scholarly journals Two typical modes in the variabilities of wintertime North Pacific basin-scale oceanic fronts and associated atmospheric eddy-driven jet

2017 ◽  
Vol 18 (9) ◽  
pp. 373-380 ◽  
Author(s):  
Liying Wang ◽  
Xiu-Qun Yang ◽  
Dejian Yang ◽  
Qian Xie ◽  
Jiabei Fang ◽  
...  
Keyword(s):  
North Pacific ◽  
Pacific Basin ◽  
Oceanic Fronts ◽  
Basin Scale ◽  
North Pacific Basin

scholarly journals Forecasting Tropical Cyclones in the Western North Pacific Basin Using the NCEP Operational HWRF: Real-Time Implementation in 2012

2015 ◽  
Vol 30 (5) ◽  
pp. 1355-1373 ◽  
Author(s):  
Vijay Tallapragada ◽  
Chanh Kieu ◽  
Samuel Trahan ◽  
Zhan Zhang ◽  
Qingfu Liu ◽  
...  
Keyword(s):  
Real Time ◽  
North Pacific ◽  
Western North Pacific ◽  
Large Scale ◽  
Environmental Modeling ◽  
Pacific Basin ◽  
Forecast Errors ◽  
Storm Intensity ◽  
Intensity Forecast ◽  
North Pacific Basin

Abstract This study documents the recent efforts of the hurricane modeling team at the National Centers for Environmental Prediction’s (NCEP) Environmental Modeling Center (EMC) in implementing the operational Hurricane Weather Research and Forecasting Model (HWRF) for real-time tropical cyclone (TC) forecast guidance in the western North Pacific basin (WPAC) from May to December 2012 in support of the operational forecasters at the Joint Typhoon Warning Center (JTWC). Evaluation of model performance for the WPAC in 2012 reveals that the model has promising skill with the 3-, 4-, and 5-day track errors being 125, 220, and 290 nautical miles (n mi; 1 n mi = 1.852 km), respectively. Intensity forecasts also show good performance, with the most significant intensity error reduction achieved during the first 24 h. Stratification of the track and intensity forecast errors based on storm initial intensity reveals that HWRF tends to underestimate storm intensity for weak storms and overestimate storm intensity for strong storms. Further analysis of the horizontal distribution of track and intensity forecast errors over the WPAC suggests that HWRF possesses a systematic negative intensity bias, slower movement, and a rightward bias in the lower latitudes. At higher latitudes near the East China Sea, HWRF shows a positive intensity bias and faster storm movement. This appears to be related to underestimation of the dominant large-scale system associated with the western Pacific subtropical high, which renders weaker steering flows in this basin.

scholarly journals Dominant Anomaly Patterns in the Near-Surface Baroclinicity and Accompanying Anomalies in the Atmosphere and Oceans. Part II: North Pacific Basin

2010 ◽  
Vol 23 (24) ◽  
pp. 6445-6467 ◽  
Author(s):  
Mototaka Nakamura ◽  
Shozo Yamane
Keyword(s):  
Heat Flux ◽  
North Pacific ◽  
Spatial Scales ◽  
Baroclinic Instability ◽  
Lower Troposphere ◽  
Pacific Basin ◽  
Mean Flow ◽  
Near Surface ◽  
Eddy Heat Flux ◽  
North Pacific Basin

Abstract Variability in the monthly-mean flow and storm track in the North Pacific basin is examined with a focus on the near-surface baroclinicity. Dominant patterns of anomalous near-surface baroclinicity found from empirical orthogonal function (EOF) analyses generally show mixed patterns of shift and changes in the strength of near-surface baroclinicity. Composited anomalies in the monthly-mean wind at various pressure levels based on the signals in the EOFs show accompanying anomalies in the mean flow up to 50 hPa in the winter and up to 100 hPa in other seasons. Anomalous eddy fields accompanying the anomalous near-surface baroclinicity patterns exhibit, broadly speaking, structures anticipated from simple linear theories of baroclinic instability, and suggest a tendency for anomalous wave fluxes to accelerate–decelerate the surface westerly accordingly. However, the relationship between anomalous eddy fields and anomalous near-surface baroclinicity in the midwinter is not consistent with the simple linear baroclinic instability theories. Composited anomalous sea surface temperature (SST) accompanying anomalous near-surface baroclinicity often exhibits moderate values and large spatial scales in the basin, rather than large values concentrated near the oceanic fronts. In the midsummer and in some cases in cold months, however, large SST anomalies are found around the Kuroshio–Oyashio Extensions. Accompanying anomalies in the net surface heat flux, SST in the preceding and following months, and meridional eddy heat flux in the lower troposphere suggest active roles played by the ocean in generating the concomitant anomalous large-scale atmospheric state in some of these cases.

