Download or read book Effects of Initial Soil Moisture on Rainfall Generation and Subsequent Hydrologic Response During the North American Monsoon written by Kinwai Tai and published by . This book was released on 2008 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Biogeoscience Approach to Ecosystems written by Edward A. Johnson and published by Cambridge University Press. This book was released on 2016-10-13 with total page 495 pages. Available in PDF, EPUB and Kindle. Book excerpt: Integrates geoscience and ecology, focusing on connections in ecological, geospheric, hydrospheric and atmospheric processes in ecosystems.

Download or read book Modelling Simulating and Forecasting Regional Climate and Weather written by Hans Von Storch and published by Frontiers Media SA. This book was released on 2020-09-11 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.

Download or read book Investigating Soil Moisture precipitation Feedback on the North American Monsoon System written by Yuechun Wang (Ph. D. in atmospheric science) and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The North American Monsoon System (NAMS) has an important influence on the local climate and water supply in the southwestern United States and northwestern Mexico during June-September. Soil moisture can affect North American Monsoon (NAM) precipitation, so an improved understanding of the nature of this relationship has the potential for improving seasonal forecasting of the NAMS. To better understand the influence of soil moisture feedback on NAM precipitation, this dissertation has three objectives: (1) Evaluate model-simulated NAM precipitation when initializing the soil moisture conditions with data from different sources; (2) Investigate the soil moisture feedback to the NAM precipitation and the underlying physical mechanisms using observational data; (3) Evaluate soil moisture memory in the NAM region. To evaluate the influence of soil moisture initialization on the NAMS, we designed four sets of sensitivity experiments in the Weather Research and Forecasting (WRF) model with extremely wet and dry initial conditions and different soil moisture products. The results revealed that the WRF model can generally reproduce the NAMS, but it overestimates NAM precipitation in higher elevation regions and underestimates NAM precipitation in lower elevation regions. The results indicate that accurate soil moisture is important for improving the model representation of the NAMS in the WRF model. To examine the local and nonlocal feedbacks of soil moisture on the NAM precipitation based on observations, we applied a multivariate statistical method known as the Stepwise Generalized Equilibrium Feedback Assessment (SGEFA) to isolate the influence of soil moisture feedbacks. Our study is the first to apply SGEFA to quantify soil moisture feedbacks in the NAM region. This analysis identified the sign and pathways of the feedbacks between soil moisture and the NAM precipitation. Wet soils in the South Rocky Mountain (SRM) tend to result in less monsoon precipitation, while above-normal soil moisture in the NAM region tends to increase NAM precipitation. Finally, to investigate soil moisture memory in the NAM region an evaluation framework derived from autocorrelation equations was applied to three CMIP6 models to identify the main controls of soil moisture memory. The analysis revealed that evapotranspiration and runoff sensitivity to soil moisture are the most important factors that are responsible for soil moisture memory in the NAM region. This doctoral research confirmed the importance of soil moisture for improving the accuracy of NAMS forecasts. A combination of observational data and regional and global models were used to identify the nature and strength of soil moisture feedback mechanisms in the NAM region. The result indicates that soil moisture can affect NAM precipitation by modifying local heat fluxes as well as large-scale circulations. The results in this study can be useful for water supply management and drought and flood forecasting in the NAM region.

Download or read book Precipitation Effects on Soil Carbon Cycling in the Sonoran Desert written by and published by . This book was released on 2006 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biological activity in desert soils is driven by water availability. The nature of individual precipitation events is critical to understanding soil moisture availability. Rain falls as discrete events (pulses) that vary in size and sequencing, resulting in soil"wet-dry cycles". Soil organisms are responsive to wet-dry cycles with rapid changes in activity. How soil activity is driven by changes in water content associated with individual pulses is poorly understood. The effects of precipitation on soil processes likely depend on ecosystem structure, which influences the soil environment. The goal of this dissertation was to determine how soil carbon cycling responds to precipitation in the context of ecosystem structure (plant composition, geomorphology) and climate. I used differences in stable carbon isotopic composition of soil organisms and plants to understand how positioning in the soil profile influences biological responses to different sized pulses. I evaluated how soil texture and grass species composition affect soil process response to rainfall in different seasons. I manipulated rainfall sequence to understand the interaction between closely spaced rainfall events of different sizes on soil processes. I evaluated the role of plant functional types in influencing soil microclimate and litter deposition and the response of soil processes to seasonal rainfall. Chamber measurements of soil and plant CO2 flux were used to understand their response to rainfall. I found that surface organisms are more responsive to small rainfall events due to the relationship between pulse size and infiltration. While soil texture and season of rainfall are important, the best predictor of the response of soil respiration to rainfall was initial activity levels. Grass species was not important. Grass roots and soil microbes differ in response to sequences of precipitation. Grasses responded less to subsequent large events if they were already 'activated' by a recent rainfall event. The effect of plant functional type was size dependent with differences occurring only with large shrubs. This work suggests that large scale simulations of soil carbon cycling in deserts should carefully consider wet-dry transitions in the context of plant functional type and initial soil condition in order to predict the responses to global change.

