scholarly journals Seasonal cycle of the Mindanao Dome in the CCSR/NIES/FRCGC atmosphere-ocean coupled model

2005 ◽  
Vol 32 (17) ◽  
Author(s):  
Tatsuo Suzuki ◽  
Takashi T. Sakamoto ◽  
Teruyuki Nishimura ◽  
Naosuke Okada ◽  
Seita Emori ◽  
...  
Keyword(s):  
Seasonal Cycle ◽  
Coupled Model ◽  
Mindanao Dome

scholarly journals Mechanisms for an Amplified Precipitation Seasonal Cycle in the U.S. West Coast under Global Warming

2019 ◽  
Vol 32 (15) ◽  
pp. 4681-4698 ◽  
Author(s):  
Lu Dong ◽  
L. Ruby Leung ◽  
Jian Lu ◽  
Fengfei Song
Keyword(s):  
West Coast ◽  
Seasonal Cycle ◽  
Hydrological Cycle ◽  
Coupled Model ◽  
Wet Season ◽  
Thermal Contrast ◽  
Budget Analysis ◽  
The Mean ◽  
Underlying Mechanisms ◽  
The U.S

Abstract The mean precipitation along the U.S. West Coast exhibits a pronounced seasonality change under warming. Here we explore the characteristics of the seasonality change and investigate the underlying mechanisms, with a focus on quantifying the roles of moisture (thermodynamic) versus circulation (dynamic). The multimodel simulations from phase 5 of the Coupled Model Intercomparison Project (CMIP5) show a simple “wet-get-wetter” response over Washington and Oregon but a sharpened seasonal cycle marked by a stronger and narrower wet season over California. Moisture budget analysis shows that changes in both regions are predominantly caused by changes in the mean moisture convergence. The thermodynamic effect due to the mass convergence of increased moisture dominates the wet-get-wetter response over Washington and Oregon. In contrast, mean zonal moisture advection due to seasonally dependent changes in land–sea moisture contrast originating from the nonlinear Clausius–Clapeyron relation dominates the sharpened wet season over California. More specifically, the stronger climatological land–sea thermal contrast in winter with warmer ocean than land results in more moisture increase over ocean than land under warming and hence wet advection to California. However, in fall and spring, the future change of land–sea thermal contrast with larger warming over land than ocean induces an opposite moisture gradient and hence dry advection to California. These results have important implications for projecting changes in the hydrological cycle of the U.S. West Coast.

Climate studies with a coupled atmosphere-upper-ocean-ice-sheet model

1989 ◽  
Vol 329 (1604) ◽  
pp. 249-261 ◽  
Keyword(s):  
Seasonal Cycle ◽  
Low Frequency ◽  
Coupled Model ◽  
Upper Ocean ◽  
Glacial Cycle ◽  
Last Interglacial ◽  
The North ◽  
Technical Report ◽  
Averaged Model

A two-dimensional zonally averaged model has been developed for simulating the seasonal cycle of the climate of the Northern Hemisphere. The atmospheric component of the model is based on the two-level quasi-geostrophic potential vorticity system of equations. At the surface, the model has land—sea resolution and incorporates detailed snow and sea-ice mass budgets. The upper ocean is represented by an integral mixed-layer model that takes into account the meridional advection and turbulent diffusion of heat. Comparisons between the computed present-day climate and climatological data show that the model does reasonably well in simulating the seasonal cycle of the temperature field. In response to a projected CO 2 trend based on the scenario of Wuebbles et al. (DOE/ NBB-0066 Technical Report 15 (1984)), the modelled annual hemispheric mean surface temperature increases by 2 °C between 1983 and 2063. In the high latitudes, the response undergoes significant seasonal variations. The largest surface warmings occur during autumn and spring. The model is then asynchronously coupled to a model that simulates the dynamics of the Greenland, the Eurasian and the North American ice sheets in order to investigate the transient response of the climate to the long-term insolation anomalies caused by orbital perturbations. Over the last interglacial-glacial cycle, the coupled model produces continental ice-volume changes that are in general agreement with the low-frequency part of palaeoclimatic records.

scholarly journals Drake Passage Oceanic pCO2: Evaluating CMIP5 Coupled Carbon–Climate Models Using in situ Observations

