Evaluation of the carbon cycle components in the Norwegian Earth System Model (NorESM)

Tjiputra, Jerry; Roelandt, C.; Bentsen, Mats; Lawrence, David M.; Lorentzen, Torbjørn; Schwinger, Jörg; Seland, Øyvind; Heinze, Christoph

doi:10.5194/gmdd-5-3035-2012

Cited by 51 publications

(58 citation statements)

References 77 publications

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“…In all our model experiments we use the fully coupled Norwegian Earth system model (NorESM1‐ME). Here we only briefly describe the key components of the model; for a more detailed description of each component, the reader is referred to Bentsen et al [] and Tjiputra et al [, and the references therein]. The NorESM1‐ME is a state‐of‐the‐art global coupled climate‐carbon cycle model.…”

Section: Methodsmentioning

confidence: 99%

Impact of idealized future stratospheric aerosol injection on the large‐scale ocean and land carbon cycles

2016

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Using an Earth system model, we simulate stratospheric aerosol injection (SAI) on top of the Representative Concentration Pathways 8.5 future scenario. Our idealized method prescribes aerosol concentration, linearly increasing from 2020 to 2100, and thereafter remaining constant until 2200. In the aggressive scenario, the model projects a cooling trend toward 2100 despite warming that persists in the high latitudes. Following SAI termination in 2100, a rapid global warming of 0.35 K yr−1 is simulated in the subsequent 10 years, and the global mean temperature returns to levels close to the reference state, though roughly 0.5 K cooler. In contrast to earlier findings, we show a weak response in the terrestrial carbon sink during SAI implementation in the 21st century, which we attribute to nitrogen limitation. The SAI increases the land carbon uptake in the temperate forest‐, grassland‐, and shrub‐dominated regions. The resultant lower temperatures lead to a reduction in the heterotrophic respiration rate and increase soil carbon retention. Changes in precipitation patterns are key drivers for variability in vegetation carbon. Upon SAI termination, the level of vegetation carbon storage returns to the reference case, whereas the soil carbon remains high. The ocean absorbs nearly 10% more carbon in the geoengineered simulation than in the reference simulation, leading to a ∼15 ppm lower atmospheric CO2 concentration in 2100. The largest enhancement in uptake occurs in the North Atlantic. In both hemispheres' polar regions, SAI delays the sea ice melting and, consequently, export production remains low. In the deep water of North Atlantic, SAI‐induced circulation changes accelerate the ocean acidification rate and broaden the affected area.

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Section: Methodsmentioning

confidence: 99%

Impact of idealized future stratospheric aerosol injection on the large‐scale ocean and land carbon cycles

2016

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“…Major updates to MICOM include the implementation of incremental remapping for isopycnal advection, estimation of the pressure gradient force through accurate vertical integration of in-situ density, modified parameterisation of isopycnal and diapycnal mixing processes, and a new split-mixed layer formulation (Bentsen et al, 2013). NorESM has options for a comprehensive treatment of aerosol and cloud chemistry (Kirkeva˚g et al, 2012), as well as ocean biogeochemistry (Assmann et al, 2010;Tjiputra et al, 2012); these are, however, deactivated in this study. Otherwise, the atmosphere (CAM4), land (CLM4), sea ice (CICE4) and coupler (CPL7) components are the same as in CESM1.…”

Section: Model System: Norwegian Earth System Modelmentioning

confidence: 97%

Seasonal-to-decadal predictions with the ensemble Kalman filter and the Norwegian Earth System Model: a twin experiment

Counillon¹,

Bethke²,

Keenlyside³

et al. 2014

Tellus A: Dynamic Meteorology and Oceanography

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A B S T R A C T Here, we firstly demonstrate the potential of an advanced flow dependent data assimilation method for performing seasonal-to-decadal prediction and secondly, reassess the use of sea surface temperature (SST) for initialisation of these forecasts. We use the Norwegian Climate Prediction Model (NorCPM), which is based on the Norwegian Earth System Model (NorESM) and uses the deterministic ensemble Kalman filter to assimilate observations. NorESM is a fully coupled system based on the Community Earth System Model version 1, which includes an ocean, an atmosphere, a sea ice and a land model. A numerically efficient coarse resolution version of NorESM is used. We employ a twin experiment methodology to provide an upper estimate of predictability in our model framework (i.e. without considering model bias) of NorCPM that assimilates synthetic monthly SST data (EnKF-SST). The accuracy of EnKF-SST is compared to an unconstrained ensemble run (FREE) and ensemble predictions made with near perfect (i.e. microscopic SST perturbation) initial conditions (PERFECT). We perform 10 cycles, each consisting of a 10-yr assimilation phase, followed by a 10-yr prediction. The results indicate that EnKF-SST improves sea level, ice concentration, 2 m atmospheric temperature, precipitation and 3-D hydrography compared to FREE. Improvements for the hydrography are largest near the surface and are retained for longer periods at depth. Benefits in salinity are retained for longer periods compared to temperature. Near-surface improvements are largest in the tropics, while improvements at intermediate depths are found in regions of large-scale currents, regions of deep convection, and at the Mediterranean Sea outflow. However, the benefits are often small compared to PERFECT, in particular, at depth suggesting that more observations should be assimilated in addition to SST. The EnKF-SST system is also tested for standard ocean circulation indices and demonstrates decadal predictability for Atlantic overturning and sub-polar gyre circulations, and heat content in the Nordic Seas. The system beats persistence forecast and shows skill for heat content in the Nordic Seas that is close to PERFECT.

