scholarly journals Reduced tree growth in the semiarid United States due to asymmetric responses to intensifying precipitation extremes

2019 ◽  
Vol 5 (10) ◽  
pp. eaaw0667 ◽  
Author(s):  
Matthew P. Dannenberg ◽  
Erika K. Wise ◽  
William K. Smith
Keyword(s):  
United States ◽  
Tree Growth ◽  
Precipitation Variability ◽  
Cool Season ◽  
Growth Anomalies ◽  
Linear Relationships ◽  
Asymmetric Responses ◽  
Hydroclimatic Variability ◽  
Negative Growth ◽  
Future Growth

Earth’s hydroclimatic variability is increasing, with changes in the frequency of extreme events that may negatively affect forest ecosystems. We examined possible consequences of changing precipitation variability using tree rings in the conterminous United States. While many growth records showed either little evidence of precipitation limitation or linear relationships to precipitation, growth of some species (particularly those in semiarid regions) responded asymmetrically to precipitation such that tree growth reductions during dry years were greater than, and not compensated by, increases during wet years. The U.S. Southwest, in particular, showed a large increase in precipitation variability, coupled with asymmetric responses of growth to precipitation. Simulations suggested roughly a twofold increase in the probability of large negative growth anomalies across the Southwest resulting solely from 20th century increases in variability of cool-season precipitation. Models project continued increases in precipitation variability, portending future growth reductions across semiarid forests of the western United States.

scholarly journals Reduced tree growth in the semiarid United States due to asymmetric responses to intensifying precipitation extremes

2020 ◽  
Author(s):  
Matthew Dannenberg ◽  
Erika Wise ◽  
William Smith
Keyword(s):  
Tree Growth ◽  
Fold Increase ◽  
Precipitation Variability ◽  
Cool Season ◽  
Growth Anomalies ◽  
Linear Relationships ◽  
Asymmetric Responses ◽  
Hydroclimatic Variability ◽  
Negative Growth ◽  
Future Growth

<p>Earth’s hydroclimatic variability is increasing, with changes in the frequency of extreme events that may negatively affect forest ecosystems. We examined possible consequences of changing precipitation variability using tree rings in the conterminous U.S. While many growth records showed either little evidence of precipitation limitation or linear relationships to precipitation, growth of some species (particularly those in semiarid regions) responded asymmetrically to precipitation, such that tree growth reductions during dry years were greater than, and not compensated by, increases during wet years. The U.S. Southwest in particular showed both a large increase in precipitation variability coupled with asymmetric responses of growth to precipitation. Simulations suggested roughly a two-fold increase in the probability of large negative growth anomalies across the Southwest resulting solely from 20<sup>th</sup> century increases in the variability of cool-season precipitation. Models project continued increases in precipitation variability, portending future growth reductions across semiarid forests of the western U.S.</p>

Spatial Patterns of Tree-Growth Anomalies in the United States and Southeastern Canada

1993 ◽  
Vol 6 (9) ◽  
pp. 1773-1786 ◽  
Author(s):  
David Meko ◽  
Edward R. Cook ◽  
David W. Stahle ◽  
Charles W. Stockton ◽  
Malcolm K. Hughes
Keyword(s):  
United States ◽  
Spatial Patterns ◽  
Tree Growth ◽  
The United States ◽  
Growth Anomalies

scholarly journals Cool season precipitation projections for California and the Western United States in NA-CORDEX models

2021 ◽  
Author(s):  
Kelly Mahoney ◽  
James D. Scott ◽  
Michael Alexander ◽  
Rachel McCrary ◽  
Mimi Hughes ◽  
...  
Keyword(s):  
United States ◽  
Climate Models ◽  
Snow Water Equivalent ◽  
Regional Climate ◽  
Regional Climate Models ◽  
Western United States ◽  
Monthly Precipitation ◽  
Wet Season ◽  
Cool Season ◽  
Projected Change

