scholarly journals Global Model selection for evaluation of Climate Change projections in the Eastern Tropical Pacific Seascape

2017 ◽  
pp. 67-81
Author(s):  
Hugo G. Hidalgo ◽  
Eric J. Alfaro
Keyword(s):  
Climate Change ◽  
Model Selection ◽  
20Th Century ◽  
General Circulation ◽  
Tropical Pacific ◽  
Global Model ◽  
Model Ensemble ◽  
Eastern Tropical Pacific ◽  
Climate Change Projections ◽  
Selection For

Two methods for selecting a subset of simulations and/or general circulation models (GCMs) from a set of 30 available simulations are compared: 1) Selecting the models based on their performance on reproducing 20th century climate, and 2) random sampling. In the first case, it was found that the performance methodology is very sensitive to the type and number of metrics used to rank the models and therefore the results are not robust to these conditions. In general, including more models in a multi-model ensemble according to their rank (of skill in reproducing 20th century climate) results in an increase in the multi-model skill up to a certain point and then the inclusion of more models degrades the skill of the multi-model ensemble. In a similar fashion when the models are introduced in the ensemble at random, there is a point where the inclusion of more models does not change significantly the skill of the multi-model ensemble. For precipitation the subset of models that produces the maximum skill in reproducing 20th century climate also showed some skill in reproducing the climate change projections of the multi-model ensemble of all simulations. For temperature, more models/simulations are needed to be included in the ensemble (at the expense of a decrease in the skill of reproducing the climate of the 20th century for the selection based on their ranks). For precipitation and temperature the use of 7 simulations out of 30 resulted in the maximum skill for both approaches to introduce the models. Citation: Hidalgo, H. & E.J. Alfaro. 2012. Global Model selection for evaluation of climate change projections in the Eastern Tropical Pacific Seascape. Rev. Biol. Trop. 60 (Suppl. 3): 67-81. Epub 2012 Dec 01.

scholarly journals Comparison of regional characteristics of land precipitation climatology projected by an MRI-AGCM multi-cumulus scheme and multi-SST ensemble with CMIP5 multi-model ensemble projections

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Rui Ito ◽  
Tosiyuki Nakaegawa ◽  
Izuru Takayabu
Keyword(s):  
Climate Change ◽  
High Resolution ◽  
General Circulation ◽  
Annual Precipitation ◽  
Cmip5 Models ◽  
Climate Projections ◽  
The Tibetan Plateau ◽  
Model Ensemble ◽  
Uncertainty Range ◽  
High Performing

AbstractEnsembles of climate change projections created by general circulation models (GCMs) with high resolution are increasingly needed to develop adaptation strategies for regional climate change. The Meteorological Research Institute atmospheric GCM version 3.2 (MRI-AGCM3.2), which is listed in the Coupled Model Intercomparison Project phase 5 (CMIP5), has been typically run with resolutions of 60 km and 20 km. Ensembles of MRI-AGCM3.2 consist of members with multiple cumulus convection schemes and different patterns of future sea surface temperature, and are utilized together with their downscaled data; however, the limited size of the high-resolution ensemble may lead to undesirable biases and uncertainty in future climate projections that will limit its appropriateness and effectiveness for studies on climate change and impact assessments. In this study, to develop a comprehensive understanding of the regional precipitation simulated with MRI-AGCM3.2, we investigate how well MRI-AGCM3.2 simulates the present-day regional precipitation around the globe and compare the uncertainty in future precipitation changes and the change projection itself between MRI-AGCM3.2 and the CMIP5 multiple atmosphere–ocean coupled GCM (AOGCM) ensemble. MRI-AGCM3.2 reduces the bias of the regional mean precipitation obtained with the high-performing CMIP5 models, with a reduction of approximately 20% in the bias over the Tibetan Plateau through East Asia and Australia. When 26 global land regions are considered, MRI-AGCM3.2 simulates the spatial pattern and the regional mean realistically in more regions than the individual CMIP5 models. As for the future projections, in 20 of the 26 regions, the sign of annual precipitation change is identical between the 50th percentiles of the MRI-AGCM3.2 ensemble and the CMIP5 multi-model ensemble. In the other six regions around the tropical South Pacific, the differences in modeling with and without atmosphere–ocean coupling may affect the projections. The uncertainty in future changes in annual precipitation from MRI-AGCM3.2 partially overlaps the maximum–minimum uncertainty range from the full ensemble of the CMIP5 models in all regions. Moreover, on average over individual regions, the projections from MRI-AGCM3.2 spread over roughly 0.8 of the uncertainty range from the high-performing CMIP5 models compared to 0.4 of the range of the full ensemble.

scholarly journals Multi-scenario and multi-model ensemble of regional climate change projections for the plain areas of the Pannonian Basin

Időjárás ◽  
2020 ◽  
Vol 124 (2) ◽  
pp. 157-190
Author(s):  
Anna Kis ◽  
Rita Pongrácz ◽  
Judit Bartholy ◽  
Milan Gocic ◽  
Mladen Milanovic ◽  
...  
Keyword(s):  
Climate Change ◽  
Pannonian Basin ◽  
Regional Climate ◽  
Regional Climate Change ◽  
Model Ensemble ◽  
Climate Change Projections

