scholarly journals Track Deflection of Typhoon Maria (2018) during a Westbound Passage Offshore of Northern Taiwan: Topographic Influence

2020 ◽  
Vol 148 (11) ◽  
pp. 4519-4544
Author(s):  
Ching-Yuang Huang ◽  
Tzu-Chi Juan ◽  
Hung-Chi Kuo ◽  
Jen-Her Chen
Keyword(s):  
Mountain Range ◽  
Vortex Center ◽  
Wind Structure ◽  
Tangential Wind ◽  
Cyclonic Flow ◽  
Case Simulation ◽  
Low Levels ◽  
Topographic Influence ◽  
East West ◽  
Northern Taiwan

AbstractThis study applies a global model (FV3GFS) with stretched resolution of approximately 7 km for simulating Typhoon Maria (2018), which exhibited a sudden northward track deflection when approaching about 150 km northeast of Taiwan. As Maria approached land, the outer cyclonic flow at the western flank of the typhoon is split around the northern part of the Central Mountain Range (CMR) in Taiwan to converge east of Taiwan with the recirculating southerly flow around the southern corner of the CMR. Such strong convergence leads to northward deflection of the west-northwestward-moving typhoon with the stronger wind mainly east of the vortex center. The radial inflow at low levels is intensified south of the vortex center and transports larger angular momentum (AM) inward with the enhanced upward motions and vertical mean AM advection to increase the azimuthal mean tangential wind in the lower-tropospheric eyewall. A vorticity budget of wavenumber-1 decomposition indicates that the track deflection is dominated by horizontal vorticity advection in response to the intensifying flow. Numerical experiments with idealized WRF also support such northward track deflection as westward tropical cyclones approach a mountain range within an offshore meridional distance of about 200 km. The northward track deflection is only slightly amplified as the terrain height is considerably increased, consistent with the real-case simulation. However, the northward track deflection is not increased as the approaching vortex is initialized closer to the northern end of the mountain range, due to the enhanced east–west symmetry of wind structure in the inner vortex.

scholarly journals Variations in the Distribution and Genetic Relationships among Luciola unmunsana Populations in South Korea

Land ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 730
Author(s):  
Tae-Su Kim ◽  
Kwanik Kwon ◽  
Gab-Sue Jang
Keyword(s):  
South Korea ◽  
Genetic Relationships ◽  
Abundant Species ◽  
Mountain Range ◽  
Eastern Region ◽  
Landscape Conservation ◽  
Conservation Area ◽  
Ecological Landscape ◽  
Close Genetic Relationship ◽  
East West

The firefly species Luciola unmunsana was first discovered on the Unmunsan Mountain in Cheongdo-gun, Gyeongsangbuk-do, South Korea and consequently named after the mountain. The population and habitats of this once-abundant species have recently decreased significantly due to light and environmental pollution caused by industrialization and urbanization. This study investigated the distribution and density of L. unmunsana around the ecological landscape conservation area of the Unmunsan Mountain. Additionally, we conducted molecular experiments on regional variations, genetic diversity and phylogenetic relationships among the various populations of L. unmunsana in South Korea. The genetic relationships among populations were also analyzed using mitochondrial DNA by collecting 15 male adults from each of the 10 regions across South Korea selected for analysis. Differences were observed between populations in the east, west and south of the Baekdudaegan Mountain Range. The firefly populations collected from the eastern region, which included Gyeongsang-do, showed a close genetic relationship with fireflies collected from the Unmunsan Mountain. Thus, the findings of this study can be used as baseline data for re-introducing L. unmunsana to the Unmunsan Mountain.

scholarly journals Genetic analysis reveals an east-west divide within North American Vitis species that mirrors their resistance to Pierce’s disease

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243445
Author(s):  
Summaira Riaz ◽  
Alan C. Tenscher ◽  
Claire C. Heinitz ◽  
Karla G. Huerta-Acosta ◽  
M. Andrew Walker
Keyword(s):  
Pierce's Disease ◽  
Mountain Range ◽  
Vitis Species ◽  
Pierce’S Disease ◽  
Southeastern Us ◽  
Wide Range ◽  
Genetic Clusters ◽  
Group 2 ◽  
United States Mexico ◽  
East West