AbstractUnderstanding future precipitation changes is critical for water supply and flood risk applications in the western United States. The North American COordinated Regional Downscaling EXperiment (NA-CORDEX) matrix of global and regional climate models at multiple resolutions (~ 50-km and 25-km grid spacings) is used to evaluate mean monthly precipitation, extreme daily precipitation, and snow water equivalent (SWE) over the western United States, with a sub-regional focus on California. Results indicate significant model spread in mean monthly precipitation in several key water-sensitive areas in both historical and future projections, but suggest model agreement on increasing daily extreme precipitation magnitudes, decreasing seasonal snowpack, and a shortening of the wet season in California in particular. While the beginning and end of the California cool season are projected to dry according to most models, the core of the cool season (December, January, February) shows an overall wetter projected change pattern. Daily cool-season precipitation extremes generally increase for most models, particularly in California in the mid-winter months. Finally, a marked projected decrease in future seasonal SWE is found across all models, accompanied by earlier dates of maximum seasonal SWE, and thus a shortening of the period of snow cover as well. Results are discussed in the context of how the diverse model membership and variable resolutions offered by the NA-CORDEX ensemble can be best leveraged by stakeholders faced with future water planning challenges.

scholarly journals ENSO and Wintertime Extreme Precipitation Events over the Contiguous United States

2008 ◽  
Vol 21 (1) ◽  
pp. 22-39 ◽  
Author(s):  
Siegfried D. Schubert ◽  
Yehui Chang ◽  
Max J. Suarez ◽  
Philip J. Pegion
Keyword(s):  
United States ◽  
West Coast ◽  
Extreme Precipitation ◽  
East Coast ◽  
Daily Precipitation ◽  
Precipitation Variability ◽  
The West ◽  
Extreme Precipitation Events ◽  
The Impact ◽  
Precipitation Events

Abstract In this study the authors examine the impact of El Niño–Southern Oscillation (ENSO) on precipitation events over the continental United States using 49 winters (1949/50–1997/98) of daily precipitation observations and NCEP–NCAR reanalyses. The results are compared with those from an ensemble of nine atmospheric general circulation model (AGCM) simulations forced with observed SST for the same time period. Empirical orthogonal functions (EOFs) of the daily precipitation fields together with compositing techniques are used to identify and characterize the weather systems that dominate the winter precipitation variability. The time series of the principal components (PCs) associated with the leading EOFs are analyzed using generalized extreme value (GEV) distributions to quantify the impact of ENSO on the intensity of extreme precipitation events. The six leading EOFs of the observations are associated with major winter storm systems and account for more than 50% of the daily precipitation variability along the West Coast and over much of the eastern part of the country. Two of the leading EOFs (designated GC for Gulf Coast and EC for East Coast) together represent cyclones that develop in the Gulf of Mexico and occasionally move and/or redevelop along the East Coast producing large amounts of precipitation over much of the southern and eastern United States. Three of the leading EOFs represent storms that hit different sections of the West Coast (designated SW for Southwest coast, WC for the central West Coast, and NW for northwest coast), while another represents storms that affect the Midwest (designated by MW). The winter maxima of several of the leading PCs are significantly impacted by ENSO such that extreme GC, EC, and SW storms that occur on average only once every 20 years (20-yr storms) would occur on average in half that time under sustained El Niño conditions. In contrast, under La Niña conditions, 20-yr GC and EC storms would occur on average about once in 30 years, while there is little impact of La Niña on the intensity of the SW storms. The leading EOFs from the model simulations and their connections to ENSO are for the most part quite realistic. The model, in particular, does very well in simulating the impact of ENSO on the intensity of EC and GC storms. The main model discrepancies are the lack of SW storms and an overall underestimate of the daily precipitation variance.

The influence of climate and drought on urban tree growth in southeast Australia and the implications for future growth under climate change

2017 ◽  
Vol 167 ◽  
pp. 275-287 ◽  
Author(s):  
Craig R. Nitschke ◽  
Scott Nichols ◽  
Kathy Allen ◽  
Cynnamon Dobbs ◽  
Stephen J. Livesley ◽  
...  
Keyword(s):  
Climate Change ◽  
Tree Growth ◽  
Urban Tree ◽  
Southeast Australia ◽  
Future Growth

scholarly journals Insights into the BRT (Boosted Regression Trees) Method in the Study of the Climate-Growth Relationship of Masson Pine in Subtropical China

Forests ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 228 ◽  
Author(s):  
Hongliang Gu ◽  
Jian Wang ◽  
Lijuan Ma ◽  
Zhiyuan Shang ◽  
Qipeng Zhang
Keyword(s):  
Tree Growth ◽  
General Circulation ◽  
Growth Response ◽  
Circulation Model ◽  
Regression Trees ◽  
Pinus Massoniana ◽  
Boosted Regression Trees ◽  
Climate Factors ◽  
Masson Pine ◽  
Hydroclimatic Variability

