Kuo-wei Lan - Academia.edu (original) (raw)

Papers by Kuo-wei Lan

International Journal of Climatology, 2016

Remote Sensing of the Changing Oceans, 2011

Journal of Marine Science and Technology

Using Advanced Very High Resolution Radiometer (AVHRR) sea surface temperatures (SSTs) at a 1.1-k... more Using Advanced Very High Resolution Radiometer (AVHRR) sea surface temperatures (SSTs) at a 1.1-km spatial resolution, we investigated the long-term SST variability in winter in the eastern Taiwan Strait (TS) in 1995~2008. We performed an empirical orthogonal function (EOF) analysis of spatial and time series variances for 15-day mean images. Sampling errors in the EOF analysis of the first three modes were selected at the 95 % significance level. These first three modes respectively accounted for 25.9 %, 16.61 % and 4.59 % of variances. In the first mode, the spatial amplitude showed positive values in the northeastern TS and negative values south of Chang-Yuen Rise (CYR). This suggests that warmer water occurred south of the CYR and a southwesterly intrusion of cold water extended north of study area. In the second mode, the lowest SSTs appeared over the CYR from the middle of December to the end of January. Results of the EOF analysis revealed heat exchange and the formation of a...

In this study we collected the catch, catch per unit effort (CPUE) and value of production of cos... more In this study we collected the catch, catch per unit effort (CPUE) and value of production of costal harvest fishery and the environmental variables in Kong-Liao region during the period of 1995~2010. The purpose was tried to understand the relationship between coastal harvest fishery industry activity and the environment variables by using generalized additive models (GAM). The catch species were changed by time. The mainly catch species are Porphyra dentate, Halymenia and Dermonema virens in fall and winter, and Pterocladia capillacea in spring and summer. Results of GAM have shown that sea surface temperature and solar radiation are positively significant factors associated with the variation of CPUE of Pterocladia capillacea. It indicated that the CPUE of Pterocladia capillacea is increased with the sea surface temperature and solar radiation in spring and summer time, but decreased in autumn and winter time.

Fisheries Research, 2014

The environmental processes associated with the climatic oscillations that drive variability in s... more The environmental processes associated with the climatic oscillations that drive variability in swordfish catch rates are largely unexplored. This study used generalized additive models fitted to longline fishery data to investigate relationships between environmental variables and catch rates to understand the processes influencing swordfish distributions in the Indian Ocean. The catch rates and distribution of swordfish in the Indian Ocean were sensitive to climatic and environmental variation. The environmental effects differ between the northwest and southwest Indian Ocean. The predicted relative abundance reveals a notable increase along the western coast of the northwest Indian Ocean during nominal Indian Ocean Dipole and negative Southern Indian Ocean Dipole (IOSD) events, and is related to the changes in net primary production and shallow mixed layer depth. The predicted relative abundances also show that the distribution of lower sea surface temperature and sea surface height deviation surrounding Madagascar increased during negative IOSD events in the southwest Indian Ocean.

In this study, we collected Taiwanese longline (LL) fishery data and environment variables during... more In this study, we collected Taiwanese longline (LL) fishery data and environment variables during the period of 1998-2004 to investigate the relationship between LL catch data of yellowfin tuna (YFT) and oceanic environmental factors using a principal component analysis (PCA).

Terrestrial, Atmospheric and Oceanic Sciences, 2009

Based upon long-term observations (1993 -2010) of satellite-derived winter sea surface temperatur... more Based upon long-term observations (1993 -2010) of satellite-derived winter sea surface temperature (SST) data, an exceptional cold-water intrusion into the southern Taiwan Strait (TS) was noted in February 2008. In the winter of 2008, La Niña caused a strong and continuous northeasterly wind that drove the cold ocean current, the China Coastal Current, more southward to penetrate the southern TS north of the Chang-Yuen Ridge. A portion of this current turned eastward to the south of Penghu Islands (PHI). The low-SST event significantly impeded local marine aquaculture and wild fish, causing the death of more than 73 tons of fish around PHI. Comparing variations of the first quarterly catches in 2008 with the long-term averages from 1993 to 2010 (excluding 2008), we noted a 50 to 80% decrease in catches from pole-and-line, long-line, and gill-net fishery. Non-migratory species dominated the composition of the catches. We also noted a greater than 230% increase in the catches from set-net fishery, with the majority being migratory species. These results illustrate the positive and negative effects of cold-water intrusion on several fish communities and species.