Future Climate Change Projections of the Kabul River Basin Using a Multi-model Ensemble of High-Resolution Statistically Downscaled Data

2018 ◽  
Vol 2 (3) ◽  
pp. 477-497 ◽  
Author(s):  
Syed Ahsan Ali Bokhari ◽  
Burhan Ahmad ◽  
Jahangir Ali ◽  
Shakeel Ahmad ◽  
Haris Mushtaq ◽  
...  
Keyword(s):  
Climate Change ◽  
High Resolution ◽  
River Basin ◽  
Future Climate ◽  
Future Climate Change ◽  
Model Ensemble ◽  
Climate Change Projections ◽  
Kabul River

scholarly journals CAPE Variations in the Current Climate and in a Climate Change

1998 ◽  
Vol 11 (8) ◽  
pp. 1997-2015 ◽  
Author(s):  
Bing Ye ◽  
Anthony D. Del Genio ◽  
Kenneth K-W. Lo
Keyword(s):  
Climate Change ◽  
Relative Humidity ◽  
General Circulation ◽  
Large Scale ◽  
Tropical Pacific ◽  
Lapse Rate ◽  
Moist Convection ◽  
Upper Troposphere ◽  
Current Climate ◽  
The Tropical Pacific

Abstract Observed variations of convective available potential energy (CAPE) in the current climate provide one useful test of the performance of cumulus parameterizations used in general circulation models (GCMs). It is found that frequency distributions of tropical Pacific CAPE, as well as the dependence of CAPE on surface wet-bulb potential temperature (Θw) simulated by the Goddard Institute for Space Studies’s GCM, agree well with that observed during the Australian Monsoon Experiment period. CAPE variability in the current climate greatly overestimates climatic changes in basinwide CAPE in the tropical Pacific in response to a 2°C increase in sea surface temperature (SST) in the GCM because of the different physics involved. In the current climate, CAPE variations in space and time are dominated by regional changes in boundary layer temperature and moisture, which in turn are controlled by SST patterns and large-scale motions. Geographical thermodynamic structure variations in the middle and upper troposphere are smaller because of the canceling effects of adiabatic cooling and subsidence warming in the rising and sinking branches of the Walker and Hadley circulations. In a forced equilibrium global climate change, temperature change is fairly well constrained by the change in the moist adiabatic lapse rate and thus the upper troposphere warms to a greater extent than the surface. For this reason, climate change in CAPE is better predicted by assuming that relative humidity remains constant and that the temperature changes according to the moist adiabatic lapse rate change of a parcel with 80% relative humidity lifted from the surface. The moist adiabatic assumption is not symmetrically applicable to a warmer and colder climate: In a warmer regime moist convection determines the tropical temperature structure, but when the climate becomes colder the effect of moist convection diminishes and the large-scale dynamics and radiative processes become relatively important. Although a prediction based on the change in moist adiabat matches the GCM simulation of climate change averaged over the tropical Pacific basin, it does not match the simulation regionally because small changes in the general circulation change the local boundary layer relative humidity by 1%–2%. Thus, the prediction of regional climate change in CAPE is also dependent on subtle changes in the dynamics.

Assessment of CMIP5 global model simulations and climate change projections for the 21 st century using a modified Thornthwaite climate classification

2013 ◽  
Vol 122 (4) ◽  
pp. 523-538 ◽  
Author(s):  
N. Elguindi ◽  
A. Grundstein ◽  
S. Bernardes ◽  
U. Turuncoglu ◽  
J. Feddema
Keyword(s):  
Climate Change ◽  
Global Model ◽  
Climate Classification ◽  
Climate Change Projections ◽  
Model Simulations

scholarly journals Tropical Climate Change Is a Puzzle—Could Aerosols Be a Piece?

Eos ◽  
2021 ◽  
Vol 102 ◽  
Author(s):  
Andrew Chapman
Keyword(s):  
Climate Change ◽  
Pacific Ocean ◽  
Tropical Climate ◽  
Tropical Pacific ◽  
Tropical Pacific Ocean ◽  
Eastern Tropical Pacific ◽  
Change Models ◽  
Tropical Climate Change

The eastern tropical Pacific Ocean hasn’t warmed as much as climate change models projected. A new study shows that aerosols in the atmosphere could be responsible.

scholarly journals Oxygen minimum zones in the tropical Pacific across CMIP5 models: mean state differences and climate change trends

2015 ◽  
Vol 12 (8) ◽  
pp. 6525-6587 ◽  
Author(s):  
A. Cabré ◽  
I. Marinov ◽  
R. Bernardello ◽  
D. Bianchi
Keyword(s):  
Climate Change ◽  
Tropical Pacific ◽  
Cmip5 Models ◽  
Upper Ocean ◽  
Intermediate Water ◽  
Climate Change Projections ◽  
Oxygen Minimum Zones ◽  
Mean State ◽  
Oxygen Minimum ◽  
The Tropical Pacific