2014 ◽  
Vol 27 (1) ◽  
pp. 76-100 ◽  
Author(s):  
ChuanLi Jiang ◽  
Sarah T. Gille ◽  
Janet Sprintall ◽  
Colm Sweeney
Keyword(s):  
Seasonal Cycle ◽  
Climate Models ◽  
Dissolved Inorganic Carbon ◽  
Coupled Model ◽  
Co2 Flux ◽  
Drake Passage ◽  
Polar Front ◽  
Intercomparison Project ◽  
Opposing Effects ◽  
Mixed Layers

Abstract Surface water partial pressure of CO2 (pCO2) variations in Drake Passage are examined using decade-long underway shipboard measurements. North of the Polar Front (PF), the observed pCO2 shows a seasonal cycle that peaks annually in August and dissolved inorganic carbon (DIC)–forced variations are significant. Just south of the PF, pCO2 shows a small seasonal cycle that peaks annually in February, reflecting the opposing effects of changes in SST and DIC in the surface waters. At the PF, the wintertime pCO2 is nearly in equilibrium with the atmosphere, leading to a small sea-to-air CO2 flux. These observations are used to evaluate eight available Coupled Model Intercomparison Project, phase 5 (CMIP5), Earth system models (ESMs). Six ESMs reproduce the observed annual-mean pCO2 values averaged over the Drake Passage region. However, the model amplitude of the pCO2 seasonal cycle exceeds the observed amplitude of the pCO2 seasonal cycle because of the model biases in SST and surface DIC. North of the PF, deep winter mixed layers play a larger role in pCO2 variations in the models than they do in observations. Four ESMs show elevated wintertime pCO2 near the PF, causing a significant sea-to-air CO2 flux. Wintertime winds in these models are generally stronger than the satellite-derived winds. This not only magnifies the sea-to-air CO2 flux but also upwells DIC-rich water to the surface and drives strong equatorward Ekman currents. These strong model currents likely advect the upwelled DIC farther equatorward, as strong stratification in the models precludes subduction below the mixed layer.

scholarly journals Storm-Track Activity in IPCC AR4/CMIP3 Model Simulations

2013 ◽  
Vol 26 (1) ◽  
pp. 246-260 ◽  
Author(s):  
Edmund K. M. Chang ◽  
Yanjuan Guo ◽  
Xiaoming Xia ◽  
Minghua Zheng
Keyword(s):  
Seasonal Cycle ◽  
Storm Track ◽  
Coupled Model ◽  
Storm Tracks ◽  
Intergovernmental Panel ◽  
Cmip3 Model ◽  
Model Simulations ◽  
Storm Track Activity ◽  
Highly Correlated ◽  
Ipcc Ar4

Abstract The climatological storm-track activity simulated by 17 Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4)/phase 3 of the Coupled Model Intercomparison Project (CMIP3) models is compared to that in the interim ECMWF Re-Analysis (ERA-Interim). Nearly half of the models show significant biases in storm-track amplitude: four models simulate storm tracks that are either significantly (>20%) too strong or too weak in both hemispheres, while four other models have interhemispheric storm-track ratios that are biased by over 10%. Consistent with previous studies, storm-track amplitude is found to be negatively correlated with grid spacing. The interhemispheric ratio of storm-track activity is highly correlated with the interhemispheric ratio of mean available potential energy, and this ratio is biased in some model simulations due to biases in the midlatitude temperature gradients. In terms of geographical pattern, the storm tracks in most CMIP3 models exhibit an equatorward bias in both hemispheres. For the seasonal cycle, most models can capture the equatorward migration and strengthening of the storm tracks during the cool season, but some models exhibit biases in the amplitude of the seasonal cycle. Possible implications of model biases in storm-track climatology have been investigated. For both hemispheres, models with weak storm tracks tend to have larger percentage changes in storm-track amplitudes over the seasonal cycle. Under global warming, for the NH, models with weak storm tracks tend to project larger percentage changes in storm-track amplitude whereas, for the SH, models with large equatorward biases in storm-track latitude tend to project larger poleward shifts. Preliminary results suggest that CMIP5 model projections also share these behaviors.

scholarly journals Projected changes in the seasonal cycle of the Atlantic meridional heat transport in MPI-ESM

2016 ◽  
Author(s):  
Matthias Fischer ◽  
Daniela I. V. Domeisen ◽  
Wolfgang A. Müller ◽  
Johanna Baehr
Keyword(s):  
Heat Transport ◽  
North Atlantic ◽  
Seasonal Cycle ◽  
Coupled Model ◽  
Change Scenario ◽  
Max Planck ◽  
Meridional Heat Transport ◽  
The North ◽  
The North Atlantic ◽  
Projected Changes

