John McGregor - Academia.edu (original) (raw)
Papers by John McGregor
Climate Risk Management, 2016
Climate change impacts are most likely to be felt by resource-dependent communities, and conseque... more Climate change impacts are most likely to be felt by resource-dependent communities, and consequently locally-relevant data are necessary to inform livelihood adaptation planning. This paper presents information for historical and future seasonal rainfall variability in Nusa Tenggara Barat (NTB) Province, Indonesia, where rural livelihoods are highly vulnerable to current climate variability and future change. Historical rainfall variability is investigated using observational data from two stations located on the islands of Lombok and Sumbawa. Future rainfall is examined using an ensemble of six downscaled climate model simulations at a spatial resolution of 14 km for 1971-2100, applying the IPCC SRES-A2 'Business as Usual' emissions scenario, and the six original global climate models (GCMs). Analyses of the observed seasonal rainfall data highlight cyclical variability and long-term declines. The observed periodicities are of about 2-4, 5, 8, 11, and 40-50 years. Furthermore, dry season rainfall is significantly correlated with the El Niño Southern Oscillation (ENSO), while wet season rainfall is weakly correlated with ENSO. The simulated rainfall data reproduce the observed seasonal cycle very well, but overestimate the magnitude of rainfall and underestimate inter-annual rainfall variability. The models also show that the observed rainfall periodicities will continue throughout the 21st century. The models project that rainfall will decline, although with wide ranges of uncertainty, depending on season and location. Crop water demand estimates show that the projected changes will potentially impact the first growing period for rice during November-March. Rainfall may also be insufficient to meet water demand for many crops in the second growing period of March-June, when high value commodities such as chillies and tobacco are produced. The results reinforce the importance to consider all uncertainties when utilizing climate projections in subsequent impact assessments. Recommendations on the effective presentation of these results to inform multi-stakeholder adaptation planning for livelihoods, agriculture and irrigation are given.
Climate Risk Management, 2016
The regional climate of Nusa Tenggara Barat (NTB) Province, eastern Indonesia is simulated for 13... more The regional climate of Nusa Tenggara Barat (NTB) Province, eastern Indonesia is simulated for 130 years (1971-2100) for the SRES A2 Delayed Development or 'Business as Usual' emissions scenario using the CSIRO conformal-cubic atmospheric model (CCAM). Regional climate simulations are generated using a multiple downscaling technique where a CCAM 200 km uniform-grid global simulation is driven by bias-corrected sea surface temperatures (SSTs) from host coupled Global Climate Models (GCMs). Next, the 200 km resolution CCAM simulations are dynamically downscaled to 14 km resolution for the islands of Lombok and Sumbawa. To provide an ensemble of results, separate simulations are performed from six host GCMs. The present-day model results are validated against available observations. Generally, the CCAM 14 km resolution simulations produce rainfall, maximum and minimum temperatures that are similar to the observations. However, the 14 km simulations have rainfall biases of around 5 mm/day in the wet December-February season and lesser biases in the other seasons. Climate projections are examined for two future time intervals centred on 2030 and 2060. The simulations of rainfall changes by 2060 suggest both increases and decreases of up to 5% in December-February, with more acute declines of 10% in some areas, and decreases of up to 10% in March-May. For the other seasons, generally little change is simulated. The regional temperatures are projected to increase by about 1°C by 2030 and 1.6-2°C by 2060. The high-resolution model outputs enable detailed differentiation between locations across the islands. Our results show that due to orographic effects there are steep climate gradients, resulting in significant local differences in climate projections. We discuss the challenges and implications of these results for adaptation planning.
The aim of the MTSRF is to ensure the health of North Queensland's public environmental assets-pa... more The aim of the MTSRF is to ensure the health of North Queensland's public environmental assets-particularly the Great Barrier Reef and its catchments, tropical rainforests including the Wet Tropics World Heritage Area, and the Torres Strait-through the generation and transfer of world class research and knowledge sharing.
