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Mid Western Us Heavy Summer Precipitation In Regional And Global Climate Models
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Book Synopsis Mid-Western U.S. Heavy Summer-precipitation in Regional and Global Climate Models by : Xiang Gao
Download or read book Mid-Western U.S. Heavy Summer-precipitation in Regional and Global Climate Models written by Xiang Gao and published by . This book was released on 2017 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Extreme precipitation events pose a significant threat to public safety, natural and managed resources, and the functioning of society. Changes in such high-impact, low-probability events have profound implications for decision-making, preparation and costs of mitigation and adaptation efforts. Understanding how extreme precipitation events will change in the future and enabling consistent and robust projections is therefore important for the public and policymakers as we prepare for consequences of climate change. Projection of extreme precipitation events, however, particularly at the local scale, presents a critical challenge: the climate model-based simulations of precipitation that we currently rely on for such projections -- general circulation models (GCMs) -- are not very realistic, mainly due to the models' coarse spatial resolution. This coarse resolution precludes adequate representation of highly influential, small-scale features such as moisture convection and topography. Regional circulation models (RCMs) provide much higher resolution and better representation of such features, and are thus often perceived as an optimum approach to producing more accurate heavy precipitation statistics than GCMs. However, they are much more computationally intensive, time-consuming and expensive to run. In a previous paper, the researchers developed an algorithm that detects the occurrence of heavy precipitation events based on climate models' well-resolved, large-scale atmospheric circulation conditions associated with those events -- rather than relying on these models' simulated precipitation. The algorithm's results corresponded with observations with much greater precision than the model-simulated precipitation. In this paper, the researchers show that using output from RCMs rather than GCMs for the new algorithm does not improve the precision of simulated extreme precipitation frequency. The algorithm thus presents a robust and economic way to assess extreme precipitation frequency across a broad range of GCMs and multiple climate change scenarios with minimal computational requirements.
Author :National Academies of Sciences, Engineering, and Medicine Publisher :National Academies Press ISBN 13 :0309471699 Total Pages :207 pages Book Rating :4.3/5 (94 download)
Book Synopsis Review of the Draft Fourth National Climate Assessment by : National Academies of Sciences, Engineering, and Medicine
Download or read book Review of the Draft Fourth National Climate Assessment written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2018-06-18 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: Climate change poses many challenges that affect society and the natural world. With these challenges, however, come opportunities to respond. By taking steps to adapt to and mitigate climate change, the risks to society and the impacts of continued climate change can be lessened. The National Climate Assessment, coordinated by the U.S. Global Change Research Program, is a mandated report intended to inform response decisions. Required to be developed every four years, these reports provide the most comprehensive and up-to-date evaluation of climate change impacts available for the United States, making them a unique and important climate change document. The draft Fourth National Climate Assessment (NCA4) report reviewed here addresses a wide range of topics of high importance to the United States and society more broadly, extending from human health and community well-being, to the built environment, to businesses and economies, to ecosystems and natural resources. This report evaluates the draft NCA4 to determine if it meets the requirements of the federal mandate, whether it provides accurate information grounded in the scientific literature, and whether it effectively communicates climate science, impacts, and responses for general audiences including the public, decision makers, and other stakeholders.