Download or read book Studies of Relations of Rainfall and Run off in the United States written by William Glenn Hoyt and published by . This book was released on 1936 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rainfall Runoff and the Effects of Initial Soil Moisture Associated with the Little Washita River Watershed Oklahoma written by Joe A. Spah and published by . This book was released on 2000 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Assessment of Intraseasonal to Interannual Climate Prediction and Predictability written by National Research Council and published by National Academies Press. This book was released on 2010-10-08 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: More accurate forecasts of climate conditions over time periods of weeks to a few years could help people plan agricultural activities, mitigate drought, and manage energy resources, amongst other activities; however, current forecast systems have limited ability on these time- scales. Models for such climate forecasts must take into account complex interactions among the ocean, atmosphere, and land surface. Such processes can be difficult to represent realistically. To improve the quality of forecasts, this book makes recommendations about the development of the tools used in forecasting and about specific research goals for improving understanding of sources of predictability. To improve the accessibility of these forecasts to decision-makers and researchers, this book also suggests best practices to improve how forecasts are made and disseminated.

Download or read book The Representation of Cumulus Convection in Numerical Models written by Kerry Emanuel and published by Springer. This book was released on 2015-03-30 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents descriptions of numerical models for testing cumulus in cloud fields. It is divided into six parts. Part I provides an overview of the problem, including descriptions of cumulus clouds and the effects of ensembles of cumulus clouds on mass, momentum, and vorticity distributions. A review of closure assumptions is also provided. A review of "classical" convection schemes in widespread use is provided in Part II. The special problems associated with the representation of convection in mesoscale models are discussed in Part III, along with descriptions of some of the commonly used mesoscale schemes. Part IV covers some of the problems associated with the representation of convection in climate models, while the parameterization of slantwise convection is the subject of Part V.

Download or read book Regional scale Model Climatology of the North American Monsoon System written by Robert Timothy Swanson and published by . This book was released on 1998 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Pennsylvania State University/National Center of Atmospheric Research Mesoscale Model 5 (MM5) is forced by the observed evolution of sea surface temperature and the National Center for Environmental Prediction (NCEP) reanalyses of the atmospheric flow on the lateral boundaries. The MM5 reproduces many of the general features of the large-scale circulation found in the NCEP reanalyses. It does, however, develop a stronger regional meridional circulation with higher precipitation rates in the Intertropical Convergence Zone (ITCZ), stronger cross-equatorial flow in the boundary layer, and greater divergent flow aloft. The model ITCZ is displaced too far north and tends to be located over the highest sea surface temperature. Mesoscale circulation features, such as diurnal land/sea breezes and gap flows across Mexico and Central America, are captured. The observed latitudinal transition from the shallow planetary boundary layer (PBL) with stratiform clouds over the cool waters of the equatorial Pacific to a relatively deeper PBL further north is simulated by the model. More tropical cyclones develop in the MM5 than were observed and they were comparatively shorter-lived and weaker. Also, the model, as presently configured, does not realistically simulate the year-to-year variations in tropical cyclones. The regional circulation during Summer 1997 was dominated by the planetary- scale El Nino/Southern Oscillation phenomenon. The normally cool waters along the equator were unusually warm with enhanced convection to the south of the mean position of the ITCZ. Large-scale subsidence over Central America and the extreme eastern Pacific Ocean led to drought conditions in that region. The number and intensity of tropical cyclones observed during summer 1997 in the eastern equatorial Pacific were reduced despite the fact that the most intense hurricane of the eight seasons occurred during that year.

