Convective self-aggregation in numerical simulations: a review

Organized convection in the Tropics occurs across a range of spatial and temporal scales and strongly influences cloud cover and humidity. One mode of organization found is “self-aggregation”, in which moist convection spontaneously organizes into one or several isolated clusters despite spatially homogeneous boundary conditions and forcing. Self-aggregation is driven by interactions between clouds, moisture, radiation, surface fluxes, and circulation, and occurs in a wide variety of idealized simulations of radiative-convective equilibrium. Here we provide a review of convective self-aggregation in numerical simulations, including its character, causes, and effects. We describe the evolution of self-aggregation including its time and length scales and the physical mechanisms leading to its triggering and maintenance, and we also discuss possible links to climate and climate change

Cumulus Friction in the Asian Monsoon of a Global Model with 7 km Mesh

Vertical Cheedela, Suvarchal K. of horizontal momentum by convective eddies (CMT) in the 7–400 km size range is examined comprehensively in data from the GEOS-5 Nature Run (G5NR), a 2-year global Mapes, Brian E. with a 7 km horizontal mesh. This diagnosis is possible because NASA offers a coarse-grained dataset of the quadratic flux terms wu and wv in addition to the model velocity variables u, v, w. We assess the time tendency of large-scale vertically integrated shear kinetic energy (SKE) due to CMT. Negative values of a few tenths of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$1W m^{-2}$$\end{document} prevail on average over warm tropical oceans, indicating that explicit convection on these scales exerts a viscous or frictional or downgradient transport effect on wind shear. However, positive as well as negative values do occur locally, based on spatial correlations u\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^\prime$$\end{document}w\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^\prime$$\end{document} and v\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^\prime$$\end{document}w\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^\prime$$\end{document} in the arrangement (“organization”) of convective motions. In the Asian monsoon, where convection and shear are both strong, the viscosity can be characterized by a regression coefficient with values of about 5% cm\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{-1}$$\end{document}, meaning that convection which yields 1 cm of precipitation decrements SKE by about 5%. Adjustment of balanced monsoon flow to such a viscous effect implies adiabatic ascent to the north of existing convection, a mechanism that may be relevant to northward-propagating large-scale variability

The 2001 Mesoscale Convective Systems over iberia and the Balearic Islands

This paper characterizes Mesoscale Convective Systems (MCSs) during 2001 over Iberia and the Balearic Islands and their meteorological settings. Enhanced infrared Meteosat imagery has been used to detect their occurrence over the Western Mediterranean region between June and December 2001 according to satellite-defined criteria based on the MCS physical characteristics. Twelve MCSs have been identified. The results show that the occurrence of 2001 MCSs is limited to the August-October period, with September being the most active period. They tend to develop during the late afternoon or early night, with preferred eastern Iberian coast locations and eastward migrations. A cloud shield area of 50.000 km(2) is rarely exceeded. When our results are compared with previous studies, it is possible to assert that though 2001 MCS activity was moderate, the convective season was substantially less prolonged than usual, with shorter MCS life cycles and higher average speeds. The average MCS precipitation rate was 3.3 mm.h(-1) but a wide range of values varying from scarce precipitation to intense events of 130 mm.24 h(-1) (6 September) were collected. The results suggest that, during 2001, MCS rainfall was the principal source of precipitation in the Mediterranean region during the convective season, but its impact varied according to the location. Synoptic analysis based on NCEP/NCAR reanalysis show that several common precursors could be identified over the Western Mediterranean Sea when the 2001 MCSs occurred: a low-level tongue of moist air and precipitable water (PW) exceeding 25 mm through the southern portion of the Western Mediterranean area, low-level zonal warm advection over 2 degrees C.24 h(-1) towards eastern Iberia, a modest 1000-850 hPa equivalent potential temperature (theta(e)) difference over 20 degrees C located close to the eastern Iberian coast, a mid level trough (sometimes a cut-off low) over Northern Africa or Southern Spain and high levels geostrophic vorticity advection exceeding 12.10(-10) s(-2) over eastern Iberia and Northern Africa. Finally, the results suggest that synoptic, orographic and a warm-air advection were the most relevant forcing mechanisms during 2001

Contabilidad agropecuaria - Emisión No. 30

En esta emisión, se realizan ejercicios para que el radio-estudiante pueda practicar, sobre el uso del debe y el haber