Comments on “Development and Evaluation of a Convection Scheme for Use in Climate Models”

Janjić, Zavisă

doi:10.1175/1520-0469(2000)057<3686:codaeo>2.0.co;2

Cited by 283 publications

(165 citation statements)

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“…Two simulations were conducted using exactly the same parameterizations, except the new Kain-Fritsch cumulus scheme Fritsch 1990, 1993) is used in one (named test_3), and in the other (named test_4) the Betts-Miller-Janjic parameterization (Betts 1986;Betts and Miller 1986;Janjic 1990Janjic , 1994Janjic , 2000 is used. Comparison of the May rainfall for test_3 and test_4 (Fig.…”

Section: Methodology For Generating Confident Future Climate Predictionsmentioning

confidence: 99%

Northern African climate at the end of the twenty-first century: an integrated application of regional and global climate models

2009

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A method for simulating future climate on regional space scales is developed and applied to northern Africa. Simulation with a regional model allows for the horizontal resolution needed to resolve the region's strong meridional gradients and the optimization of parameterizations and land-surface model. The control simulation is constrained by reanalysis data, and realistically represents the present day climate. Atmosphere-ocean general circulation model (AOGCM) output provides SST and lateral boundary condition anomalies for 2081-2100 under a business-as-usual emissions scenario, and the atmospheric CO 2 concentration is increased to 757 ppmv. A ninemember ensemble of future climate projections is generated by using output from nine AOGCMs. The consistency of precipitation projections for the end of the twenty-first century is much greater for the regional model ensemble than among the AOGCMs. More than 77% of ensemble members produce the same sign rainfall anomaly over much of northern Africa. For West Africa, the regional model projects wetter conditions in spring, but a midsummer drought develops during June and July, and the heat stoke risk increases across the Sahel. Wetter conditions resume in late summer, and the likelihood of flooding increases. The regional model generally projects wetter conditions over eastern Central Africa in June and drying during August through September. Severe drought impacts parts of East Africa in late summer. Conditions become wetter in October, but the enhanced rainfall does not compensate for the summertime deficit. The risk of heat stroke increases over this region, although the threat is not projected to be as great as in the Sahel.

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Section: Methodology For Generating Confident Future Climate Predictionsmentioning

confidence: 99%

Northern African climate at the end of the twenty-first century: an integrated application of regional and global climate models

2009

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“…An additional dynamic feature of the NMMB is the consideration of various parameterization schemes which can be incorporated into the numerical simulations. In our experiments, the parameterization schemes of Betts-Miller-Janjic (Betts, 1986;Betts and Miller, 1986;Janjic, 1994Janjic, , 2000, Ferrier (Ferrier et al, 2002), Mellor-Yamada-Janjic (Janjic et al, 2001) and Monin-Obukhov (Monin and Obukhov, 1954) have been utilized for the convection, cloud microphysics, turbulence and surface layer, respectively, as well as the NOAH land model (Ek et al, 2003). Moreover, only the greenhouse gases are taken into account and not the emitted short lived atmospheric gases.…”