Book Synopsis Twenty-first-century Changes in U.S. Regional Heavy Precipitation Frequency Based on Resolved Atmospheric Patterns by :
Download or read book Twenty-first-century Changes in U.S. Regional Heavy Precipitation Frequency Based on Resolved Atmospheric Patterns written by and published by . This book was released on 2017 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: Precipitation-gauge observations and atmospheric reanalysis are combined to develop an analogue method for detecting heavy precipitation events based on prevailing large-scale atmospheric conditions. Combinations of atmospheric variables for circulation (geopotential height and wind vector) and moisture (surface specific humidity, column and up to 500-hPa precipitable water) are examined to construct analogue schemes for the winter [December-February (DJF)] of the "Pacific Coast California" (PCCA) region and the summer [June-August (JJA)] of the Midwestern United States (MWST). The detection diagnostics of analogue schemes are calibrated with 1979-2005 and validated with 2006-14 NASA Modern-Era Retrospective Analysis for Research and Applications (MERRA). All analogue schemes are found to significantly improve upon MERRA precipitation in characterizing the occurrence and interannual variations of observed heavy precipitation events in the MWST. When evaluated with the late twentieth-century climate model simulations from phase 5 of the Coupled Model Intercomparison Project (CMIP5), all analogue schemes produce model medians of heavy precipitation frequency that are more consistent with observations and have smaller intermodel discrepancies than model-based precipitation. Under the representative concentration pathways (RCP) 4.5 and 8.5 scenarios, the CMIP5-based analogue schemes produce trends in heavy precipitation occurrence through the twenty-first century that are consistent with model-based precipitation, but with smaller intermodel disparity. The median trends in heavy precipitation frequency are positive for DJF over PCCA but are slightly negative for JJA over MWST. Overall, the analyses highlight the potential of the analogue as a powerful diagnostic tool for model deficiencies and its complementarity to an evaluation of heavy precipitation frequency based on model precipitation alone. Keywords: North America; Atmospheric circulation; Extreme events; Flood events; General circulation models; Model evaluation/performance.
Book Synopsis 21st Century Changes in U.S. Heavy Precipitation Frequency Based on Resolved Atmospheric Patterns by :
Download or read book 21st Century Changes in U.S. Heavy Precipitation Frequency Based on Resolved Atmospheric Patterns written by and published by . This book was released on 2016 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gridded precipitation-gauge observations and global atmospheric reanalysis are combined to develop an analogue method for detecting the occurrence of heavy precipitation events based on the prevailing large-scale atmospheric conditions. Combinations of different atmospheric variables for circulation features (geopotential height and wind vector) and moisture plumes (surface specific humidity, column precipitable water, and precipitable water up to 500hPa) are examined to construct the analogue schemes for the winter (DJF) of the Pacific Coast California (PCCA) and the summer (JJA) of the Midwestern United States (MWST). The detection diagnostics of various analogue schemes are calibrated with 27-yr (1979-2005) and then validated with 9-yr (2006-2014) NASA Modern-Era Retrospective Analysis for Research and Applications (MERRA). All of the analogue schemes are found to significantly improve upon MERRA precipitation in characterizing the number and interannual variations of observed heavy precipitation events in the MWST which is one of weakest regions for MERRA summer precipitation. When evaluated with the late 20th century simulations from an ensemble of climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5), all analogue schemes produce model medians of heavy precipitation frequency that are more consistent with observations and have smaller inter-model discrepancies when compared with the model-based precipitation. Further, the performances of analogue schemes with vector winds are comparable to those of geopotential height, and no analogue scheme with one of three water vapor content variables is clearly superior to another. Under two radiative forcing scenarios (Representative Concentration Pathways 4.5 and 8.5), the CMIP5-based analogue schemes produce a trend in the occurrence of heavy events through the 21st century consistent with the model-based precipitation, but with smaller inter-model disparity. The strongest reduction in the disparity of the results is seen for the RCP8.5 scenario. The median trends in DJF heavy precipitation frequency for PCCA are positive, but for JJA heavy event frequency over the MWST region, the median trends are slightly negative. Overall, the presented analyses highlight the potential of the analogue as a powerful diagnostic tool for model deficiencies and its complementarity to an evaluation that considers modeled precipitation alone to assess heavy precipitation frequency. The consistency found here between projections from analogues and model precipitation increases confidence in projected heavy precipitation frequency changes in a warming climate.
Author :U.S. Global Change Research Program Publisher :Cambridge University Press ISBN 13 :0521144078 Total Pages :193 pages Book Rating :4.5/5 (211 download)
Book Synopsis Global Climate Change Impacts in the United States by : U.S. Global Change Research Program
Download or read book Global Climate Change Impacts in the United States written by U.S. Global Change Research Program and published by Cambridge University Press. This book was released on 2009-08-24 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: Summarizes the science of climate change and impacts on the United States, for the public and policymakers.