International Journal of Remote Sensing, 2012

IEEE Geoscience and Remote Sensing Letters, 2000

ABSTRACT Sea surface temperature (SST) data for three years from the Advanced Microwave Scanning ... more ABSTRACT Sea surface temperature (SST) data for three years from the Advanced Microwave Scanning Radiometer for the Earth Observing System are used to statistically evaluate the temporal scales of the global SST fronts (SSTFs). Using the entropy-based edge detection method which is very resistant to impulsive noises, temporal autocorrelation of the dissimilarities of two SST groups across the SSTF is calculated in 10-km-gridded map. In general, the derived temporal scales, defined as eee-folding scales in this study, range from 10 to 40 days. Long temporal scales of up to 100 days are found in areas where the stationary ocean currents maintain the frontal structures.

ICES Journal of Marine Science, 2011

In this study, the Taiwanese longline (LL) fishery data were divided into two types: regular LL a... more In this study, the Taiwanese longline (LL) fishery data were divided into two types: regular LL and deep LL. Furthermore, we collected environmental variables, such as sea surface temperature (SST), subsurface temperature, chlorophyll a concentration, net primary productivity, windspeed, and the north tropical Atlantic SST index (NTA) during the period 1998 -2007 to investigate the relationship between LL catch data and oceanic environmental factors using principal component analysis (PCA). After the daily LL was separated into two types of LL, the results indicated that the deep LL was the major fishery catching yellowfin tuna (YFT) in the equatorial Atlantic Ocean. In 2003 -2005, especially in 2005, the monthly catch by deep LL was double those of other years. The spatial distribution of the nominal catch per unit effort (cpue) by deep LL showed the maximum aggregation of YFT in waters with temperature above 24 -258C. The YFT mainly aggregated in the equatorial Atlantic, extending east in the first and second quarters of the year. In the third quarter of the year, the SST decreased off West Africa and the YFT migrated westwards to 158W. Results of PCA indicated that higher subsurface water temperatures resulted in a deeper thermocline and caused a higher cpue of YFT, but the influence of NTA on the cpue of YFT seemed to be insignificant.

Fisheries Research, 2012

Using cloud-free Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) s... more Using cloud-free Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) sea surface temperature (SST) and daily set longline fishery data, we studied the relationship between albacore (ALB) fishing grounds and thermal conditions in the southern Indian Ocean. SST and Jensen-Shannon divergence (JSD) maps with a daily spatiotemporal resolution were related to sites with high catches per unit effort (CPUE) (>11 fish/10 3 hooks). A high JSD is considered to be an index of a SST front. In winter, high CPUE occurred in the vicinity of the North Subtropical Front (Belkin and , where SST was 15-19 • C and JSD was 0.3-0.9. Histograms of the high CPUE plotted against SST and JSD indicated that 95% of the high CPUEs were in the 16-18.5 • C SST range and 97% were in the 0.4-0.9 JSD range. These ranges of SST and JSD are optimum ranges. These cloud-free SST/JSD analyses clearly demonstrate the seasonal north-south movement of the optimum SST and JSD band, which corresponds to the North Subtropical Front in the southern Indian Ocean. Monthly maps of joint probability density (JPD) with the optimum ranges of SST and JSD revealed that high CPUEs are located in the narrow bands with high JPD (>50%).

