Synoptic-Statistical Approach to Regional Downscaling of IPCC Twenty-First-Century Climate Projections: Seasonal Rainfall over the Hawaiian Islands*

2009 ◽  
Vol 22 (16) ◽  
pp. 4261-4280 ◽  
Author(s):  
Oliver Timm ◽  
Henry F. Diaz
Keyword(s):  
Climate Change ◽  
Statistical Downscaling ◽  
Hawaiian Islands ◽  
Dry Season ◽  
First Century ◽  
Climate Projections ◽  
Climate Change Scenarios ◽  
Wet Season ◽  
Near Surface ◽  
Twenty First Century

Abstract A linear statistical downscaling technique is applied to the projection of the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) climate change scenarios onto Hawaiian rainfall for the late twenty-first century. Hawaii’s regional rainfall is largely controlled by the strength of the trade winds. During the winter months, disturbances in the westerlies can produce heavy rainfall throughout the islands. A diagnostic analysis of sea level pressure (SLP), near-surface winds, and rainfall measurements at 134 weather observing stations around the islands characterize the correlations between the circulation and rainfall during the nominal wet season (November–April) and dry season (May–October). A comparison of the base climate twentieth-century AR4 model simulations with reanalysis data for the period 1970–2000 is used to define objective selection criterion for the AR4 models. Six out of 21 available models were chosen for the statistical downscaling. These were chosen on the basis of their ability to more realistically simulate the modern large-scale circulation fields in the Hawaiian Islands region. For the AR4 A1B emission scenario, the six analyzed models show important changes in the wind fields around Hawaii by the late twenty-first century. Two models clearly indicate opposite signs in the anomalies. One model projects 20%–30% rainfall increase over the islands; the other model suggests a rainfall decrease of about 10%–20% during the wet season. It is concluded from the six-model ensemble that the most likely scenario for Hawaii is a 5%–10% reduction of the wet-season precipitation and a 5% increase during the dry season, as a result of changes in the wind field. The authors discuss the sources of uncertainties in the projected rainfall changes and consider future improvements of the statistical downscaling work and implications for dynamical downscaling methods.

Characterizing Climate-Change Impacts on the 1.5-yr Flood Flow in Selected Basins across the United States: A Probabilistic Approach

2011 ◽  
Vol 15 (18) ◽  
pp. 1-16 ◽  
Author(s):  
John F. Walker ◽  
Lauren E. Hay ◽  
Steven L. Markstrom ◽  
Michael D. Dettinger
Keyword(s):  
Climate Change ◽  
United States ◽  
Probabilistic Approach ◽  
The United States ◽  
Empirical Orthogonal Functions ◽  
First Century ◽  
Climate Projections ◽  
Climate Change Scenarios ◽  
Twenty First Century ◽  
Temporal Shifts

Abstract The U.S. Geological Survey Precipitation-Runoff Modeling System (PRMS) model was applied to basins in 14 different hydroclimatic regions to determine the sensitivity and variability of the freshwater resources of the United States in the face of current climate-change projections. Rather than attempting to choose a most likely scenario from the results of the Intergovernmental Panel on Climate Change, an ensemble of climate simulations from five models under three emissions scenarios each was used to drive the basin models. Climate-change scenarios were generated for PRMS by modifying historical precipitation and temperature inputs; mean monthly climate change was derived by calculating changes in mean climates from current to various future decades in the ensemble of climate projections. Empirical orthogonal functions (EOFs) were fitted to the PRMS model output driven by the ensemble of climate projections and provided a basis for randomly (but representatively) generating realizations of hydrologic response to future climates. For each realization, the 1.5-yr flood was calculated to represent a flow important for sediment transport and channel geomorphology. The empirical probability density function (pdf) of the 1.5-yr flood was estimated using the results across the realizations for each basin. Of the 14 basins studied, 9 showed clear temporal shifts in the pdfs of the 1.5-yr flood projected into the twenty-first century. In the western United States, where the annual peak discharges are heavily influenced by snowmelt, three basins show at least a 10% increase in the 1.5-yr flood in the twenty-first century; the remaining two basins demonstrate increases in the 1.5-yr flood, but the temporal shifts in the pdfs and the percent changes are not as distinct. Four basins in the eastern Rockies/central United States show at least a 10% decrease in the 1.5-yr flood; the remaining two basins demonstrate decreases in the 1.5-yr flood, but the temporal shifts in the pdfs and the percent changes are not as distinct. Two basins in the eastern United States show at least a 10% decrease in the 1.5-yr flood; the remaining basin shows little or no change in the 1.5-yr flood.

