The exchange across the tropical tropopause in overshooting convective cores

Abstract

Abstract. Coordinated measurements of Indian MST radar and radiosonde during the passage of overshooting convective cores in SAFAR pilot campaign (May-November 2008) are utilized to quantify the mass flux across the tropopause and strength of the turbulence in up-and down-draft cores. The distribution of retrieved mass flux is found to be wide, ranging from −0.6 (downward flux) to 0.8 kg m −2 s −1 (upward flux). The net mass flux, is, however, from the troposphere to stratosphere, in spite of the existence of significant amount of downward flux. For the first time, the turbulence strength in the vicinity of the tropopause in convective cores is quantified. Large spectral widths with magnitudes >4 m s −1 are observed during convection. However, such large spectral widths are rare and are observed only for 1.6% of total observations. The average spectral width (and also the variation or standard deviation) in draft cores is found to be ∼4.5 times larger than that in fair-weather. The turbulence strength in updraft cores is much higher than that of in downdraft cores. The mean (median) spectral width in updraft cores is larger by ∼0.8 m s −1 (a factor of ∼2) than that of in downdraft cores. The turbulence strength does not show any systematic variation with the intensity of convection in both up-and down-draft cores. The distributions and mean values of mass flux and turbulence strength obtained in the present study will be useful to quantify the STE due to direct intrusion of mass by overshooting convection and the exchange of constituents (in particular water vapor) due to turbulence in a better way.

Morphology of the vertical structure of precipitation over India and adjoining oceans based on long-term measurements of TRMM PR

“…None of the studies compared the vertical profiles as a function of season, region, and rain type to know why and where (at what height) the variations are large? Most of the above studies have not discussed the regional and seasonal variability of the shallow rain in India and its surroundings. It will be shown later that the shallow rain, indeed, is important and occurs preferentially in some regions of India. None of the above studies quantified the morphological features of virga rain (rain that evaporates before reaching the surface), like its vertical structure and its occurrence in different seasons and types of rain. Although the impact of overshooting convection on stratosphere‐troposphere exchange is known to a great extent through case studies [ Holton et al ., ; Rao et al ., ], several fundamental statistical issues remain. For example, how often the convection penetrates into the upper troposphere (and overshoots the tropopause)?…”

“…6. Although the impact of overshooting convection on stratosphere-troposphere exchange is known to a great extent through case studies [Holton et al, 1995;Rao et al, 2010], several fundamental statistical issues remain. For example, how often the convection penetrates into the upper troposphere (and overshoots the tropopause)?…”

An Analysis of a Severe Turbulence Event Encountered by an Aircraft over the South China Sea and the Application of Numerical Weather Prediction Models in the Early Alerting of the Event

“…Occurrence of clear air turbulence in the tropics has been reported in Roach and Bysouth [1]. Severe turbulence in the significant convection over the tropics has been observed in the radar as reported in Rao et al [2]. Ahmad and Proctor [3] studied some convection induced turbulence cases using large eddy simulations and found that there were areas of significant turbulence upwind of the convection in the upper level of the troposphere.…”

RainForest: A random forest algorithm for quantitative precipitation estimation over Swizerland

“…Secondly, this is a way for the regressor to account for the spatial precipitation structure over Switzerland, for example Alpine regions with relatively poor visibility, where precipitation tends to be underestimated by the RZC product are characterized by low radar fractions from the three lower radars (Albis, La Dôle and Monte Lema). Surprisingly the spectral width 10 S w seems to play a relatively large role, which can be due to the fact that it is an indicator of convection (Hooper et al, 2005;Rao et al, 2010), which leads to different relations between precipitation and radar observables. Note also that the relatively low importance of the height (in fact this is the average weighted height of the observations aloft) and the visibility is likely explained by the fact that these variables are already included in the exponential weighting (Section 3.3 and, for the visibility, in the correction of Z h and Z v ( Table 2).…”