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Geology topics

M. E. Hansen

Publications and source records attributed to M. E. Hansen.

6 recordsLinked to original sources
USGS2010

CO2calc: A User-Friendly Seawater Carbon Calculator for Windows, Mac OS X, and iOS (iPhone)

A user-friendly, stand-alone application for the calculation of carbonate system parameters was developed by the U.S. Geological Survey Florida Shelf Ecosystems Response to Climate Change Project in response to its Ocean Acidification Task. The application, by Mark Hansen and Lisa Robbins, USGS St. Petersburg, FL, Joanie Kleypas, NCAR, Boulder, CO, and Stephan Meylan, Jacobs Technology, St. Petersburg, FL, is intended as a follow-on to CO2SYS, originally developed by Lewis and Wallace (1998) and later modified for Microsoft Excel? by Denis Pierrot (Pierrot and others, 2006). Besides eliminating the need for using Microsoft Excel on the host system, CO2calc offers several improvements on CO2SYS, including: An improved graphical user interface for data entry and results Additional calculations of air-sea CO2 fluxes (for surface water calculations) The ability to tag data with sample name, comments, date, time, and latitude/longitude The ability to use the system time and date and latitude/ longitude (automatic retrieval of latitude and longitude available on iPhone? 3, 3GS, 4, and Windows? hosts with an attached National Marine Electronics Association (NMEA)-enabled GPS) The ability to process multiple files in a batch processing mode An option to save sample information, data input, and calculated results as a comma-separated value (CSV) file for use with Microsoft Excel, ArcGIS,? or other applications An option to export points with geographic coordinates as a KMZ file for viewing and editing in Google EarthTM

Open-File Report↗
USGS1997

Accelerated relative sea-level rise and rapid coastal erosion: Testing a causal relationship for the Louisiana barrier islands

The role of relative sea-level rise as a cause for the rapid erosion of Louisiana's barrier island coast is investigated through a numerical implementation of a modified Bruun rule that accounts for the low percentage of sand-sized sediment in the eroding Louisiana shoreface. Shore-normal profiles from 150 km of coastline west of the Mississippi delta are derived from bathymetric surveys conducted during the 1880s. 1930s and 1980s. An RMS difference criterion is employed to test whether an equilibrium profile form is maintained between survey years. Only about half the studied profiles meet the equilibrium Criterion this represents a significant limitation on the potential applicability of the Bruun rule. The profiles meeting the equilibrium criterion, along with measured rates of relative sea-level rise, are used to hindcast shoreline retreat rates at 37 locations within the study area. Modeled and observed shoreline retreat rates show no significant correlation. Thus in terms of the Bruun approach relative sea-level rise has no power for hindcasting (and presumably forecasting) rates of coastal erosion for the Louisiana barrier islands.

Marine Geology↗
USGS1997

Bathymetric comparisons adjacent to the Louisiana barrier islands: Processes of large-scale change

This paper summarizes the results of a comparative bathymetric study encompassing 150 km of the Louisiana barrier-island coast. Bathymetric data surrounding the islands and extending to 12 m water depth were processed from three survey periods: the 1880s, the 1930s, and the 1980s. Digital comparisons between surveys show large-scale, coherent patterns of sea-floor erosion and accretion related to the rapid erosion and disintegration of the islands. Analysis of the sea-floor data reveals two primary processes driving this change: massive longshore transport, in the littoral zone and at shoreface depths; and increased sediment storage in ebb-tidal deltas. Relative sea-level rise, although extraordinarily high in the study area, is shown to be an indirect factor in causing the area's rapid shoreline retreat rates.

Louisiana↗