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quantities that may influence convection initiation, maintenance, and organization associated with bores. While detailed bore studies will appear in the subsequent literature, Wilson and Roberts (2006) show statistics on the frequency of bore-related IHOP_2002 convection initiation in this issue. h. Topographic and land surface effects Numerous studies have illustrated the importance of regional gradients in surface characteristics for accurately predicting the onset of convection (e.g., Anthes et al
quantities that may influence convection initiation, maintenance, and organization associated with bores. While detailed bore studies will appear in the subsequent literature, Wilson and Roberts (2006) show statistics on the frequency of bore-related IHOP_2002 convection initiation in this issue. h. Topographic and land surface effects Numerous studies have illustrated the importance of regional gradients in surface characteristics for accurately predicting the onset of convection (e.g., Anthes et al
particles in marine stratocumulus and cumulus clouds . Quart. J. Roy. Meteor. Soc. , 129 , 1329 – 1350 . Greenwald , T. J. , G. L. Stephens , S. A. Christopher , and T. H. VonderHaar , 1995 : Observations of the global characteristics and regional radiative effects of marine cloud liquid water . J. Climate , 8 , 2928 – 2946 . Gultepe , I. , and G. A. Isaac , 2004 : Aircraft observations of cloud droplet number concentration: Implications for climate studies . Quart. J. Roy
particles in marine stratocumulus and cumulus clouds . Quart. J. Roy. Meteor. Soc. , 129 , 1329 – 1350 . Greenwald , T. J. , G. L. Stephens , S. A. Christopher , and T. H. VonderHaar , 1995 : Observations of the global characteristics and regional radiative effects of marine cloud liquid water . J. Climate , 8 , 2928 – 2946 . Gultepe , I. , and G. A. Isaac , 2004 : Aircraft observations of cloud droplet number concentration: Implications for climate studies . Quart. J. Roy
, 2009a ; Aksoy et al. 2005 , 2006a , b ; Houtekamer et al. 2005 , 2009 ; Tong and Xue 2005 ; Dirren et al. 2007 ; Meng and Zhang 2007 , 2008a , b ; Whitaker et al. 2008 ; Torn and Hakim 2008a , 2009a ; Buehner et al. 2010a , b ). There are several recent review articles on the EnKF including, Evensen (2003 , 2007) , Hamill (2006) , and Ehrendorfer (2007) . However, none of these is dedicated to EnKF applications ranging from regional to meso- and convective scales in limited
, 2009a ; Aksoy et al. 2005 , 2006a , b ; Houtekamer et al. 2005 , 2009 ; Tong and Xue 2005 ; Dirren et al. 2007 ; Meng and Zhang 2007 , 2008a , b ; Whitaker et al. 2008 ; Torn and Hakim 2008a , 2009a ; Buehner et al. 2010a , b ). There are several recent review articles on the EnKF including, Evensen (2003 , 2007) , Hamill (2006) , and Ehrendorfer (2007) . However, none of these is dedicated to EnKF applications ranging from regional to meso- and convective scales in limited
companion article (Keller et al. 2018, manuscript submitted to Mon. Wea. Rev ., hereafter Part II) covers research progress related to ET’s downstream impacts, including downstream cyclogenesis, cyclone evolution after becoming extratropical, effects on the midlatitude flow and predictability, and phenomena such as predecessor rain events. 2. Classifiers Jones et al. (2003) discussed the need to develop improved conceptual models of, and diagnostic tools for, ET, with a particular focus toward the
companion article (Keller et al. 2018, manuscript submitted to Mon. Wea. Rev ., hereafter Part II) covers research progress related to ET’s downstream impacts, including downstream cyclogenesis, cyclone evolution after becoming extratropical, effects on the midlatitude flow and predictability, and phenomena such as predecessor rain events. 2. Classifiers Jones et al. (2003) discussed the need to develop improved conceptual models of, and diagnostic tools for, ET, with a particular focus toward the
applications in the future, but a lot of work has been accomplished since. At the Canadian Meteorological Centre (CMC), a global EnKF has been used operationally since January 2005 to provide the initial conditions for a global ensemble prediction system ( Houtekamer et al. 2005 ). In this system, observation preprocessing is done by a higher-resolution variational analysis system. At the time of this writing, the global EnKF is also used to provide initial and lateral boundary conditions to a regional
applications in the future, but a lot of work has been accomplished since. At the Canadian Meteorological Centre (CMC), a global EnKF has been used operationally since January 2005 to provide the initial conditions for a global ensemble prediction system ( Houtekamer et al. 2005 ). In this system, observation preprocessing is done by a higher-resolution variational analysis system. At the time of this writing, the global EnKF is also used to provide initial and lateral boundary conditions to a regional