Pierce’s disease (PD) caused by the bacterium Xylella fastidiosa is a deadly disease of grapevines. This study used 20 SSR markers to genotype 326 accessions of grape species collected from the southeastern and southwestern United States, Mexico and Costa Rica. Two hundred sixty-six of these accessions, and an additional 12 PD resistant hybrid cultivars developed from southeastern US grape species, were evaluated for PD resistance. Disease resistance was evaluated by quantifying the level of bacteria in stems and measuring PD symptoms on the canes and leaves. Both Bayesian clustering and principal coordinate analyses identified two groups with an east-west divide: group 1 consisted of grape species from the southeastern US and Mexico, and group 2 consisted of accessions collected from the southwestern US and Mexico. The Sierra Madre Oriental mountain range appeared to be a phylogeographic barrier. The state of Texas was identified as a potential hybridization zone. The hierarchal STRUCTURE analysis on each group showed clustering of unique grape species. An east-west divide was also observed for PD resistance. With the exception of Vitis candicans and V. cinerea accessions collected from Mexico, all other grape species as well as the resistant southeastern hybrid cultivars were susceptible to the disease. Southwestern US grape accessions from drier desert regions showed stronger resistance to the disease. Strong PD resistance was observed within three distinct genetic clusters of V. arizonica which is adapted to drier environments and hybridizes freely with other species across its wide range.

scholarly journals Sensitivity of Tropical Cyclone Intensification to Axisymmetric Heat Sources: The Role of Low-Level Heating and Cooling from Different Microphysical Processes

2018 ◽  
Vol 75 (12) ◽  
pp. 4229-4246
Author(s):  
Georgina Paull ◽  
Konstantinos Menelaou ◽  
M. K. Yau
Keyword(s):  
Tropical Cyclone ◽  
Hurricane Katrina ◽  
Heat Sources ◽  
Absolute Vorticity ◽  
Heating And Cooling ◽  
Tangential Wind ◽  
Case Simulation ◽  
Microphysical Processes ◽  
Background State

Abstract Latent heat release from condensational heating has been recognized as one of the dominating energy sources of a tropical cyclone. Here we argue that other microphysical processes may also play an important role. From an analysis of a real-case simulation of Hurricane Katrina (2005), it was found that cooling from evaporation and melting of some frozen hydrometeors radially outside the eyewall region can have similar magnitudes as condensational heating. Based on this finding, idealized thermally forced experiments were performed. The specified heating and cooling functions mimic those found in the Hurricane Katrina run. The results indicated that the addition of cooling enhances the lower-level inward radial winds, which in turn increases the acceleration of the lower-level tangential winds through an enhanced transport of absolute vorticity. Sensitivity experiments on varying the structure of the cooling functions and the background state of the vortex demonstrate that the lower-level tangential wind acceleration is more sensitive to changes in the vertical structure and location of the cooling than the radial characteristics. In addition, the lower-level acceleration is sensitive to variations in the inertial and static stabilities rather than the vertical tangential wind shear of the initial vortex and its environment.

scholarly journals Sensitivity of Tropical Cyclone Intensification to Axisymmetric Heat Sources: The Role of Inertial Stability

2017 ◽  
Vol 74 (7) ◽  
pp. 2325-2340 ◽  
Author(s):  
Georgina Paull ◽  
Konstantinos Menelaou ◽  
M. K. Yau
Keyword(s):  
Tropical Cyclone ◽  
Heat Source ◽  
Wrf Model ◽  
Thermodynamic Efficiency ◽  
Heat Sources ◽  
Nonlinear Simulation ◽  
Wind Structure ◽  
Tangential Wind ◽  
Balanced Model

