scholarly journals Ocean Surface Flux Algorithm Effects on Earth System Model Energy and Water Cycles

2021 ◽  
Vol 8 ◽  
Author(s):  
J. E. Jack Reeves Eyre ◽  
Xubin Zeng ◽  
Kai Zhang
Keyword(s):  
Surface Flux ◽  
Ocean Surface ◽  
Earth System Model ◽  
Surface Fluxes ◽  
System Model ◽  
Earth System ◽  
Ocean Heat Uptake ◽  
Wind Speeds ◽  
Global Mean ◽  
Water Cycles

Earth system models parameterize ocean surface fluxes of heat, moisture, and momentum with empirical bulk flux algorithms, which introduce biases and uncertainties into simulations. We investigate the atmosphere and ocean model sensitivity to algorithm choice in the Energy Exascale Earth System Model (E3SM). Flux differences between algorithms are larger in atmosphere simulations (where wind speeds can vary) than ocean simulations (where wind speeds are fixed by forcing data). Surface flux changes lead to global scale changes in the energy and water cycles, notably including ocean heat uptake and global mean precipitation rates. Compared to the control algorithm, both COARE and University of Arizona (UA) algorithms reduce global mean precipitation and top of atmosphere radiative biases. Further, UA may slightly reduce biases in ocean meridional heat transport. We speculate that changes seen here, especially in the ocean, could be even larger in coupled simulations.

scholarly journals The iron budget in ocean surface waters in the 20th and 21st centuries: projections by the Community Earth System Model version 1

2013 ◽  
Vol 10 (5) ◽  
pp. 8505-8559 ◽  
Author(s):  
K. Misumi ◽  
K. Lindsay ◽  
J. K. Moore ◽  
S. C. Doney ◽  
F. O. Bryan ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Surface Waters ◽  
Ocean Surface ◽  
Equatorial Pacific ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Iron Supply ◽  
Eastern Equatorial Pacific ◽  
Community Earth System Model

Abstract. We investigated the simulated iron budget in ocean surface waters in the 1990s and 2090s using the Community Earth System Model version 1 and the Representative Concentration Pathway 8.5 future CO2 emission scenario. We assumed that exogenous iron inputs did not change during the whole simulation period; thus, iron budget changes were attributed solely to changes in ocean circulation and mixing in response to projected global warming. The model simulated the major features of ocean circulation and dissolved iron distribution for the present climate reasonably well. Detailed iron budget analysis revealed that roughly 70% of the iron supplied to surface waters in high-nutrient, low-chlorophyll (HNLC) regions is contributed by ocean circulation and mixing processes, but the dominant supply mechanism differed in each HNLC region: vertical mixing in the Southern Ocean, upwelling in the eastern equatorial Pacific, and deposition of iron-bearing dust in the subarctic North Pacific. In the 2090s, our model projected an increased iron supply to HNLC surface waters, even though enhanced stratification was predicted to reduce iron entrainment from deeper waters. This unexpected result could be attributed largely to changes in the meridional overturning and gyre-scale circulations that intensified the advective supply of iron to surface waters, especially in the eastern equatorial Pacific. The simulated primary and export productions in the 2090s decreased globally by 6% and 13%, respectively, whereas in the HNLC regions, they increased by 11% and 6%, respectively. Roughly half of the elevated production could be attributed to the intensified iron supply. The projected ocean circulation and mixing changes are consistent with recent observations of responses to the warming climate and with other Coupled Model Intercomparison Project model projections. We conclude that future ocean circulation and mixing changes will likely elevate the iron supply to HNLC surface waters and will potentially buffer future reductions in ocean productivity. External inputs of iron to the oceans are likely to be modified with climate change. Future work must incorporate robust estimates of these processes affecting the marine iron cycle.

scholarly journals The IITM Earth System Model: Transformation of a Seasonal Prediction Model to a Long-Term Climate Model

2015 ◽  
Vol 96 (8) ◽  
pp. 1351-1367 ◽  
Author(s):  
P. Swapna ◽  
M. K. Roxy ◽  
K. Aparna ◽  
K. Kulkarni ◽  
A. G. Prajeesh ◽  
...  
Keyword(s):  
Prediction Model ◽  
Surface Temperature ◽  
Mixed Layer ◽  
Climate Model ◽  
Seasonal Prediction ◽  
Earth System Model ◽  
System Model ◽  
Cold Bias ◽  
Earth System ◽  
Global Mean

