, William C.; Hock, Regine; Holschuh, Nicholas; Kopp, Robert E.; Landerer, Felix; Larour, Eric; Menemenlis, Dimitris; Merrifield, Mark; Mitrovica, Jerry X.; Nerem, R. Steven; Nias, Isabel J.; Nieves, Veronica; Nowicki, Sophie; Pangaluru, Kishore; Piecuch, Christopher G.; Ray, Richard D.; Rounce, David R.; Schlegel, Nicole-Jeanne; Seroussi, Helene; Shirzaei, Manoochehr; Sweet, William; Velicogna, Isabella; Vinogradova, Nadya; Wahl, Thomas; Wiese, David N.; Willis, Michael J. (American Geophysical Union, 2020-07-20)
    Global sea level provides an important indicator of the state of the warming climate, but changes in regional sea level are most relevant for coastal communities around the world. With improvements to the sea-level observing system, the knowledge of regional sea-level change has advanced dramatically in recent years. Satellite measurements coupled with in situ observations have allowed for comprehensive study and improved understanding of the diverse set of drivers that lead to variations in sea level in space and time. Despite the advances, gaps in the understanding of contemporary sea-level change remain and inhibit the ability to predict how the relevant processes may lead to future change. These gaps arise in part due to the complexity of the linkages between the drivers of sea-level change. Here we review the individual processes which lead to sea-level change and then describe how they combine and vary regionally. The intent of the paper is to provide an overview of the current state of understanding of the processes that cause regional sea-level change and to identify and discuss limitations and uncertainty in our understanding of these processes. Areas where the lack of understanding or gaps in knowledge inhibit the ability to provide the needed information for comprehensive planning efforts are of particular focus. Finally, a goal of this paper is to highlight the role of the expanded sea-level observation network—particularly as related to satellite observations—in the improved scientific understanding of the contributors to regional sea-level change.