scholarly journals Numerical Study of Explosively Developing Extratropical Cyclones in the Northwestern Pacific Region

2008 ◽  
Vol 136 (2) ◽  
pp. 712-740 ◽  
Author(s):  
Akira Kuwano-Yoshida ◽  
Yoshio Asuma
Keyword(s):  
Pacific Ocean ◽  
Heat Release ◽  
Latent Heat ◽  
Moisture Distribution ◽  
Northwestern Pacific ◽  
Extratropical Cyclones ◽  
Latent Heat Release ◽  
Northwestern Pacific Ocean ◽  
Asian Continent ◽  
Upper Level

Abstract Numerical simulations of six explosively developing extratropical cyclones in the northwestern Pacific Ocean region are conducted using a regional mesoscale numerical model [the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5)]. Cyclones are categorized according to the locations where they form and develop: Okhotsk–Japan Sea (OJ) cyclones originate over the eastern Asian continent and develop over the Sea of Japan or the Sea of Okhotsk, Pacific Ocean–land (PO–L) cyclones also form over the Asian continent and develop over the northwestern Pacific Ocean, and Pacific Ocean–ocean (PO–O) cyclones form and develop over the northwestern Pacific Ocean. Two cases (the most extreme and normal deepening rate cases for each cyclone type) are selected and simulated. Simulations show that the extreme cyclone of each type is characterized by a different mesoscale structure and evolutionary path, which strongly reflect the larger-scale environment: an OJ cyclone has the smallest deepening rates, associated with a distinct upper-level shortwave trough, a clear lower-level cold front, and a precipitation area that is far from the cyclone center; a PO–L cyclone has moderate deepening rates with high propagation speeds under zonally stretched upper-level jets; and a PO–O cyclone has the strongest deepening rates associated with large amounts of precipitation near its center. Sensitivity experiments involving the latent heat release associated with water vapor condensation show that PO–O cyclones rarely develop without a release of latent heat and their structures are drastically different from the control runs, while OJ cyclones exhibit almost the same developments and have similar structures to the control runs. These tendencies can be seen in both extreme and normal deepening rate cases. These results reveal that the importance of latent heat release to explosive cyclone development varies among the cyclone types, as is reflected by the cyclone origin, frontal structure, moisture distribution, and jet stream configuration.

scholarly journals The Poleward Motion of Extratropical Cyclones from a Potential Vorticity Tendency Analysis

2016 ◽  
Vol 73 (4) ◽  
pp. 1687-1707 ◽  
Author(s):  
Talia Tamarin ◽  
Yohai Kaspi
Keyword(s):  
Heat Release ◽  
Latent Heat ◽  
Potential Vorticity ◽  
Growth Stage ◽  
Baroclinic Instability ◽  
Propagation Time ◽  
Latent Heat Release ◽  
Low Level ◽  
Upper Level ◽  
Tendency Analysis

Abstract The poleward propagation of midlatitude storms is studied using a potential vorticity (PV) tendency analysis of cyclone-tracking composites, in an idealized zonally symmetric moist GCM. A detailed PV budget reveals the important role of the upper-level PV and diabatic heating associated with latent heat release. During the growth stage, the classic picture of baroclinic instability emerges, with an upper-level PV to the west of a low-level PV associated with the cyclone. This configuration not only promotes intensification, but also a poleward tendency that results from the nonlinear advection of the low-level anomaly by the upper-level PV. The separate contributions of the upper- and lower-level PV as well as the surface temperature anomaly are analyzed using a piecewise PV inversion, which shows the importance of the upper-level PV anomaly in advecting the cyclone poleward. The PV analysis also emphasizes the crucial role played by latent heat release in the poleward motion of the cyclone. The latent heat release tends to maximize on the northeastern side of cyclones, where the warm and moist air ascends. A positive PV tendency results at lower levels, propagating the anomaly eastward and poleward. It is also shown here that stronger cyclones have stronger latent heat release and poleward advection, hence, larger poleward propagation. Time development of the cyclone composites shows that the poleward propagation increases during the growth stage of the cyclone, as both processes intensify. However, during the decay stage, the vertical alignment of the upper and lower PV anomalies implies that these processes no longer contribute to a poleward tendency.