Continental Shelf Research, 2009

It is well known that upwelling of subsurface water is dominant around the Taiwan Bank (TB) and t... more It is well known that upwelling of subsurface water is dominant around the Taiwan Bank (TB) and the Penghu (PH) Islands in the southern Taiwan Strait in summertime. Sea surface temperature (SST) frontal features and related phenomena around the TB upwelling and the PH upwelling were investigated using long-term AVHRR (1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005) and SeaWiFS (1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005) data received at the station of National Taiwan Ocean University. SST and chlorophyll-a (Chl-a) images with a spatial resolution of 0.011 were generated and used for the monthly SST and Chl-a maps. SST fronts were extracted from each SST images and gradient magnitudes (GMs); the orientations were derived for the SST fronts. Monthly maps of cold fronts where the cooler SSTs were over a shallower bottom were produced from the orientation.

Climatic Change, 2013

Variations in the abundance and distribution of pelagic tuna populations have been associated wit... more Variations in the abundance and distribution of pelagic tuna populations have been associated with large-scale climate indices such as the Southern Oscillation Index in the Pacific Ocean and the North Atlantic Oscillation in the Atlantic Ocean. Similarly to the Pacific and Atlantic, variability in the distribution and catch rates of tuna species have also been observed in association with the Indian Ocean Dipole (IOD), a basin-scale pattern of sea surface and subsurface temperatures that affect climate in the Indian Ocean. The environmental processes associated with the IOD that drive variability in tuna populations, however, are largely unexplored. To better understand these processes, we investigated longline catch rates of yellowfin tuna and their distributions in the western Indian Ocean in relation to IOD events, sea surface water temperatures (SST) and estimates of net primary productivity (NPP). Catch per unit effort (CPUE) was observed to be negatively correlated to the IOD with a periodicity centred around 4 years. During positive IOD events, SSTs were relatively higher, NPP was lower, CPUE decreased and catch distributions were restricted to the northern and western margins of the western Indian Ocean. During negative IOD events, lower SSTs and higher NPP were associated with increasing CPUE, particularly in the Arabian Sea and seas surrounding Madagascar, and catches expanded into central regions of the western Indian Ocean. These findings provide preliminary insights into some of the key environmental features driving the distribution of yellowfin tuna in the western Indian Ocean and associated variability in fisheries catches.

International Journal of Remote Sensing, 2010

This study presents finer structures and inter-seasonal evolutions of sea surface temperature (SS... more This study presents finer structures and inter-seasonal evolutions of sea surface temperature (SST) fronts in wintertime in the northern South China Sea (SCS) by applying an entropy-based edge detection method to 7-year (2001-2007) satellite-derived SST images with a grid ...

Climatic Change, 2014

Grey mullet (Mugil cephalus L.) is one of the most important commercial species of fish in the co... more Grey mullet (Mugil cephalus L.) is one of the most important commercial species of fish in the coastal fisheries of Taiwan. In this study, we analyzed the long-term records of grey mullet catch per unit effort (CPUE) in the Taiwan Strait (TS) to investigate the influences of climatic indices on the annual catch of grey mullet at multiple timescales. A wavelet analysis revealed that variations in climatic indices, namely the Pacific Decadal Oscillation (PDO), the Oceanic Niño Index, and sea surface temperatures (SSTs) might have affected the abundance and migration behavior of grey mullet in the TS in winter. The CPUE of grey mullet showed significant high correspondence with the annual PDO index (R 2 =0.82, p<0.01). The results suggested that the PDO affects the migration of grey mullet, but that increases in SSTs are a more important influence on the decreased catches of grey mullet after 1980. Mean SSTs increased 1.01°C at the Chang-Yuen Rise in the TS from 1984 to 2009. The 20°C isotherms in the TS in the winter also shifted from 23after 1998. The fishing grounds of grey mullet also shifted to the north following changes in the 20°C isotherm in the TS.