Abstract. We analyze simulations of the Pacific Ocean oxygen minimum zones (OMZs) from 11 Earth System model contributions to the Coupled Model Intercomparison Project Phase 5, focusing on the mean state and climate change projections. The simulations tend to overestimate the volume of the OMZs, especially in the tropics and Southern Hemisphere. Compared to observations, five models introduce incorrect meridional asymmetries in the distribution of oxygen including larger southern OMZ and weaker northern OMZ, due to interhemispheric biases in intermediate water mass ventilation. Seven models show too deep an extent of the tropical hypoxia compared to observations, stemming from a deficient equatorial ventilation in the upper ocean combined with a too large biologically-driven downward flux of particulate organic carbon at depth, caused by too high particle export from the euphotic layer and too weak remineralization in the upper ocean. At interannual timescales, the dynamics of oxygen in the eastern tropical Pacific OMZ is dominated by biological consumption and linked to natural variability in the Walker circulation. However, under the climate change scenario RCP8.5, all simulations yield small and discrepant changes in oxygen concentration at mid depths in the tropical Pacific by the end of the 21st century due to an almost perfect compensation between warming-related decrease in oxygen saturation and decrease in biological oxygen utilization. Climate change projections are at odds with recent observations that show decreasing oxygen levels at mid depths in the tropical Pacific. Out of the OMZs, all the CMIP5 models predict a decrease of oxygen over most of the surface, deep and high latitudes ocean due to an overall slow-down of ventilation and increased temperature.

scholarly journals Hydrological response to climate change of the Brahmaputra basin using CMIP5 general circulation model ensemble

2017 ◽  
Vol 9 (3) ◽  
pp. 434-448 ◽  
Author(s):  
A. K. M. Saiful Islam ◽  
Supria Paul ◽  
Khaled Mohammed ◽  
Mutasim Billah ◽  
Md. Golam Rabbani Fahad ◽  
...  
Keyword(s):  
Climate Change ◽  
Fresh Water ◽  
General Circulation ◽  
Water Discharge ◽  
Model Parameters ◽  
Projection Data ◽  
Hydrological Response ◽  
Model Ensemble ◽  
Brahmaputra Basin ◽  
Monsoon Flow

Abstract The Ganges–Brahmaputra–Meghna river system carries the world's third-largest fresh water discharge and Brahmaputra alone carries about 67% of the total annual flow of Bangladesh. Climate change will be expected to alter the hydrological cycles and the flow regime of these basins. Assessment of the fresh water availability of the Brahmaputra Basin in the future under climate change condition is crucial for both society and the ecosystem. SWAT, a semi-distributed physically based hydrological model, has been applied to investigate hydrological response of the basin. However, it is a challenging task to calibrate and validate models over this ungauged and poor data basin. A model derived by using gridded rainfall data from the Tropical Rainfall Measuring Mission (TRMM) satellite and temperature data from reanalysis product ERA-Interim provides acceptable calibration and validation. Using the SWAT-CUP with SUFI-2 algorithm, sensitivity analysis of model parameters was examined. A calibrated model was derived using new climate change projection data from the multi-model ensemble CMIP5 Project over the South Asia CORDEX domain. The uncertainty of predicting monsoon flow is less than that of pre-monsoon flow. Most of the regional climate models (RCMs) show an increasing tendency of the discharge of Brahmaputra River at Bahadurabad station during monsoon, when flood usually occurs in Bangladesh.

scholarly journals Calibrating Climate Change Time-Slice Projections with Estimates of Seasonal Forecast Reliability

2016 ◽  
Vol 29 (10) ◽  
pp. 3831-3840 ◽  
Author(s):  
M. Matsueda ◽  
A. Weisheimer ◽  
T. N. Palmer
Keyword(s):  
Climate Change ◽  
General Circulation ◽  
Circulation Model ◽  
Seasonal Forecast ◽  
Time Slice ◽  
Climate Change Signal ◽  
Seasonal Forecasts ◽  
Low Resolution ◽  
Climate Change Projections ◽  
Resolution Model

Abstract In earlier work, it was proposed that the reliability of climate change projections, particularly of regional rainfall, could be improved if such projections were calibrated using quantitative measures of reliability obtained by running the same model in seasonal forecast mode. This proposal is tested for fast atmospheric processes (such as clouds and convection) by considering output from versions of the same atmospheric general circulation model run at two different resolutions and forced with prescribed sea surface temperatures and sea ice. Here output from the high-resolution version of the model is treated as a proxy for truth. The reason for using this approach is simply that the twenty-first-century climate change signal is not yet known and, hence, no climate change projections can be verified using observations. Quantitative assessments of reliability of the low-resolution model, run in seasonal hindcast mode, are used to calibrate climate change time-slice projections made with the same low-resolution model. Results show that the calibrated climate change probabilities are closer to the proxy truth than the uncalibrated probabilities. Given that seasonal forecasts are performed operationally already at several centers around the world, in a seamless forecast system they provide a resource that can be used without cost to help calibrate climate change projections and make them more reliable for users.

Sign in / Sign up

Export Citation Format

Share Document