A Numerical Study of the Role of Humidity in the Updraft Driven by Moist Slantwise Convection

Innocentini, Valdir; Neto, Ernesto Dos Santos Caetano

doi:10.1175/1520-0469(1992)049<1092:ansotr>2.0.co;2

Cited by 11 publications

(9 citation statements)

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“…Previous studies have shown that both WSP (Chong, ; Clark et al, ; Innocentini & Neto, ; Kingsmill et al, ; Lin et al, ) and CFP (Bodine & Rasmussen, ) are mainly produced by MCSs, which themselves are greatly affected by cloud microphysical processes. In this part, we begin by discussing the microphysical and thermodynamic vertical structures of MCSs in the WSP and CFP.…”

Section: Probable Mechanism For Wsp and Cfp In Terms Of Cloud Microphmentioning

confidence: 99%

A Study of Cloud Microphysical Processes Associated With Torrential Rainfall Event Over Beijing

et al. 2018

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The evolution of mesoscale convective systems (MCSs) leading to a heavy rainstorm event that occurred in Beijing on 21 July 2012 was simulated using the Weather Research and Forecasting model. Observational analyses indicated that this event can be divided into an earlier‐occurring warm‐sector precipitation (WSP) and a later‐occurring cold‐frontal precipitation (CFP). Owing to the considerable differences in their ambient weather conditions, the features and evolution of the cloud microphysics were different. Diagnoses of the mass‐ and heat‐hydrometeor budgets showed that the major differences in rainwater source were that the graupel melting (PGMLT) and the collection of snow by rain (PRACS_s2r) had similar magnitudes in the WSP, and PGMLT was larger than PRACS_s2r in the CFP, while the accretion growth of cloud droplets (PRA) was always the largest in both phases. The main cooling effect in the WSP was due to the evaporation of rainwater (PRE) and cloud water, while it was PRE and PGMLT for the CFP. The mechanisms of how microphysical processes influenced the precipitation were explored. It was found that the strong PRA in the WSP was conducive to the formation of a supercooled water level and evoked a seeding effect. However, graupel processes were crucial for the CFP. The strong sublimation processes of graupel and snow associated with the collection of droplets by graupel caused more latent heat release and drove airflow to reach a higher convection height. Moreover, the stronger PGMLT cooled the air in the MCS and reduced the effect of cloud droplet accretion growth.

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Section: Probable Mechanism For Wsp and Cfp In Terms Of Cloud Microphmentioning

confidence: 99%

A Study of Cloud Microphysical Processes Associated With Torrential Rainfall Event Over Beijing

et al. 2018

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“…To prevent this problem, the supersaturation is removed after submitting the saturated layer to a pseudoadiabatic process as described below. A similar procedure was adopted by Innocentini and Neto (1992).…”

Section: Latent and Sensible Heatmentioning

confidence: 99%

The Impact of Spume Droplets and Wave Stress Parameterizations on Simulated Near-Surface Maritime Wind and Temperature

