scholarly journals Exceptionally cold water days in the southern Taiwan Strait: their predictability and relation to La Niña

2018 ◽  
Vol 18 (7) ◽  
pp. 1999-2010 ◽  
Author(s):  
Yu-Hsin Cheng ◽  
Ming-Huei Chang
Keyword(s):  
Wind Speed ◽  
Cold Water ◽  
Warning System ◽  
Taiwan Strait ◽  
La Niña ◽  
Occurrence Probability ◽  
Relative Operating Characteristic ◽  
Technology System ◽  
La Nina ◽  
The Taiwan Strait

Abstract. The objectives of this study were to assess the predictability of exceptionally cold water in the Taiwan Strait (TS) and to develop a warning system on the basis of the scientific mechanism, which is a component of the information technology system currently under development in Taiwan to protect aquaculture against extreme hazards. Optimum interpolation sea surface temperature (SST) data were used to find exceptionally cold water days from January 1995 to May 2017. We found that the SST and wind speed over the TS are low and strong in La Niña winters, respectively. According to tests conducted using relative operating characteristic curves, predictions based on the Oceanic Niño Index and integrated wind speed can be employed at lead times of 60–120 and 0–25 days, respectively. This study utilized these two proxies to develop a possible warning mechanism and concluded four colors of warning light: (1) blue, meaning normal (0 % occurrence probability); (2) cyan, meaning warning (∼ 50 % occurrence probability); (3) yellow, meaning moderate risk (∼ 60 % occurrence probability); and (4) red, meaning high risk (∼ 75 % occurrence probability). Hindcasting winters over the period 1995–2017 successfully predicted the cold water hazards in the winters of 2000, 2008, and 2011 prior to the coldest day by ∼ 20 days.

scholarly journals Exceptionally cold water days in the southern Taiwan Strait: their predictability and relation to La Niña

2018 ◽  
Author(s):  
Yu-Hsin Cheng ◽  
Ming-Huei Chang
Keyword(s):  
Wind Speed ◽  
Cold Water ◽  
Warning System ◽  
Taiwan Strait ◽  
La Niña ◽  
Relative Operating Characteristic ◽  
Technology System ◽  
La Nina ◽  
Extreme Hazards ◽  
The Taiwan Strait

Abstract. The objectives of this study were to assess the predictability of exceptionally cold water in the Taiwan Strait (TS) and to develop a warning system on the base of scientific mechanism, which is a component of the information technology system currently under development in Taiwan to protect aquaculture against extreme hazards. Optimum interpolation sea surface temperature (SST) data were used to find exceptionally cold water days from January 1995 to May 2017. We found that the SST and wind speed over the TS are low and strong in La Niña winters, respectively. According to tests conducted using relative operating characteristic curves, predictions based on the Oceanic Niño Index and integrated wind speed can be employed at lead times of 60–210 and 0–30 days, respectively. This study utilized these two proxies to develop a possible warning mechanism and concluded four colors of warning light: (1) blue, meaning normal; (2) cyan, meaning warning; (3) yellow, meaning moderate risk; and (4) red, meaning high risk. Hindcasting winters over the period 1995–2017 successfully predicted the cold water hazards in the winters of 2000, 2008, 2011, and 2012 in prior to the coldest day ~ 20 days.

Satellite Observation of the Mesoscale Features in the Taiwan Strait

2006 ◽  
Author(s):  
Nan-Jung Kuo ◽  
Chung-Ru Ho ◽  
Shih-Jen Huang
Keyword(s):  
Shear Wave ◽  
Feature Tracking ◽  
Cold Water ◽  
Phase Speed ◽  
Satellite Observation ◽  
Taiwan Strait ◽  
Infrared Images ◽  
The Taiwan Strait ◽  
Monsoon Winds ◽  
Kinematic Properties