Journal of Hydrometeorology, 2004
A multimode Chameleon Surface Model (CHASM) with different levels of complexity in parameterizing... more A multimode Chameleon Surface Model (CHASM) with different levels of complexity in parameterizing surface energy balance is coupled to a limited-area model (DARLAM) to investigate the impacts of complexity in land surface representations on the model simulation of a tropical synoptic event. A low pressure system is examined in two sets of numerical experiments to discuss: (i) does land surface parameterization influence regional numerical weather simulations? and (ii) can the complexity of land surface schemes in numerical models be represented by parameter tuning? The model-simulated tracks of the low pressure center do not, overall, show large sensitivity to the different CHASM modes coupled to the limited-area model. However, the landing position of the system, as one measurement of the track difference, can be influenced by several degrees in latitude and about one degree in longitude. Some of the track differences are larger than the intrinsic numerical noise in the model estimated from two sets of random perturbation runs. In addition, the landing time of the low pressure system can differ by about 14 h. The differences in the model-simulated central pressure exceed the model intrinsic numerical noise and such variations consistent with the differences seen in simulated surface fluxes. Furthermore, different complexity in the land surface scheme can significantly affect the model rainfall and temperature simulations associated with the low center, with differences in rainfall up to 20 mm day Ϫ1 and in surface temperature up to 2ЊC. Explicitly representing surface resistance and bare ground evaporation components in CHASM produces the most significant impacts on the surface processes. Results from the second set of experiments, in which the CHASM modes are calibrated by parameter tuning, demonstrate that the effects of the physical processes represented by extra complexity in some CHASM modes cannot be substituted for by parameter tuning in simplified land surface schemes.
ABSTRACT This presentation describes a number of climate simulations using CCAM, with an emphasis... more ABSTRACT This presentation describes a number of climate simulations using CCAM, with an emphasis on tropical domains. The behaviour of tropical waves within CCAM is compared with that of other models by showing results from the aqua-planet intercomparison. Variable-resolution simulations of present-day climate over Asia and Indonesia are also presented, including some detailed diagnostics of the Asian monsoon. Finally, results are shown from a pilot simulation of climate change, performed over Fiji at 8 km resolution. Introduction In recent years, it has become quite common to use limited-area models as regional climate models (RCMs), to downscale from GCM simulations (e.g. McGregor 1997, Wang et al. 2004), and this approach was used earlier at CSIRO with the DARLAM limited-area model. This is known as dynamical downscaling, and it can provide the detailed climate information needed for assessing a range of climate impacts. A recent development is the use of variable-resolution GCMs as RCMs. An advantage is the avoidance of lateral boundary reflections, which can produce spurious vertical velocities and associated spurious rainfall near the boundaries of a limited-area model. This downscaling technique also avoids problems caused by the host and fine-scale climate models having different temperature or moisture biases. This approach is currently used at CSIRO, downscaling with a variable-resolution global atmospheric model, the Conformal-Cubic Atmospheric Model (CCAM). CCAM may be run in stand-alone mode with modest stretching, or in a variety of nudged modes for stronger stretching (i.e. for small domains of interest). The presentation will mainly show applications of the regional modelling system over the tropics. It is quite challenging to capture the behaviour of the Asian and equatorial monsoons, as they are strongly affected by both the treatment of convective parameterization and the treatment of the high orography of the Tibetan plateau. The islands of the Maritime Continent also pose extra difficulties for simulating precipitation over the Indonesian region (Neale and Slingo 2003). A brief description of the CCAM modelling system will be given, and then its tropical behaviour described in the context of the aquaplanet intercomparison. Next, the current CCAM downscaling methodologies are described. Results are then presented from a number of climate simulations performed over various tropical locations.
Boundary-Layer Meteorology
Two land surface schemes, SCAM and CSIRO9, were used to model the measured energy fluxes during t... more Two land surface schemes, SCAM and CSIRO9, were used to model the measured energy fluxes during the OASIS (Observations At Several Interacting Scales) field program. The measurements were taken at six sites along a 100 km rainfall gradient. Two types of simulations were conducted: (1) offline simulations forced with measured atmospheric input data at each of the six sites, and (2) regional simulations with the two land surface schemes coupled to the regional climate model DARLAM.The two land surface schemes employ two different canopy modelling concepts: in SCAM the vegetation is conceptually above the ground surface, while CSIRO9 employs the more commonly used `horizontally tiled' approach in which the vegetation cover is modelled by conceptually placing it beside bare ground. Both schemes utilize the same below-ground components (soil hydrological and thermal models) to reduce the comparison to canopy processes only. However, the ground heat flux, soil evaporation and evapotranspiration are parameterised by the two canopy treatments somewhat differently.
