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= ζ ˙ is the rate of change of vorticity due to momentum forcing. Diabatic processes in the free atmosphere arise mainly from the release of latent heat due to condensation and freezing and from absorption and emission of longwave radiation, which in a numerical model are computed by parameterization schemes. We will explicitly include the contributions from three parameterization schemes in the diagnostic: The convection scheme (conv), the gridscale precipitation or microphysics scheme (gsp
= ζ ˙ is the rate of change of vorticity due to momentum forcing. Diabatic processes in the free atmosphere arise mainly from the release of latent heat due to condensation and freezing and from absorption and emission of longwave radiation, which in a numerical model are computed by parameterization schemes. We will explicitly include the contributions from three parameterization schemes in the diagnostic: The convection scheme (conv), the gridscale precipitation or microphysics scheme (gsp
Aerosol Effects on Clouds and Precipitation over Central Europe in Different Weather Regimesprofiles then lead to differences in the stability and relative humidity, both of which are highly relevant to cloud formation and precipitation. The advantage of this method is that the dominating weather regime and the environmental conditions in the planetary boundary layer and at cloud base are not changed. To cover different weather regimes, this technique is applied to days with weak synoptic forcing (airmass convection) and strong synoptic forcing (passage of frontal zones). In each of these
profiles then lead to differences in the stability and relative humidity, both of which are highly relevant to cloud formation and precipitation. The advantage of this method is that the dominating weather regime and the environmental conditions in the planetary boundary layer and at cloud base are not changed. To cover different weather regimes, this technique is applied to days with weak synoptic forcing (airmass convection) and strong synoptic forcing (passage of frontal zones). In each of these
2006 ). Multiple integrations of NWP models (ensembles) can be used to provide probabilistic information but can be set up in different ways, depending on the represented sources of uncertainty. Recent studies have shown that in different weather regimes, different sources of uncertainty dominate: in cases of strong large-scale forcing, initial and boundary conditions uncertainty contributes more to the overall uncertainty, whereas in weak large-scale forcing, model error is more important
2006 ). Multiple integrations of NWP models (ensembles) can be used to provide probabilistic information but can be set up in different ways, depending on the represented sources of uncertainty. Recent studies have shown that in different weather regimes, different sources of uncertainty dominate: in cases of strong large-scale forcing, initial and boundary conditions uncertainty contributes more to the overall uncertainty, whereas in weak large-scale forcing, model error is more important
second moment can be expressed in terms of the normalized variance or in terms of the unnormalized standard deviation b. Previous tests of the CC06 theory So far, few studies have directly tested the assumptions and predictions of CC06. Cohen and Craig (2006) used a convection-permitting model in a radiative–convective equilibrium setup with different large-scale forcing and vertical wind shear strengths and found that p ( m ) was well approximated by an exponential distribution for all settings
second moment can be expressed in terms of the normalized variance or in terms of the unnormalized standard deviation b. Previous tests of the CC06 theory So far, few studies have directly tested the assumptions and predictions of CC06. Cohen and Craig (2006) used a convection-permitting model in a radiative–convective equilibrium setup with different large-scale forcing and vertical wind shear strengths and found that p ( m ) was well approximated by an exponential distribution for all settings
vapor transport that supplies moisture to the base of the WCB ( Wernli 1997 ; Dacre et al. 2019 ). The WCB starts to ascend across the warm front of the cyclone (label 2 in Fig. 1 ), collocated with a region of upper- and lower-tropospheric quasigeostrophic forcing for ascent ( Binder et al. 2016 ). WCB ascent is accompanied by strong latent heat release due to stratiform and convective cloud and precipitation formation ( Neiman and Shapiro 1993 ; Oertel et al. 2019 ), which is sensitive to the
