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Moisture Patterns (moisture + pattern)

Distribution by Scientific Domains
Engineering57%

Kinds of Moisture Patterns

  • soil moisture pattern
    		•

    Selected Abstracts

    Evaluating explicit and implicit routing for watershed hydro-ecological models of forest hydrology at the small catchment scale

    HYDROLOGICAL PROCESSES, Issue 8 2001
    C. L. Tague
    Abstract This paper explores the behaviour and sensitivity of a watershed model used for simulating lateral soil water redistribution and runoff production. In applications such as modelling the effects of land-use change in small headwater catchments, interactions between soil moisture, runoff and ecological processes are important. Because climate, soil and canopy characteristics are spatially variable, both the pattern of soil moisture and the associated outflow must be represented in modelling these processes. This study compares implicit and explicit routing approaches to modelling the evolution of soil moisture pattern and spatially variable runoff production. It also addresses the implications of using different landscape partitioning strategies. This study presents the results of calibration and application of these different routing and landscape partitioning approaches on a 60 ha forested watershed in Western Oregon. For comparison, the different approaches are incorporated into a physically based hydro-ecological model, RHESSys, and the resulting simulated soil moisture, runoff production and sensitivity to unbiased error are examined. Results illustrate that both routing approaches can be calibrated to achieve a reasonable fit between observed and modelled outflow. Calibrated values for effective watershed hydraulic conductivity are higher for the explicit routing approach, which illustrates differences between the two routing approaches in their representation of internal watershed dynamics. The explicit approach illustrates a seasonal shift in drainage organization from watershed to more local control as climate goes from a winter wet to a summer dry period. Assumptions used in the implicit approach maintain the same pattern of drainage organization throughout the season. The implicit approach is also more sensitive to random error in soil and topographic input information, particularly during wetter periods. Comparison between the two routing approaches illustrates the advantage of the explicit routing approach, although the loss of computational efficiency associated with the explicit routing approach is noted. To compare different strategies for partitioning the landscape, the use of a non-grid-based method of partitioning is introduced and shown to be comparable to grid-based partitioning in terms of simulated soil moisture and runoff production. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    Impact of soil moisture on the development of a Sahelian mesoscale convective system: a case-study from the AMMA Special Observing Period

    THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue S1 2010
    Christopher M. Taylor
    Abstract Interactions between the land and atmosphere play an important role in the precipitation of the Sahel. The African Monsoon Multidisciplinary Analysis Special Observing Period provided observations with which to illuminate potential feedback mechanisms. This case-study highlights a major storm which developed over northern Mali in an area where a research aircraft was surveying the atmospheric response to soil moisture features. Soil moisture variability is characterized using satellite land-surface temperature data whilst cloud images illustrate the evolution of the storm and its relationship to the surface. Measurements in the planetary boundary layer (PBL) indicate mesoscale variations in pre-storm humidity and temperature consistent with high evaporation from wet soils. The storm developed above a dry surface within a wetter region with cells first appearing along a wet,dry soil boundary. This suggests that the storm was triggered in association with low-level convergence driven by the soil moisture pattern. A gravity wave propagating away from a remote mature storm also appears to have played an important role in the initiation, though only in the region of the soil moisture contrast did deep convection become established. Once organised into a Mesoscale Convective System, convection developed over wet areas as well as dry, and indeed at this stage, convection became more intense over wetter soils. This behaviour is consistent with the large gradients in PBL humidity. The study illustrates the complexity of soil moisture,convection feedback loops and highlights the mechanisms which may operate at different stages of a storm's life cycle. Copyright © 2009 Royal Meteorological Society [source]

    Mechanisms of positive biodiversity,production relationships: insights provided by ,13C analysis in experimental Mediterranean grassland plots

    ECOLOGY LETTERS, Issue 5 2001
    Maria C. Caldeira
    We investigated the role of water use in a Mediterranean grassland, in which diversity was experimentally manipulated, and a positive relationship was observed between plant species richness and productivity. Soil moisture patterns and stable carbon isotope ratios (,13C) in leaves indicated greater water use by plants growing in species-rich mixtures compared to monocultures. These results suggest that complementarity or facilitation may be the mechanism responsible for the positive relationship between plant diversity and ecosystem processes. [source]

