scholarly journals Modelling the impacts of climate change on tropospheric ozone over three centuries

2011 ◽  
Vol 11 (2) ◽  
pp. 6805-6843 ◽  
Author(s):  
G. B. Hedegaard ◽  
A. Gross ◽  
J. H. Christensen ◽  
W. May ◽  
H. Skov ◽  
...  
Keyword(s):  
Climate Change ◽  
Ozone Concentration ◽  
General Circulation ◽  
Climate Model ◽  
Transport Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
The Arctic

Abstract. The ozone chemistry over three centuries has been simulated based on climate prediction from a global climate model and constant anthropogenic emissions in order to separate out the effects on air pollution from climate change. Four decades in different centuries has been simulated using the chemistry version of the atmospheric long-range transport model; the Danish Eulerian Hemispheric Model (DEHM) forced with meteorology predicted by the ECHAM5/MPI-OM coupled Atmosphere-Ocean General Circulation Model. The largest changes in both meteorology, ozone and its precursors is found in the 21st century, however, also significant changes are found in the 22nd century. At surface level the ozone concentration is predicted to increase due to climate change in the areas where substantial amounts of ozone precursors are emitted. Elsewhere a significant decrease is predicted at the surface. In the free troposphere a general increase is found in the entire Northern Hemisphere except in the tropics, where the ozone concentration is decreasing. In the Arctic the ozone concentration will increase in the entire air column, which most likely is due to changes in transport. The change in temperature, humidity and the naturally emitted Volatile Organic Compounds (VOCs) are governing with respect to changes in ozone both in the past, present and future century.

scholarly journals Mid-Pliocene global climate simulation with MRI-CGCM2.3: set-up and initial results of PlioMIP Experiments 1 and 2

2012 ◽  
Vol 5 (3) ◽  
pp. 793-808 ◽  
Author(s):  
Y. Kamae ◽  
H. Ueda
Keyword(s):  
General Circulation ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Climate Simulation ◽  
Polar Regions ◽  
The North ◽  
Set Up

Abstract. The mid-Pliocene (3.3 to 3.0 million yr ago), a globally warm period before the Quaternary, is recently attracting attention as a new target for paleoclimate modelling and data-model synthesis. This paper reports set-ups and results of experiments proposed in Pliocene Model Intercomparison Project (PlioMIP) using a global climate model, MRI-CGCM2.3. We conducted pre-industrial and mid-Pliocene runs by using the coupled atmosphere-ocean general circulation model (AOGCM) and its atmospheric component (AGCM) for the PlioMIP Experiments 2 and 1, respectively. In addition, we conducted two types of integrations in AOGCM simulation, with and without flux adjustments on sea surface. General characteristics of differences in the simulated mid-Pliocene climate relative to the pre-industrial in the three integrations are compared. In addition, patterns of predicted mid-Pliocene biomes resulting from the three climate simulations are compared in this study. Generally, difference of simulated surface climate between AGCM and AOGCM is larger than that between the two AOGCM runs, with and without flux adjustments. The simulated climate shows different pattern between AGCM and AOGCM particularly over low latitude oceans, subtropical land regions and high latitude oceans. The AOGCM simulations do not reproduce wetter environment in the subtropics relative to the present-day, which is suggested by terrestrial proxy data. The differences between the two types of AOGCM runs are small over the land, but evident over the ocean particularly in the North Atlantic and polar regions.

scholarly journals Mid-Pliocene global climate simulation with MRI-CGCM2.3: set-up and initial results of PlioMIP Experiments 1 and 2

2012 ◽  
Vol 5 (1) ◽  
pp. 383-423 ◽  
Author(s):  
Y. Kamae ◽  
H. Ueda
Keyword(s):  
General Circulation ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Climate Simulation ◽  
Polar Regions ◽  
The North ◽  
Set Up