In this paper, we discuss the kinematic properties of the mesoscale features in the Taiwan Strait (TS). Two kinds of mesoscale features can be seen in the TS. One is the shear wave; it is a lateral wavelike train with phase speed and wave period. The other one is the eddy-like cold-water wedge; it mainly rotates with a little translation. The shear wave mainly occurs in the boundary of the China cold water along the western TS in winter and spring. The eddy-like cold-water wedge can be seen in the mid-winter when the strong southward China coastal cold water covers up most of the northern TS and creates a very unstable front with the northward warm water. In this study, selected NOAA satellite AVHRR channel 4 infrared images during 2000–2003 are considered to detect the movement of the above mesoscale features through a feature-tracking method. It is found that the development of these features is highly related to the monsoon winds. Meanwhile, the local tidal pattern can also affect their movements.

Cross Flows in the Taiwan Strait in Winter*

2014 ◽  
Vol 44 (3) ◽  
pp. 801-817 ◽  
Author(s):  
L.-Y. Oey ◽  
Y.-L. Chang ◽  
Y.-C. Lin ◽  
M.-C. Chang ◽  
S. Varlamov ◽  
...  
Keyword(s):  
Cold Water ◽  
Numerical Models ◽  
Taiwan Strait ◽  
Finite Amplitude ◽  
Winter Monsoon ◽  
Coastal Current ◽  
Wind Regime ◽  
Calanus Sinicus ◽  
Northeasterly Wind ◽  
The Taiwan Strait

Abstract In winter, a branch of the China Coastal Current can turn in the Taiwan Strait to join the poleward-flowing Taiwan Coastal Current. The associated cross-strait flows have been inferred from hydrographic and satellite data, from observed abundances off northwestern Taiwan of cold-water copepod species Calanus sinicus and, in late March of 2012, also from debris found along the northwestern shore of Taiwan of a ship that broke two weeks earlier off the coast of China. The dynamics related to such cross flows have not been previously explained and are the focus of this study using analytical and numerical models. It is shown that the strait’s currents can be classified into three regimes depending on the strength of the winter monsoon: equatorward (poleward) for northeasterly winds stronger (weaker) than an upper (lower) bound and cross-strait flows for relaxing northeasterly winds between the two bounds. These regimes are related to the formation of the stationary Rossby wave over the Changyun Ridge off midwestern Taiwan. In the weak (strong) northeasterly wind regime, a weak (no) wave is produced. In the relaxing wind regime, cross-strait currents are triggered by an imbalance between the pressure gradient and wind and are amplified by the finite-amplitude meander downstream of the ridge where a strong cyclone develops.

scholarly journals Fenomena Anomali Iklim El Nino dan La Nina: Kecenderungan Jangka Panjang dan Pengaruhnya terhadap Produksi Pangan

2016 ◽  
Vol 24 (1) ◽  
pp. 28 ◽  
Author(s):  
Bambang Irawan
Keyword(s):  
El Niño ◽  
Food Production ◽  
El Nino ◽  
Warning System ◽  
La Niña ◽  
Cycle Period ◽  
Climate Anomaly ◽  
Corn Production ◽  
Irrigation Network ◽  
La Nina

