Taxonomic review of dwarf species of Eumicrotremus (Actinopterygii: Cottoidei: Cyclopteridae) with descriptions of two new species from the western North Pacific

Zootaxa ◽  
2017 ◽  
Vol 4282 (2) ◽  
pp. 337 ◽  
Author(s):  
SOO JEONG LEE ◽  
JIN-KOO KIM ◽  
YOSHIAKI KAI ◽  
SHIN’ICHIRO IKEGUCHI ◽  
TETSUJI NAKABO

A taxonomic review of the dwarf species of the genus Eumicrotremus (Actinopterygii: Cottoidei: Cyclopteridae), previously recognized as belonging to Lethotremus, established the existence of three species, viz. Eumicrotremus awae (Jordan and Snyder, 1902), Eumicrotremus uenoi sp. nov., and Eumicrotremus jindoensis sp. nov., from the western North Pacific. Eumicrotremus awae, known from the Pacific coast of Honshu Is. (Chiba southward to Mie), is characterized by the absence of spiny tubercles or fleshy papillae on the body, the anterior three mandibular pores each with a barbel-like tube, interorbital and suborbital pores usually absent, the opercular flap rounded, many papillae present on the ventral disk and the caudal-fin relatively short, 21.0–30.5% of SL (standard length). Eumicrotremus uenoi, known from the western coast of Honshu Is. and the southern coast of Korean Peninsula, is characterized by the absence of spiny tubercles or fleshy papillae on the body (or weak if present), the anterior three mandibular pores each with a barbel-like tube, interorbital and suborbital pores usually present, the opercular flap rounded, the ventral disk with many papillae and the caudal-fin relatively short, 19.5–31.4% of SL. Eumicrotremus jindoensis, known from the southwestern coast of Korean Peninsula, and the coasts of Yellow Sea, is characterized by a smooth soft body, triangular opercular flap, absence of papillae on the ventral disk and a long caudal fin, 32.7–42.1% of SL. Sequence variations of the mictochondrial DNA cytochrome c oxidase subunit I (mtDNA COI) and the nuclear myh6 genes supported the validity of the three species. 

2020 ◽  
Vol 54 (3-4) ◽  
pp. 2237-2248 ◽  
Author(s):  
Qiong Wu ◽  
Xiaochun Wang ◽  
Li Tao

AbstractIn this study, we analyzed the impacts of Western North Pacific Subtropical High (WNPSH) on tropical cyclone (TC) activity on both interannual and interdecadal timescales. Based on a clustering analysis method, we grouped TCs in the Western North Pacific into three clusters according to their track patterns. We mainly focus on Cluster 1 (C1) TCs in this work, which is characterized by forming north of 15° N and moving northward. On interannual timescale, the number of C1 TCs is influenced by the intensity variability of the WNPSH, which is represented by the first Empirical Orthogonal Function (EOF) of 850 hPa geopotential height of the region. The WNPSH itself is modulated by the El Niño–Southern Oscillation at its peak phase in the previous winter, as well as Indian and Atlantic Ocean sea surface temperature anomalies in following seasons. The second EOF mode shows the interdecadal change of WNPSH intensity. The interdecadal variability of WNPSH intensity related to the Pacific climate regime shift could cause anomalies of the steering flow, and lead to the longitudinal shift of C1 TC track. Negative phases of interdecadal Pacific oscillation are associated with easterly anomaly of steering flow, westward shift of C1 TC track, and large TC impact on the East Asia coastal area.


2018 ◽  
Vol 31 (19) ◽  
pp. 7739-7749 ◽  
Author(s):  
Si Gao ◽  
Langfeng Zhu ◽  
Wei Zhang ◽  
Zhifan Chen

This study finds a significant positive correlation between the Pacific meridional mode (PMM) index and the frequency of intense tropical cyclones (TCs) over the western North Pacific (WNP) during the peak TC season (June–November). The PMM influences the occurrence of intense TCs mainly by modulating large-scale dynamical conditions over the main development region. During the positive PMM phase, anomalous off-equatorial heating in the eastern Pacific induces anomalous low-level westerlies (and cyclonic flow) and upper-level easterlies (and anticyclonic flow) over a large portion of the main development region through a Matsuno–Gill-type Rossby wave response. The resulting weaker vertical wind shear and larger low-level relative vorticity favor the genesis of intense TCs over the southeastern part of the WNP and their subsequent intensification over the main development region. The PMM index would therefore be a valuable predictor for the frequency of intense TCs over the WNP.


