Comparison of NCAR community climate model (CCM) climates

Hurrell, James W.

doi:10.1007/bf00220675

Cited by 27 publications

(10 citation statements)

References 52 publications

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“…This is most obvious in northern high latitudes. Such a cold bias in this altitude is also seen in some GCMs (see earlier references, and also Hurrell, 1995, who discuss this aspect in more detail). Now the model is compared with observations and analyses for Dec 30, 1992 of CLAES and ECMWF respectively.…”

Section: The Middle Atmosphere Of the Model In The Uncoupled Casesupporting

confidence: 65%

Use of coupled ozone fields in a 3-D circulation model of the middle atmosphere

Reddmann¹,

Ruhnke²,

Kouker³

1999

Ann Geophysicae

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Abstract. With a detailed chemistry scheme for the middle atmosphere up to 70 km which has been added to the 3-D Karlsruhe simulation model of the middle atmosphere (KASIMA), the eects of coupling chemistry and dynamics through ozone are studied for the middle atmosphere. An uncoupled version using an ozone climatology for determining heating rates and a coupled version using on-line ozone are compared in a 10-month integration with meteorological analyses for the winter 1992/93 as the lower boundary condition. Both versions simulate the meteorological situation satisfactorily, but exhibit a too cold lower stratosphere. The on-line ozone diers from the climatological data between 20 and 40 km by exhibiting too high ozone values, whereas in the lower mesosphere the ozone values are too low. The coupled model version is stable and diers only above 40 km signi®cantly from the uncoupled version. Direct heating eects are identi®ed to cause most of the dierences. The well-known negative correlation between temperature and ozone is reproduced in the model. As a result, the coupled version slightly approaches the climatological ozone ®eld. Further feedback eects are studied by using the on-line ozone ®eld as a basis for an arti®cial climatology. For non-disturbed ozone conditions realistic monthly and zonally averaged ozone data are sucient to determine the heating rates for modelling the middle atmosphere.

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Section: The Middle Atmosphere Of the Model In The Uncoupled Casesupporting

confidence: 65%

Use of coupled ozone fields in a 3-D circulation model of the middle atmosphere

Reddmann¹,

Ruhnke²,

Kouker³

1999

Ann Geophysicae

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“…Vegetation influences climate via albedo feedbacks, interception of rain and snow, and the radiative and turbulent effects on soil, snow, and surface winds. The model has been validated against observations [Thompson and Pollard, 1995;Yip and Crowley, 1994], compares favorably with other models [Yip and Crowley, 1994;Hurrell et al, 1994], and is receiving increased use in paleoclimate studies [Crowley et al, 1993;Otto-Bliesner, 1993;Foley et al, 1994;Pollard and Schulz, 1994;Barron et al, 1995;Sloan et al, 1996].…”

Section: Model and Boundary Conditionsmentioning

confidence: 86%

Effect of vegetation on an ice‐age climate model simulation

Crowley¹,

Baum²

1997

J. Geophys. Res.

109

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Abstract. A growing number of studies suggest that vegetation changes can significantly influence regional climate variations. Herein we utilize a climate model (GENESIS) with a land surface vegetation package to evaluate the potential role of the very large vegetation changes that occurred during the last glacial maximum (LGM). In particular, we focus on the potential response to a significant reduction in the area of tropical rainforest. Simulations employed a global vegetation reconstruction for the LGM and Climate/Long-Range Investigation, Mapping and Prediction (CLIMAP) sea surface temperature (SST) estimates. Results indicate that expansion of dryland vegetation causes a 15-30% additional LGM cooling for Australia (0.4øC) and Africa (0.9øC), respectively. Turnover from conifer to tundra also causes cooling of 2ø-4øC or more in western Europe and Siberia. However, for the largest rainforest area (Amazon Basin), inclusion of realistic vegetation increased modeled temperatures 2ø-4øC and decreased precipitation by 10-35%. These latter results are similar to those obtained with sensitivity experiments of the effects of future Amazon deforestation. Initial assessment of the potential effect of decreased stomatal resistance due to lower ice age CO2 levels indicates little significant response to this effect. Comparison of model-predicted low-elevation LGM temperature changes with estimates from proxy data indicate that inclusion of realistic vegetation estimates for the LGM results in slightly more than 50% agreement between models and data for low-elevation sites in low-mid latitudes. Data at variance with model predictions would appear to be explainable by considering additional changes in vegetation, ice age dust, or a 1 ø-2øC cooling below CLIMAP values. This conclusion is at variance with a 3ø-4øC tropical cooling suggested by some studies for explaining estimated land temperature changes during the LGM. In some western European sites model temperatures are colder than proxy data by 2ø-8øC. This model-data discrepancy may be explained by less sea ice in the subpolar North Atlantic than stipulated by CLIMAP, a conclusion consistent with new marine data from that region.

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“…This type of dry bias also occurs in the new version of the NCAR climate model, CCM2, with higher resolution (cf. Hurrell et al, 1993). As noted earlier, another factor may be the natural variability as shown in the observational analysis.…”

Section: Model Descriptionmentioning

confidence: 96%