Characteristics and environmental conditions of quasi‐stationary convective clusters during the warm season in Japan

The characteristics and environmental properties of warm-season quasi-stationary convective clusters (QSCCs) in Japan were statistically investigated using operational weather radar and upper-air sounding data from May to October during 2005–2012. The characteristics of the environmental conditions for the development of QSCCs were described through a comparison with those for no-rain cases. We identified 4133 QSCCs over the Japanese major islands. By compiling numerous QSCC samples, the horizontal scales of QSCCs with a circular shape are about 20 km on average with a maximum of 72 km, indicating that warm-season QSCCs in Japan are meso-β-scale phenomena. The analyses of the environmental conditions for the QSCC and no-rain cases showed that the amount of moisture in the lower layer controls the stability condition for the development of the QSCCs, and that the magnitudes of the wind shear and the helicity in the lower troposphere distinguish the kinematic environments for the development of the QSCCs. An increase in the middle-level moisture leads to a larger amount of precipitable water vapour in the QSCC environments, suggesting that atmospheric moistening before the development stage of convection plays an important role in the development of the QSCCs. Additionally, the precipitation intensity has a higher correlation with the convective instability, whereas the precipitation area correlates with the shear intensity. A comparison between slower- and faster-moving CCs indicated that the precipitation intensity of the slower-moving CCs is stronger. This feature is related to a higher convective instability for the slower-moving ones.

[1]  Joseph B. Klemp,et al.  The Dependence of Numerically Simulated Convective Storms on Vertical Wind Shear and Buoyancy , 1982 .

[2]  Matthias Steiner,et al.  Climatological Characterization of Three-Dimensional Storm Structure from Operational Radar and Rain Gauge Data , 1995 .

[3]  T. Kato,et al.  Formation and Maintenance Processes of a Stationary Band-shaped Heavy Rainfall Observed in Niigata on 4 August 1998 , 2001 .

[4]  T. Kato,et al.  Formation Factors of 2004 Niigata-Fukushima and Fukui Heavy Rainfalls and Problems in the Predictions using a Cloud-Resolving Model , 2005 .

[5]  Morris L. Weisman,et al.  “A Theory for Strong Long-Lived Squall Lines” Revisited , 2004 .

[6]  T. Kato,et al.  Kinetic Energy Budget Analysis on the Development of a Meso-β-Scale Vortex Causing Heavy Rainfall, Observed over Aomori Prefecture in Northern Japan on 11 November 2007 , 2012 .

[7]  Y. Takayabu,et al.  The development of organized convection associated with the MJO during TOGA COARE IOP: Trimodal characteristics , 2004 .

[8]  T. Takemi,et al.  Environmental Stability for Afternoon Rain Events in the Kanto Plain in Summer , 2011 .

[9]  R. Plant,et al.  A ‘Boscastle‐type’ quasi‐stationary convective system over the UK Southwest Peninsula , 2014 .

[10]  E. Rasmussen,et al.  A Baseline Climatology of Sounding-Derived Supercell and Tornado Forecast Parameters , 1998 .

[11]  T. Takemi.  A sensitivity of squall-line intensity to environmental static stability under various shear and moisture conditions , 2007 .

[12]  I. Orlanski.  A rational subdivision of scales for atmospheric processes , 1975 .

[13]  T. Takemi.  Convection and precipitation under various stability and shear conditions: Squall lines in tropical versus midlatitude environment , 2014 .

[14]  C. Chappell.  Quasi-Stationary Convective Events , 1986 .

[15]  G. M. Barnes,et al.  The Environment of Fast- and Slow-Moving Tropical Mesoscale Convective Cloud Lines , 1984 .

[16]  T. Kato.  Statistical Study of Band-Shaped Rainfall Systems, the Koshikijima and Nagasaki Lines, Observed around Kyushu Island, Japan , 2005 .

[17]  P. Markowski,et al.  Mesoscale Meteorology in Midlatitudes , 2010 .

