The Global Climate for June–August 1988: A Swing to the Positive Phase of the Southern Oscillation, Drought in the United States, and Abundant Rain in Monsoon Areas

1988 ◽  
Vol 1 (11) ◽  
pp. 1153-1174 ◽  
Author(s):  
Chester F. Ropelewski
Keyword(s):  
United States ◽  
Southern Oscillation ◽  
Global Climate ◽  
The United States ◽  
Positive Phase

scholarly journals Is There an Optimal ENSO Pattern That Enhances Large-Scale Atmospheric Processes Conducive to Tornado Outbreaks in the United States?

2013 ◽  
Vol 26 (5) ◽  
pp. 1626-1642 ◽  
Author(s):  
Sang-Ki Lee ◽  
Robert Atlas ◽  
David Enfield ◽  
Chunzai Wang ◽  
Hailong Liu
Keyword(s):  
United States ◽  
Large Scale ◽  
Southern Oscillation ◽  
The United States ◽  
Tropical Pacific ◽  
Positive Phase ◽  
Eastern Tropical Pacific ◽  
Climate Signal ◽  
Upper Level ◽  
Tornado Outbreaks

Abstract The record-breaking U.S. tornado outbreaks in the spring of 2011 prompt the need to identify long-term climate signals that could potentially provide seasonal predictability for U.S. tornado outbreaks. This study uses both observations and model experiments to show that a positive phase TransNiño may be one such climate signal. Among the top 10 extreme outbreak years during 1950–2010, seven years including the top three are identified with a strongly positive phase TransNiño. The number of intense tornadoes in April–May is nearly doubled during the top 10 positive TransNiño years from that during 10 neutral years. TransNiño represents the evolution of tropical Pacific sea surface temperatures (SSTs) during the onset or decay phase of the El Niño–Southern Oscillation. A positive phase TransNiño is characterized by colder than normal SSTs in the central tropical Pacific and warmer than normal SSTs in the eastern tropical Pacific. Modeling experiments suggest that warmer than normal SSTs in the eastern tropical Pacific work constructively with colder than normal SSTs in the central tropical Pacific to force a strong and persistent teleconnection pattern that increases both the upper-level westerly and lower-level southwesterly over the central and eastern United States. These anomalous winds advect more cold and dry upper-level air from the high latitudes and more warm and moist lower-level air from the Gulf of Mexico converging into the east of the Rockies, and also increase both the lower-tropospheric (0–6 km) and lower-level (0–1 km) vertical wind shear values therein, thus providing large-scale atmospheric conditions conducive to intense tornado outbreaks over the United States.

scholarly journals A U.S. CLIVAR Project to Assess and Compare the Responses of Global Climate Models to Drought-Related SST Forcing Patterns: Overview and Results

2009 ◽  
Vol 22 (19) ◽  
pp. 5251-5272 ◽  
Author(s):  
Siegfried Schubert ◽  
David Gutzler ◽  
Hailan Wang ◽  
Aiguo Dai ◽  
Tom Delworth ◽  
...  
Keyword(s):  
United States ◽  
Southern Oscillation ◽  
Global Climate ◽  
Global Climate Model ◽  
The United States ◽  
Signal To Noise ◽  
The Pacific ◽  
Precipitation Response ◽  
Sst Forcing ◽  
The Impact

Abstract The U.S. Climate Variability and Predictability (CLIVAR) working group on drought recently initiated a series of global climate model simulations forced with idealized SST anomaly patterns, designed to address a number of uncertainties regarding the impact of SST forcing and the role of land–atmosphere feedbacks on regional drought. The runs were carried out with five different atmospheric general circulation models (AGCMs) and one coupled atmosphere–ocean model in which the model was continuously nudged to the imposed SST forcing. This paper provides an overview of the experiments and some initial results focusing on the responses to the leading patterns of annual mean SST variability consisting of a Pacific El Niño–Southern Oscillation (ENSO)-like pattern, a pattern that resembles the Atlantic multidecadal oscillation (AMO), and a global trend pattern. One of the key findings is that all of the AGCMs produce broadly similar (though different in detail) precipitation responses to the Pacific forcing pattern, with a cold Pacific leading to reduced precipitation and a warm Pacific leading to enhanced precipitation over most of the United States. While the response to the Atlantic pattern is less robust, there is general agreement among the models that the largest precipitation response over the United States tends to occur when the two oceans have anomalies of opposite signs. Further highlights of the response over the United States to the Pacific forcing include precipitation signal-to-noise ratios that peak in spring, and surface temperature signal-to-noise ratios that are both lower and show less agreement among the models than those found for the precipitation response. The response to the positive SST trend forcing pattern is an overall surface warming over the world’s land areas, with substantial regional variations that are in part reproduced in runs forced with a globally uniform SST trend forcing. The precipitation response to the trend forcing is weak in all of the models. It is hoped that these early results, as well as those reported in the other contributions to this special issue on drought, will serve to stimulate further analysis of these simulations, as well as suggest new research on the physical mechanisms contributing to hydroclimatic variability and change throughout the world.