Abstract With the goal of building an Earth system model appropriate for detection, attribution, and projection of changes in the South Asian monsoon, a state-of-the-art seasonal prediction model, namely the Climate Forecast System version 2 (CFSv2) has been adapted to a climate model suitable for extended climate simulations at the Indian Institute of Tropical Meteorology (IITM), Pune, India. While the CFSv2 model has been skillful in predicting the Indian summer monsoon (ISM) on seasonal time scales, a century-long simulation with it shows biases in the ocean mixed layer, resulting in a 1.5°C cold bias in the global mean surface air temperature, a cold bias in the sea surface temperature (SST), and a cooler-than-observed troposphere. These biases limit the utility of CFSv2 to study climate change issues. To address biases, and to develop an Indian Earth System Model (IITM ESMv1), the ocean component in CFSv2 was replaced at IITM with an improved version, having better physics and interactive ocean biogeochemistry. A 100-yr simulation with the new coupled model (with biogeochemistry switched off) shows substantial improvements, particularly in global mean surface temperature, tropical SST, and mixed layer depth. The model demonstrates fidelity in capturing the dominant modes of climate variability such as the ENSO and Pacific decadal oscillation. The ENSO–ISM teleconnections and the seasonal leads and lags are also well simulated. The model, a successful result of Indo–U.S. collaboration, will contribute to the IPCC’s Sixth Assessment Report (AR6) simulations, a first for India.

scholarly journals Effects of snow grain shape on climate simulations: sensitivity tests with the Norwegian Earth System Model

2017 ◽  
Vol 11 (6) ◽  
pp. 2919-2942 ◽  
Author(s):  
Petri Räisänen ◽  
Risto Makkonen ◽  
Alf Kirkevåg ◽  
Jens B. Debernard
Keyword(s):  
Grain Size ◽  
Sea Ice ◽  
Grain Shape ◽  
Earth System Model ◽  
System Model ◽  
Blowing Snow ◽  
Earth System ◽  
Spherical Case ◽  
The Impact ◽  
Global Mean

Abstract. Snow consists of non-spherical grains of various shapes and sizes. Still, in radiative transfer calculations, snow grains are often treated as spherical. This also applies to the computation of snow albedo in the Snow, Ice, and Aerosol Radiation (SNICAR) model and in the Los Alamos sea ice model, version 4 (CICE4), both of which are employed in the Community Earth System Model and in the Norwegian Earth System Model (NorESM). In this study, we evaluate the effect of snow grain shape on climate simulated by NorESM in a slab ocean configuration of the model. An experiment with spherical snow grains (SPH) is compared with another (NONSPH) in which the snow shortwave single-scattering properties are based on a combination of three non-spherical snow grain shapes optimized using measurements of angular scattering by blowing snow. The key difference between these treatments is that the asymmetry parameter is smaller in the non-spherical case (0.77–0.78 in the visible region) than in the spherical case ( ≈  0.89). Therefore, for the same effective snow grain size (or equivalently, the same specific projected area), the snow broadband albedo is higher when assuming non-spherical rather than spherical snow grains, typically by 0.02–0.03. Considering the spherical case as the baseline, this results in an instantaneous negative change in net shortwave radiation with a global-mean top-of-the-model value of ca. −0.22 W m−2. Although this global-mean radiative effect is rather modest, the impacts on the climate simulated by NorESM are substantial. The global annual-mean 2 m air temperature in NONSPH is 1.17 K lower than in SPH, with substantially larger differences at high latitudes. The climatic response is amplified by strong snow and sea ice feedbacks. It is further demonstrated that the effect of snow grain shape could be largely offset by adjusting the snow grain size. When assuming non-spherical snow grains with the parameterized grain size increased by ca. 70 %, the climatic differences to the SPH experiment become very small. Finally, the impact of assumed snow grain shape on the radiative effects of absorbing aerosols in snow is discussed.

scholarly journals Sea-spray geoengineering in the HadGEM2-ES earth-system model: radiative impact and climate response

2012 ◽  
Vol 12 (22) ◽  
pp. 10887-10898 ◽  
Author(s):  
A. Jones ◽  
J. M. Haywood
Keyword(s):  
Direct Effect ◽  
Indirect Effects ◽  
Earth System Model ◽  
System Model ◽  
Sea Spray ◽  
Earth System ◽  
Global Mean Temperature ◽  
Radiative Impact ◽  
The Impact ◽  
Global Mean

Abstract. The radiative impact and climate effects of geoengineering using sea-spray aerosols have been investigated in the HadGEM2-ES Earth system model using a fully prognostic treatment of the sea-spray aerosols and also including their direct radiative effect. Two different emission patterns were considered, one to maximise the direct effect in clear skies, the other to maximise the indirect effects of the sea-spray on low clouds; in both cases the emissions were limited to 10% of the ocean area. While the direct effect was found to be significant, the indirect effects on clouds were much more effective in reducing global mean temperature as well as having less of an impact on global mean precipitation per unit temperature reduction. The impact on the distribution of precipitation was found to be similar in character, but less in degree, to that simulated by a previous study using a much simpler treatment of this geoengineering process.

scholarly journals Preindustrial-Control and Twentieth-Century Carbon Cycle Experiments with the Earth System Model CESM1(BGC)