Abstract. The mid-Pliocene (3.3 to 3.0 million yr ago), a globally warm period before the Quaternary, is recently attracting attention as a new target for paleoclimate modelling and data-model synthesis. This paper reports set-ups and results of experiments proposed in Pliocene Model Intercomparison Project (PlioMIP) using with a global climate model, MRI-CGCM2.3. We conducted pre-industrial and mid-Pliocene runs by using of the coupled atmosphere-ocean general circulation model (AOGCM) and its atmospheric component (AGCM) for the PlioMIP Experiments 2 and 1, respectively. In addition, we conducted two types of integrations in AOGCM simulation, with and without flux adjustments on sea surface. General characteristics of differences in the simulated mid-Pliocene climate relative to the pre-industrial in the three integrations are compared in this study. Generally, difference of simulated surface climate between AGCM and AOGCM is larger than that between the two AOGCM runs, with and without flux adjustments. The simulated climate shows different pattern between AGCM and AOGCM particularly over low latitude oceans, subtropical land regions, and high latitude oceans. The AOGCM simulations do not reproduce wetter environment in the subtropics relative to the present-day, which is suggested by terrestrial proxy data. The differences between the two types of AOGCM runs are little over the land but evident over the ocean particularly in the North Atlantic and polar regions.

scholarly journals Composite Analysis of Winter Cyclones in a GCM: Influence on Climatological Humidity

2006 ◽  
Vol 19 (9) ◽  
pp. 1652-1672 ◽  
Author(s):  
Mike Bauer ◽  
Anthony D. Del Genio
Keyword(s):  
Water Vapor ◽  
General Circulation ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Cloud Properties ◽  
Frontal Zones ◽  
Goddard Institute ◽  
Ageostrophic Circulation

Abstract The role of midlatitude baroclinic cyclones in maintaining the extratropical winter distribution of water vapor in an operational global climate model is investigated. A cyclone identification and tracking algorithm is used to compare the frequency of occurrence, propagation characteristics, and composite structure of 10 winters of storms in the Goddard Institute for Space Studies general circulation model (GCM) and in two reanalysis products. Cyclones are the major dynamical source of water vapor over the extratropical oceans in the reanalyses. The GCM produces fewer, generally weaker, and slower-moving cyclones than the reanalyses and is especially deficient in storms associated with secondary cyclogenesis. Composite fields show that GCM cyclones are shallower and drier aloft than those in the reanalyses and that their vertical structure is less tilted in the frontal region because of the GCM’s weaker ageostrophic circulation. This is consistent with the GCM’s underprediction of midlatitude cirrus. The GCM deficiencies do not appear to be primarily due to parameterization errors; the model is too dry despite producing less storm precipitation than is present in the reanalyses and in an experimental satellite precipitation dataset, and the weakness and shallow structure of GCM cyclones is already present at storm onset. These shortcomings may be common to most climate GCMs that do not resolve the mesoscale structure of frontal zones, and this may account for some universal problems in climate GCM midlatitude cloud properties.

scholarly journals The Tropical Atmospheric El Niño Signal in Satellite Precipitation Data and a Global Climate Model

2007 ◽  
Vol 20 (14) ◽  
pp. 3580-3601 ◽  
Author(s):  
Yonghua Chen ◽  
Anthony D. Del Genio ◽  
Junye Chen
Keyword(s):  
El Niño ◽  
General Circulation ◽  
Climate Model ◽  
El Nino ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Western Indian Ocean ◽  
Correlation Technique ◽  
Atmospheric Response