scholarly journals A prognostic pollen emissions model for climate models (PECM1.0)

2017 ◽  
Author(s):  
Matthew C. Wozniak ◽  
Allison Steiner
Keyword(s):  
United States ◽  
Land Cover ◽  
Climate Models ◽  
Climate Model ◽  
Vegetation Type ◽  
Global Climate ◽  
The United States ◽  
Global Climate Models ◽  
Pollen Counts ◽  
Surface Pollen

Abstract. We develop a prognostic model of Pollen Emissions for Climate Models (PECM) for use within regional and global climate models to simulate pollen counts over the seasonal cycle based on geography, vegetation type and meteorological parameters. Using modern surface pollen count data, empirical relationships between prior-year annual average temperature and pollen season start dates and end dates are developed for deciduous broadleaf trees (Acer, Alnus, Betula, Fraxinus, Morus, Platanus, Populus, Quercus, Ulmus), evergreen needleleaf trees (Cupressaceae, Pinaceae), grasses (Poaceae; C3, C4), and ragweed (Ambrosia). This regression model explains as much as 57 % of the variance in pollen phenological dates, and it is used to create a climate-flexible phenology that can be used to study the response of wind-driven pollen emissions to climate change. The emissions model is evaluated in a regional climate model (RegCM4) over the continental United States by prescribing an emission potential from PECM and transporting pollen as aerosol tracers. We evaluate two different pollen emissions scenarios in the model: (1) using a taxa-specific land cover database, phenology and emission potential, and (2) a PFT-based land cover, phenology and emission potential. The resulting surface concentrations for both simulations are evaluated against observed surface pollen counts in five climatic subregions. Given prescribed pollen emissions, the RegCM4 simulates observed concentrations within an order of magnitude, although the performance of the simulations in any subregion is strongly related to the land cover representation and the number of observation sites used to create the empirical phenological relationship. The taxa-based model provides a better representation of the phenology of tree-based pollen counts than the PFT-based model, however we note that the PFT-based version provides a useful and climate-flexible emissions model for the general representation of the pollen phenology over the United States.

scholarly journals Assessing the influence of an extended hurricane season on inland flooding potential in the Southeast United States

2016 ◽  
Author(s):  
Monica H. Stone ◽  
Sagy Cohen
Keyword(s):  
United States ◽  
Tropical Cyclones ◽  
Climate Warming ◽  
Global Climate ◽  
River Basins ◽  
The United States ◽  
Southeast United States ◽  
Global Climate Warming ◽  
Hurricane Season ◽  
Near Future

Abstract. Recent tropical cyclones, like Hurricane Katrina, have been some of the worst the United States has experienced. Tropical cyclones are expected to intensify, bringing about 20 % more precipitation, in the near future in response to global climate warming. Further, global climate warming may extend the hurricane season. This study focuses on four major river basins (Neches, Pearl, Mobile, and Roanoke) in the Southeast United States that are frequently impacted by tropical cyclones. An analysis of the timing of tropical cyclones that impact these river basins found that most occur during the low discharge season, and thus rarely produce riverine flooding conditions. However, an extension of the current hurricane season of June–November, due to global climate warming, could encroach upon the high discharge seasons in these basins, increasing the susceptibility for riverine hurricane-induced flooding. This analysis shows that an extension of the hurricane season to May–December (just 2 months longer) increased the number of days that would be at risk to flooding were the average tropical cyclone to occur by 37–258 %, depending on the timing of the hurricane season in relation to the high discharge seasons on these rivers. Future research should aim to extend this analysis to all river basins in the United States that are impacted by tropical cyclones in order to provide a bigger picture of which areas are likely to experience the worst increases in flooding risk due to a probable extension of the hurricane season with expected global climate change in the near future.

Changes in Observed Daily Precipitation over the United States between 1950–79 and 1980–2009

2013 ◽  
Vol 14 (1) ◽  
pp. 105-121 ◽  
Author(s):  
R. W. Higgins ◽  
V. E. Kousky
Keyword(s):  
United States ◽  
Great Plains ◽  
El Niño ◽  
Daily Precipitation ◽  
El Nino ◽  
Southern Oscillation ◽  
Heavy Precipitation ◽  
The United States ◽  
Enso Cycle ◽  
Precipitation Events