[18]  H. Niino,et al.  Climatology of Environmental Parameters for Mesoscale Convections in Japan , 2005 .

[19]  Zhiyong Meng,et al.  General Features of Squall Lines in East China , 2013 .

[20]  Richard H. Johnson,et al.  Mesoscale Processes Contributing to Extreme Rainfall in a Midlatitude Warm-Season Flash Flood* , 2008 .

[21]  Luigi Foschini,et al.  Mesoscale Meteorological Features Associated with Heavy Precipitation in the Southern Alpine Region , 2000 .

[22]  B. Geerts.  Mesoscale Convective Systems in the Southeast United States during 1994–95: A Survey , 1998 .

[23]  T. Kato.  Numerical Simulation of the Band-shaped Torrential Rain Observed over Southern Kyushu, Japan on 1 August 1993 , 1998 .

[24]  H. Takayama,et al.  Analytical and numerical study of the 26 June 1998 orographic rainband observed in Western Kyushu, Japan , 2000 .

[25]  Silvio Davolio,et al.  Orographic triggering of long lived convection in three dimensions , 2009 .

[26]  Howard B. Bluestein,et al.  Formation of Mesoscale Lines of Pirecipitation: Severe Squall Lines in Oklahoma during the Spring , 1985 .

[27]  H. Uyeda,et al.  Algorithm for the Identification and Tracking of Convective Cells Based on Constant and Adaptive Threshold Methods Using a New Cell-Merging and -Splitting Scheme , 2012 .

[28]  T. Kato.  Structure of the Band-Shaped Precipitation System Inducing the Heavy Rainfall Observed over Northern Kyushu, Japan on 29 June 1999 , 2006 .

[29]  T. Glickman,et al.  Glossary of Meteorology , 2000 .

[30]  Howard B. Bluestein,et al.  Formation of Mesoscale Lines of Precipitation: Nonsevere Squall Lines in Oklahoma during the Spring , 1987 .

[31]  S. Anquetin,et al.  Numerical simulation of orographic rainbands , 2003 .

[32]  Robert Davies-Jones,et al.  Streamwise Vorticity: The Origin of Updraft Rotation in Supercell Storms , 1984 .

[33]  Curtis N. James,et al.  Mesoscale organization and structure of orographic precipitation producing flash floods in the Lago Maggiore region , 2015 .

[34]  Richard H. Johnson,et al.  Organizational Modes of Midlatitude Mesoscale Convective Systems , 2000 .

[35]  Pedro M. M. Soares,et al.  Sensitivity of moist convection to environmental humidity , 2004 .

[36]  J. Michael Fritsch,et al.  The Large-Scale Environments of the Global Populations of Mesoscale Convective Complexes , 2000 .

[37]  T. Takemi.  Characteristics of Summertime Afternoon Rainfall and Its Environmental Conditions in and around the Nobi Plain , 2014 .

[38]  R. Maddox.  Meoscale Convective Complexes , 1980 .

[39]  C. Doswell,et al.  Flash Flood Forecasting: An Ingredients-Based Methodology , 1996 .

[40]  Collected Reprint Series.  7. Mesoscale Convective Complexes in the Americas , 2013 .

[41]  Joseph J. George,et al.  Weather Forecasting for Aeronautics , 2014 .

[42]  Edward J. Zipser,et al.  The Role of Environmental Shear and Thermodynamic Conditions in Determining the Structure and Evolution of Mesoscale Convective Systems during TOGA COARE , 1998 .

[43]  T. Takemi,et al.  Factors responsible for the vertical development of tropical oceanic cumulus convection , 2004 .

[44]  T. Takemi.  Environmental stability control of the intensity of squall lines under low‐level shear conditions , 2007 .

[45]  T. Takemi.  Relationship between Cumulus Activity and Environmental Moisture during the CINDY2011/DYNAMO Field Experiment as Revealed from Convection-Resolving Simulations , 2015 .