Book Synopsis Predicting Climate Change Impacts on Precipitation for Western North America by : Nicole R. McKechnie
Download or read book Predicting Climate Change Impacts on Precipitation for Western North America written by Nicole R. McKechnie and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Global Circulation Models (GCMs) are used to create projections of possible future climate characteristics under global climate change scenarios. Future local and regional precipitation scenarios can be developed by downscaling synoptic CGM data. Daily 500-mb geopotential heights from the Canadian Centre for Climate Modeling and Analysis's CGCM2 are used to represent future (2020-2050) synoptics and are compared to daily historical (1960-1990) 500-mb geopotential height reanalysis data. The comparisons are made based on manually classified synoptic patterns identified by Changnon et al. (1993.Mon. Weather Rev. 121:633-647). Multiple linear regression models are used to link the historical synoptic pattern frequencies and precipitation amounts for 372 weather stations across western North America,. The station-specific models are then used to forecast future precipitation amounts per weather station based on synoptic pattern frequencies forecast by the CGCM2 climate change forcing scenario. Spatial and temporal variations in precipitation are explored to determine monthly, seasonal and annual trends in climate change impacts on precipitation in western North America. The resulting precipitation scenarios demonstrate a decrease in precipitation from 10 to 30% on an annual basis for much of the south and western regions of the study area. Seasonal forecasts show variations of the same regions with decreases in precipitation and select regions with increases in future precipitation. A major advancement of this analysis was the application of synoptic pattern downscaling to summer precipitation scenarios for western North America.
Book Synopsis Seasonal Variation in Temperature, Precipitation and Streamflow Across the Midwestern United States by : Pratik Pathak
Download or read book Seasonal Variation in Temperature, Precipitation and Streamflow Across the Midwestern United States written by Pratik Pathak and published by . This book was released on 2016 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: A great deal of attention has been given to global climate change by the hydrologic community. Temperature, precipitation and streamflow trend analysis, on different spatial and temporal scales, is important in understanding the impact of climate change. Midwest region is the heartland of agriculture production in U.S., and change in hydrologic variables may affect both quantity and quality of production. In the study, mean, maximum and minimum temperature along with mean precipitation for 106 climate divisions in the Midwest were analyzed to test the existence of monotonic trend and shift changes in the seasonal hydrological time series. In addition to that, trend and shift in 88 streamflow stations in the Midwest and its relation with temperature and precipitation were analyzed. Mann Kendall test with and without considering lag-1 auto-correlation were employed to analyze the trend. Non-parametric Pettitt test was used to analyze the shift; Sen's slope estimator was used to identify the magnitude of hydrological trend. Discrete Wavelet analysis was done to analyze the effect of periodicities on trends and shifts in hydrological variables. In addition, association between the occurrence of shifts and phases of climate indices, such as El Nino Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO), was investigated. The results indicated significant increasing trend in mean and minimum temperature for majority of the climate divisions in all the seasons studied. While, increase in maximum temperature in winter and spring was observed, majority of the climate divisions showed decreasing trend in summer and fall. Increasing trend in precipitation was detected mostly in spring, summer and fall as compared to winter. Persistence was mostly observed for all the variables during the summer season and when accounted for, trend remained for most of the climate divisions. Spatially prevalent shifts were noticed, which were in agreement with gradual trend for most of the hydrologic variables. The results of the wavelet analysis indicated D2 (dyadic scale of 4 years) and D3 (dyadic scale of 8 years) to be the most effective periodic component in detecting trend in winter, spring and summer. D1 (dyadic scale of 2 years) and D3 proved to be the most effective in detecting trend in temperature data in fall. Likewise, precipitation and streamflow showed the dominance of D3 component in detecting real trend in the data. Majority of shift changes coincided with PDO and ENSO phases. The use of wavelet helped in detecting the typical timescale of ENSO and the effect of coupled climate indices on hydrologic variables. A possible linkage between streamflow, temperature and precipitation trend across some regions were detected clearly corroborating the importance of exploring the synergism between meteorological, climatic and hydrologic factors to assess the changing character of the variables. The contribution from this research include a better understanding of the changes in the hydrology of the Midwest that can help in better water management decisions.