<strong>English</strong><br />El Nino occurrence tends to increase with longer duration, higher magnitude of climate anomaly, and shorter cycle period of occurrence. Climate anomaly induces decrease of rainfall and water availability with further consequence on food production decline by 3.06 percent for each El Nino case. Contrary to El Nino which causes rainfall and food production decreases, La Nina causes increases in rainfall and improves food production by 1.08 percent. The lowest production decrease induced by El Nino and the highest production increase caused by La Nina was observed on corn production indicating that corn production is the most sensitive to climate anomaly. To reduce possible food production decrease induced by El Nino a comprehensive mitigating policy is essential. The policy consists of three major efforts, namely: (1) establishment of earlier warning system on climate anomaly, (2) development of efficient dissemination system on climate anomaly information, and (3) developing, disseminating and facilitating farmers to implement cultural techniques adaptive to drought condition as well as improving, rehabilitating irrigation network and developing rainfall harvesting techniques.<br /><br /><br /><strong>Indonesian</strong><br />Frekuensi kejadian El Nino cenderung meningkat dengan durasi yang semakin panjang, tingkat anomali iklim yang semakin besar, dan siklus kejadian yang semakin pendek. Anomali iklim tersebut menyebabkan penurunan curah hujan dan ketersediaan air irigasi yang selanjutnya berimplikasi pada penurunan produksi pangan sebesar 3,06 persen untuk setiap kejadian El Nino. Sebaliknya, kejadian La Nina cenderung diikuti dengan peningkatan curah hujan dan merangsang peningkatan produksi pangan sebesar 1,08 persen untuk setiap kejadian La Nina. Penurunan produksi pangan akibat El Nino dan peningkatan produksi pangan akibat La Nina paling tinggi terjadi pada produksi jagung. Hal ini menunjukkan bahwa produksi jagung paling sensitif terhadap peristiwa anomali iklim. Dalam rangka menekan dampak negatif El Nino terhadap produksi pangan maka diperlukan kebijakan penanggulangan yang komprehensif yang meliputi tiga upaya pokok yaitu : (1) pengembangan sistem deteksi dini anomali iklim, (2) pengembangan sistem diseminasi informasi yang efisien tentang anomali iklim, dan (3) mengembangkan, mendiseminasikan dan memfasilitasi petani untuk menerapkan teknik budidaya tanaman yang adaptif terhadap situasi kekeringan di samping membangun dan merehabilitasi jaringan irigasi serta mengembangkan teknik pemanenan curah hujan.

scholarly journals Effect of the El Niño–Southern Oscillation (ENSO) Cycle on the Catches and Habitat Patterns of Three Swimming Crabs in the Taiwan Strait

2021 ◽  
Vol 8 ◽  
Author(s):  
Muhamad Naimullah ◽  
Yan-Lun Wu ◽  
Ming-An Lee ◽  
Kuo-Wei Lan
Keyword(s):  
El Niño ◽  
Habitat Suitability ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
Sea Temperature ◽  
Enso Events ◽  
La Nina ◽  
The Taiwan Strait ◽  
Swimming Crabs

The swimming crabs is a crucial predator species in benthic habitats and a high value in commercial fishery industries in subtropical and tropical Asia. The climate variability caused by El Niño–Southern Oscillation (ENSO) events has substantial impacts on the catch and habitat of this species. In this study, a weighted habitat suitability index (HSI) model was constructed using logbooks and voyage data records from Taiwanese crab vessels (2013–2019) with the addition of environmental variables to examine the influence of ENSO events on catch rates (CRs) and habitat suitability for Charybdis feriatus, Portunus pelagicus, and Portunus sanguinolentus in the Taiwan Strait (TS). The autumn (September–October) is the major fishing season for catching these three swimming crab species in the TS. A high CR of P. sanguinolentus was observed across the TS, whereas high CRs of P. pelagicus and C. feriatus were recorded in areas in the southern and northern TS, respectively, during autumn. Moreover, the CRs for C. feriatus and P. pelagicus were higher (&gt;7.0 and &gt;8.0 kg/h) during La Niña events, with the increase being more than 40.0% compared with the CRs under normal and El Niño events in autumn. For P. sanguinolentus, the CRs were higher during both La Niña and El Niño events (&gt;8.0 kg/h) compared with normal years. The high CRs for C. feriatus and P. sanguinolentus during autumn in La Niña years co-occurred with high sea temperature and low salinity, whereas the high CR of P. pelagicus co-occurred with high sea temperature and high salinity. Furthermore, the high CRs for C. feriatus and P. pelagicus were observed in areas with high HSI in the La Niña years but were distributed more widely with a lower HSI during normal and El Niño years. The low CRs for C. feriatus and P. pelagicus during normal and El Niño years and the low CR for P. sanguinolentus in normal years during autumn were highly consistent with substantial shrinkage of suitable habitats. Our findings suggest that ENSO events strongly affected the catch and habitat suitability of C. feriatus, P. pelagicus, and P. sanguinolentus during autumn in the TS.

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