Abstract. We investigate the effect of a projected reduction in the Atlantic Ocean meridional heat transport (OHT) on changes in its seasonal cycle. We analyze a climate projection experiment with the Max-Planck Institute Earth System Model (MPI-ESM) performed for the Coupled Model Intercomparison Project phase 5 (CMIP5). In the RCP8.5 climate change scenario, the OHT declines in MPI-ESM in the North Atlantic by 30–50 % by the end of the 23rd century. The decline in the OHT is accompanied by a change in the seasonal cycle of the total OHT and its components. We decompose the OHT into overturning and gyre component. For the total OHT seasonal cycle, we find a northward shift of 5 degrees and latitude dependent temporal shifts of 1 to 6 months that are mainly associated with changes in the meridional velocity field. We find that the shift in the OHT seasonal cycle predominantly results from changes in the wind-driven surface circulation which projects onto the overturning component of the OHT in the tropical and subtropical North Atlantic. This leads to latitude dependent shifts of 1 to 6 months in the overturning component. In the subpolar North Atlantic, we find that the reduction of the North Atlantic Deep Water formation in RCP8.5 and changes in the gyre heat transport result in a strongly weakened seasonal cycle with a weakened seasonal amplitude by the end of the 23rd century and thus changes the OHT seasonal cycle in the SPG.

The Seasonal Cycle of Atmospheric Heating and Temperature

2013 ◽  
Vol 26 (14) ◽  
pp. 4962-4980 ◽  
Author(s):  
Aaron Donohoe ◽  
David S. Battisti
Keyword(s):  
Seasonal Cycle ◽  
Atmospheric Carbon Dioxide ◽  
Climate Models ◽  
Energy Transport ◽  
Coupled Model ◽  
Atmospheric Temperature ◽  
Heat Fluxes ◽  
Energy Fluxes ◽  
Atmospheric Heating ◽  
Model Average

Abstract The seasonal cycle of the heating of the atmosphere is divided into a component due to direct solar absorption in the atmosphere and a component due to the flux of energy from the surface to the atmosphere via latent, sensible, and radiative heat fluxes. Both observations and coupled climate models are analyzed. The vast majority of the seasonal heating of the northern extratropics (78% in the observations and 67% in the model average) is due to atmospheric shortwave absorption. In the southern extratropics, the seasonal heating of the atmosphere is entirely due to atmospheric shortwave absorption in both the observations and the models, and the surface heat flux opposes the seasonal heating of the atmosphere. The seasonal cycle of atmospheric temperature is surface amplified in the northern extratropics and nearly barotropic in the Southern Hemisphere; in both cases, the vertical profile of temperature reflects the source of the seasonal heating. In the northern extratropics, the seasonal cycle of atmospheric heating over land differs markedly from that over the ocean. Over the land, the surface energy fluxes complement the driving absorbed shortwave flux; over the ocean, they oppose the absorbed shortwave flux. This gives rise to large seasonal differences in the temperature of the atmosphere over land and ocean. Downgradient temperature advection by the mean westerly winds damps the seasonal cycle of heating of the atmosphere over the land and amplifies it over the ocean. The seasonal cycle in the zonal energy transport is 4.1 PW. Finally, the authors examine the change in the seasonal cycle of atmospheric heating in 11 models from phase 3 of the Coupled Model Intercomparison Project (CMIP3) due to a doubling of atmospheric carbon dioxide from preindustrial concentrations. The seasonal heating of the troposphere is everywhere enhanced by increased shortwave absorption by water vapor; it is reduced where sea ice has been replaced by ocean, which increases the effective heat storage reservoir of the climate system and thereby reduces the seasonal magnitude of energy fluxes between the surface and the atmosphere. As a result, the seasonal amplitude of temperature increases in the upper troposphere (where atmospheric shortwave absorption increases) and decreases at the surface (where the ice melts).

scholarly journals Total cloud cover from satellite observations and climate models

2010 ◽  
Vol 10 (9) ◽  
pp. 21023-21046 ◽  
Author(s):  
P. Probst ◽  
R. Rizzi ◽  
E. Tosi ◽  
V. Lucarini ◽  
T. Maestri
Keyword(s):  
Seasonal Cycle ◽  
Cloud Cover ◽  
Climate Models ◽  
Climate Model ◽  
Coupled Model ◽  
Time Frame ◽  
Satellite Observations ◽  
Latitudinal Belt ◽  
Zonal Average ◽  
Model Diagnosis