Book Synopsis Large Ensembles of Regional Climate Simulations Over the Western United States by : Sihan Li
Download or read book Large Ensembles of Regional Climate Simulations Over the Western United States written by Sihan Li and published by . This book was released on 2017 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: Large ensembles of regional climate simulations were generated from the weather@home distributed volunteer computing project over the western US domain. Weather@home uses the U.K. Met Office Hadley Centre’s regional climate model HadRM3P (~0.22°) nested within the atmospheric global model HadAM3P (1.875 longitude° by 1.25 latitude°). Simulations from HadRM3P were evaluated against observational datasets, and were found to be able to faithfully reproduce various properties of the recent past climate of the western US. In an effort to explore local anthropogenically forced climate responses, especially precipitation response, over the complex terrain, western US climate was simulated for the recent past (1986-2014) and future (2031-2059). The large initial-condition ensemble of regional climate simulations provides detailed information of precipitation changes at local grid point level, with high signal-to-noise ratio, while results from the host global climate model are analyzed for synoptic-scale mechanisms driving the regional changes. Both winter and summer precipitation changes have a large dynamic origin. Winter precipitation changes are associated with a southeastward extension of the Aleutian low-pressure center and strengthening and eastward expansion of the upper subtropical jet stream. Summer precipitation changes are associated with a high-pressure anomaly centered over the northwest at the 500-hPa level, contributing to drying in the northwest, and the wetting in the southwest is associated with stronger increase in water vapor. The pattern of circulation change associated with changes in extreme (wet) monthly precipitation is similar to that for changes in mean monthly precipitation, but the changes are more intense. The changes of extreme precipitation vary spatially, with the least relative increase in Western Oregon-Washington, and the most relative increase in the Great Basin. Precipitation increase more on the leeward side of the Cascade Range than on the windward side, and this difference across mountain barrier is present in changes of both seasonal mean and extreme precipitation, suggesting common physical drivers. These large ensembles also present unique datasets to thoroughly assess the impact of internal variability on climate projections from a high-resolution regional model. We quantify the magnitude of changes forced by increasing greenhouse gas concentrations relative to internal variability and find that simulations spanning 10 to 30 years (the timespans used in the majority of published studies of regional climate modeling) often lead to unfounded confidence in results because of low grid-point level signal-to-noise ratios that furthermore vary considerably by season, variable and location. We offer a rule of thumb for determining the minimum adequate ensemble size N[subscript min] to detect a response to anthropogenic forcing in different climate variables, and a minimum adequate ensemble size N[subscript min(delta x)] required for detecting spatial heterogeneity of such responses. Our results underscore the problem that increasing model resolution without increasing ensemble size does not necessarily advance the understanding of regional and local climate response to anthropogenic forcing. To summarize, the combination of high resolution over the complex terrain of western US and large numbers of simulations allow us to explore the effects of local and regional climate change in a way not otherwise possible.
Book Synopsis CLIMATE CHANGE AND ECOSYSTEM IMPACTS ASSOCIATED WITH SHIFTS IN THE MID-LATITUDE STORM TRACK IN THE WESTERN UNITED STATES. by : Stephanie McAfee
Download or read book CLIMATE CHANGE AND ECOSYSTEM IMPACTS ASSOCIATED WITH SHIFTS IN THE MID-LATITUDE STORM TRACK IN THE WESTERN UNITED STATES. written by Stephanie McAfee and published by . This book was released on 2009 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the more robust 21st century projections from the most recent Intergovernmental Panel on Climate Change report (IPCC AR4) is a northward shift in the mean location of the Northern Hemisphere storm track. In the western United States, cool-season precipitation provides most of the water for domestic and industrial consumption, irrigation and power generation. In addition, winter precipitation is particularly effective in recharging soil moisture; as a result, it provides a strong control on the productivity of vegetation and on wildfire. Consequently, there is great interest in understanding 1) how changes in the storm track influence regional climate; 2) spatial and temporal variability in its impact; 3) how well general circulation models simulate the regional climate dynamics that bring precipitation to the West; and 4) whether errors in climate simulation might impact assessment of ecological changes. In order to investigate climate change in the western United States associated with shifts in the storm track, I analyzed the relationship between climate and the Northern Annular Mode (NAM). When the storm track is displaced to the north, there is an earlier transition to warm-season circulation patterns and weather conditions. However, the relationship between the winter NAM and climate is not stable over time. Further analysis identified changes in the correlations between the NAM and tree-ring width, precipitation and temperatures associated with changes in the phase of the Atlantic Multidecadal Oscillation and Pacific Decadal Oscillation. Examining 18 of the IPCC AR4 coupled climate models demonstrated cool-season precipitation errors approaching 300% over western North America. These errors are related to difficulties in representing orography, given the coarse resolution of models, and they may influence the quality of precipitation projections into the future. A simple test using the Köppen classification system found that these precipitation errors lead to underestimating the area of the United States in dryland ecosystem types by up to 89% and consequently allowed for much greater expansion of dryland in the future than is actually likely. These studies suggest that the West is likely to experience greater drought in the future. However, no single tool can yet quantify that change.