vapor transport that supplies moisture to the base of the WCB ( Wernli 1997 ; Dacre et al. 2019 ). The WCB starts to ascend across the warm front of the cyclone (label 2 in Fig. 1 ), collocated with a region of upper- and lower-tropospheric quasigeostrophic forcing for ascent ( Binder et al. 2016 ). WCB ascent is accompanied by strong latent heat release due to stratiform and convective cloud and precipitation formation ( Neiman and Shapiro 1993 ; Oertel et al. 2019 ), which is sensitive to the
stationary wavenumber of free Rossby waves in a zonal channel approaches the dominant wavenumber of the stationary forcing due to orography or diabatic heating ( Charney and Eliassen 1949 ; Held 1983 ). The mechanism requires Rossby waves to travel around the entire globe in the zonal direction ( Yang et al. 1997 ; Wirth 2020a , 1–3), and this is facilitated in the real atmosphere by a circumglobal jet with strong waveguidability ( Branstator 1983 , 2002 ; Manola et al. 2013 ). Resonance appears
stationary wavenumber of free Rossby waves in a zonal channel approaches the dominant wavenumber of the stationary forcing due to orography or diabatic heating ( Charney and Eliassen 1949 ; Held 1983 ). The mechanism requires Rossby waves to travel around the entire globe in the zonal direction ( Yang et al. 1997 ; Wirth 2020a , 1–3), and this is facilitated in the real atmosphere by a circumglobal jet with strong waveguidability ( Branstator 1983 , 2002 ; Manola et al. 2013 ). Resonance appears
. Res. , 107 , 8306 , doi: 10.1029/2001JD000879 . Wang , H. , G. Feingold , R. Wood , and J. Kazil , 2010 : Modelling microphysical and meteorological controls on precipitation and cloud cellular structures in Southeast Pacific stratocumulus . Atmos. Chem. Phys. , 10 , 6347 – 6362 , doi: 10.5194/acp-10-6347-2010 . 10.5194/acp-10-6347-2010 Yokohata , T. , S. Emori , T. Nozawa , Y. Tsushima , T. Ogura , and M. Kimoto , 2005 : Climate response to volcanic forcing
. Res. , 107 , 8306 , doi: 10.1029/2001JD000879 . Wang , H. , G. Feingold , R. Wood , and J. Kazil , 2010 : Modelling microphysical and meteorological controls on precipitation and cloud cellular structures in Southeast Pacific stratocumulus . Atmos. Chem. Phys. , 10 , 6347 – 6362 , doi: 10.5194/acp-10-6347-2010 . 10.5194/acp-10-6347-2010 Yokohata , T. , S. Emori , T. Nozawa , Y. Tsushima , T. Ogura , and M. Kimoto , 2005 : Climate response to volcanic forcing
wind into its divergent and rotational components. The shape of the spectrum and the associated variability might thus be related to the variable dynamical mechanisms driving the small- and large-scale flows, rather than the variability associated with a dynamical mechanism on the mesoscale range. The relationship between the spectra and the small- and large-scale dynamical forcing mechanisms are examined in the following two subsections. b. Small-scale variability and precipitation rate The high
wind into its divergent and rotational components. The shape of the spectrum and the associated variability might thus be related to the variable dynamical mechanisms driving the small- and large-scale flows, rather than the variability associated with a dynamical mechanism on the mesoscale range. The relationship between the spectra and the small- and large-scale dynamical forcing mechanisms are examined in the following two subsections. b. Small-scale variability and precipitation rate The high
outflow height ( Schäfler and Harnisch 2015 ). During WCB ascent air rises ahead of the cold front and across the warm front in a region of quasigeostrophic forcing for ascent ( Binder et al. 2016 ) which results in precipitation below the WCB airstream. The strong latent heat release due to condensation further contributes to upward motion through cross-isentropic ascent. On average, this latent heat release amounts to 20 K within 48 h ( Madonna et al. 2014 ). In the following, we use the potential
outflow height ( Schäfler and Harnisch 2015 ). During WCB ascent air rises ahead of the cold front and across the warm front in a region of quasigeostrophic forcing for ascent ( Binder et al. 2016 ) which results in precipitation below the WCB airstream. The strong latent heat release due to condensation further contributes to upward motion through cross-isentropic ascent. On average, this latent heat release amounts to 20 K within 48 h ( Madonna et al. 2014 ). In the following, we use the potential