Abstract Aspects of the tropical atmospheric response to El Niño related to the global energy and water cycle are examined using satellite retrievals from the Tropical Rainfall Measuring Mission and the Advanced Microwave Scanning Radiometer-E and simulations from the Goddard Institute for Space Studies (GISS) general circulation model (GCM). The El Niño signal is extracted from climate fields using a linear cross-correlation technique that captures local and remote in-phase and lagged responses. Passive microwave and radar precipitation anomalies for the 1997/98 and 2002/03 El Niños and the intervening La Niña are highly correlated, but anomalies in stratiform–convective rainfall partitioning in the two datasets are not. The GISS GCM produces too much rainfall in general over ocean and too little over land. Its atmospheric response to El Niño is weaker and decays a season too early. Underestimated stratiform rainfall fraction (SRF) and convective downdraft mass flux in the GISS GCM and excessive shallow convective and low stratiform cloud result in latent heating that peaks at lower altitudes than inferred from the data. The GISS GCM also underestimates the column water vapor content throughout the Tropics, which causes it to overestimate outgoing longwave radiation. The response of both quantities to interannual Hadley circulation anomalies is too weak. The GISS GCM’s Walker circulation also exhibits a weak remote response to El Niño, especially over the Maritime Continent and western Indian Ocean. This appears to be a consequence of weak static stability due to the model’s lack of upper-level stratiform anvil heating, excessive low-level heating, and excessive dissipation due to cumulus momentum mixing. Our results suggest that parameterizations of mesoscale updrafts, convective downdrafts, and cumulus-scale pressure gradient effects on momentum transport are keys to a reasonable GISS GCM simulation of tropical interannual variability.

scholarly journals Optimal Spectral Nudging for Global Dynamic Downscaling

2017 ◽  
Vol 145 (3) ◽  
pp. 909-927 ◽  
Author(s):  
Martina Schubert-Frisius ◽  
Frauke Feser ◽  
Hans von Storch ◽  
Sebastian Rast
Keyword(s):  
General Circulation ◽  
Climate Model ◽  
Global Climate ◽  
Spatial Scales ◽  
Global Climate Model ◽  
Circulation Model ◽  
Prognostic Variables ◽  
Reanalysis Dataset ◽  
Spectral Nudging ◽  
High Dependency

This study analyzes a method of constructing a homogeneous, high-resolution global atmospheric hindcast. The method is the spectral nudging technique, which was applied to a state-of-the-art general circulation model (ECHAM6, T255L95). Large spatial scales of the global climate model prognostic variables were spectrally nudged toward a reanalysis dataset (NCEP-1, T62L28) for the past few decades. The main idea is the addition of dynamically consistent regional weather details to the coarse-grid NCEP-1 reanalysis. A large number of sensitivity experiments was performed, using different nudging e-folding times, vertical profiles, wavenumbers, and variables. Comparisons with observations and several reanalyses showed a high dependency on the variations of the nudging configuration. At the global scale, the accordance is very high for extratropical regions and lower in the tropics. A wavenumber truncation of 30, a relatively short e-folding time of 50 min, and a plateau-shaped nudging profile applied only to divergence and vorticity generally yielded the best results. This is one of the first global spectral nudging hindcast studies and the first applying an altitude-dependent profile to selected prognostic variables. The method can be applied to reconstructing the history of extreme events such as intense storms within the context of ongoing climate change.

scholarly journals Technical Note: Description and assessment of a nudged version of the new dynamics Unified Model

2007 ◽  
Vol 7 (6) ◽  
pp. 17261-17297 ◽  
Author(s):  
P. J. Telford ◽  
P. Braesicke ◽  
O. Morgenstern ◽  
J. A. Pyle
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Reanalysis Data ◽  
Technical Note ◽  
Unified Model ◽  
Quantitative Assessments

Abstract. We present a "nudged" version of the Met Office general circulation model, the Unified Model. We constrain this global climate model using ERA-40 reanalysis data with the aim of reproducing the observed "weather" over a year from September 1999. Quantitative assessments are made of its performance, focussing on dynamical aspects of nudging and demonstrating that the "weather" is well simulated.

scholarly journals Technical Note: Description and assessment of a nudged version of the new dynamics Unified Model

2008 ◽  
Vol 8 (6) ◽  
pp. 1701-1712 ◽  
Author(s):  
P. J. Telford ◽  
P. Braesicke ◽  
O. Morgenstern ◽  
J. A. Pyle
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Analysis Data ◽  
Technical Note ◽  
Unified Model ◽  
Quantitative Assessments