Revision of the genus Anophryocephalus Baylis, 1922 from pinnipeds in the Holarctic, with descriptions of Anophryocephalus nunivakensis sp.nov. and A. eumetopii sp.nov. (Tetrabothriidae) and evaluation of records from the Phocidae

1991 ◽  
Vol 69 (6) ◽  
pp. 1653-1668 ◽  
Author(s):  
Eric P. Hoberg ◽  
Ann M. Adams ◽  
Robert L. Rausch
Keyword(s):  
Bering Sea ◽  
North Pacific ◽  
Pacific Basin ◽  
Genital Papilla ◽  
High Latitudes ◽  
Eumetopias Jubatus ◽  
The North ◽  
Phoca Largha ◽  
The North Pacific ◽  
North Pacific Basin

Anophryocephalus Baylis, 1922 is emended to include tetrabothriid cestodes with intricate scolices (paired auricular appendages and bothridial operculae), complex genital atria (muscular chamber ventral to the vagina; muscular pad adjacent to the aperture of the male canal), and atrophy of the dorsal osmoregulatory system. Anophryocephalus anophrys (type), A. skrjabini, and A. ochotensis are redescribed. Anophryocephalus nunivakensis sp.nov., from Phoca largha, has bothridial operculae with broad anterior apertures, an ovoid cirrus sac (57–95 μm in diameter), a ventrolaterally directed male canal (26–44 μm long in mature segments), and 26–56 testes. Anophryocephalus eumetopii sp.nov., from Eumetopias jubatus, has bothridial operculae with narrow, slitlike, diagonally directed apertures, a spheroidal cirrus sac (51–72 μm in diameter), a prominent genital papilla and ventrolaterally directed male canal (36–51 μm long in mature segments), and 32–66 testes. Postlarval ontogeny of the scolex among some species of Anophryocephalus appears similar to that known for Tetrabothrius spp., suggesting uniformity in morphogenesis of the holdfast among the Tetrabothriidae. Anophryocephalus spp. are typical parasites of pinnipeds in the Holarctic, and contrary to previous reports, A. skrjabini and A. ochotensis are exclusively parasites of Phoca spp. and Eumetopias jubatus, respectively, at high latitudes in the North Pacific basin and Bering Sea.

scholarly journals Structural and Intensity Changes of Concentric Eyewall Typhoons in the Western North Pacific Basin

2013 ◽  
Vol 141 (8) ◽  
pp. 2632-2648 ◽  
Author(s):  
Yi-Ting Yang ◽  
Hung-Chi Kuo ◽  
Eric A. Hendricks ◽  
Melinda S. Peng
Keyword(s):  
Environmental Conditions ◽  
North Pacific ◽  
Western North Pacific ◽  
Extended Period ◽  
Vertical Shear ◽  
Pacific Basin ◽  
Internal Dynamics ◽  
Intensity Changes ◽  
North Pacific Basin ◽  
Replacement Cycle

Abstract An objective method is developed to identify concentric eyewalls (CEs) for typhoons using passive microwave satellite imagery from 1997 to 2011 in the western North Pacific basin. Three CE types are identified: a CE with an eyewall replacement cycle (ERC; 37 cases), a CE with no replacement cycle (NRC; 17 cases), and a CE that is maintained for an extended period (CEM; 16 cases). The inner eyewall (outer eyewall) of the ERC (NRC) type dissipates within 20 h after CE formation. The CEM type has its CE structure maintained for more than 20 h (mean duration time is 31 h). Structural and intensity changes of CE typhoons are demonstrated using a T–Vmax diagram (where T is the brightness temperature and Vmax is the best-track estimated intensity) for a time sequence of the intensity and convective activity (CA) relationship. While the intensity of typhoons in the ERC and CEM cases weakens after CE formation, the CA is maintained or increases. In contrast, the CA weakens in the NRC cases. The NRC (CEM) cases typically have fast (slow) northward translational speeds and encounter large (small) vertical shear and low (high) sea surface temperatures. The CEM cases have a relatively high intensity (63 m s−1), and the moat size (61 km) and outer eyewall width (70 km) are approximately 50% larger than the other two categories. Both the internal dynamics and environmental conditions are important in the CEM cases, while the NRC cases are heavily influenced by the environment. The ERC cases may be dominated by the internal dynamics because of more uniform environmental conditions.

Operational Evaluation of a Selective Consensus in the Western North Pacific Basin

2007 ◽  
Vol 22 (3) ◽  
pp. 671-675 ◽  
Author(s):  
Charles R. Sampson ◽  
John A. Knaff ◽  
Edward M. Fukada
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Systematic Approach ◽  
Prediction Models ◽  
Weather Prediction ◽  
Pacific Basin ◽  
Joint Typhoon Warning Center ◽  
Numerical Weather Prediction Models ◽  
North Pacific Basin

Abstract The Systematic Approach Forecast Aid (SAFA) has been in use at the Joint Typhoon Warning Center since the 2000 western North Pacific season. SAFA is a system designed for determination of erroneous 72-h track forecasts through identification of predefined error mechanisms associated with numerical weather prediction models. A metric for the process is a selective consensus in which model guidance suspected to have 72-h error greater than 300 n mi (1 n mi = 1.85 km) is first eliminated prior to calculating the average of the remaining model tracks. The resultant selective consensus should then provide improved forecasts over the nonselective consensus. In the 5 yr since its introduction into JTWC operations, forecasters have been unable to produce a selective consensus that provides consistent improved guidance over the nonselective consensus. Also, the rate at which forecasters exercised the selective consensus option dropped from approximately 45% of all forecasts in 2000 to 3% in 2004.

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