scholarly journals Impact of Assimilating Upper-Level Dropsonde Observations Collected during the TCI Field Campaign on the Prediction of Intensity and Structure of Hurricane Patricia (2015)

2019 ◽  
Vol 147 (8) ◽  
pp. 3069-3089 ◽  
Author(s):  
Jie Feng ◽  
Xuguang Wang
Keyword(s):  
Heat Release ◽  
Latent Heat ◽  
Inner Core ◽  
Motion Vector ◽  
Latent Heat Release ◽  
Field Campaign ◽  
Cyclone Intensity ◽  
Warm Core ◽  
Upper Level ◽  
The Impact

Abstract The dropsondes released during the Tropical Cyclone Intensity (TCI) field campaign provide high-resolution kinematic and thermodynamic measurements of tropical cyclones within the upper-level outflow and inner core. This study investigates the impact of these upper-level TCI dropsondes on analyses and prediction of Hurricane Patricia (2015) during its rapid intensification (RI) phase using an ensemble–variational data assimilation system. In the baseline experiment (BASE), both kinematic and thermodynamic observations of TCI dropsondes at all levels except the upper levels are assimilated. The upper-level wind and thermodynamic observations are assimilated in additional experiments to investigate their respective impacts. Compared to BASE, assimilating TCI upper-level wind observations improves the accuracy of outflow analyses verified against independent atmospheric motion vector (AMV) observations. It also strengthens the tangential and radial wind near the upper-level eyewall. The inertial stability within the upper-level eyewall is enhanced, and the maximum outflow is more aligned toward the inner core. Additionally, the analyses including the upper-level thermodynamic observations produce a warmer and drier core at high levels. Assimilating both upper-level kinematic and thermodynamic observations also improves the RI forecast. Compared to BASE, assimilating the upper-level wind induces more upright and inward-located eyewall convection, resulting in more latent heat release closer to the warm core. This process leads to stronger inner-core warming. Additionally, the initial warmer upper-level inner core produced by assimilating TCI thermodynamic observations also intensifies the convection and latent heat release within the eyewall, thus further contributing to the improved intensity forecasts.

scholarly journals The influence of the coastal front on heavy rainfall events along the east coast

2019 ◽  
Author(s):  
◽  
Chasity B. Henson
Keyword(s):  
Tropical Cyclone ◽  
Heat Release ◽  
Latent Heat ◽  
Heavy Rainfall ◽  
East Coast ◽  
Latent Heat Release ◽  
Rainfall Events ◽  
Upper Level ◽  
Heavy Rainfall Events ◽  
Frontal Boundary

Coastal fronts are commonly found along the East Coast of the United States and can often be associated with intense rainfall and flooding due to elevated convection on the cold side of the boundary. Five heavy rainfall events ([greater to or equal than] 250 mm 24 hr-1) during the fall months along the East Coast were investigated using numerical weather prediction (NWP) models to determine the influence of an upper-level trough/cut-off low, an offshore tropical cyclone, a frontal boundary, and a moisture plume on the intense precipitation. Using experimental NWP simulations, it was determined that the tropical cyclone had an impact on the moisture plume and subsequent location of precipitation due to an associated deformation zone. The tropical cyclone prolonged the events by 6 hours, but inhibited the amount of moisture and resulting precipitation by deterring southeasterly flow. Evaporation from precipitation (surface heat fluxes) contributed to less than 25% (33%) of the precipitation, while latent heat release had the largest impact on the rain totals due to positive feedback from convection and an influence on the frontal boundary. Terrain also impacted the frontal boundary in each event, altering precipitation totals. Parcel trajectories confirmed regions of frontogenesis to be the main source of lift for the release of gravitational instability and convective initiation in each event, while the extratropical cyclone provided upper-level support for ascent and organized the plume of deep tropospheric moisture perpendicular to the front. Three of the five events lasted multiple days due to negative PV advection by the irrotational wind, in response to latent heat release in the region of convection, acting to slow the propagation of the upper-level low.

scholarly journals Numerical Simulations of the Genesis of Typhoon Nuri (2008): Sensitivity to Initial Conditions and Implications for the Roles of Intense Convection and Moisture Conditions