Abstract This study examines the influences of an axisymmetric heat source on the tangential wind structure of a tropical cyclone (TC). Specifically, the response of a TC due to the effect of convection located in varying inertial stability profiles was calculated. Using an idealized heat source, the thermodynamic efficiency hypothesis and the dynamic hypothesis for lower-level tangential wind acceleration are studied with the use of a balanced 2D model. These two frameworks for calculating the lower-level tangential wind acceleration are then compared to an idealized but thermally forced version of a nonlinear 3D model (WRF). It is found that using either of the 2D balanced model approaches to calculate the tangential wind acceleration results in an underestimation when compared to the full nonlinear simulation. In addition, the thermodynamic efficiency approach also shows a radial shift in the location of the maximum lower-level tangential wind acceleration. Sensitivity experiments in the context of the WRF Model in varying background inertial instabilities were investigated. It is shown that as the eyewall-like heating is shifted to larger values of inertial stability, there is a decrease in the induced secondary circulation in tandem with a spinup of the lower-level tangential winds. This intensification appears to be modulated by the low-level radial advection of absolute vorticity.

Asymmetric Rainband Processes Leading to Secondary Eyewall Formation in a Model Simulation of Hurricane Matthew (2016)

2021 ◽  
Vol 78 (1) ◽  
pp. 29-49
Author(s):  
Chau-Lam Yu ◽  
Anthony C. Didlake ◽  
Fuqing Zhang ◽  
Robert G. Nystrom
Keyword(s):  
Wind Field ◽  
Model Simulation ◽  
Wind Maximum ◽  
Low Level ◽  
Secondary Eyewall Formation ◽  
Positive Acceleration ◽  
Radial Extent ◽  
Tangential Wind ◽  
Low Levels ◽  
Left Quadrant

AbstractThe dynamics of an asymmetric rainband complex leading into secondary eyewall formation (SEF) are examined in a simulation of Hurricane Matthew (2016), with particular focus on the tangential wind field evolution. Prior to SEF, the storm experiences an axisymmetric broadening of the tangential wind field as a stationary rainband complex in the downshear quadrants intensifies. The axisymmetric acceleration pattern that causes this broadening is an inward-descending structure of positive acceleration nearly 100 km wide in radial extent and maximizes in the low levels near 50 km radius. Vertical advection from convective updrafts in the downshear-right quadrant largely contributes to the low-level acceleration maximum, while the broader inward-descending pattern is due to horizontal advection within stratiform precipitation in the downshear-left quadrant. This broad slantwise pattern of positive acceleration is due to a mesoscale descending inflow (MDI) that is driven by midlevel cooling within the stratiform regions and draws absolute angular momentum inward. The MDI is further revealed by examining the irrotational component of the radial velocity, which shows the MDI extending downwind into the upshear-left quadrant. Here, the MDI connects with the boundary layer, where new convective updrafts are triggered along its inner edge; these new upshear-left updrafts are found to be important to the subsequent axisymmetrization of the low-level tangential wind maximum within the incipient secondary eyewall.

scholarly journals Track Deflection of Typhoon Nesat (2017) as Realized by Multiresolution Simulations of a Global Model

2019 ◽  
Vol 147 (5) ◽  
pp. 1593-1613 ◽  
Author(s):  
Ching-Yuang Huang ◽  
Chien-Hsiang Huang ◽  
William C. Skamarock
Keyword(s):  
Large Scale ◽  
Model Simulation ◽  
Global Model ◽  
Mountain Range ◽  
Latent Heating ◽  
The West ◽  
Topographical Effects ◽  
Typhoon Center ◽  
Underlying Mechanisms ◽  
Northern Taiwan

Abstract Typhoon Nesat (2017) headed west-northwestward toward Taiwan but took a relatively larger northward deflection about 300 km away and then a leftward deflection after landfall at northern Taiwan. A global model MPAS, employing a multiresolution of 60–15–3 km mesh, is used to investigate the underlying mechanisms of the track changes. The global model simulations are capable of resolving the detailed topographical effects of the Central Mountain Range (CMR) in Taiwan, giving reasonable 5 day tracks in agreement with the observations for Typhoons Soudelor (2015) and Megi (2016), and comparing better with the observed deflection of Nesat (2017) than the regional model simulation of WRF. Sensitivity experiments indicate that flattening the CMR only partially reduces the track deflection of Nesat, while the elimination of the initial cyclone over the South China Sea disables the possible Fujiwhara effect and leads to a southward-biased track with much weaker northward deflection. The northward deflection of Nesat is mainly in response to the wavenumber-1 (WN-1) horizontal PV advection as the southerly flow east of the typhoon center is enhanced by convergence with the outer cyclonic typhoon flow and the large-scale southwesterlies. Upward motions and PV in the troposphere thus are much stronger to the east of the center than to the west, resulting in westward translation induced by negative WN-1 vertical PV advection but eastward translation induced by positive WN-1 vertical differential latent heating to the east. Near landfall, with stronger upward motions produced over the northern CMR, vertical differential latent heating averaged in 3–8-km height becomes negative and thus retards the westward translation.

