Global lakes and reservoirs: An investigation to which extent dynamic water body shapes have an impact on the estimates of the total water storage derived from GRACE

Annika Walter

doi:10.23784/HN128-01

Global lakes and reservoirs: An investigation to which extent dynamic water body shapes have an impact on the estimates of the total water storage derived from GRACE

^*Korrespondierende/r Autor/-in für diese Arbeit

Abstract

Die Satellitenmission Gravity Recovery and Climate Experiment (GRACE) misst Schwerefeldschwankungen, die durch Massenumverteilungen in der Atmosphäre, auf den Kontinenten und in den Ozeanen entstehen. Da die Umverteilung auf den Kontinenten auf Änderungen des Gesamtwasserspeichers (TWS), ausgedrückt als äquivalente Wasserhöhen (EWH), zurückzuführen sind, können die Beobachtungen für die quantitative Bestimmung globaler Süßwasservariationen, welche in Zeiten von knapper werdenden Wasserressourcen eine hohe gesellschaftliche Bedeutung hat, verwendet werden. Liegt der Fokus explizit auf grundwasserbezogenen Veränderungen, dann müssen alle anderen Speicherkomponenten (hier: Oberflächengewässer) aus den GRACE Beobachtungen herausgerechnet werden. Hierfür muss das empfangene Signal in seine einzelnen Komponenten zerlegt werden. Um dies zu erreichen, kann unter Berücksichtigung von sowohl statischen als auch dynamischen Oberflächenausdehnungen eine Schätzung des Wasservolumens durch die Vorwärtsmodellierung von Satellitenaltimetrie- und Fernerkundungsdaten vorgenommen werden. Es wird diskutiert, dass die Verwendung einer dynamischen anstelle von einer statischen Oberflächenausdehnung (1) die äquivalenten Wasserhöhenwerte in einer Größenordnung zwischen 0,006 cm und 0,243 cm verändert, (2) die größte Abweichung für den See Mead verursacht und (3) die Frage, ob eine dynamische oder eine statische Oberflächenausdehnung in Betracht gezogen werden sollte, von der Interaktion verschiedener Parameter bestimmt wird.

Originalsprache	Englisch
Seiten (von - bis)	6-10
Seitenumfang	5
Fachzeitschrift	Hydrographische Nachrichten
Ausgabenummer	128
DOIs	https://doi.org/10.23784/HN128-01
Publikationsstatus	Veröffentlicht - 1 Juni 2024

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title = "Global lakes and reservoirs: An investigation to which extent dynamic water body shapes have an impact on the estimates of the total water storage derived from GRACE",

abstract = "The satellite mission Gravity Recovery and Climate Experiment (GRACE) measures gravity field variations caused by mass redistributions across the atmosphere, the continents and the oceans. Since the redistributions over the continents are linked to changes in the total water storage (TWS), expressed as equivalent water heights (EWH), the observations can be used to quantitatively assess global freshwater variations, which is of great social importance in times of increasingly scarce water resources. If the focus of interest refers to groundwater related variations explicitly, all other storage compartments (here: surface waters) have to be reduced from the GRACE observations. Therefore, the retrieved signal has to be decomposed into its individual components. To achieve this, the water volume can be estimated by forward modelling satellite altimetry and remote sensing data, considering both static and dynamic surface expansions. It will be discussed, that using a dynamic instead of a static surface area extent (1) will change the equivalent water height values in a magnitude between 0.006 cm and 0.243 cm, (2) causes the largest deviation for the Lake Mead and (3) that the question whether a dynamic or a static water body shape should be considered is driven by the interaction of various parameters.",

author = "Annika Walter",

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N2 - The satellite mission Gravity Recovery and Climate Experiment (GRACE) measures gravity field variations caused by mass redistributions across the atmosphere, the continents and the oceans. Since the redistributions over the continents are linked to changes in the total water storage (TWS), expressed as equivalent water heights (EWH), the observations can be used to quantitatively assess global freshwater variations, which is of great social importance in times of increasingly scarce water resources. If the focus of interest refers to groundwater related variations explicitly, all other storage compartments (here: surface waters) have to be reduced from the GRACE observations. Therefore, the retrieved signal has to be decomposed into its individual components. To achieve this, the water volume can be estimated by forward modelling satellite altimetry and remote sensing data, considering both static and dynamic surface expansions. It will be discussed, that using a dynamic instead of a static surface area extent (1) will change the equivalent water height values in a magnitude between 0.006 cm and 0.243 cm, (2) causes the largest deviation for the Lake Mead and (3) that the question whether a dynamic or a static water body shape should be considered is driven by the interaction of various parameters.

AB - The satellite mission Gravity Recovery and Climate Experiment (GRACE) measures gravity field variations caused by mass redistributions across the atmosphere, the continents and the oceans. Since the redistributions over the continents are linked to changes in the total water storage (TWS), expressed as equivalent water heights (EWH), the observations can be used to quantitatively assess global freshwater variations, which is of great social importance in times of increasingly scarce water resources. If the focus of interest refers to groundwater related variations explicitly, all other storage compartments (here: surface waters) have to be reduced from the GRACE observations. Therefore, the retrieved signal has to be decomposed into its individual components. To achieve this, the water volume can be estimated by forward modelling satellite altimetry and remote sensing data, considering both static and dynamic surface expansions. It will be discussed, that using a dynamic instead of a static surface area extent (1) will change the equivalent water height values in a magnitude between 0.006 cm and 0.243 cm, (2) causes the largest deviation for the Lake Mead and (3) that the question whether a dynamic or a static water body shape should be considered is driven by the interaction of various parameters.

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