    Assessing factors that influence spatial variations in duff moisture

    HYDROLOGICAL PROCESSES, Issue 15 2008
    L. D. Raaflaub
    Abstract Patterns and spatial variations in the moisture of the decomposing organic matter on the forest floor (the duff) of a montane forest were analysed in an effort to determine the primary factors shaping these patterns. Above and below canopy meteorological conditions were monitored to determine the influence of canopy cover on duff moisture. The spatial and temporal distributions of duff moisture were assessed through daily duff moisture measurements collected at regular intervals in ten 10 × 10 m plots representing a variety of canopy types and densities. Meteorological conditions ranged from very wet to very dry and resulted in duff moisture variations that were more pronounced during wet periods than in extended periods of drying. Investigations on the influence of canopy type, tree density, and tree proximity on duff moisture patterns indicated that canopy type and tree proximity are the most important factors affecting duff moisture. Interception seems to be the primary controller of duff moisture patterns with an influence at the centimetre scale. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Analysis of soil moisture patterns in forested and suburban catchments in Baltimore, Maryland, using high-resolution photogrammetric and LIDAR digital elevation datasets

    HYDROLOGICAL PROCESSES, Issue 2 2006
    D. E. Tenenbaum
    Abstract Field observations of near-surface soil moisture, collected over several seasons in a watershed in suburban Maryland, are compared with values of the topographic soil moisture index generated using digital elevation models (DEMs) at a range of grid cell sizes from photogrammetric and light detection and ranging (LIDAR) data sources. A companion set of near-surface soil moisture observations, DEMs and topographic index values are also presented for a nearby forested catchment. The degree to which topographic index values are an effective indicator of near-surface soil moisture conditions varies in the two environments. The urbanizing environment requires topographic index values from a DEM with a much finer grid cell resolution than the LIDAR data can provide, and the relationship is stronger in wetter conditions. In the forested environment, the DEM resolution required is considerably lower and adequately supported by the photogrammetric data, and the relationship is strong under all moisture conditions. These results provide some insights into the length scales of near-surface hydrological processes in the urbanizing environment, and the resolution of terrain data required to model those processes. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    APPLICATION OF THE RHESSys MODEL TO A CALIFORNIA SEMIARID SHRUBLAND WATERSHED,

    JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 3 2004
    Christina Tague
    ABSTRACT: Distributed hydrologic models which link seasonal streamflow and soil moisture patterns with spatial patterns of vegetation are important tools for understanding the sensitivity of Mediterranean type ecosystems to future climate and land use change. RHESSys (Regional Hydro-Ecologic Simulation System) is a coupled spatially distributed hydroecological model that is designed to be able to represent these feedbacks between hydrologic and vegetation carbon and nutrient cycling processes. However, RHESSys has not previously been applied to semiarid shrubland watersheds. In this study, the hydrologic submodel of RHESSys is evaluated by comparing model predictions of monthly and annual streamflow to stream gage data and by comparing RHESSys behavior to that of another hydrologic model of similar complexity, MIKESHE, for a 34 km2 watershed near Santa Barbara, California. In model intercomparison, the differences in predictions of temporal patterns in streamflow, sensitivity of model predictions to calibration parameters and landscape representation, and differences in model estimates of soil moisture patterns are explored. Results from this study show that both models adequately predict seasonal patterns of streamflow response relative to observed data, but differ significantly in terms of estimates of soil moisture patterns and sensitivity of those patterns to the scale of landscape tessellation used to derive spatially distributed elements. This sensitivity has implications for implementing RHESSys as a tool to investigate interactions between hydrology and ecosystem processes. [source]

    A simple model of coupled synoptic waves in the land surface and atmosphere of the northern Sahel

    THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 637 2008
    Douglas J. Parker
    Abstract A simple dynamic model is developed to describe the observed interactions between the atmosphere and the soil moisture patterns of the northern Sahel. In the model, the atmosphere follows quasi-geostrophic dynamics, while land-atmosphere coupling is described by simple linear relationships. Dry surfaces heat the atmospheric boundary layer, while wet surfaces cool the boundary layer, relative to the equilibrium state of the atmosphere and land surface. In turn, cloud processes, which are assumed to maximise in the cool, humid phase of an atmospheric disturbance, cool the land surface through wetting (rainfall) and reduction of the incoming solar flux. These assumptions lead to a linear system which can be solved numerically to obtain modal solutions, and the adjoints (optimal excitation) of these. Moist convective influences on the atmospheric state are not explored in detail. The coupling with the land surface leads to the existence of unstable modes, which do not exist in the atmosphere-only part of the system. Solutions can be easterly or westerly propagating, according to wave number, with the longer waves tending to be easterly. Propagation relies on a favourable configuration between the atmospheric and soil moisture anomalies: easterly propagation requires the surface temperature pattern to be shifted to the east of the atmospheric temperature pattern. In contrast, optimal excitation of the fastest-growing mode occurs when the atmospheric pattern has a thermal anomaly lying to the east of a strong surface temperature (and moisture) anomaly. These results have value for weather prediction, and indicate the usefulness of soil moisture data for forecasters. Copyright © 2008 Royal Meteorological Society [source]