Download or read book Assessing the Effects of Climate Change in a Semiarid Basin Utilizing a Fully Distributed Hydrologic Model written by Gretchen Hawkins and published by . This book was released on 2012 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: The North American Monsoon (NAM) is characterized by high inter- and intra-seasonal variability, and potential climate change effects have been forecasted to increase this variability. The potential effects of climate change to the hydrology of the southwestern U.S. is of interest as they could have consequences to water resources, floods, and land management. I applied a distributed watershed model, the Triangulated Irregular Network (TIN)-based Real-time Integrated Basin Simulator (tRIBS), to the Beaver Creek basin in Arizona. This sub-basin of the Verde River is representative of the regional topography, land cover, and soils distribution. As such, it can serve to illustrate the utility of distributed models for change assessment studies. Model calibration was performed utilizing radar-based NEXRAD data, and comparisons were done to two additional sources of precipitation data: ground-based stations and the North American Land Data Assimilation System (NLDAS). Comparisons focus on the spatiotemporal distributions of precipitation and stream discharge. Utilizing the calibrated model, I applied scenarios from the HadCM3 General Circulation Model (GCM) which was dynamically downscaled by the Weather Research and Forecast (WRF) model, to refine the representation of Arizona's regional climate. Two time periods were examined, a historical 1990-2000 and a future 2031-2040, to evaluate the hydrologic consequence in the form of differences and similarities between the decadal averages for temperature, precipitation, stream discharge and evapotranspiration. Results indicate an increase in mean air temperature over the basin by 1.2 C. The average decadal precipitation amounts increased between the two time periods by 2.4 times that of the historical period and had an increase in variability that was 3 times the historical period. For the future period, modeled streamflow discharge in the summer increased by a factor of 3. There was no significant change in the average evapotranspiration (ET). Overall trends of increase precipitation and variability for future climate scenarios have a more significant effect on the hydrologic response than temperature increases in the system during NAM in this study basin. The results from this study suggest that water management in the Beaver Creek will need to adapt to higher summer streamflow amounts.

Download or read book The Monsoons and Climate Change written by Leila Maria Véspoli de Carvalho and published by Springer. This book was released on 2015-12-22 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a global overview examining monsoon variability in South Asia, Australian, South America and North American, as well as a focus on glaciers and monsoon systems. Monsoon systems are important components of the Earth's climate and play fundamental roles in water and energy balances. The variability and changes in the monsoons affect millions of people and the economies of many countries. This book presents the physical mechanisms involved with monsoon systems, including recent modeling advances addressing climate changes and future projections. The Monsoons and Climate Change will be of interest to both graduate students and researchers.

Download or read book ENABLING HYDROLOGICAL INTERPRETATION OF MONTHLY TO SEASONAL PRECIPITATION FORECASTS IN THE CORE NORTH AMERICAN MONSOON REGION written by and published by . This book was released on 2009 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of the research undertaken in this dissertation was to use medium-range to seasonal precipitation forecasts for hydrologic applications for catchments in the core North American Monsoon (NAM) region. To this end, it was necessary to develop a better understanding of the physical and statistical relationships between runoff processes and the temporal statistics of rainfall. To achieve this goal, development of statistically downscaled estimates of warm season precipitation over the core region of the North American Monsoon Experiment (NAME) were developed. Currently, NAM precipitation is poorly predicted on local and regional scales by Global Circulation Models (GCMs). The downscaling technique used here, the K-Nearest Neighbor (KNN) model, combines information from retrospective GCM forecasts with simultaneous historical observations to infer statistical relationships between the low-resolution GCM fields and the locally-observed precipitation records. The stochastic nature of monsoon rainfall presents significant challenges for downscaling efforts and, therefore, necessitate a regionalization and an ensemble or probabilistic-based approach to quantitative precipitation forecasting. It was found that regionalization of the precipitation climatology prior to downscaling using KNN offered significant advantages in terms of improved skill scores. Selected output variables from retrospective ensemble runs of the National Centers for Environmental Predictions medium-range forecast (MRF) model were fed into the KNN downscaling model. The quality of the downscaled precipitation forecasts was evaluated in terms of a standard suite of ensemble verification metrics. This study represents the first time the KNN model has been successfully applied within a warm season convective climate regime and shown to produce skillful and reliable ensemble forecasts of daily precipitation out to a lead time of four to six days, depending on the forecast month. Knowledge of the behavior of the regional hydrologic systems in NAM was transferred into a modeling framework aimed at improving intra-seasonal hydrologic predictions. To this end, a robust lumped-parameter computational model of intermediate conceptual complexity was calibrated and applied to generate streamflow in three unregulated test basins in the core region of the NAM. The modeled response to different time-accumulated KNN-generated precipitation forcing was investigated. Although the model had some difficulty in accurately simulating hydrologic fluxes on the basis of Hortonian runoff principles only, the preliminary results achieved from this study are encouraging. The primary and most novel finding from this study is an improved predictability of the NAM system using state-of-the-art ensemble forecasting systems. Additionally, this research significantly enhanced the utility of the MRF ensemble forecasts and made them reliable for regional hydrologic applications. Finally, monthly streamflow simulations (from an ensemble-based approach) have been demonstrated. Estimated ensemble forecasts provide quantitative estimates of uncertainty associated with our model forecasts.