2020 ◽  
Vol 55 (11-12) ◽  
pp. 3469-3483
Author(s):  
Hongjie Zhang ◽  
Liang Wu ◽  
Ronghui Huang ◽  
Jau-Ming Chen ◽  
Tao Feng

2020 ◽  
Author(s):  
Tat Fan Cheng ◽  
Mengqian Lu

<p>There has been growing interest in studying precipitation recycling and identifying relationships between moisture sources and receptors. The network built upon the relationships is crucial for the knowledge of the atmospheric water cycle, weather prediction, and adaptation to hydroclimatic disasters. This study aims to provide an interesting perspective of a Source-to-Receptor (SR) network to study the dynamics of the East Asian Summer Monsoon (EASM). By prescribing 24 sources and 6 EASM subregions, the SR network during the wet season is quantified using the two-dimensional physically-based Dynamical Recycling Model (DRM). Results reveal that in addition to oceanic sources, land sources including the often-overlooked plateau regions play an important role in supplying moisture to most EASM subregions. A seesaw relationship of the Indian Ocean/South Asia sector from April to June and the Pacific Ocean/East Asia sector from July to September is evidenced in the intraseasonal variation of the SR network for EASM subregions including South China coast and Taiwan, Yangtze River basin, South Japan and Korean Peninsula. Conversely, weaker intraseasonal variation is seen in the SR network for the Yellow River basin and North China. During heavy rainfall days, the zonal oscillation of western North Pacific Subtropical High (WNPSH) is deemed crucial to modulate the SR network through enhanced contributions from Bay of Bengal, Indochina, Indian subcontinent and Southwest China (the Philippine Sea and western North Pacific) during the positive (negative) phase. Coupled circulations such as two distinct pressure dipoles and coherent upper-level wave trains from mid-latitudes are responsible for bridging the moisture routes. Lastly, preceding winter/springtime El Niño is likely associated with the enhanced (weakened) moisture supply from the southwesterly (Pacific Ocean) sources. Longer-term variabilities such as the Pacific Decadal Oscillation is also considered influential to the SR network. We believe that the attributable atmospheric bridges and the SR network itself can offer insights to the current understanding of EASM and model simulations of the monsoon systems and the water cycles.</p>


2010 ◽  
Vol 23 (19) ◽  
pp. 5109-5125 ◽  
Author(s):  
Yu Kosaka ◽  
Hisashi Nakamura

Abstract A global survey is conducted for atmospheric anomaly patterns of meridional teleconnection over the summer hemisphere associated with anomalous tropical convection. The patterns may be akin to the Pacific–Japan (PJ) teleconnection pattern analyzed in detail in the companion paper. From the survey, meridional teleconnections are identified over five regions, namely, the western North Pacific and Central/North America in boreal summer, as well as the western South Indian Ocean, central South Pacific, and western South Atlantic in austral summer. All of the patterns are observed in the western peripheries of the summertime surface subtropical anticyclones over the individual ocean basins. Although all of the patterns can convert available potential energy (APE) efficiently from the vertically sheared subtropical westerly jets, the efficiencies of barotropic energy conversion from the mean flow and diabatic APE generation differ from one pattern to another. Still, all of the patterns gain energy as the net, to maintain themselves against dissipative processes. Both the anomalous moisture convergence near the surface and the midtropospheric anomalous ascent required for the vorticity and thermal balance act to sustain the anomalous tropical convection, while the wind-evaporation feedback contributes positively only to the PJ pattern over the western North Pacific. Examination of common features and discrepancies among the five teleconnection patterns with respect to their structures and energetics reveals that climatological background features, including the largest horizontal extent of the Asian monsoon system and the North Pacific subtropical anticyclone, in addition to particularly high SST over the Pacific warm pool, render the PJ pattern an outstanding mode of variability.


2014 ◽  
Vol 27 (1) ◽  
pp. 140-154 ◽  
Author(s):  
Richard C. Y. Li ◽  
Wen Zhou ◽  
Tim Li

Abstract This study investigates the influences of the Pacific–Japan (PJ) teleconnection pattern on synoptic-scale variability (SSV) in the western North Pacific (WNP). The PJ pattern exhibits salient intraseasonal variations, with a dominant peak at 10–50 days. During positive PJ phases, strengthened SSV is found in the WNP, with a much stronger and better organized synoptic wave train structure. Such a synoptic-scale wave train, however, is greatly weakened during negative PJ phases. Examination of the vertical profiles of the observational data suggests that environmental parameters are generally more (less) favorable for the growth of synoptic disturbances under positive (negative) PJ conditions. Observational results are further verified with an anomaly atmospheric general circulation model, which reveals faster (slower) growth of the synoptic-scale wave train when the environmental anomalies associated with positive (negative) PJ phases are incorporated into the summer mean state of the model. In addition, sensitivity experiments indicate that thermodynamic parameters of the planetary boundary layer (PBL) play a determining role in controlling the development of synoptic disturbances in the WNP. The increase (decrease) in background PBL moisture during positive (negative) PJ phases enhances (suppresses) perturbation moisture convergence and thus the convective heating associated with SSV, leading to strengthened (weakened) synoptic-scale activity in the WNP. Serving as potential seed disturbances for cyclogenesis, the strengthened (weakened) synoptic-scale activity may also contribute to the enhancement (suppression) in intraseasonal TC frequency during positive (negative) PJ phases.