2014 ◽  
Vol 27 (24) ◽  
pp. 8981-9005 ◽  
Author(s):  
Keith Lindsay ◽  
Gordon B. Bonan ◽  
Scott C. Doney ◽  
Forrest M. Hoffman ◽  
David M. Lawrence ◽  
...  
Keyword(s):  
Twentieth Century ◽  
Carbon Cycle ◽  
Time Scales ◽  
Seasonal Cycle ◽  
Earth System Model ◽  
Surface Fluxes ◽  
Atmospheric Co2 ◽  
System Model ◽  
Biogeochemical Model ◽  
Earth System

Abstract Version 1 of the Community Earth System Model, in the configuration where its full carbon cycle is enabled, is introduced and documented. In this configuration, the terrestrial biogeochemical model, which includes carbon–nitrogen dynamics and is present in earlier model versions, is coupled to an ocean biogeochemical model and atmospheric CO2 tracers. The authors provide a description of the model, detail how preindustrial-control and twentieth-century experiments were initialized and forced, and examine the behavior of the carbon cycle in those experiments. They examine how sea- and land-to-air CO2 fluxes contribute to the increase of atmospheric CO2 in the twentieth century, analyze how atmospheric CO2 and its surface fluxes vary on interannual time scales, including how they respond to ENSO, and describe the seasonal cycle of atmospheric CO2 and its surface fluxes. While the model broadly reproduces observed aspects of the carbon cycle, there are several notable biases, including having too large of an increase in atmospheric CO2 over the twentieth century and too small of a seasonal cycle of atmospheric CO2 in the Northern Hemisphere. The biases are related to a weak response of the carbon cycle to climatic variations on interannual and seasonal time scales and to twentieth-century anthropogenic forcings, including rising CO2, land-use change, and atmospheric deposition of nitrogen.

scholarly journals The iron budget in ocean surface waters in the 20th and 21st centuries: projections by the Community Earth System Model version 1

2014 ◽  
Vol 11 (1) ◽  
pp. 33-55 ◽  
Author(s):  
K. Misumi ◽  
K. Lindsay ◽  
J. K. Moore ◽  
S. C. Doney ◽  
F. O. Bryan ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Surface Waters ◽  
Ocean Surface ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Model Version ◽  
Iron Supply ◽  
Community Earth System Model ◽  
Project Model

Abstract. We investigated the simulated iron budget in ocean surface waters in the 1990s and 2090s using the Community Earth System Model version 1 and the Representative Concentration Pathway 8.5 future CO2 emission scenario. We assumed that exogenous iron inputs did not change during the whole simulation period; thus, iron budget changes were attributed solely to changes in ocean circulation and mixing in response to projected global warming, and the resulting impacts on marine biogeochemistry. The model simulated the major features of ocean circulation and dissolved iron distribution for the present climate. Detailed iron budget analysis revealed that roughly 70% of the iron supplied to surface waters in high-nutrient, low-chlorophyll (HNLC) regions is contributed by ocean circulation and mixing processes, but the dominant supply mechanism differed by region: upwelling in the eastern equatorial Pacific and vertical mixing in the Southern Ocean. For the 2090s, our model projected an increased iron supply to HNLC waters, even though enhanced stratification was predicted to reduce iron entrainment from deeper waters. This unexpected result is attributed largely to changes in gyre-scale circulations that intensified the advective supply of iron to HNLC waters. The simulated primary and export production in the 2090s decreased globally by 6 and 13%, respectively, whereas in the HNLC regions, they increased by 11 and 6%, respectively. Roughly half of the elevated production could be attributed to the intensified iron supply. The projected ocean circulation and mixing changes are consistent with recent observations of responses to the warming climate and with other Coupled Model Intercomparison Project model projections. We conclude that future ocean circulation has the potential to increase iron supply to HNLC waters and will potentially buffer future reductions in ocean productivity.

scholarly journals Effects of strongly eddying oceans on multidecadal climate variability in the Community Earth System Model

2020 ◽  
Author(s):  
André Jüling ◽  
Anna von der Heydt ◽  
Henk A. Dijkstra
Keyword(s):  
Climate Variability ◽  
Surface Temperature ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Multidecadal Variability ◽  
Global Mean Surface Temperature ◽  
Ocean Flows ◽  
Community Earth System Model ◽  
Global Mean

Abstract. Climate variability on multidecadal time scales appears to be organized in pronounced patterns with clear expressions in sea surface temperature, such as the Atlantic Multidecadal Variability and the Pacific Decadal Oscillation. These patterns are now well studied both in observations and global climate models and are important in the attribution of climate change. Results from CMIP5 models have indicated large biases in these patterns with consequences for ocean heat storage variability and eventually the global mean surface temperature. In this paper, we use two multi-century Community Earth System Model simulations at coarse (1°) and fine (0.1°) ocean model horizontal grid spacing to study the effects of the representation of mesoscale ocean flows on major patterns of multidecadal variability. We find that resolving mesoscale ocean flows both improves the characteristics of the modes of variability with respect to observations and increases the amplitude of the heat content variability in the individual ocean basins. The effect on the global mean surface temperature is relatively minor.

Sign in / Sign up

Export Citation Format

Share Document