Dendroclimatology and dendroecology have entered mainstream dendrochronology research in subtropical and tropical areas. Our study focused on the use of the chronology series of Masson pine (Pinus massoniana Lamb.), the most widely distributed tree species in the subtropical wet monsoon climate regions in China, to understand the tree growth response to ecological and hydroclimatic variability. The boosted regression trees (BRT) model, a nonlinear machine learning method, was used to explore the complex relationship between tree-ring growth and climate factors on a larger spatial scale. The common pattern of an asymptotic growth response to the climate indicated that the climate-growth relationship may be linear until a certain threshold. Once beyond this threshold, tree growth will be insensitive to some climate factors, after which a nonlinear relationship may occur. Spring and autumn climate factors are important controls of tree growth in most study areas. General circulation model (GCM) projections of future climates suggest that warming climates, especially temperatures in excess of those of the optimum growth threshold (as estimated by BRT), will be particularly threatening to the adaptation of Masson pine.

scholarly journals Seasonal Variations in Temperature–Suicide Associations across South Korea

2019 ◽  
Vol 11 (4) ◽  
pp. 731-739
Author(s):  
Adam J. Kalkstein ◽  
Miloslav Belorid ◽  
P. Grady Dixon ◽  
Kyu Rang Kim ◽  
Keith A. Bremer
Keyword(s):  
South Korea ◽  
Nonlinear Modeling ◽  
Warm Season ◽  
Cool Season ◽  
Delayed Effects ◽  
Distributed Lag ◽  
Significant Relationships ◽  
Linear Relationships ◽  
Significant Temperature ◽  
Seasonal Signal

Abstract South Korea has among the highest rates of suicide in the world, and previous research suggests that suicide frequency increases with anomalously high temperatures, possibly as a result of increased sunshine. However, it is unclear whether this temperature–suicide association exists throughout the entire year. Using distributed lag nonlinear modeling, which effectively controls for nonlinear and delayed effects, we examine temperature–suicide associations for both a warm season (April–September) and a cool season (October–March) for three cities across South Korea: Seoul, Daegu, and Busan. We find consistent, statistically significant, mostly linear relationships between relative risk of suicide and daily temperature in the cool season but few associations in the warm season. This seasonal signal of statistically significant temperature–suicide associations only in the cool season exists among all age segments, but especially for those 35 and older, along with both males and females. We further use distributed lag nonlinear modeling to examine cloud cover–suicide associations and find few significant relationships. This result suggests that that high daily temperatures in the cool season, and not exposure to sun, are responsible for the strong temperature–suicide associations found in South Korea.

scholarly journals Interdecadal Seesaw of Precipitation Variability between North China and the Southwest United States

2019 ◽  
Vol 32 (10) ◽  
pp. 2951-2968 ◽  
Author(s):  
Qing Yang ◽  
Zhuguo Ma ◽  
Peili Wu ◽  
Nicholas P. Klingaman ◽  
Lixia Zhang
Keyword(s):  
United States ◽  
North Pacific ◽  
Large Scale ◽  
North China ◽  
Atlantic Multidecadal Oscillation ◽  
Precipitation Variability ◽  
Circulation Anomaly ◽  
Potential Predictability ◽  
Southwest United States ◽  
Rainfall Anomalies

Abstract This paper reports a consistent seesaw relationship between interdecadal precipitation variability over North China and the Southwest United States, which can be found in observations and simulations with several models. Idealized model simulations suggest the seesaw could be mainly driven by the interdecadal Pacific oscillation (IPO), through a large-scale circulation anomaly occupying the entire northern North Pacific, while the Atlantic multidecadal oscillation (AMO) contributes oppositely and less. Modulation of precipitation by the IPO tends to be intensified when the AMO is in the opposite phase, but weakened when the AMO is in the same phase. The warm IPO phase is associated with an anomalous cyclone over the northern North Pacific; consequently, anomalous southwesterly winds bring more moisture and rainfall to the Southwest United States, while northwesterly wind anomalies prevail over North China with negative rainfall anomalies. The east–west seesaw of rainfall anomalies reverses sign when the circulation anomaly becomes anticyclonic during the cold IPO phase. The IPO-related tropical SST anomalies affect the meridional temperature gradient over the North Pacific and adjacent regions and the mean meridional circulation. In the northern North Pacific, the atmospheric response to IPO forcing imposes an equivalent barotropic structure throughout the troposphere. An important implication from this study is the potential predictability of drought-related water stresses over these arid and semiarid regions, with the progress of our understanding and prediction of the IPO and AMO.

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