Book Synopsis Regional Climate Model Evaluations of Long-term Changes in Total Precipitation and High Precipitation Events by :
Download or read book Regional Climate Model Evaluations of Long-term Changes in Total Precipitation and High Precipitation Events written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Climate Extremes Over the Mid-Atlantic States by : Emily K. Aiken
Download or read book Climate Extremes Over the Mid-Atlantic States written by Emily K. Aiken and published by . This book was released on 2018 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: Much of our current risk assessment, especially for extreme events and natural disasters, comes from the assumption that the likelihood of future extreme events can be predicted based on the past. However, as global temperatures rise, established climate ranges may no longer be applicable, as historic records for extremes such as heat waves and floods may no longer accurately predict the changing future climate. To assess extremes (present-day and future) over the contiguous United States, I used NOAA’s Climate Extremes Index (CEI), which evaluates extremes in maximum and minimum temperature, extreme one-day precipitation, days without precipitation, and the Palmer Drought Severity Index (PDSI). The CEI is a spatially sensitive index that uses percentile-based thresholds rather than absolute values to determine climate “extremeness,” and is thus well-suited to compare extreme climate across regions. I used regional climate model data from the North American Regional Climate Change Assessment Program (NARCCAP) and the Coordinated Regional Downscaling Experiment (CORDEX) to compare a late 20th century reference period to a mid-21st century business as usual (RCP8.5 and SRES A2) greenhouse gas-forcing scenario. Additionally, I used CMIP3 and CMIP5 data to compare regional climate model data to its global climate model boundary forcings, to see what added value the regional climate models provide in the Mid-Atlantic region. Results show a universal increase in extreme temperatures across all models, with annual average maximum and minimum temperatures exceeding historic 90th percentile thresholds over more than 90% of the area assessed by 2068. Results for precipitation indicators have greater spatial variability from model to model, but indicate an overall movement towards less frequent but more extreme precipitation days in the future.
Book Synopsis Changing Precipitation Regimes and Terrestrial Ecosystems by : Jake F. Weltzin
Download or read book Changing Precipitation Regimes and Terrestrial Ecosystems written by Jake F. Weltzin and published by University of Arizona Press. This book was released on 2003-01-01 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: By the beginning of the twenty-first century, few people could deny the reality of global change. But while most alarm has been over increasing temperatures, other changes are occurring in precipitation patternsÑvariations that may be due in part to global warming but also to factors such as changes in atmospheric circulation and land surfaces. This volume provides a central source of information about this newly emerging area of global change research. It presents ongoing investigations into the responses of plant communities and ecosystems to the experimental manipulation of precipitation in a variety of field settingsÑparticularly in the western and central United States, where precipitation is already scarce or variable. By exploring methods that can be used to predict responses of ecosystems to changes in precipitation regimes, it demonstrates new approaches to global change research and highlights the importance of precipitation regimes in structuring ecosystems. The contributors first document the importance of precipitation, soil characteristics, and soil moisture to plant life. They then focus on the roles of precipitation amount, seasonality, and frequency in shaping varied terrestrial ecosystems: desert, sagebrush steppe, oak savanna, tall- and mixed-grass prairie, and eastern deciduous forest. These case studies illustrate many complex, tightly woven, interactive relationships among precipitation, soils, and plantsÑrelationships that will dictate the responses of ecosystems to changes in precipitation regimes. The approaches utilized in these chapters include spatial comparisons of vegetation structure and function across different ecosytems; analyses of changes in plant architecture and physiology in response to temporal variation in precipitation; experiments to manipulate water availability; and modeling approaches that characterize the relationships between climate variables and vegetation types. All seek to assess vegetation responses to major shifts in climate that appear to be occurring at present and may become the norm in the future. As the first volume to discuss and document current and cutting-edge concepts and approaches to research into changing precipitation regimes and terrestrial ecosystems, this book shows the importance of developing reliable predictions of the precipitation changes that may occur with global warming. These studies clearly demonstrate that patterns of environmental variation and the nature of vegetation responses are complex phenomena that are only beginning to be understood, and that these experimental approaches are critical for our understanding of future change.