Innocentini

Gonçalves

2010

Journal of Physical Oceanography

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The influence of ocean gravity waves on the wind and temperature above the surface is investigated using a one-dimensional boundary layer model. The effect of the wave-induced stress is evaluated using three parameterizations: wave age (WaAg), wave steepness (WaSt), and wind action on the wave spectrum (WiAc). It is found that while the WaAg is more effective in reducing the wind for young waves, in the WaSt approach the maximum reduction is for old waves. On the other hand, the WiAc is very sensitive to the energy present in high frequencies corresponding to periods less than 2 s, which are found in both young and mature spectra. Since observations show that most of the wave stress is due to the small-period wave energy, in this aspect the WaSt parameterization is not recommended; WaAg is not as accurate; and thus WiAc is the best among the three, although its computational cost is the highest.The droplet load contribution to the total surface stress can be neglected for the droplet spectrum produced by 10-m wind speeds up to 15 m s 21 , but its importance increases with the speed and its magnitude becomes about 1 /5 of the total stress for wind speed ;30 m s 21. Concerning the latent and sensible heat fluxes accompanying the production of spume droplets by waves, a feasible microphysical formulation for operational use in weather forecasting models is proposed. The droplet spectrum is assumed to be a product of two functions, one depending on the windsea Reynolds number and the other on the droplet radius spectrum. The bulk effect of the latter is analytically evaluated and stored in a table as a function of air temperature T a , relative humidity R % , and significant wave height H s . In numerical experiments with initial sea surface temperature 5 K higher than the air surface, latent and sensible heat contributions to the air temperature are computed as a function of the wave spectra. The launched droplet spectrum (which increases the air temperature due to sensible heat) and the relative humidity (which controls the cooling due to the droplet evaporation) define the heat budget and the air temperature evolution. Although in these experiments the sea temperature is much higher than the air temperature, the results show a noticeable dominance of the evaporative cooling in the lower atmosphere mainly for smaller significant wave height. Some air warming is noticeable only from a threshold around H s $ 5 m.

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“…8, 11;Xu 1992, p. 637;Persson and Warner 1995, their Fig. 13;Innocentini anddos Santos Caetano Neto 1992, p. 1099;Zhang and Cho 1995, their Fig. 3).…”

Section: Introductionmentioning

confidence: 97%

Vertical Motions in Precipitation Bands in Three Winter Cyclones

Cronce

Rauber

Knupp

et al. 2007

Journal of Applied Meteorology and Climatology

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The University of Alabama in Huntsville Mobile Integrated Profiling System 915-MHz profiler was deployed in January and February of 2004 to measure vertical air velocities in finescale precipitation bands in winter cyclones. The profiler was placed to sample the "wraparound" quadrant of three winter cyclones in the central and southern United States, and it obtained high-resolution measurements of the vertical structure of a series of bands in each storm. The data revealed bands that were up to 6 km deep, 10-50 km wide, and spaced about 5-20 km apart. Measurements of vertical air motion w within these bands were retrieved from the Doppler spectra using the lower-bound method, adapted to account for the effects of spectral broadening caused by the horizontal wind, wind shear, and turbulence. Derived vertical air motions ranged from Ϫ4.3 to 6.7 m s Ϫ1 , with an uncertainty of about Ϯ0.6 m s Ϫ1 . Approximately 29% of the 1515 total derived values were negative, 35% exceeded 1 m s Ϫ1 , and 9% exceeded 2.0 m s Ϫ1 . These values are consistent with studies in the Pacific Northwest, except that more extreme values were observed in one band than have been previously reported. There was a high correlation between values of signal-to-noise ratio (SNR) and w within each band (0.60 Յ r Յ 0.85), in the composite of bands from each cyclone (0.59 Յ r Յ 0.79), and in the overall analysis (r ϭ 0.68). The strongest updrafts were typically between 2.0 and 4.0 m s Ϫ1 and were located near the center of each band in regions of high SNR. Regions of downdrafts within the bands had maximum values between Ϫ1.0 and Ϫ4.3 m s Ϫ1 and were typically located along the edges of the bands in regions of low SNR. These results are consistent with snow growth and sublimation processes. The magnitudes of the vertical velocities in the core of the bands were comparable to theoretical predictions for moist symmetric instability (MSI) under inviscid conditions but would appear to be somewhat larger than expected for MSI when turbulent mixing is considered, suggesting that other instabilities, such as potential instability, may have contributed to the band development in these storms.

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A Numerical Study of the Role of Humidity in the Updraft Driven by Moist Slantwise Convection

Cited by 11 publications

References 0 publications

A Study of Cloud Microphysical Processes Associated With Torrential Rainfall Event Over Beijing

A Study of Cloud Microphysical Processes Associated With Torrential Rainfall Event Over Beijing

The Impact of Spume Droplets and Wave Stress Parameterizations on Simulated Near-Surface Maritime Wind and Temperature

Vertical Motions in Precipitation Bands in Three Winter Cyclones

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