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“…The former version, used in this work, is the core version of NorESM Iversen et al, 2012), named NorESM1-M. The latter version (Tjiputra et al, 2012) is named NorESM1-ME. Both NorESM1 versions use CAM4-Oslo for the atmospheric part Table 1.…”

Section: Model Description: Noresm1 and Cam4-oslomentioning

confidence: 99%

“…NorESM1 is a fully coupled global model that is used for simulations under the CMIP5 protocol for the upcoming fifth assessment report from IPCC Iversen et al, 2012). Model-representation of processes leading to anthropogenic aerosol radiative forcing is described here, whilst estimates of climate response are discussed by Bentsen et al (2012), Iversen et al (2012), and Tjiputra et al (2012). Sand et al (2013) present a model study on Arctic climate response to remote and local forcing of black carbon, also using NorESM1.…”

Section: Introductionmentioning

confidence: 99%

Aerosol–climate interactions in the Norwegian Earth System Model – NorESM1-M

Kirkevåg¹,

et al. 2013

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Abstract. The objective of this study is to document and evaluate recent changes and updates to the module for aerosols and aerosol-cloud-radiation interactions in the atmospheric module CAM4-Oslo of the core version of the Norwegian Earth System Model (NorESM), NorESM1-M. Particular attention is paid to the role of natural organics, sea salt, and mineral dust in determining the gross aerosol properties as well as the anthropogenic contribution to these properties and the associated direct and indirect radiative forcing.The aerosol module is extended from earlier versions that have been published, and includes life-cycling of sea salt, mineral dust, particulate sulphate, black carbon, and primary and secondary organics. The impacts of most of the numerous changes since previous versions are thoroughly explored by sensitivity experiments. The most important changes are: modified prognostic sea salt emissions; updated treatment of precipitation scavenging and gravitational settling; inclusion of biogenic primary organics and methane sulphonic acid (MSA) from oceans; almost doubled production of landbased biogenic secondary organic aerosols (SOA); and increased ratio of organic matter to organic carbon (OM/OC) for biomass burning aerosols from 1.4 to 2.6.Compared with in situ measurements and remotely sensed data, the new treatments of sea salt and dust aerosols give smaller biases in near-surface mass concentrations and aerosol optical depth than in the earlier model version. The model biases for mass concentrations are approximately unchanged for sulphate and BC. The enhanced levels of modeled OM yield improved overall statistics, even though OM is still underestimated in Europe and overestimated in North America.The global anthropogenic aerosol direct radiative forcing (DRF) at the top of the atmosphere has changed from a small positive value to −0.08 W m −2 in CAM4-Oslo. The sensitivity tests suggest that this change can be attributed to the new treatment of biomass burning aerosols and gravitational settling. Although it has not been a goal in this study, the new DRF estimate is closer both to the median model estimate from the AeroCom intercomparison and the best estimate in IPCC AR4. Estimated DRF at the ground surface has increased by ca. 60 %, to −1.89 W m −2 . We show that this can be explained by new emission data and omitted mixing of constituents between updrafts and downdrafts in convective clouds.The increased abundance of natural OM and the introduction of a cloud droplet spectral dispersion formulation are the most important contributions to a considerably decreased estimate of the indirect radiative forcing (IndRF). The IndRF is also found to be sensitive to assumptions about the coating of insoluble aerosols by sulphate and OM. The IndRF of −1.2 W m −2 , which is closer to the IPCC AR4 estimates than the previous estimate of −1.9 W m −2 , has thus been obtained without imposing unrealistic artificial lower bounds on cloud droplet number concentrations.

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Evaluation of the carbon cycle components in the Norwegian Earth System Model (NorESM)

Cited by 51 publications

References 77 publications

Impact of idealized future stratospheric aerosol injection on the large‐scale ocean and land carbon cycles

Impact of idealized future stratospheric aerosol injection on the large‐scale ocean and land carbon cycles

Seasonal-to-decadal predictions with the ensemble Kalman filter and the Norwegian Earth System Model: a twin experiment

Aerosol–climate interactions in the Norwegian Earth System Model – NorESM1-M

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