Section: Model Descriptionmentioning

confidence: 99%

Direct radiative effects during intense Mediterranean desert dust outbreaks

et al. 2018

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Abstract. The direct radiative effect (DRE) during 20 intense and widespread dust outbreaks, which affected the broader Mediterranean basin over the period March 2000-February 2013, has been calculated with the NMMB-MONARCH model at regional (Sahara and European continent) and shortterm temporal (84 h) scales. According to model simulations, the maximum dust aerosol optical depths (AODs) range from ∼ 2.5 to ∼ 5.5 among the identified cases. At midday, dust outbreaks locally induce a NET (shortwave plus longwave) strong atmospheric warming (DRE ATM values up to 285 W m −2 ; Niger-Chad; dust AODs up to ∼ 5.5) and a strong surface cooling (DRE NETSURF values down to −337 W m −2 ), whereas they strongly reduce the downward radiation at the ground level (DRE SURF values down to −589 W m −2 over the Eastern Mediterranean, for extremely high dust AODs, 4.5-5). During night-time, reverse effects of smaller magnitude are found. At the top of the atmosphere (TOA), positive (planetary warming) DREs up to 85 W m −2 are found over highly reflective surfaces (Niger-Chad; dust AODs up to ∼ 5.5) while negative (planetary cooling) DREs down to −184 W m −2 (Eastern Mediterranean; dust AODs 4.5-5) are computed over dark surfaces at noon. Dust outbreaks significantly affect the mean regional radiation budget, with NET DREs ranging from −8.5 to 0.5 W m −2 , from −31.6 to 2.1 W m −2 , from −22.2 to 2.2 W m −2 and from −1.7 to 20.4 W m −2 for TOA, SURF, NETSURF and ATM, respectively. Although the shortwave DREs are larger than the longwave ones, the latter are comparable or even larger at TOA, particularly over the Sahara at midday. As a response to the strong surface day-time cooling, dust outbreaks cause a reduction in the regional sensible and latent heat fluxes by up to 45 and 4 W m −2 , respectively, averaged over land areas of the simulation domain. Dust outbreaks reduce the temperature at 2 m by up to 4 K during day-time, whereas a reverse tendency of similar magnitude is found during nighttime. Depending on the vertical distribution of dust loads and time, mineral particles heat (cool) the atmosphere by up to 0.9 K (0.8 K) during day-time (night-time) within atmospheric dust layers. Beneath and above the dust clouds, mineral particles cool (warm) the atmosphere by up to 1.3 K (1.2 K) at noon (night-time). On a regional mean basis, negative feedbacks on the total emitted dust (reduced by 19.5 %) and dust AOD (reduced by 6.9 %) are found when dust interacts with the radiation. Through the consideration of dust radiative effects in numerical simulations, the model positive and negative biases for the downward surface SW or LW radiation, respectively, with respect to Baseline Surface Radiation Network (BSRN) measurements, are reduced. In addition, they also reduce the model near-surface (at 2 m) nocturnal cold biases by up to 0.5 K (regional averages), as well as the model warm biases at 950 and 700 hPa, where the dust concentration is maximized, by up to 0.4 K. However, improvements are relatively small and do not happen in all ...

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“…The selected physics options were Thompson (Microphysics Options) (Thompson et al, 2004), Betts-Miller-Janjic (Cumulus Parameterization Options) (Janjic, 1994(Janjic, , 2000, RRTMG (Radiation Physics Options), and BouLac (PBL Physics Options) based on the results of meteorological model performance evaluation . The ARW outputs were processed using MCIPv3.4.1 Otte and Pleim, 2010) to generate model-ready meteorology for chemical transport simulations.…”

Section: Cmaq-hemmentioning

confidence: 99%

Multi-model study of mercury dispersion in the atmosphere: vertical and interhemispheric distribution of mercury species

et al. 2017

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Abstract. Atmospheric chemistry and transport of mercury play a key role in the global mercury cycle. However, there are still considerable knowledge gaps concerning the fate of mercury in the atmosphere. This is the second part of a model intercomparison study investigating the impact of atmospheric chemistry and emissions on mercury in the atmosphere. While the first study focused on ground-based observations of mercury concentration and deposition, here we investigate the vertical and interhemispheric distribution and speciation of mercury from the planetary boundary layer to the lower stratosphere. So far, there have been few model studies investigating the vertical distribution of mercury, mostly focusing on single aircraft campaigns. Here, we present a first comprehensive analysis based on various aircraft observations in Europe, North America, and on intercontinental flights.The investigated models proved to be able to reproduce the distribution of total and elemental mercury concentrations in the troposphere including interhemispheric trends. One key aspect of the study is the investigation of mercury oxidation in the troposphere. We found that different chemistry schemes were better at reproducing observed oxidized mercury patterns depending on altitude. High concentrations of oxidized mercury in the upper troposphere could be reproduced with oxidation by bromine while elevated concentrations in the lower troposphere were better reproduced by OH and ozone chemistry. However, the results were not always conclusive as the physical and chemical parameterizations in the chemistry transport models also proved to have a substantial impact on model results.

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Comments on “Development and Evaluation of a Convection Scheme for Use in Climate Models”

Cited by 283 publications

References 0 publications

Northern African climate at the end of the twenty-first century: an integrated application of regional and global climate models

Northern African climate at the end of the twenty-first century: an integrated application of regional and global climate models

Direct radiative effects during intense Mediterranean desert dust outbreaks

Multi-model study of mercury dispersion in the atmosphere: vertical and interhemispheric distribution of mercury species

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