scholarly journals Changes in the Risk of Cool-Season Tornadoes over Southern Australia due to Model Projections of Anthropogenic Warming

2010 ◽  
Vol 23 (9) ◽  
pp. 2440-2449 ◽  
Author(s):  
B. Timbal ◽  
R. Kounkou ◽  
G. A. Mills
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Weather Prediction ◽  
First Century ◽  
Climate Projections ◽  
Cool Season ◽  
Near Surface ◽  
Impact Of Climate Change ◽  
Twenty First Century ◽  
The Impact

Abstract Anthropogenic climate change is likely to be felt most acutely through changes in the frequency of extreme meteorological events. However, quantifying the impact of climate change on these events is a challenge because the core of the climate change science relies on general circulation models to detail future climate projections, and many of these extreme events occur on small scales that are not resolved by climate models. This note describes an attempt to infer the impact of climate change on one particular type of extreme meteorological event—the cool-season tornadoes of southern Australia. The Australian Bureau of Meteorology predicts threat areas for cool-season tornadoes using fine-resolution numerical weather prediction model output to define areas where the buoyancy of a near-surface air parcel and the vertical wind shear each exceed specified thresholds. The diagnostic has been successfully adapted to coarser-resolution climate models and applied to simulations of the current climate, as well as future projections of the climate over southern Australia. Simulations of the late twentieth century are used to validate the models’ ability to reproduce the climatology of the risk of cool-season tornado formation by comparing these with similar computations based on historical reanalyses. Model biases are overcome by setting model specific thresholds to define the cool-season tornado risk. The diagnostic, applied to simulations of the twenty-first century, is then used to quantify the impact of the projected climate change on cool-season tornado risk. The sign of the response is consistent across all models: a decrease of the risk of formation during the twenty-first century is projected, driven by the thermodynamical response. The thermal response is modulated by the dynamical response, which varies between models. The projected decrease in tornadoes risk during the cool season is consistent with the projection of positive southern annular mode trends and the known influence of this mode of variability on interannual to intraseasonal time-scale variations in cool-season tornado occurrence.

CLIMATE CHANGE SCENARIOS FOR THE U.S. NATIONAL ASSESSMENT

2003 ◽  
Vol 84 (12) ◽  
pp. 1711-1724 ◽  
Author(s):  
Michael C. MacCracken ◽  
Eric J. Barron ◽  
David R. Easterling ◽  
Benjamin S. Felzer ◽  
Thomas R. Karl
Keyword(s):  
Climate Change ◽  
Twentieth Century ◽  
Climate Models ◽  
Climatic Conditions ◽  
First Century ◽  
Climate Change Scenarios ◽  
Climate Scenarios ◽  
National Assessment ◽  
Twenty First Century ◽  
The U.S

In support of the U.S. National Assessment of the Potential Consequences of Climate Variability and Change, climate scenarios were prepared to serve as the basis for evaluating the vulnerability of environmental and societal systems to changes projected for the twenty-first century. Since publication of the results of the assessment at the end of 2000, the National Research Council's report Climate Change Science: An Analysis of Some Key Questions, and the U.S. government's U.S. Climate Action Report—2002 have both relied on the assessment's findings. Because of the importance of these findings, it is important to directly address questions regarding the representativeness and usefulness of the model-based projections on which the findings were based. In particular, criticisms have focused on whether the climate models that were relied upon adequately represented twentieth-century conditions and whether their projections of conditions for the twenty-first century were outliers. Reexamination of the approach used in developing and evaluating the climate scenarios indicates that the results from the two primary climate modeling groups that were relied upon allowed the generation of climate scenarios that span much of the range of possible future climatic conditions projected by the larger set of model simulations, which was compiled for the IPCCs Third Assessment Report. With the set of models showing increasing agreement in their simulations of twentieth-century trends in climate and of projected changes in climate on subcontinental to continental scales, the climate scenarios that were generated seem likely to provide a plausible representation of the types of climatic conditions that could be experienced during the twenty-first century. Warming, reduced snow cover, and more intense heavy precipitation events were projected by all models, suggesting such changes are quite likely. However, significant differences remain in the projection of changes in precipitation and of the regional departures in climate from the larger-scale patterns. For this reason, evaluating potential impacts using climate scenarios based on models exhibiting different regional responses is a necessary step to ensuring a representative analysis. Utilizing an even more encompassing set of scenarios in the future could help move from mainly qualitative toward more certain and quantitative conclusions.

