Abstract
Abstract. Although it is generally accepted that the level of neutral buoyancy (LNB) is only a coarse estimate of updraft depth, the LNB is still used to understand and predict storm structure in both observations and modeling. This study uses case studies to quantify the variability associated with using environmental soundings to predict detrainment levels. Nine dual-Doppler convective cases were used to determine the observed level of maximum detrainment (LMD) to compare with the LNB. The LNB for each case was calculated with a variety of methods and with a variety of sources (including both observed and simulated soundings). The most representative LNB was chosen as the proximity sounding from NARR using the most unstable parcel and including ice processes. The observed cases were a mix of storm morphologies, including both supercell and multicell storms. As expected, the LMD was generally below the LNB, the mean offset for all cases being 2.2 km. However, there was a marked difference between the supercell and non-supercell cases. The two supercell cases had LMDs of 0.3 km and 0.0 km below the LNB. The remaining cases had LMDs that ranged from 4.0 km below to 1.6 km below the LNB, with a mean offset of 2.8 km below. Observations also showed that evolution of the LMD over the lifetime of the storm can be significant (e.g., >2 km altitude change in 30 min), and this time evolution is lacking from models with coarse time steps, missing significant changes in detrainment levels that may strongly impact the amount of boundary layer mass transported to the upper troposphere and lower stratosphere.
Highlights
The most efficient method for transporting heat, moisture, and chemical tracers from the boundary layer to the upper troposphere and lower stratosphere is through moist convection (e.g., Dickerson, 1987; Pickering et al, 1988; Mullendore et al, 2005)
The level of maximum detrainment (LMD) was generally below the level of neutral buoyancy (LNB), the mean offset for all cases being 2.2 km
Using a method proposed in Mullendore et al (2009), nine dual-Doppler convective cases were used to determine the observed level of maximum detrainment (LMD) to compare with the LNB
Summary
The most efficient method for transporting heat, moisture, and chemical tracers from the boundary layer to the upper troposphere and lower stratosphere is through moist convection (e.g., Dickerson, 1987; Pickering et al, 1988; Mullendore et al, 2005). To understand the potential for deep convective transport in certain storm regimes, we need to understand the relationship between the LNB and the observed level of maximum detrainment (LMD, Mullendore et al, 2009). This relationship was analyzed for tropical convection in a recent study by Takahashi and Luo (2012). They used CloudSat reflectivity data as a proxy for LMD (“LNB maxMass” in their paper), and compared this to LNB values derived from ECMWF analysis profiles. 10.9 either 0.5 or 1.0 km resolution in the horizontal (see dualDoppler processing articles cited above)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