Abstract. We present a "nudged" version of the Met Office general circulation model, the Unified Model. We constrain this global climate model using ERA-40 re-analysis data with the aim of reproducing the observed "weather" over a year from September 1999. Quantitative assessments are made of its performance, focusing on dynamical aspects of nudging and demonstrating that the "weather" is well simulated.

scholarly journals Climate Impact of Cloud Water Inhomogeneity through Microphysical Processes in a Global Climate Model

2020 ◽  
Vol 33 (12) ◽  
pp. 5195-5212 ◽  
Author(s):  
Haruka Hotta ◽  
Kentaroh Suzuki ◽  
Daisuke Goto ◽  
Matthew Lebsock
Keyword(s):  
Enhancement Factor ◽  
General Circulation ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Climate Impact ◽  
Cloud Water ◽  
Satellite Observations ◽  
Low Latitudes

AbstractThis study investigates how subgrid cloud water inhomogeneity within a grid spacing of a general circulation model (GCM) links to the global climate through precipitation processes. The effect of the cloud inhomogeneity on autoconversion rate is incorporated into the GCM as an enhancement factor using a prognostic cloud water probability density function (PDF), which is assumed to be a truncated skewed-triangle distribution based on the total water PDF originally implemented. The PDF assumption and the factor are evaluated against those obtained by global satellite observations and simulated by a global cloud-system-resolving model (GCRM). Results show that the factor implemented exerts latitudinal variations, with higher values at low latitudes, qualitatively consistent with satellite observations and the GCRM. The GCM thus validated for the subgrid cloud inhomogeneity is then used to investigate how the characteristics of the enhancement factor affect global climate through sensitivity experiments with and without the factor incorporated. The latitudinal variation of the factor is found to have a systematic impact that reduces the cloud water and the solar reflection at low latitudes in the manner that helps mitigate the too-reflective cloud bias common among GCMs over the tropical oceans. Due to the limitation of the factor arising from the PDF assumption, however, no significant impact is found in the warm rain formation process. Finally, it is shown that the functional form for the PDF in a GCM is crucial to properly characterize the observed cloud water inhomogeneity and its relationship with precipitation.

scholarly journals Climatology of Borneo Vortices in the HadGEM3-GC31 General Circulation Model

2021 ◽  
pp. 1-61
Author(s):  
Ju Liang ◽  
Jennifer L. Catto ◽  
Matthew Hawcroft ◽  
Kevin I. Hodges ◽  
Mouleong Tan ◽  
...  
Keyword(s):  
General Circulation ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Deep Convection ◽  
Circulation Model ◽  
Winter Precipitation ◽  
Reanalysis Data ◽  
Horizontal Resolution ◽  
Hadley Centre

AbstractBorneo Vortices (BVs) are intense precipitating winter storms that develop over the equatorial South China Sea and strongly affect the weather and climate over the western Maritime Continent due to their association with deep convection and heavy rainfall. In this study, the ability of the HadGEM3-GC31 (Hadley Centre Global Environment Model 3 - Global Coupled vn. 3.1) global climate model to simulate the climatology of BVs at different horizontal resolutions are examined using an objective feature tracking algorithm. The HadGEM3-GC31 at the N512 ( 25 km) horizontal resolution simulates BVs with well-represented characteristics, including their frequency, spatial distribution and their lower-tropospheric structures when compared with BVs identified in a climate reanalysis, whereas the BVs in the N96 (∼135 km) and N216 (∼65 km) simulations are much weaker and less frequent. Also, the N512 simulation better captures the contribution of BVs to the winter precipitation in Borneo and Malay Peninsula compared with precipitation from a reanalysis data and from observations, while the N96 and N216 simulations underestimate this contribution due to the overly weak low-level convergence of the simulated BVs. The N512 simulation also exhibits an improved ability to reproduce the modulation of BV activity by the occurrence of northeasterly cold surges and active phases of Madden-Julian Oscillation in the region, including increased BV track densities, intensities and lifetimes. A sufficiently high model resolution is thus found to be important to realistically simulate the present-climate precipitation extremes associated with BVs and to study their possible changes in a warmer climate.

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