USGS Science⌕ Search

Geology topics

M. Anderson

Publications and source records attributed to M. Anderson.

6 recordsLinked to original sources
USGS2025

Performance mapping and weighting for the evapotranspiration models of the OpenET ensemble

Evapotranspiration (ET) accounts for the majority of water available from precipitation in the terrestrial water cycle, and improvements to the accuracy, resolution, and coverage of ET data can enhance hydrologic models and assessments. The OpenET collaboration of six remotely sensed ET modeling teams has demonstrated that an ensemble approach to ET estimation generally provides improved accuracy relative to individual ensemble members. The performance of individual models has been shown to vary by land cover type and climate zone, but a thorough study of the variables that influence model performance differences has not yet been conducted. In this paper, we model the performance of OpenET models relative to flux tower data as a function of variables such as land cover type and precipitation. These performance models are used to map estimated OpenET model performance across the conterminous United States. We develop relative weights based on these modeled performance metrics and show that a performance-weighted ensemble improves accuracy relative to the current OpenET ensemble method to varying degrees. The monthly mean absolute error of the weighted ensemble is reduced relative to the current method by 8% in agricultural settings, by 23% in shrublands and mixed forests, and by 5% in grasslands and evergreen forests. We produce weight maps that can be used to generate performance-weighted ensemble values for OpenET data. The results can be used to inform model selection and provide insight about the controls on model performance that could lead to model refinement.

Water Resources Research↗
USGS2013

Late Miocene-Pleistocene evolution of a Rio Grande rift subbasin, Sunshine Valley-Costilla Plain, San Luis Basin, New Mexico and Colorado

The Sunshine Valley-Costilla Plain, a structural subbasin of the greater San Luis Basin of the northern Rio Grande rift, is bounded to the north and south by the San Luis Hills and the Red River fault zone, respectively. Surficial mapping, neotectonic investigations, geochronology, and geophysics demonstrate that the structural, volcanic, and geomorphic evolution of the basin involves the intermingling of climatic cycles and spatially and temporally varying tectonic activity of the Rio Grande rift system. Tectonic activity has transferred between range-bounding and intrabasin faults creating relict landforms of higher tectonic-activity rates along the mountain-piedmont junction. Pliocene–Pleistocene average long-term slip rates along the southern Sangre de Cristo fault zone range between 0.1 and 0.2 mm/year with late Pleistocene slip rates approximately half (0.06 mm/year) of the longer Quaternary slip rate. During the late Pleistocene, climatic influences have been dominant over tectonic influences on mountain-front geomorphic processes. Geomorphic evidence suggests that this once-closed subbasin was integrated into the Rio Grande prior to the integration of the once-closed northern San Luis Basin, north of the San Luis Hills, Colorado; however, deep canyon incision, north of the Red River and south of the San Luis Hills, initiated relatively coeval to the integration of the northern San Luis Basin. Long-term projections of slip rates applied to a 1.6 km basin depth defined from geophysical modeling suggests that rifting initiated within this subbasin between 20 and 10 Ma. Geologic mapping and geophysical interpretations reveal a complex network of northwest-, northeast-, and north-south–trending faults. Northwest- and northeast-trending faults show dual polarity and are crosscut by north-south– trending faults. This structural model possibly provides an analog for how some intracontinental rift structures evolve through time.

Colorado, New Mexico↗
USGS2008

Significance of model credibility in estimating climate projection distributions for regional hydroclimatological risk assessments

Ensembles of historical climate simulations and climate projections from the World Climate Research Programme's (WCRP's) Coupled Model Intercomparison Project phase 3 (CMIP3) multi-model dataset were investigated to determine how model credibility affects apparent relative scenario likelihoods in regional risk assessments. Methods were developed and applied in a Northern California case study. An ensemble of 59 twentieth century climate simulations from 17 WCRP CMIP3 models was analyzed to evaluate relative model credibility associated with a 75-member projection ensemble from the same 17 models. Credibility was assessed based on how models realistically reproduced selected statistics of historical climate relevant to California climatology. Metrics of this credibility were used to derive relative model weights leading to weight-threshold culling of models contributing to the projection ensemble. Density functions were then estimated for two projected quantities (temperature and precipitation), with and without considering credibility-based ensemble reductions. An analysis for Northern California showed that, while some models seem more capable at recreating limited aspects twentieth century climate, the overall tendency is for comparable model performance when several credibility measures are combined. Use of these metrics to decide which models to include in density function development led to local adjustments to function shapes, but led to limited affect on breadth and central tendency, which were found to be more influenced by 'completeness' of the original ensemble in terms of models and emissions pathways. ?? 2007 Springer Science+Business Media B.V.

Climatic Change↗
USGS2004

Structural model of the San Bernardino basin, California, from analysis of gravity, aeromagnetic, and seismicity data

The San Bernardino basin is an area of Quaternary extension between the San Jacinto and San Andreas Fault zones in southern California. New gravity data are combined with aeromagnetic data to produce two- and three-dimensional models of the basin floor. These models are used to identify specific faults that have normal displacements. In addition, aeromagnetic maps of the basin constrain strike-slip offset on many faults. Relocated seismicity, focal mechanisms, and a seismic reflection profile for the basin area support interpretations of the gravity and magnetic anomalies. The shape of the basin revealed by our interpretations is different from past interpretations, broadening its areal extent while confining the deepest parts to an area along the modern San Jacinto fault, west of the city of San Bernardino. Through these geophysical observations and related geologic information, we propose a model for the development of the basin. The San Jacinto fault-related strike-slip displacements started on fault strands in the basin having a stepping geometry thus forming a pull-apart graben, and finally cut through the graben in a simpler, bending geometry. In this model, the San Bernardino strand of the San Andreas Fault has little influence on the formation of the basin. The deep, central part of the basin resembles classic pull-apart structures and our model describes a high level of detail for this structure that can be compared to other pull-apart structures as well as analog and numerical models in order to better understand timing and kinematics of pull-apart basin formation. Copyright 2004 by the American Geophysical Union.

Journal of Geophysical Research B: Solid Earth↗