Author :Intergovernmental Panel on Climate Change. Working Group II. Publisher :Cambridge University Press ISBN 13 :9780521634557 Total Pages :532 pages Book Rating :4.6/5 (345 download)
Book Synopsis The Regional Impacts of Climate Change by : Intergovernmental Panel on Climate Change. Working Group II.
Download or read book The Regional Impacts of Climate Change written by Intergovernmental Panel on Climate Change. Working Group II. and published by Cambridge University Press. This book was released on 1998 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cambridge, UK : Cambridge University Press, 1998.
Book Synopsis Winter Extreme Precipitation Along the North American West Coast by : Michael D. Warner
Download or read book Winter Extreme Precipitation Along the North American West Coast written by Michael D. Warner and published by . This book was released on 2014 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: Most extreme precipitation events that occur along the North American west coast are associated with winter atmospheric river (AR) events, causing flooding, landslides, extensive property damage, and loss of life. The studies contained within this dissertation use a combination of NCDC precipitation observations, NCEP-NCAR reanalysis, a 10-model ensemble of historical and future CMIP5 climate model simulations, and an NCEP-NCAR reanalysis driven regionally downscaled WRF model simulation to characterize the synoptic evolution of AR events along the North American west coast, the spatial variability of precipitation along the coast and inland, and changes in AR intensity and frequency that are expected by the end of the 21st century. Most regional flooding events are associated with precipitation periods of 24 hours or less, and two-day precipitation totals identify nearly all major events. Precipitation areas of major events are generally narrow, roughly 200 km in width, and most are associated with ARs. Composite evolutions indicate negative anomalies in sea-level pressure and upper-level height in the central Pacific, high-pressure anomalies over the southwest U.S., large positive 850-hPa temperature anomalies along the coast and offshore, and enhanced precipitable water and integrated water vapor fluxes in southwest- to northeast-oriented swaths. A small subset of extreme precipitation events over the southern portion of the domain is associated with a very different synoptic evolution: a sharp trough in northwesterly flow and post-cold-frontal convection. High precipitable water values are more frequent during the summer but are not associated with heavy precipitation because of upper-level ridging over the eastern Pacific and weak onshore flow that limits upward vertical velocities. Global climate models have sufficient resolution to simulate synoptic features associated with AR events, such as high values of vertically integrated vapor transport (IVT) approaching the coast. Ten CMIP5 simulations are used to identify changes in ARs impacting the west coast of North America between historical (1970-1999) and end-of-century (2070-2099) representative concentration pathway (RCP) 8.5 runs. The most extreme ARs are identified in both time periods by the 99th percentile of IVT days along a north-south transect offshore of the coast. Integrated water vapor (IWV) and IVT are predicted to increase, while lower-tropospheric winds change little. Winter-mean precipitation along the West Coast increases by 11-18% (4-6% °C[superscript -1]) while precipitation on extreme IVT days increases by 15-39% (5-19% °C[superscript -1]). The frequency of IVT days above the historical 99th percentile threshold increases as much as 290% by the end of this century. There appear to be only very slight changes in annual AR climatology from historical to future time periods when considering the most extreme events (99th percentile). However, when evaluating by the number of future days exceeding the historical threshold, there are significant increases in extreme IVT events in all months, especially when the majority of events take place. The peaks in historical and future frequency occur in similar months given the amount of model variability. Extreme IVT events appear to be occurring slightly earlier in the season, particularly in the northern part of the domain, and these results are similar to other studies. Spatially, 10-model mean historical composites of IVT reveal canonical AR conditions. At locations farther south, there is less model agreement on what AR events should look like, both in spatial extent and intensity; whereas farther north, the various models agree more. The future composites indicate very little spatial change. The models behave similarly in both the historical and future runs, suggesting little change in dynamics. The future-historical difference plots highlight the largest changes expected in the future, namely increases in IVT intensity which are primarily associated with thermodynamic changes related to future IWV increases due to warming. The dynamically downscaled NCEP-NCAR reanalysis-driven WRF model, run with a 36-km resolution outer domain and a 12-km nest, contains more realistic terrain than most GCMs and highlights the spatial precipitation distribution over the Pacific Northwest. Winter precipitation in the Pacific Northwest correlates well with offshore daily IVT (as high as &sim0.8) with spatial signatures indicative of frequent coastal mid-latitude cyclones impacting the coast. However, the most extreme AR events did not correlate as highly as expected with daily precipitation (as high as ~ 0.4), despite ARs accounting for 8% or more of the total winter precipitation. When wind direction was taken into account, the correlations were much higher (~.7-0.8), indicating wind direction is an important factor when extreme precipitation occurs along the coast.