Abstract. Global and zonal monthly means of cloud cover fraction for total cloudiness (CF) from the ISCCP D2 dataset are compared to same quantity produced by the 20th century simulations of 21 climate models from the World Climate Research Programme's (WCRP's) Coupled Model Intercomparison Project phase 3 (CMIP3) multi-model dataset archived by the Program for Climate Model Diagnosis and Intercomparison (PCMDI). The comparison spans the time frame from January 1984 to December 1999 and the global and zonal average of CF are studied. The restriction to total cloudiness depends on the output of some models that does not include the 3D cloud structure. It is shown that the global mean of CF for the PCMDI/CMIP3 models, averaged over the whole period, exhibits a considerable variance and generally underestimates the ISCCP value. Very large discrepancies among models, and between models and observations, are found in the polar areas, where both models and satellite observations are less reliable, and especially near Antarctica. For this reason the zonal analysis is focused over the 60° S–60° N latitudinal belt, which includes the tropical area and mid latitudes. The two hemispheres are analyzed separately to show the variation of the amplitude of the seasonal cycle. Most models overestimate the yearly averaged values of CF over all of the analysed areas, while differences emerge in their ability to capture the amplitude of the seasonal cycle. The models represent, in a qualitatively correct way, the magnitude and the weak sign of the seasonal cycle over the whole geographical domain, but overestimate the strength of the signal in the tropical areas and at mid-latitudes, when taken separately. The interannual variability of the two yearly averages and of the amplitude of the seasonal cycle is greatly underestimated by all models in each area analysed. This work shows that the climate models have an heterogeneous behaviour in simulating the CF over different areas of the Globe, with a very wide span both with observed CF and among themselves. Some models agree quite well with the observations in one or more of the metrics employed in this analysis, but not a single model has a statistically significant agreement with the observational datasets on yearly averaged values of CF and on the amplitude of the seasonal cycle over all analysed areas.

scholarly journals Evaluation of the CMIP6 marine subtropical stratocumulus cloud albedo and its controlling factors

2021 ◽  
Vol 21 (12) ◽  
pp. 9809-9828
Author(s):  
Bida Jian ◽  
Jiming Li ◽  
Guoyin Wang ◽  
Yuxin Zhao ◽  
Yarong Li ◽  
...  
Keyword(s):  
Seasonal Cycle ◽  
Climate Models ◽  
Coupled Model ◽  
Liquid Water Path ◽  
Marine Stratocumulus ◽  
Cloud Albedo ◽  
Regional Energy ◽  
Ensemble Mean ◽  
Cloud Liquid Water Path

Abstract. The cloud albedo in the marine subtropical stratocumulus regions plays a key role in regulating the regional energy budget. Based on 12 years of monthly data from multiple satellite datasets, the long-term, monthly and seasonal cycle of averaged cloud albedo in five stratocumulus regions were investigated to intercompare the atmosphere-only simulations between phases 5 and 6 of the Coupled Model Intercomparison Project (AMIP5 and AMIP6). Statistical results showed that the long-term regressed cloud albedos were underestimated in most AMIP6 models compared with the satellite-driven cloud albedos, and the AMIP6 models produced a similar spread as AMIP5 over all regions. The monthly averaged values and seasonal cycle of cloud albedo of AMIP6 ensemble mean showed a better correlation with the satellite-driven observations than that of the AMIP5 ensemble mean. However, the AMIP6 model still failed to reproduce the values and amplitude in some regions. By employing the Modern-Era Retrospective Analysis for Research and Applications Version 2 (MERRA-2) data, this study estimated the relative contributions of different aerosols and meteorological factors on the long-term variation of marine stratocumulus cloud albedo under different cloud liquid water path (LWP) conditions. The multiple regression models can explain ∼ 65 % of the changes in the cloud albedo. Under the monthly mean LWP ≤ 65 g m−2, dust and black carbon dominantly contributed to the changes in the cloud albedo, while dust and sulfur dioxide aerosol contributed the most under the condition of 65 g m−2 < LWP ≤ 120 g m−2. These results suggest that the parameterization of cloud–aerosol interactions is crucial for accurately simulating the cloud albedo in climate models.

scholarly journals Drivers of future seasonal cycle changes of oceanic pCO<sub>2</sub>