scholarly journals Projection of Global Wave Climate Change toward the End of the Twenty-First Century

2012 ◽  
Vol 26 (21) ◽  
pp. 8269-8288 ◽  
Author(s):  
Alvaro Semedo ◽  
Ralf Weisse ◽  
Arno Behrens ◽  
Andreas Sterl ◽  
Lennart Bengtsson ◽  
...  
Keyword(s):  
Climate Change ◽  
Climate Model ◽  
Global Climate Model ◽  
Wave Climate ◽  
Ocean Model ◽  
First Century ◽  
Climate Projections ◽  
Moderate Increase ◽  
Intergovernmental Panel ◽  
Twenty First Century

Abstract Wind-generated waves at the sea surface are of outstanding importance for both their practical relevance in many aspects, such as coastal erosion, protection, or safety of navigation, and for their scientific relevance in modifying fluxes at the air–sea interface. So far, long-term changes in ocean wave climate have been studied mostly from a regional perspective with global dynamical studies emerging only recently. Here a global wave climate study is presented, in which a global wave model [Wave Ocean Model (WAM)] is driven by atmospheric forcing from a global climate model (ECHAM5) for present-day and potential future climate conditions represented by the Intergovernmental Panel for Climate Change (IPCC) A1B emission scenario. It is found that changes in mean and extreme wave climate toward the end of the twenty-first century are small to moderate, with the largest signals being a poleward shift in the annual mean and extreme significant wave heights in the midlatitudes of both hemispheres, more pronounced in the Southern Hemisphere and most likely associated with a corresponding shift in midlatitude storm tracks. These changes are broadly consistent with results from the few studies available so far. The projected changes in the mean wave periods, associated with the changes in the wave climate in the middle to high latitudes, are also shown, revealing a moderate increase in the equatorial eastern side of the ocean basins. This study presents a step forward toward a larger ensemble of global wave climate projections required to better assess robustness and uncertainty of potential future wave climate change.

scholarly journals Urban Areas and Urban–Rural Contrasts under Climate Change: What Does the EURO-CORDEX Ensemble Tell Us?—Investigating near Surface Humidity in Berlin and Its Surroundings

Atmosphere ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 730 ◽  
Author(s):  
Gaby S. Langendijk ◽  
Diana Rechid ◽  
Daniela Jacob
Keyword(s):  
Climate Change ◽  
Relative Humidity ◽  
Urban Areas ◽  
Regional Climate ◽  
First Century ◽  
Wilcoxon Test ◽  
Climate Change Signal ◽  
Model Ensemble ◽  
Near Surface ◽  
Twenty First Century

Climate change will impact urban areas. Decision makers need useful climate information to adapt adequately. This research aims to improve understanding of changes in moisture and temperature projected under climate change in Berlin compared to its surroundings. Simulations for the Representative Concentration Pathway (RCP) 8.5 scenario from the European Coordinated Regional Climate Downscaling Experiment (EURO-CORDEX) 0.11° are analyzed, showing a difference in moisture and temperature variables between Berlin and its surroundings. The running mean over 30 years shows a divergence throughout the twenty-first century for relative humidity between Berlin and its surroundings. Under this scenario, Berlin gets drier over time. The Mann-Kendall test quantifies a robust decreasing trend in relative humidity for the multi-model ensemble throughout the twenty-first century. The Mann-Whitney-Wilcoxon test for relative humidity indicates a robust climate change signal in Berlin. It is drier and warmer in Berlin compared to its surroundings for all months with the largest difference existing in summer. Additionally, the change in humidity for the period 2070–2099 compared to 1971–2000 is larger in the summer months. This study presents results to better understand near surface moisture change and related variables under long-term climate change in urban areas compared to their rural surroundings using a regional climate multi-model ensemble.