Download or read book Insights on Seasonal Fluxes in a Desert Shrubland Watershed written by Ryan Templeton and published by . This book was released on 2011 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: The North American Monsoon System (NAMS) contributes ~55% of the annual rainfall in the Chihuahuan Desert during the summer months. Relatively frequent, intense storms during the NAMS increase soil moisture, reduce surface temperature and lead to runoff in ephemeral channels. Quantifying these processes, however, is difficult due to the sparse nature of coordinated observations. In this study, I present results from a field network of rain gauges (n = 5), soil probes (n = 48), channel flumes (n = 4), and meteorological equipment in a small desert shrubland watershed (~0.05 km2) in the Jornada Experimental. Using this high-resolution network, I characterize the temporal and spatial variability of rainfall, soil conditions and channel runoff within the watershed from June 2010 to September 2011, covering two NAMS periods. In addition, CO2, water and energy measurements at an eddy covariance tower quantify seasonal, monthly and event-scale changes in land-atmosphere states and fluxes. Results from this study indicate a strong seasonality in water and energy fluxes, with a reduction in Bowen ratio (B, the ratio of sensible to latent heat fluxes) from winter (B = 14) to summer (B = 3.3). This reduction is tied to shallow soil moisture availability during the summer (s = 0.040 m3/m3) as compared to the winter (s = 0.004 m3/m3). During the NAMS, I analyzed four consecutive rainfall-runoff events to quantify the soil moisture and channel flow responses and how water availability impacted the land-atmosphere fluxes. Spatial hydrologic variations during events occur over distances as short as ~15 m. The field network also allowed comparisons of several approaches to estimate evapotranspiration (ET). I found a more accurate ET estimate (a reduction of mean absolute error by 38%) when using distributed soil moisture data, as compared to a standard water balance approach based on the tower site. In addition, use of spatially-varied soil moisture data yielded a more reasonable relationship between ET and soil moisture, an important parameterization in many hydrologic models. The analyses illustrates the value of high-resolution sampling for quantifying seasonal fluxes in desert shrublands and their improvements in closing the water balance in small watersheds.

Download or read book Hydrologic Effects of Rainfall Augmentation written by Alan M. Lumb and published by . This book was released on 1969 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Monsoon Rains Great Rivers and the Development of Farming Civilisations in Asia written by Peter D. Clift and published by Cambridge University Press. This book was released on 2021-01-07 with total page 349 pages. Available in PDF, EPUB and Kindle. Book excerpt: A detailed review of climate change and its impacts on farming systems since the Neolithic, including anticipated future changes.

Download or read book Sensitivity of Convective Precipitation Forecasts to Soil Moisture and Vegetation written by Thomas William Collow and published by . This book was released on 2014 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: Land surface properties play a major role in convective precipitation events through impacting the amount of surface evaporation which results in changes to near surface temperature and humidity. This study examines the effects of using soil moisture data from the North American Regional Reanalysis (NARR) and the Soil Moisture Ocean Salinity Satellite (SMOS) on short term weather forecasts using the Weather Research and Forecasting Model (WRF). SMOS soil moisture data were compared to in-situ observations and it was found that although they captured the spatial variation in soil moisture, the actual measurements had a dry bias of roughly 0.10 m3/m3. Large differences existed between the in-situ observations, even for probes only a few meters apart. Observations from different sensors within a SMOS footprint differed from each other by a larger amount than they differed from the SMOS retrieval. Removing the mean and normalizing the data brought the in-situ observations into better agreement with each other and with SMOS but they still contained substantial differences. WRF sensitivity experiments demonstrated that changes to initial values of soil moisture resulted in no significant changes in precipitation. However, more of an impact was seen when the vegetation was changed, with barren vegetation yielding a substantial decrease in precipitation. Adding soil moisture resulted in significant changes to 2 m temperature and dewpoint relative to the control runs for each vegetation type. However, it was found that convective available potential energy and moist static energy change little, as the temperature and humidity impacts on these variables cancel each other out, which explain the limited precipitation response. SMOS data resulted in no significant changes in precipitation forecasts but had some impacts on temperature and humidity forecasts. However, because these results were not seen in all cases, no definitive conclusions about the usefulness of SMOS for high resolution numerical modeling can be made at this time. These results provide major implications for future satellite missions such as Soil Moisture Active Passive showing that experiments using true data assimilation methods which give only partial weight to satellite data may also not provide significant improvements to weather forecasts.