2018 ◽  
Author(s):  
M. Angeles Gallego ◽  
Axel Timmermann ◽  
Tobias Friedrich ◽  
Richard E. Zeebe
Keyword(s):  
Seasonal Cycle ◽  
Dissolved Inorganic Carbon ◽  
Coupled Model ◽  
Co2 Concentration ◽  
Ecosystem Model ◽  
Total Alkalinity ◽  
Seasonal Effect ◽  
Total Change ◽  
Cycle Amplitude ◽  
Ocean Carbon

Abstract. Recent observations show that the seasonal amplitude of surface ocean partial pressure of CO2 (pCO2) has been increasing on average at a rate of 2–3 μatm per year (Landschützer et al., 2018). Future increases of pCO2 seasonality are expected, as marine CO2 will increase in response to increasing anthropogenic carbon emissions (McNeil et al., 2016). Here we use 7 different global coupled atmosphere/ocean/carbon cycle/ecosystem model simulations, conducted as part of the Coupled Model Intercomparison Project Phase 5 (CMIP5), to study future projections of the pCO2 annual cycle amplitude and to elucidate the causes of its amplification. We find, that for the RCP8.5 emission scenario the seasonal amplitude (climatological maximum-minus-minimum) of upper ocean pCO2 will increase by a factor of 1.5 to 3 times over the next 60–80 years. To understand the drivers and mechanisms that control the pCO2 seasonal amplification we develop a complete analytical Taylor expansion of pCO2 seasonality in terms of its four drivers: dissolved inorganic carbon (DIC), total alkalinity (TA), temperature (T) and salinity (S). Using this linear approximation we show that the DIC and T terms are the dominant contributors to the total change in pCO2 seasonality. At first order, their future intensification can be traced back to a doubling of the annual mean pCO2, which enhances DIC and alters the ocean carbonate chemistry. Regional differences in the projected seasonal cycle amplitude are generated by spatially varying sensitivity terms. The subtropical and equatorial regions (40° S–40° N), will experience a ≈ 30–80 μatm increase in seasonal cycle amplitude almost exclusively due a larger CO2 concentration that amplifies the T seasonal effect on solubility. This mechanism is further reinforced by an overall increase in the seasonal cycle of T, as a result of stronger ocean stratification and a projected shoaling of mean mixed layer depths. The Southern Ocean will experience a seasonal cycle amplification of ≈ 90–120 μatm in response to the mean pCO2-driven change of the DIC contribution and to a lesser extent to the T contribution. However, a decrease of the DIC seasonal cycle amplitude somewhat counteracts this regional amplification mechanism.

Analysis of the Atmospheric Water Cycle for the Laurentian Great Lakes Region using CMIP6 models

2021 ◽  
pp. 1-47
Author(s):  
Samar Minallah ◽  
Allison L. Steiner
Keyword(s):  
Great Lakes ◽  
Seasonal Cycle ◽  
Water Cycle ◽  
Coupled Model ◽  
Moisture Flux ◽  
Laurentian Great Lakes ◽  
Convective Precipitation ◽  
Great Lakes Region ◽  
Total Precipitation ◽  
Atmospheric Water

AbstractThis study evaluates the historical climatology and future changes of the atmospheric water cycle for the Laurentian Great Lakes region using 15 Coupled Model Intercomparison Project Phase 6 (CMIP6) models. While the models have unique seasonal characteristics in the historical (1981 – 2010) simulations, common patterns emerge by the mid-century SSP2-4.5 scenario (2041 – 2070), including a prevalent shift in the precipitation seasonal cycle with summer drying and wetter winter-spring months, and a ubiquitous increase in the magnitudes of convective precipitation, evapotranspiration, and moisture inflow into the region. The seasonal cycle of moisture flux convergence is amplified (i.e., the magnitude of winter convergence and summer divergence increases), which is the primary driver of future total precipitation changes. Precipitation recycling ratio is also projected to decline in summer and increase in winter by the mid-century, signifying a larger contribution of the regional moisture (via evapotranspiration) to total precipitation in the colder months. Many models (6/15) do not include representation of the Great Lakes, while others (4/15) have major inconsistencies in how the lakes are simulated both in terms of spatial representation and treatment of lake processes. In models with some lake presence, contribution of lake grid cells to the regional evapotranspiration magnitude can be more than 50% in winter. In future, winter months have a larger increase in evaporation over water surfaces than the surrounding land, which corroborates past findings of sensitivity of deep lakes to climate warming and highlights the importance of lake representation in these models for reliable regional hydroclimatic assessments.

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