scholarly journals Observed Kinematic and Thermodynamic Structure in the Hurricane Boundary Layer during Intensity Change

2019 ◽  
Vol 147 (8) ◽  
pp. 2765-2785 ◽  
Author(s):  
Kyle Ahern ◽  
Mark A. Bourassa ◽  
Robert E. Hart ◽  
Jun A. Zhang ◽  
Robert F. Rogers
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Inner Core ◽  
Intensity Change ◽  
Conditional Stability ◽  
Thermodynamic Structure ◽  
Wind Structure ◽  
Tangential Wind ◽  
Axisymmetric Structure ◽  
Hurricane Boundary Layer

Abstract The axisymmetric structure of the inner-core hurricane boundary layer (BL) during intensification [IN; intensity tendency ≥20 kt (24 h)−1, where 1 kt ≈ 0.5144 m s−1], weakening [WE; intensity tendency <−10 kt (24 h)−1], and steady-state [SS; the remainder] periods are analyzed using composites of GPS dropwindsondes from reconnaissance missions between 1998 and 2015. A total of 3091 dropsondes were composited for analysis below 2.5-km elevation—1086 during IN, 1042 during WE, and 963 during SS. In nonintensifying hurricanes, the low-level tangential wind is greater outside the radius of maximum wind (RMW) than for intensifying hurricanes, implying higher inertial stability (I2) at those radii for nonintensifying hurricanes. Differences in tangential wind structure (and I2) between the groups also imply differences in secondary circulation. The IN radial inflow layer is of nearly equal or greater thickness than nonintensifying groups, and all groups show an inflow maximum just outside the RMW. Nonintensifying hurricanes have stronger inflow outside the eyewall region, likely associated with frictionally forced ascent out of the BL and enhanced subsidence into the BL at radii outside the RMW. Equivalent potential temperatures (θe) and conditional stability are highest inside the RMW of nonintensifying storms, which is potentially related to TC intensity. At greater radii, inflow layer θe is lowest in WE hurricanes, suggesting greater subsidence or more convective downdrafts at those radii compared to IN and SS hurricanes. Comparisons of prior observational and theoretical studies are highlighted, especially those relating BL structure to large-scale vortex structure, convection, and intensity.

scholarly journals A Latent Heat Retrieval and Its Effects on the Intensity and Structure Change of Hurricane Guillermo (1997). Part II: Numerical Simulations

2012 ◽  
Vol 69 (11) ◽  
pp. 3128-3146 ◽  
Author(s):  
Stephen R. Guimond ◽  
Jon M. Reisner
Keyword(s):  
Numerical Simulations ◽  
Tropical Cyclones ◽  
Latent Heat ◽  
Inner Core ◽  
Doppler Radar ◽  
Model Parameters ◽  
Saturation State ◽  
Wind Structure ◽  
Tangential Wind ◽  
Airborne Doppler Radar