2014 ◽  
Vol 29 (6) ◽  
pp. 1402-1424 ◽  
Author(s):  
Zhan Li ◽  
Zhaoxia Pu
Keyword(s):  
Numerical Simulations ◽  
Heat Release ◽  
Latent Heat ◽  
Initial Conditions ◽  
Deep Convection ◽  
Tropical Cyclone Genesis ◽  
Latent Heat Release ◽  
Numerical Predictions ◽  
Upper Level ◽  
The Impact

Abstract The sensitivity of numerical simulations of the genesis of Typhoon Nuri (2008) to initial conditions is examined using the Advanced Research core of the Weather Research and Forecasting (WRF) Model. The initial and boundary conditions are derived from two different global analyses at different lead times. One simulation successfully captures the processes of Nuri’s genesis and early intensification, whereas other simulations fail to predict the genesis of Nuri. Discrepancies between simulations with and without Nuri’s development are diagnosed. Significant differences are found in the development and organization of the intense convection during Nuri’s pregenesis phase. In the developing case, convection evolves and organizes into a “pouch” center of a westward-propagating wavelike disturbance. In the nondeveloping case, the convection fails to develop and organize. Favorable conditions for the development of deep convection include strong closed circulation patterns with high humidity, especially at the middle levels. An additional set of sensitivity experiments is performed to examine the impact of the moisture field on numerical simulations of Nuri’s genesis. Results confirm that the enhancement of mid- to upper-level moisture is favorable for Nuri’s genesis, mainly because moist conditions benefit deep convection, which produces diabatic heating from latent heat release when vertical airmass flux maxima occur in the mid- to upper-level atmosphere. The substantial warming at upper levels induced by latent heat release from persistent deep convection contributes to the drop in Nuri’s minimum central sea level pressure. Overall, results from this study demonstrate that it is essential to accurately represent the initial conditions in numerical predictions of tropical cyclone genesis.

Major and trace element compositions and resource potential of ferromanganese crust at Takuyo Daigo Seamount, northwestern Pacific Ocean

2016 ◽  
Vol 50 (6) ◽  
pp. 527-537 ◽  
Author(s):  
Tatsuo Nozaki ◽  
Ayaka Tokumaru ◽  
Yutaro Takaya ◽  
Yasuhiro Kato ◽  
Katsuhiko Suzuki ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Trace Element ◽  
Ferromanganese Crust ◽  
Northwestern Pacific ◽  
Northwestern Pacific Ocean ◽  
Resource Potential

scholarly journals Characterization of Bacterial Communities in Bioaerosols over Northern Chinese Marginal Seas and the Northwestern Pacific Ocean in Spring

2019 ◽  
Vol 58 (4) ◽  
pp. 903-917 ◽  
Author(s):  
Manman Ma ◽  
Yu Zhen ◽  
Tiezhu Mi
Keyword(s):  
Pacific Ocean ◽  
Yellow Sea ◽  
Bacterial Communities ◽  
Bohai Sea ◽  
The Yellow Sea ◽  
Northwestern Pacific ◽  
Particle Sizes ◽  
Marine Aerosols ◽  
Northwestern Pacific Ocean ◽  
The Bohai Sea

AbstractStudies of the community structures of bacteria in marine aerosols of different particle sizes have not been reported. Aerosol samples were collected using a six-stage bioaerosol sampler over the Bohai Sea, the Yellow Sea, and northwestern Pacific Ocean in the spring of 2014. The diversity and composition of these samples were investigated by Illumina high-throughput sequencing, and 130 genera were detected in all of the samples; the most abundant bacterial genus was Bacteroides, followed by Prevotella and Megamonas. The Chao1 and Shannon diversity indices ranged from 193 to 1044 and from 5.44 to 8.33, respectively. The bacterial community structure in coarse particles (diameter larger than 2.1 μm) was more complex and diverse than that in fine particles (diameter less than 2.1 μm) in marine bioaerosols from over the Yellow Sea and northwestern Pacific Ocean, while the opposite trend was observed for samples collected over the Bohai Sea. Although we were sampling over marine regions, the sources of the bioaerosols were mostly continental. Temperature and wind speed significantly influenced the bacterial communities in marine aerosols of different particle sizes. There may be a bacterial background in the atmosphere in the form of several dominant taxa, and the bacterial communities are likely mixed constantly during transmission.

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