S.S. Saatchi | USGS Science

USGS2025

A U.S. scientific community vision for sustained earth observations of greenhouse gases to support local to global action

Managing carbon stocks in the land, ocean, and atmosphere under changing climate requires a globally-integrated view of carbon cycle processes at local and regional scales. The growing Earth Observation (EO) record is the backbone of this multi-scale system, providing local information with discrete coverage from surface measurements and regional information at global scale from satellites. Carbon flux information, anchored by inverse estimates from spaceborne Greenhouse Gas (GHG) concentrations, provides an important top-down view of carbon emissions and sinks, but currently lacks global continuity at assessment and management scales (< 100 km). Partial-column data can help separate signals in the boundary layer from the overlying atmosphere, providing an opportunity to enhance surface sensitivity and bring flux resolution down from that of column-integrated data (100–500 km). Based on a workshop held in September 2024, the carbon cycle community envisions a carbon observation system leveraging GHG partial columns in the lower and upper troposphere to weave together information across scales from surface and satellite EO data, and integration of top- down/bottom-up analyses to link process understanding to global assessment.

AGU Advances↗

USGS1996

Erosional and depositional patterns associated with the 1993 Missouri River floods inferred from SIR-C and TOPSAR radar data

The Missouri River floods of 1993 caused significant and widespread damage to the floodplains between Kansas City and St. Louis. Immediately downstream of levee breaks, flood waters scoured the bottoms. As the floodwaters continued, they spread laterally and deposited massive amounts of sand as crevasse splays on top of agricultural fields. We explore the use of radar interferometry and backscatter data for quantitative estimation of scour and deposition for Jameson Island/Arrow Rock Bottoms and Lisbon Bottoms, two bottoms that were heavily damaged during the floods and subsequently abandoned. Shuttle imaging radar C (SIR-C) L band (24 cm) HH (horizontally transmitted and horizontally received) radar backscatter data acquired in October 1994 were used together with a distorted Born approximation canopy scattering model to determine that the abundance of natural leafy forbs controlled the magnitude of backscatter for former agricultural fields. Forb areal density was found to be inversely correlated with thickness of sand deposited during the floods, presumably because thick sands prevented roots from reaching nutrient rich, moist bottoms soils. Using the inverse relationship, a lower bound for the mass of sand added was found to be 6.3 million metric tons over the 17 km 2 study area. Digital elevation data from topographic synthetic aperture radar (TOPSAR) C band (5.6 cm) interferometric observations acquired in August 1994 were compared to a series of elevation profiles collected on the ground. Vertical errors in TOPSAR were estimated to range from 1 to 2 m, providing enough accuracy to generate an estimate of total mass (4.7 million metric tons) removed during erosion of levees and scour of the bottoms terrains. Net accretion of material to the study areas is consistent with the geologic record of major floods where sediment-laden floodwaters crested over natural levees, initially scoured into the bottoms, and then deposited sands as crevasse splays as the flows spread out and slowed by frictional dissipation. The addition of artificial levees to the Missouri River system has undoubtedly enhanced flood damage, although quantitative estimation of the degree of enhancement will require additional work.

Journal of Geophysical Research E: Planets↗