scholarly journals Downscaled Climate Change Scenarios for Baja California and the North American Monsoon during the Twenty-First Century

2012 ◽  
Vol 25 (17) ◽  
pp. 5904-5915 ◽  
Author(s):  
Tereza Cavazos ◽  
Sarahí Arriaga-Ramírez
Keyword(s):  
Climate Change ◽  
North American ◽  
General Circulation ◽  
Baja California ◽  
General Circulation Models ◽  
First Century ◽  
North American Monsoon ◽  
Climate Change Scenarios ◽  
The North ◽  
Twenty First Century

Abstract Regional climate change scenarios for Baja California/Southern California (BCC) and the North American monsoon (NAM) were produced as part of the Baja California State Climate Change Action Program (PEACC-BC). Bias-corrected and spatially downscaled scenarios (BCSD) from six general circulation models (GCMs) with a total of 12 realizations were analyzed for two scenarios of the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES): B1 (low emissions) and A2 (high emissions) during the twenty-first century. A validation of the original GCM realizations and the BCSD scenarios with observed data during 1961–90 show that the ensemble GCM produces too much precipitation during autumn and winter, which could be the cause of the observed delay of the summer monsoon rains; the ensemble BCSD considerably improves the mean annual cycles and spatial distributions of precipitation and temperature in the region. However, both ensembles greatly underestimate the observed interannual variability of precipitation. BCSD scenarios of temperature and precipitation during the twenty-first century were evaluated on the basis of the multimodel median change relative to 1961–90. The scenarios of precipitation change show large interannual variations and larger uncertainties than the scenarios of temperature change. The A2 scenarios show the largest reductions of precipitation in the last 20 yr of the twenty-first century; a decrease of 30% is projected for BCC mainly in winter and spring, while precipitation in the NAM region could be weakened by 20% during winter, spring, and summer. After 2050, a significant reduction of precipitation is expected in northwestern Mexico and the southwestern United States south of 35°N, and temperature changes larger than 2°C warming.

scholarly journals Analysis of Streamflow Response to Changing Climate Conditions Using SWAT Model

2020 ◽  
Vol 6 (2) ◽  
pp. 194-209 ◽  
Author(s):  
Han Thi Oo ◽  
Win Win Zin ◽  
Cho Cho Thin Kyi
Keyword(s):  
Climate Change ◽  
Rainfall Intensity ◽  
Swat Model ◽  
Winter Season ◽  
Climate Impact ◽  
Dry Season ◽  
Low Flow ◽  
Climate Change Scenarios ◽  
Wet Season ◽  
The Impact

The understanding of climate change is curial for the security of hydrologic conditions of river basins and it is very important to study the climate change impacts on streamflow by analyzing the different climate scenarios with the help of the hydrological models. The main purpose of this study is to project the future climate impact on streamflow by using the SWAT model. The multi-model projections indicated that Upper Ayeyarwady River Basin is likely to become hotter in dry season under low rainfall intensity with increasing temperature and likely to become wetter but warmer in both rainy and winter season because of high rainfall intensity with increased temperature in future. The impact of climate change scenarios is predicted to decrease the annual streamflow by about 0.30 to 1.92% under RCP2.6, 5.59 to 7.29% under RCP4.5 and 10.43 to 11.92% under RCP8.5. Based on the change in high and low flow percentage with respect to the baseline period, the difference between high and low flow variation range will increase year by year based on future scenarios. Therefore, it can be concluded that it may occur more low flow in the dry season which leads to increase in water scarcity and drought and more high flow in the wet season which can cause flooding, water insecurity, stress, and other water-related disasters.

Sign in / Sign up

Export Citation Format

Share Document