Abstract In Part I of this study, a new algorithm for retrieving the latent heat field in tropical cyclones from airborne Doppler radar was presented and fields from rapidly intensifying Hurricane Guillermo (1997) were shown. In Part II, the usefulness and relative accuracy of the retrievals is assessed by inserting the heating into realistic numerical simulations at 2-km resolution and comparing the generated wind structure to the radar analyses of Guillermo. Results show that using the latent heat retrievals as forcing produces very low intensity and structure errors (in terms of tangential wind speed errors and explained wind variance) and significantly improves simulations relative to a predictive run that is highly calibrated to the latent heat retrievals by using an ensemble Kalman filter procedure to estimate values of key model parameters. Releasing all the heating/cooling in the latent heat retrieval results in a simulation with a large positive bias in Guillermo’s intensity that motivates the need to determine the saturation state in the hurricane inner-core retrieval through a procedure similar to that described in Part I of this study. The heating retrievals accomplish high-quality structure statistics by forcing asymmetries in the wind field with the generally correct amplitude, placement, and timing. In contrast, the latent heating fields generated in the predictive simulation contain a significant bias toward large values and are concentrated in bands (rather than discrete cells) stretched around the vortex. The Doppler radar–based latent heat retrievals presented in this series of papers should prove useful for convection initialization and data assimilation to reduce errors in numerical simulations of tropical cyclones.

scholarly journals Intense precipitation events in the Central range of the Iberian Peninsula

2017 ◽  
Author(s):  
Manuel Mora García ◽  
Jesus Riesco Martín ◽  
José Miguel Sánchez Llorente ◽  
Luís Rivas Soriano ◽  
Fernando de Pablo Dávila
Keyword(s):  
Iberian Peninsula ◽  
Moisture Flux ◽  
Synoptic Situation ◽  
Mountain Range ◽  
The North ◽  
Low Level Jet ◽  
Low Levels ◽  
Using Data ◽  
Precipitation Events ◽  
High Range

Abstract. Intense orographic precipitation associated with the Central range was analysed using data from 19 episodes, with the highest average values for the study area, of precipitation accumulated within 24 h, occurring between years 1958 to 2010. All events were associated with a south-westerly tropospheric flow, a low level jet, and high moisture flux at low levels. The observed moisture flux was higher than 100 m g (s kg)−1 and the dry and wet Froude numbers were greater than 1. The selected area to study this synoptic situation was Gredos, broad and high range, which is located in the eastern part of the Central mountain range and generates leeward orographic shadow. The effect of the Central range on the spatial distribution of precipitation on the Iberian Peninsula plateau results in a sharp increase in precipitation in the south of the Central mountain range, followed by a decrease to the north of this range.

Analysis and Simulations of a Heavy Rainfall Event Associated with the Passage of a Shallow Front over Northern Taiwan on 2 June 2017

2021 ◽  
Keyword(s):  
Heavy Rainfall ◽  
Heavy Rainfall Event ◽  
Mountain Range ◽  
Cold Air ◽  
Taipei Basin ◽  
Resolution Model ◽  
Northern Side ◽  
High Resolution Model ◽  
River Valleys ◽  
Northern Taiwan

Abstract From 0200 to 1000 LST 2 June 2017, the shallow, East-West oriented Mei-Yu front (< 1 km) cannot move over the Yang-Ming Mountains (with peaks ∼ 1120 m) when it first arrives. The postfrontal cold air at the surface is deflected by the Yang-Ming Mountains and moves through the Keelung River and Tamsui River valleys into the Taipei Basin. The shallow northerly winds are anchored along the northern side of the Yang-Ming Mountains for 8 hours. In addition, the southwesterly barrier jet with maximum winds in the 900–950-hPa layer brings in abundant moisture and converges with the northwesterly flow in the southwestern flank of the Mei-Yu frontal cyclone. Therefore, torrential rain (> 600 mm) occurs over the northern side of the Yang-Ming Mountains. From 1100 to 1200 LST, with the gradual deepening of the postfrontal cold air, the front finally passes over the Yang-Ming Mountains and arrives at the Taipei Basin, which results in an E-W oriented rainband with the rainfall maxima over the northwestern coast and Taipei Basin. From 1300 to 1400 LST, the frontal rainband continues to move southward with rainfall over the northwestern slopes of the Snow Mountains. In the prefrontal southwesterly flow, the orographic lifting of the moisture-laden low-level winds results in heavy rainfall on the southwestern slopes of the Snow Mountains and the Central Mountain Range. With the terrain of the Yang-Ming Mountains removed in the high-resolution model, the Mei-Yu front moves quickly southward without a rainfall maximum over the northern tip of Taiwan.

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