Annals of Glaciology
The response of the Antarctic ice sheet to climate change over the next 500 years is calculated u... more The response of the Antarctic ice sheet to climate change over the next 500 years is calculated using the output of a transient-coupled ocean-atmosphere simulation assuming the atmospheric CO2value increases up to three times present levels. The main effects on the ice sheet on this time-scale include increasing rates of accumulation, minimal surface melting, and basal melting of ice shelves. A semi-Lagrangian transport scheme for moisture was used to improve the model’s ability to represent realistic rates of accumulation under present-day conditions, and thereby increase confidence in the anomalies calculated under a warmer climate. The response of the Antarctic ice sheet to the warming is increased accumulation inland, offset by loss from basal melting from the floating ice, and increased ice flow near the grounding line. The preliminary results of this study show that the change to the ice-sheet balance for the transient-coupled model forcing amounted to a minimal sea-level cont...
Climate Dynamics, Jan 31, 2009
A ten-year mean (1989-1998) climatology of the Asian summer monsoon is studied using the CSIRO Co... more A ten-year mean (1989-1998) climatology of the Asian summer monsoon is studied using the CSIRO Conformal-Cubic Atmospheric Model (CCAM) to downscale NCEP reanalyses. The aim of the current study is to validate the model results against previous work on this topic, in order to identify model strengths and weaknesses in simulating the Asian summer monsoon. The model results are compared with available observations and are presented in two parts. In the first part, the mean summer rainfall, maximum and minimum temperatures and winds are compared with the observations. The second part focuses on validation of the monsoon onset. The model captures the mean characteristics such as the cross-equatorial flow of low-level winds over the Indian Ocean and near the Somali coast, rainfall patterns, onset indices, northward movements, active-break and revival periods.
Meteorology and Atmospheric Physics, 2011
ABSTRACT A number of uncertainties exist in climate simulation because the results of climate mod... more ABSTRACT A number of uncertainties exist in climate simulation because the results of climate models are influenced by factors such as their dynamic framework, physical processes, initial and driving fields, and horizontal and vertical resolution. The uncertainties of the model results may be reduced, and the credibility can be improved by employing multi-model ensembles. In this paper, multi-model ensemble results using 10-year simulations of five regional climate models (RCMs) from December 1988 to November 1998 over Asia are presented and compared. The simulation results are derived from phase II of the Regional Climate Model Inter-comparison Project (RMIP) for Asia. Using the methods of the arithmetic mean, the weighted mean, multivariate linear regression, and singular value decomposition, the ensembles for temperature, precipitation, and sea level pressure are carried out. The results show that the multi-RCM ensembles outperform the single RCMs in many aspects. Among the four ensemble methods used, the multivariate linear regression, based on the minimization of the root mean square errors, significantly improved the ensemble results. With regard to the spatial distribution of the mean climate, the ensemble result for temperature was better than that for precipitation. With an increasing number of models used in the ensembles, the ensemble results were more accurate. Therefore, a multi-model ensemble is an efficient approach to improve the results of regional climate simulations.
Drought-proofing' Australia is a concept that fires the imagination of the Australian people, par... more Drought-proofing' Australia is a concept that fires the imagination of the Australian people, particularly during severe drought. One recurring suggestion to achieve this aim is to form a large water expanse in central Australia, with the assumption that moisture evaporating from such an expanse would later precipitate over agricultural regions in eastern Australia. This premise then opens the debate as to whether such a large water expanse would actually modify Australia's rainfall regime. This question has been asked before, and as reported in Warren (1945) the usual conclusion has been that there would be minimal change. There are now longer data records than
Agu Fall Meeting Abstracts, Dec 1, 2002
The CSIRO cubic-conformal model is an atmospheric general circulation model with a quasi-uniform ... more The CSIRO cubic-conformal model is an atmospheric general circulation model with a quasi-uniform grid based on 6 panels covering the globe. Here we run the model with a horizontal grid-spacing of approximately 200 km, and with 18 vertical levels.ÿThe model can be driven either by sea surface temperatures alone or, as is done here, with nudging to the winds from the NCEP reanalyses. ÿAn e-folding time of 24 hours is used for the nudging. ÿThe model includes tracer transport using semi-Lagragian advection in the horizontal and total variation diminishing advection in the vertical. The model includes sub-grid scale parameterizations of vertical diffusion and convection with downdrafts. We run forward simulations using relatively simple estimates of CO2 emissions for fossil fuel burning, and biospheric and air-sea exchange. We compare time-series of concentrations at specified grid-cells with hourly data compiled by the World Data Centre for Greenhouse Gases. Preliminary results show that, despite the simplified CO2 sources, some features of the CO2 timeseries are modeled well.