Book Synopsis The Multiscale Global Monsoon System by : Chih-pei Chang
Download or read book The Multiscale Global Monsoon System written by Chih-pei Chang and published by World Scientific. This book was released on 2021-01-04 with total page 419 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Multiscale Global Monsoon System is the 4th and most up-to-date edition of the global monsoon book series produced by a group of leading international experts invited by the World Meteorological Organization's Working Group on Tropical Meteorology Research. The contents reflect the state of the knowledge of all scales of monsoon in the world's monsoon regions. It includes 31 chapters in five parts: Regional Monsoons, Extreme Weather, Intraseasonal Variations, Climate Change, and Field Experiments.
Book Synopsis Why Precipitation and Forest Structure are Changing in the Eastern US: Insight from Analysis of Large Empirical and Climate Model Datasets by : Travis D. Andrews
Download or read book Why Precipitation and Forest Structure are Changing in the Eastern US: Insight from Analysis of Large Empirical and Climate Model Datasets written by Travis D. Andrews and published by . This book was released on 2015 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: Improved projections of future climate trends, climate extremes and ecological responses are critical to inform policy and natural resource management aimed at sustainability and preparedness. Considerable attention has been focused on understanding drought, due to concerns over crop yield and forest mortality. However, some regions, such as the eastern US, have experienced increased summer precipitation over the past half century and the causes and ecological implications are not well understood. Greenhouse gases and regional effects of agricultural irrigation have been shown to be primary drivers of precipitation enhancement, although far-downstream effects of irrigation on moist, forested regions remain unclear. In addition, correctly anticipating forest responses to increasing precipitation, and other aspects of a changing climate, requires understanding the interaction of long-term successional processes across regional-to-continental spatial scales. Here I, 1) investigated how agricultural irrigation enhances regional and far-downstream precipitation; and, 2) developed a new data-driven model of forest dynamics that quantifies compositional and structural response to competition, disturbance, and climate anomalies. This work combined modeling experiments using the National Center for Atmospheric Research (NCAR) community earth system model (CESM) and analysis of large long-term datasets from the National Oceanic and Atmospheric Administration (NOAA) and US Forest Service (USFS) forest inventory and analysis (FIA). Results indicated that moisture advection from irrigation in the western U.S. enhances stratiform precipitation in the densely populated greater New York City region, where very-heavy precipitation events were 11% more intense and occurred 23% more frequently. Forest modeling provided validation and quantification of fundamental ideas underlying forest succession (e.g., self-thinning, resource limitation tolerance) and revealed increased summer precipitation may enhance forest net primary productivity up to +32% (+0.52+/-0.08 Mg C ha-1 yr-1). However, climate warming was associated with increased occurrence of weather disturbances and disease resulting in reduced productivity by as much as -29% (-0.55 +/-0.08 Mg C ha-1 yr-1). Well-known successional shifts in species-group dominance were attributed to disturbance susceptibility and a gradient of tolerance to resource limitation. Collectively this work provides new insight for climate mitigation efforts, robust comparisons for global vegetation models, and context for water resource and forest management.
Book Synopsis Rainfall of the United States with Annual, Seasonal and Other Charts by : Alfred Judson Henry
Download or read book Rainfall of the United States with Annual, Seasonal and Other Charts written by Alfred Judson Henry and published by . This book was released on 1897 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:
