Changes in marine environments affect fishery resources at different spatial and temporal scales in marine ecosystems. Predictions from species distribution models are available to parameterize the environmental characteristics that influence the biology, range, and habitats of the species of interest. This study used generalized additive models (GAMs) fitted to two spatiotemporal fishery data sources, namely 1° spatial grid and observer record longline fishery data from 2006 to 2010, to investigate the relationship between catch rates of yellowfin tuna and oceanographic conditions by using multispectral satellite images and to develop a habitat preference model. The results revealed that the cumulative deviances obtained using the selected GAMs were 33.6% and 16.5% in the 1° spatial grid and observer record data, respectively. The environmental factors in the study were significant in the selected GAMs, and sea surface temperature explained the highest deviance. The results suggest that areas with a higher sea surface temperature, a sea surface height anomaly of approximately −10.0 to 20 cm, and a chlorophyll-a concentration of approximately 0.05–0.25 mg/m³ yield higher catch rates of yellowfin tuna. The 1° spatial grid data had higher cumulative deviances, and the predicted relative catch rates also exhibited a high correlation with observed catch rates. However, the maps of observer record data showed the high-quality spatial resolutions of the predicted relative catch rates in the close-view maps. Thus, these results suggest that models of catch rates of the 1° spatial grid data that incorporate relevant environmental variables can be used to infer possible responses in the distribution of highly migratory species, and the observer record data can be used to detect subtle changes in the target fishing grounds.

This study investigates the roles of atmospheric moisture transport under the influence of topography for summer extreme precipitation over North China (NC) during 1979–2016. Based on rain gauge precipitation data and a reanalysis, 38 extreme precipitation days in NC during the 38 years were selected and associated moisture fluxes estimated. The results show that there is a dominant moisture influx of 311.8 kg m⁻¹ s⁻¹ into NC along its southern boundary from tropical oceans, and a secondary influx of 107.9 kg m⁻¹ s⁻¹ across its western boundary carried by mid-latitude westerlies. The outflux across the eastern boundary is 206.9 kg m⁻¹ s⁻¹ and across the northern boundary is 76.0 kg m⁻¹ s⁻¹, giving a net moisture gain over NC of 136.8 kg m⁻¹ s⁻¹. During extreme precipitation days, the moisture flux convergence (MFC) was much larger, exceeding 4 × 10⁻⁵ kg m⁻¹ s⁻¹. The MFC maximum core, the pronounced moisture transport, and the striking extreme precipitation zone over NC are all anchored to the east of the steep slopes of the surrounding topography. Moreover, a remarkably high humidity and strong upward motion also occur near steep slopes, indicating the critical role of the adjacent topography on the extreme precipitations. Simulations with and without the topography in NC using the Weather and Research Forecasting model for six selected out of the 38 extreme precipitation days demonstrate that the surrounding topography reinforces the MFC over NC by 16% relative to the case without terrain, primarily through enhanced wind convergence and higher moisture content, as well as stronger vertical motion induced by diabatic heating. The interactions between moisture convergence and topographic settings strengthen the extreme precipitation over NC.

Skipjack tuna are the most abundant commercial species in Taiwan’s pelagic purse seine fisheries. However, the rapidly changing marine environment increases the challenge of locating target fish in the vast ocean. The aim of this study was to identify the potential fishing grounds of skipjack tuna in the Western and Central Pacific Ocean (WCPO). The fishing grounds of skipjack tuna were simulated using the habitat suitability index (HSI) on the basis of global fishing activities and remote sensing data from 2012 to 2015. The selected environmental factors included sea surface temperature and front, sea surface height, sea surface salinity, mixed layer depth, chlorophyll a concentration, and finite-size Lyapunov exponents. The final input factors were selected according to their percentage contribution to the total efforts. Overall, 68.3% of global datasets and 35.7% of Taiwanese logbooks’ fishing spots were recorded within 5 km of suitable habitat in the daily field. Moreover, 94.9% and 79.6% of global and Taiwan data, respectively, were identified within 50 km of suitable habitat. Our results showed that the model performed well in fitting daily forecast and actual fishing position data. Further, results from this study could benefit habitat monitoring and contribute to managing sustainable fisheries for skipjack tuna by providing wide spatial coverage information on habitat variation.

The Tibetan Plateau has an important impact on regional water cycle, ecosystem, disastrous weather formation, and climate change. China has conducted the Third Tibetan Plateau Experiment-Observation of Boundary Layer and Troposphere (2014–2017) Project in order to reveal the physical process of meteorology and atmosphere over the Tibetan Plateau. The observational instruments for cloud and precipitation processes in this field experiment include the C-band continuous wave radar, Ka-band millimetre wave cloud radar, ground-based raindrop disdrometer, lidar ceilometer etc. In this paper, the characteristics of convective clouds and precipitation as well as raindrop size distribution were analysed by using observed data and FY-2E satellite TBB data from July 1 to August 31, 2014. The result shows that the convective activities mainly distributed in the central and southeast part of the Tibetan Plateau and the precipitation had a quasi-two-week cycle during the observational period. Due to the solar heating effect over the plateau, both convective clouds and precipitation processes had obvious daily variation. There were four precipitation peaks in a day, which were 0:00–1:00, 12:00–13:00, 17:00–18:00, 19:00–22:00 (LST) respectively. The convections first appeared at 11:00, and the first precipitation peak happened at around 12:00, which was mainly caused by local thermal convection with relative lower cloud-top height and wider drop spectrum. Then the convections merged and developed to their maximum at 17:00–18:00, during which cloud-base height had a sharp decrease at 17:00 and widest raindrop spectrum and the second precipitation peak happened in this period. At night the precipitation tended to be advective but remained high and lasted until 6:00 and then dissipated. During 18:00–24:00 there was a precipitation peak around 19:00–22:00 and the cloud-top height was as high as that in the afternoon and the number of smaller drops increased. After midnight, the cloud-top height as well as precipitation started to decrease and tended to be more advective, but a forth precipitation peak happened during 0:00–1:00. In the forenoon there were few convections happened. The mean cloud-top height was around 11.5 km (ASL), and its maximum value exceeded 19 km, and the mean cloud-base height was 6.88 km (ASL) during the observation period. Precipitation was mainly short-lasting and showery, and usually lasted less than 1 h, and the mean precipitation intensity was 1.2 mm/h. The result also shows that the raindrop size distribution over the Tibetan Plateau was wider than that over plain at the same latitude and season, because of which the rainfall could be more easily produced over the plateau than that over plain. Rain happened more at night than at noon. However, there were more larger-size raindrops at daytime than at night. Γ distribution was found to be more suitable for the raindrop size distribution than M-P distribution over the Tibetan Plateau.

Material exchange between oceans and currents is crucial for biogeochemical processes in marginal seas, such as the Kuroshio intrusion in the Luzon Strait, which contributes to nutrient and phytoplankton growth in the adjacent water. Therefore, it is necessary to understand changes in major current systems and their possible effects on marine ecology. In this study, we applied an edge-detection method to satellite-derived sea-surface temperature (SST) images to identify the SST front as the index of Kuroshio intrusion during 1985–2017. Chlorophyll-a (Chl-a) concentrations and geostrophic currents (determined from satellite observations after 1993) were examined by comparing long-term variations related to the Kuroshio front using empirical-mode decomposition analysis. The Kuroshio intrusion into the Luzon Strait gradually decreased after the 1990s, as did the Chl-a concentrations and current speed in the Strait. In contrast, the speed of the Kuroshio Current in the eastern Philippine tended to increase, indicating that the northward Kuroshio Current from the eastern Philippines became stronger, curtailing the westward intrusion of the branch current into the Luzon Strait. The speed of the Kuroshio Current correlated with the bifurcation of the North Equatorial Current (NEC), which is upstream of the Kuroshio Current starting from the southeast Philippines. Therefore, the NEC bifurcation latitude may have shifted more southward, which strengthened the water mass and current speed of the Kuroshio, resulting in decreased westward motion of the Kuroshio through the Luzon Strait. Consequently, the weakening Kuroshio intrusion may have caused a decreasing trend of biogeochemical processes in the South China Sea.