Climate Risk Management, 2016
Climate change impacts are most likely to be felt by resource-dependent communities, and conseque... more Climate change impacts are most likely to be felt by resource-dependent communities, and consequently locally-relevant data are necessary to inform livelihood adaptation planning. This paper presents information for historical and future seasonal rainfall variability in Nusa Tenggara Barat (NTB) Province, Indonesia, where rural livelihoods are highly vulnerable to current climate variability and future change. Historical rainfall variability is investigated using observational data from two stations located on the islands of Lombok and Sumbawa. Future rainfall is examined using an ensemble of six downscaled climate model simulations at a spatial resolution of 14 km for 1971-2100, applying the IPCC SRES-A2 'Business as Usual' emissions scenario, and the six original global climate models (GCMs). Analyses of the observed seasonal rainfall data highlight cyclical variability and long-term declines. The observed periodicities are of about 2-4, 5, 8, 11, and 40-50 years. Furthermore, dry season rainfall is significantly correlated with the El Niño Southern Oscillation (ENSO), while wet season rainfall is weakly correlated with ENSO. The simulated rainfall data reproduce the observed seasonal cycle very well, but overestimate the magnitude of rainfall and underestimate inter-annual rainfall variability. The models also show that the observed rainfall periodicities will continue throughout the 21st century. The models project that rainfall will decline, although with wide ranges of uncertainty, depending on season and location. Crop water demand estimates show that the projected changes will potentially impact the first growing period for rice during November-March. Rainfall may also be insufficient to meet water demand for many crops in the second growing period of March-June, when high value commodities such as chillies and tobacco are produced. The results reinforce the importance to consider all uncertainties when utilizing climate projections in subsequent impact assessments. Recommendations on the effective presentation of these results to inform multi-stakeholder adaptation planning for livelihoods, agriculture and irrigation are given.
Climate Risk Management, 2016
The regional climate of Nusa Tenggara Barat (NTB) Province, eastern Indonesia is simulated for 13... more The regional climate of Nusa Tenggara Barat (NTB) Province, eastern Indonesia is simulated for 130 years (1971-2100) for the SRES A2 Delayed Development or 'Business as Usual' emissions scenario using the CSIRO conformal-cubic atmospheric model (CCAM). Regional climate simulations are generated using a multiple downscaling technique where a CCAM 200 km uniform-grid global simulation is driven by bias-corrected sea surface temperatures (SSTs) from host coupled Global Climate Models (GCMs). Next, the 200 km resolution CCAM simulations are dynamically downscaled to 14 km resolution for the islands of Lombok and Sumbawa. To provide an ensemble of results, separate simulations are performed from six host GCMs. The present-day model results are validated against available observations. Generally, the CCAM 14 km resolution simulations produce rainfall, maximum and minimum temperatures that are similar to the observations. However, the 14 km simulations have rainfall biases of around 5 mm/day in the wet December-February season and lesser biases in the other seasons. Climate projections are examined for two future time intervals centred on 2030 and 2060. The simulations of rainfall changes by 2060 suggest both increases and decreases of up to 5% in December-February, with more acute declines of 10% in some areas, and decreases of up to 10% in March-May. For the other seasons, generally little change is simulated. The regional temperatures are projected to increase by about 1°C by 2030 and 1.6-2°C by 2060. The high-resolution model outputs enable detailed differentiation between locations across the islands. Our results show that due to orographic effects there are steep climate gradients, resulting in significant local differences in climate projections. We discuss the challenges and implications of these results for adaptation planning.
The aim of the MTSRF is to ensure the health of North Queensland's public environmental assets-pa... more The aim of the MTSRF is to ensure the health of North Queensland's public environmental assets-particularly the Great Barrier Reef and its catchments, tropical rainforests including the Wet Tropics World Heritage Area, and the Torres Strait-through the generation and transfer of world class research and knowledge sharing.