-resolution regions ( Medvigy et al. 2013 ; Sakaguchi et al. 2016 ), and overall regional climate metrics ( Medvigy et al. 2010 ; Harris and Lin 2014 ; Harris et al. 2016 ; Sakaguchi et al. 2015 ; Zarzycki et al. 2015 ; Huang et al. 2016 ). Boundary effects have also been evaluated, finding few artifacts in propagating waves throughout the variable-resolution domain ( Harris and Lin 2013 ; Hagos et al. 2013 ; Park et al. 2014 ; Zarzycki et al. 2015 ). So far the most challenging issue for VR models is
-resolution regions ( Medvigy et al. 2013 ; Sakaguchi et al. 2016 ), and overall regional climate metrics ( Medvigy et al. 2010 ; Harris and Lin 2014 ; Harris et al. 2016 ; Sakaguchi et al. 2015 ; Zarzycki et al. 2015 ; Huang et al. 2016 ). Boundary effects have also been evaluated, finding few artifacts in propagating waves throughout the variable-resolution domain ( Harris and Lin 2013 ; Hagos et al. 2013 ; Park et al. 2014 ; Zarzycki et al. 2015 ). So far the most challenging issue for VR models is
vegetation, climate, and terrain. The region’s tall trees, many reaching 30 to 60 m in height, act as “force multipliers,” with much of the damage to buildings and power lines associated not with direct wind damage but from the impact of falling trees. Strong winds, predominantly during major cyclones, account for 80% of regional tree mortality, rather than old age or disease ( Kirk and Franklin 1992 ). Heavy precipitation in the autumn, which saturates Northwest soils by mid-November, enhances the
vegetation, climate, and terrain. The region’s tall trees, many reaching 30 to 60 m in height, act as “force multipliers,” with much of the damage to buildings and power lines associated not with direct wind damage but from the impact of falling trees. Strong winds, predominantly during major cyclones, account for 80% of regional tree mortality, rather than old age or disease ( Kirk and Franklin 1992 ). Heavy precipitation in the autumn, which saturates Northwest soils by mid-November, enhances the
difficult ( McCarthy 1996 ), probably limiting more widespread usage. e. Neglected effects It is important to note that the concept of MSI, like gravitational instability, is based upon parcel theory. Therefore, the caveats and limitations with using parcel theory for gravitational convection also apply to using parcel theory for slantwise convection. [For further discussion on parcel theory as applied to symmetric instability, see Thorpe et al. (1989) .] In particular
difficult ( McCarthy 1996 ), probably limiting more widespread usage. e. Neglected effects It is important to note that the concept of MSI, like gravitational instability, is based upon parcel theory. Therefore, the caveats and limitations with using parcel theory for gravitational convection also apply to using parcel theory for slantwise convection. [For further discussion on parcel theory as applied to symmetric instability, see Thorpe et al. (1989) .] In particular
or a linear form CDN (10) X lfP = 0.75 +0.067 V. Results of recent turbulence sensor comparison experiments suggest that much of the source of datascatter in C~)~q (V) plots and of the systematic differences between data sets is due to calibration uncertaintiesassociated with sensor performance in the field. The effects (if any) of fetch, wind duration and unsteadinessremain obscured in this experimental data scatter. Vertical transfer of momentum over land may be described
or a linear form CDN (10) X lfP = 0.75 +0.067 V. Results of recent turbulence sensor comparison experiments suggest that much of the source of datascatter in C~)~q (V) plots and of the systematic differences between data sets is due to calibration uncertaintiesassociated with sensor performance in the field. The effects (if any) of fetch, wind duration and unsteadinessremain obscured in this experimental data scatter. Vertical transfer of momentum over land may be described
(x, t + At), themidpoint of the trajectory (x - a/2, t + At/2), andthe departure point (x - a, t), and a is still the distancethe fluid particle is displaced in time At. In the above formulation the evaluation of R(1/2)involves extrapolated quantities and, therefore, couldpotentially lead to instability. Temperton and Staniforth (1987) did not find this to be a problem whensome weak nonlinear metric effects were evaluated inthis way in a shallow-water model integrated on a polarstereographic
(x, t + At), themidpoint of the trajectory (x - a/2, t + At/2), andthe departure point (x - a, t), and a is still the distancethe fluid particle is displaced in time At. In the above formulation the evaluation of R(1/2)involves extrapolated quantities and, therefore, couldpotentially lead to instability. Temperton and Staniforth (1987) did not find this to be a problem whensome weak nonlinear metric effects were evaluated inthis way in a shallow-water model integrated on a polarstereographic