Abstract Changes in observed daily precipitation over the conterminous United States between two 30-yr periods (1950–79 and 1980–2009) are examined using a 60-yr daily precipitation analysis obtained from the Climate Prediction Center (CPC) Unified Raingauge Database. Several simple measures are used to characterize the changes, including mean, frequency, intensity, and return period. Seasonality is accounted for by examining each measure for four nonoverlapping seasons. The possible role of the El Niño–Southern Oscillation (ENSO) cycle as an explanation for differences between the two periods is also examined. There have been more light (1 mm ≤ P < 10 mm), moderate (10 mm ≤ P < 25 mm), and heavy (P ≥ 25 mm) daily precipitation events (P) in many regions of the country during the more recent 30-yr period with some of the largest and most spatially coherent increases over the Great Plains and lower Mississippi Valley during autumn and winter. Some regions, such as portions of the Southeast and the Pacific Northwest, have seen decreases, especially during the winter. Increases in multiday heavy precipitation events have been observed in the more recent period, especially over portions of the Great Plains, Great Lakes, and Northeast. These changes are associated with changes in the mean and frequency of daily precipitation during the more recent 30-yr period. Difference patterns are strongly related to the ENSO cycle and are consistent with the stronger El Niño events during the more recent 30-yr period. Return periods for both heavy and light daily precipitation events during 1950–79 are shorter during 1980–2009 at most locations, with some notable regional exceptions.

Drivers of Twenty-First Century U.S. Winter Precipitation Trends in CMIP6 Models: A Storyline-Based Approach

2021 ◽  
pp. 1-48
Author(s):  
Daniel F. Schmidt ◽  
Kevin M. Grise
Keyword(s):  
Climate Models ◽  
Southern Oscillation ◽  
Global Climate ◽  
The United States ◽  
Winter Precipitation ◽  
Global Climate Models ◽  
First Century ◽  
Precipitation Trend ◽  
Twenty First Century ◽  
Precipitation Trends

AbstractClimate change during the twenty-first century has the potential to substantially alter geographic patterns of precipitation. However, regional precipitation changes can be very difficult to project, and in some regions, global climate models do not even agree on the sign of the precipitation trend. Since some of this uncertainty is due to internal variability rather than model bias, models cannot be used to narrow the possibilities to a single outcome, but they can usefully quantify the range of plausible outcomes and identify the combination of dynamical drivers that would be likely to produce each.This study uses a storylines approach—a type of regression-based analysis—to identify some of the key dynamical drivers that explain the variance in 21st century U.S. winter precipitation trends across CMIP6 models under the SSP3-7.0 emissions scenario. This analysis shows that the spread in precipitation trends is not primarily driven by differences in modeled climate sensitivity. Key drivers include global-mean surface temperature, but also tropical upper-troposphere temperature, the El Niño-Southern Oscillation (ENSO), the Pacific-North America (PNA) pattern, and the East Pacific (EP) dipole (a dipole pattern in geopotential heights over North America’s Pacific coast). Combinations of these drivers can reinforce or cancel to produce various high- or low-impact scenarios for winter precipitation trends in various regions of the United States. For example, the most extreme winter precipitation trends in the southwestern U.S. result from opposite trends in ENSO and EP, whereas the wettest winter precipitation trends in the midwestern U.S. result from a combination of strong global warming and a negative PNA trend.

The Contemporary US Energy System Overview Including A Comparison With China

2016 ◽  
Author(s):  
Michael B. McElroy
Keyword(s):  
Climate Change ◽  
United States ◽  
Global Climate ◽  
Energy System ◽  
The United States ◽  
Economic Benefits ◽  
Personal Consumption ◽  
Energy Economy ◽  
Near Term ◽  
Reduce Emissions

The discussion in chapter 2 addressed what might be described as a microview of the US energy economy— how we use energy as individuals, how we measure our personal consumption, and how we pay for it. We turn attention now to a more expansive perspective— the use of energy on a national scale, including a discussion of associated economic benefits and costs. We focus specifically on implications for emissions of the greenhouse gas CO2. If we are to take the issue of human- induced climate change seriously— and I do— we will be obliged to adjust our energy system markedly to reduce emissions of this gas, the most important agent for human- induced climate change. And we will need to do it sooner rather than later. This chapter will underscore the magnitude of the challenge we face if we are to successfully chart the course to a more sustainable climate- energy future. We turn later to strategies that might accelerate our progress toward this objective.We elected in this volume to focus on the present and potential future of the energy economy of the United States. It is important to recognize that the fate of the global climate system will depend not just on what happens in the United States but also to an increasing extent on what comes to pass in other large industrial economies. China surpassed the United States as the largest national emitter of CO2 in 2006. The United States and China together were responsible in 2012 for more than 42% of total global emissions. Add Russia, India, Japan, Germany, Canada, United Kingdom, South Korea, and Iran to the mix (the other members of the top 10 emitting countries ordered in terms of their relative contributions), and we can account for more than 60% of the global total. Given the importance of China to the global CO2 economy (more than 26% of the present global total and likely to increase significantly in the near term), I decided that it would be instructive to include here at least some discussion of the situation in China— to elaborate what the energy economies of China and the United States have in common, outlining at the same time the factors and challenges that set them apart.

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