Journal of Hydrometeorology, 2004
A multimode Chameleon Surface Model (CHASM) with different levels of complexity in parameterizing... more A multimode Chameleon Surface Model (CHASM) with different levels of complexity in parameterizing surface energy balance is coupled to a limited-area model (DARLAM) to investigate the impacts of complexity in land surface representations on the model simulation of a tropical synoptic event. A low pressure system is examined in two sets of numerical experiments to discuss: (i) does land surface parameterization influence regional numerical weather simulations? and (ii) can the complexity of land surface schemes in numerical models be represented by parameter tuning? The model-simulated tracks of the low pressure center do not, overall, show large sensitivity to the different CHASM modes coupled to the limited-area model. However, the landing position of the system, as one measurement of the track difference, can be influenced by several degrees in latitude and about one degree in longitude. Some of the track differences are larger than the intrinsic numerical noise in the model estimated from two sets of random perturbation runs. In addition, the landing time of the low pressure system can differ by about 14 h. The differences in the model-simulated central pressure exceed the model intrinsic numerical noise and such variations consistent with the differences seen in simulated surface fluxes. Furthermore, different complexity in the land surface scheme can significantly affect the model rainfall and temperature simulations associated with the low center, with differences in rainfall up to 20 mm day Ϫ1 and in surface temperature up to 2ЊC. Explicitly representing surface resistance and bare ground evaporation components in CHASM produces the most significant impacts on the surface processes. Results from the second set of experiments, in which the CHASM modes are calibrated by parameter tuning, demonstrate that the effects of the physical processes represented by extra complexity in some CHASM modes cannot be substituted for by parameter tuning in simplified land surface schemes.
ABSTRACT This presentation describes a number of climate simulations using CCAM, with an emphasis... more ABSTRACT This presentation describes a number of climate simulations using CCAM, with an emphasis on tropical domains. The behaviour of tropical waves within CCAM is compared with that of other models by showing results from the aqua-planet intercomparison. Variable-resolution simulations of present-day climate over Asia and Indonesia are also presented, including some detailed diagnostics of the Asian monsoon. Finally, results are shown from a pilot simulation of climate change, performed over Fiji at 8 km resolution. Introduction In recent years, it has become quite common to use limited-area models as regional climate models (RCMs), to downscale from GCM simulations (e.g. McGregor 1997, Wang et al. 2004), and this approach was used earlier at CSIRO with the DARLAM limited-area model. This is known as dynamical downscaling, and it can provide the detailed climate information needed for assessing a range of climate impacts. A recent development is the use of variable-resolution GCMs as RCMs. An advantage is the avoidance of lateral boundary reflections, which can produce spurious vertical velocities and associated spurious rainfall near the boundaries of a limited-area model. This downscaling technique also avoids problems caused by the host and fine-scale climate models having different temperature or moisture biases. This approach is currently used at CSIRO, downscaling with a variable-resolution global atmospheric model, the Conformal-Cubic Atmospheric Model (CCAM). CCAM may be run in stand-alone mode with modest stretching, or in a variety of nudged modes for stronger stretching (i.e. for small domains of interest). The presentation will mainly show applications of the regional modelling system over the tropics. It is quite challenging to capture the behaviour of the Asian and equatorial monsoons, as they are strongly affected by both the treatment of convective parameterization and the treatment of the high orography of the Tibetan plateau. The islands of the Maritime Continent also pose extra difficulties for simulating precipitation over the Indonesian region (Neale and Slingo 2003). A brief description of the CCAM modelling system will be given, and then its tropical behaviour described in the context of the aquaplanet intercomparison. Next, the current CCAM downscaling methodologies are described. Results are then presented from a number of climate simulations performed over various tropical locations.
Boundary-Layer Meteorology
Two land surface schemes, SCAM and CSIRO9, were used to model the measured energy fluxes during t... more Two land surface schemes, SCAM and CSIRO9, were used to model the measured energy fluxes during the OASIS (Observations At Several Interacting Scales) field program. The measurements were taken at six sites along a 100 km rainfall gradient. Two types of simulations were conducted: (1) offline simulations forced with measured atmospheric input data at each of the six sites, and (2) regional simulations with the two land surface schemes coupled to the regional climate model DARLAM.The two land surface schemes employ two different canopy modelling concepts: in SCAM the vegetation is conceptually above the ground surface, while CSIRO9 employs the more commonly used `horizontally tiled' approach in which the vegetation cover is modelled by conceptually placing it beside bare ground. Both schemes utilize the same below-ground components (soil hydrological and thermal models) to reduce the comparison to canopy processes only. However, the ground heat flux, soil evaporation and evapotranspiration are parameterised by the two canopy treatments somewhat differently.