2015 ◽  
Vol 29 (1) ◽  
pp. 381-398 ◽  
Author(s):  
W. Zhang ◽  
G. A. Vecchi ◽  
H. Murakami ◽  
G. Villarini ◽  
L. Jia

Abstract This study investigates the association between the Pacific meridional mode (PMM) and tropical cyclone (TC) activity in the western North Pacific (WNP). It is found that the positive PMM phase favors the occurrence of TCs in the WNP while the negative PMM phase inhibits the occurrence of TCs there. Observed relationships are consistent with those from a long-term preindustrial control experiment (1000 yr) of a high-resolution TC-resolving Geophysical Fluid Dynamics Laboratory (GFDL) Forecast-Oriented Low Ocean Resolution (FLOR) coupled climate model. The diagnostic relationship between the PMM and TCs in observations and the model is further supported by sensitivity experiments with FLOR. The modulation of TC genesis by the PMM is primarily through the anomalous zonal vertical wind shear (ZVWS) changes in the WNP, especially in the southeastern WNP. The anomalous ZVWS can be attributed to the responses of the atmosphere to the anomalous warming in the northwestern part of the PMM pattern during the positive PMM phase, which resembles a classic Matsuno–Gill pattern. Such influences on TC genesis are strengthened by a cyclonic flow over the WNP. The significant relationship between TCs and the PMM identified here may provide a useful reference for seasonal forecasting of TCs and interpreting changes in TC activity in the WNP.


2008 ◽  
Vol 21 (13) ◽  
pp. 3165-3179 ◽  
Author(s):  
So-Young Yim ◽  
Sang-Wook Yeh ◽  
Renguang Wu ◽  
Jong-Ghap Jhun

Abstract A recent study suggested that the relationship between the East Asian summer monsoon (EASM) and the western North Pacific summer monsoon (WNPSM) experienced a decadal change around 1993–94. Based on a longer-term integration of a hybrid coupled model, the present study investigates decadal variations in the relationship between the EASM and the WNPSM. Apparent decadal variations in the above relationship have been identified in the model simulation. The authors have analyzed the spatial pattern and variability during strong and weak EASM–WNPSM correlation periods. The purpose of this study is to understand potential reasons for decadal variations in the relationship between the two submonsoons. It is found that the precipitation variability associated with the WNPSM (ENSO) is enhanced over the East Asia and western North Pacific regions during periods when the EASM–WNPSM relationship is strong (weak). The large variability in precipitation associated with the WNPSM during strong periods strengthens the Pacific–Japan-like atmospheric teleconnection from the tropical western Pacific. In contrast, the Pacific–Japan-like pattern is not significant during weak periods. On the other hand, the large ENSO amplitude during weak periods results in an enhanced precipitation variability associated with ENSO. The results suggest that ENSO can destructively interfere with the relationship between the EASM and the WNPSM.


2021 ◽  
Author(s):  
Haili Wang ◽  
Chunzai Wang

Abstract Based on satellite era data after 1979, we find that the tropical cyclone (TC) variations in the Western North Pacific (WNP) can be divided into three-periods: a high-frequency period from 1979-1997 (P1), a low-frequency period from 1998-2010 (P2), and a high-frequency period from 2011-2020 (P3). Previous studies have focused on WNP TC activity during P1 and P2. Here we use observational data to study the WNP TC variation and its possible mechanisms during P3. Compared with P2, more TCs during P3 are due to the large-scale atmospheric environmental conditions of positive relative vorticity, negative vertical velocity and weak vertical wind shear. Warmer SST is found during P3, which is favorable for TC genesis. The correlation between the WNP TC frequency and SST shows a significant positive correlation around the equator and a significant negative correlation around 36°N, which is similar to the warm phase of the Pacific Decadal Oscillation (PDO). The correlation coefficient between the PDO and TC frequency is 0.71, significant at 99% confidence level. The results indicate that the increase of the WNP TC frequency during 2011-2020 is associated with the phase transition of the PDO and warmer SST. Therefore, more attention should be given to the warmer SST and PDO phase when predicting WNP TC activity.


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