Annals of Glaciology
The response of the Antarctic ice sheet to climate change over the next 500 years is calculated u... more The response of the Antarctic ice sheet to climate change over the next 500 years is calculated using the output of a transient-coupled ocean-atmosphere simulation assuming the atmospheric CO2value increases up to three times present levels. The main effects on the ice sheet on this time-scale include increasing rates of accumulation, minimal surface melting, and basal melting of ice shelves. A semi-Lagrangian transport scheme for moisture was used to improve the model’s ability to represent realistic rates of accumulation under present-day conditions, and thereby increase confidence in the anomalies calculated under a warmer climate. The response of the Antarctic ice sheet to the warming is increased accumulation inland, offset by loss from basal melting from the floating ice, and increased ice flow near the grounding line. The preliminary results of this study show that the change to the ice-sheet balance for the transient-coupled model forcing amounted to a minimal sea-level cont...
Climate Dynamics, Jan 31, 2009
A ten-year mean (1989-1998) climatology of the Asian summer monsoon is studied using the CSIRO Co... more A ten-year mean (1989-1998) climatology of the Asian summer monsoon is studied using the CSIRO Conformal-Cubic Atmospheric Model (CCAM) to downscale NCEP reanalyses. The aim of the current study is to validate the model results against previous work on this topic, in order to identify model strengths and weaknesses in simulating the Asian summer monsoon. The model results are compared with available observations and are presented in two parts. In the first part, the mean summer rainfall, maximum and minimum temperatures and winds are compared with the observations. The second part focuses on validation of the monsoon onset. The model captures the mean characteristics such as the cross-equatorial flow of low-level winds over the Indian Ocean and near the Somali coast, rainfall patterns, onset indices, northward movements, active-break and revival periods.
Meteorology and Atmospheric Physics, 2011
ABSTRACT A number of uncertainties exist in climate simulation because the results of climate mod... more ABSTRACT A number of uncertainties exist in climate simulation because the results of climate models are influenced by factors such as their dynamic framework, physical processes, initial and driving fields, and horizontal and vertical resolution. The uncertainties of the model results may be reduced, and the credibility can be improved by employing multi-model ensembles. In this paper, multi-model ensemble results using 10-year simulations of five regional climate models (RCMs) from December 1988 to November 1998 over Asia are presented and compared. The simulation results are derived from phase II of the Regional Climate Model Inter-comparison Project (RMIP) for Asia. Using the methods of the arithmetic mean, the weighted mean, multivariate linear regression, and singular value decomposition, the ensembles for temperature, precipitation, and sea level pressure are carried out. The results show that the multi-RCM ensembles outperform the single RCMs in many aspects. Among the four ensemble methods used, the multivariate linear regression, based on the minimization of the root mean square errors, significantly improved the ensemble results. With regard to the spatial distribution of the mean climate, the ensemble result for temperature was better than that for precipitation. With an increasing number of models used in the ensembles, the ensemble results were more accurate. Therefore, a multi-model ensemble is an efficient approach to improve the results of regional climate simulations.
Drought-proofing' Australia is a concept that fires the imagination of the Australian people, par... more Drought-proofing' Australia is a concept that fires the imagination of the Australian people, particularly during severe drought. One recurring suggestion to achieve this aim is to form a large water expanse in central Australia, with the assumption that moisture evaporating from such an expanse would later precipitate over agricultural regions in eastern Australia. This premise then opens the debate as to whether such a large water expanse would actually modify Australia's rainfall regime. This question has been asked before, and as reported in Warren (1945) the usual conclusion has been that there would be minimal change. There are now longer data records than
Agu Fall Meeting Abstracts, Dec 1, 2002
The CSIRO cubic-conformal model is an atmospheric general circulation model with a quasi-uniform ... more The CSIRO cubic-conformal model is an atmospheric general circulation model with a quasi-uniform grid based on 6 panels covering the globe. Here we run the model with a horizontal grid-spacing of approximately 200 km, and with 18 vertical levels.ÿThe model can be driven either by sea surface temperatures alone or, as is done here, with nudging to the winds from the NCEP reanalyses. ÿAn e-folding time of 24 hours is used for the nudging. ÿThe model includes tracer transport using semi-Lagragian advection in the horizontal and total variation diminishing advection in the vertical. The model includes sub-grid scale parameterizations of vertical diffusion and convection with downdrafts. We run forward simulations using relatively simple estimates of CO2 emissions for fossil fuel burning, and biospheric and air-sea exchange. We compare time-series of concentrations at specified grid-cells with hourly data compiled by the World Data Centre for Greenhouse Gases. Preliminary results show that, despite the simplified CO2 sources, some features of the CO2 timeseries are modeled well.