Spatial and Temporal Variability of Sea Surface Temperature in the Yellow Sea and East China Sea over the Past 141 Years (original) (raw)
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Continental Shelf Research, 2014
Based on monthly mean HadISST data, climatological characteristics and long-term changes of sea surface temperature (SST) over marginal seas of China are analyzed for the time period 1870-2011. The results show that (1) The smallest and largest spatial SST differences among various areas are seen in August and January respectively, with the coolest month occurring in February for all of the seas and the warmest month occurring in August for all but South China Sea (SCS); (2) The warming trends of the marginal seas of China during the time periods analyzed are generally larger than the global and hemispheric averages, with the East China Sea seeing the largest warming of all seas; (3) All of the sea areas see significant rising trends of annual mean SST in the last 140 years and the last 50 years, with larger and more significant warming generally occurs in autumn and winter; (4) The last 30 years especially the last 14 years undergo a slowdown of warming in the marginal seas of China, and the slowdown in the last 14 years is more evident than the global and northern hemispheric averages; (5) A weak upwelling current exists in western SCS, and the upwelling intensity has a significant positive correlation with the SCS summer monsoon index, with both seeing a decreasing trend in the last 64 years.
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Seasonal and regional temperature changes in China over the 50 year period 1951–2000
Meteorology and Atmospheric Physics, 2005
Statistical tests were used to detect the variations of winter (December to February), summer (June to August), and annual mean temperatures of 160 representative stations in China during the period from 1951 to 2000. Changes of temperature in the observed time series that exceed the confidence level of 0.01 were classified as significant temperature rises or drops. The stations with significant temperature rises were classified into several temperature rise types, by the use of a clustering method. A search was made for sudden, or abrupt, temperature changes at each of the 160 stations. Possible reasons for the observed temperature variations are discussed. The statistical analysis reveals that for the 160 stations, significant rises occur in 53.1% of their annual mean temperatures, 51.9% of their winter temperatures, and 13.8% of their summer temperatures. Temperature rises increase with latitude. In contrast, significant drops occur in annual mean temperatures at 1 station, winter temperatures at 3 stations, and summer temperatures at 5 stations. Approximately 50% of stations with significant temperature variations are in the form of abrupt changes. The abrupt temperature changes all occurred in the 1970s, most often in 1979 and 1980. The abrupt changes are shown to be related to the subtropical high in South China Sea. The temperature rises in winter are shown to be linked to the presence of an anomalously strong zonal circulation in Eurasia, and a weak polar vortex, since the 1980s. The summer temperature rise in South China also has a link with the increase in size and intensity of the subtropical high, over the same period. Some of the station temperature drops in summer were related to a weaker summer monsoon. The annual mean temperature rise at 71.8% of the stations was influenced mainly by their winter temperature rises. For 8.2% of the stations, the annual mean temperature rise was connected to their summer temperature rise, and for 12.9% of the stations it was related to both the summer and winter temperature rises.
Paleoceanography and Paleoclimatology, 2021
Limited instrumental records of sea surface temperature (SST) have hindered our ability to fully understand the natural long-term climate variability driven by surface ocean-atmosphere interactions, particularly in Southeast and East Asia where approximately 30% of the world's population resides (Morton & Blackmore, 2001; United Nations, 2019). Recent modeling studies have begun to document the uncertainty in the centennial-scale behavior of SST in the Western Pacific Ocean and surrounding seas, further emphasizing our need to reconstruct ocean hydrography at a high temporal resolution over longer periods (Karnauskas et al., 2012; Samanta et al., 2018). Complicating our understanding of climate in the marginal seas of the Maritime Continent are the changing interactions between climate drivers of surrounding areas. Climate drivers in Southeast Asia and the marginal seas, including the South China Sea (SCS), are complex and operate at multiple frequencies. For example, the East Asian Monsoon (EAM) varies primarily on a seasonal timescale, whereas the El Niño Southern Oscillation (ENSO) and the Interdecadal Pacific Oscillation (IPO) exert influence on interannual to interdecadal timescales, respectively. The EAM is defined by seasonal shifts in winds and moisture delivery to East Asia from the Indian and Pacific Oceans. In the summer, winds blow from the Indian Ocean over the SCS onto the Asian continent, driving precipitation. In the winter, winds reverse, delivering cold, dry air from the Pacific Ocean across the East Asian continent to the SCS. These winds have a significant impact, driving seasonal changes in ocean circulation, temperature and precipitation (Lau & Li, 1984; B.
Comparing the current and early 20th century warm periods in China
Earth-Science Reviews, 2018
Most estimates of Chinese regional Surface Air Temperatures since the late-19th century have identified two relatively warm periods – 1920s–40s and 1990s–present. However, there is considerable debate over how the two periods compare to each other. Some argue the current warm period is much warmer than the earlier warm period. Others argue the earlier warm period was comparable to the present. In this collaborative paper, including authors from both camps, the reasons for this ongoing debate are discussed. Several different estimates of Chinese temperature trends, both new and previously published, are considered. A study of the effects of urbanization bias on Chinese temperature trends was carried out using the new updated version of the Global Historical Climatology Network (GHCN) – version 4 (currently in beta production). It is shown that there are relatively few rural stations with long records, but urbanization bias artificially makes the early warm period seem colder and the recent warm period seem warmer. However, current homogenization approaches (which attempt to reduce non-climatic biases) also tend to have similar effects, making it unclear whether reducing or increasing the relative warmth of each period is most appropriate. A sample of 17 Chinese temperature proxy series (12 regional and 5 national) is compared and contrasted specifically for the period since the 19th century. Most proxy series imply a warm early-20th century period and a warm recent period, but the relative warmth of these two periods differs between proxies. Also, with some proxies, one or other of the warm periods is absent.
Decadal Variation of Wintertime Sea Surface Temperature in
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Long-term advanced very-high-resolution radiometer (AVHRR) data with a resolution of 0.04° provided clearer views of sea surface temperature (SST) warming and variation associated with ENSO in the Taiwan Strait (TS) during wintertime . Over the 33 year period, the spatial average of winter SST warming in the TS reached to 3°C. From 1981-2001, the SST exhibited an increasing trend, with the fastest warming taking place from 1991-2001 after which it seemed to pause. From 2002-2012, the SST showed a cooling trend (-0.08°C/yr). Spatial variation of the warming was distinct, with the highest values concentrated in the winter fronts region, formed by the cold China Coastal Current (CCC) and the warm Kuroshio Branch (KB), indicating northwestward movements of the winter fronts. Influence of ENSO events on winter SST was significant, with higher SST in the CCC region in El Niño years. Temporal SST EOF results in modes 1 and 2 show a long-term warming trend and interannual variations, respectively. Consequently, the combined impacts of global ocean warming and climate variability in future will result in increasing the uncertain of SST variability in the TS.
Anomalous summer climate in China influenced by the tropical Indo-Pacific Oceans
Climate Dynamics, 2011
Possible influences of three coupled oceanatmosphere phenomena in the Indo-Pacific Oceans, El Niño, El Niño Modoki and the Indian Ocean Dipole (IOD), on summer climate in China are studied based on data analysis for the summers of 1951-2007. Partial correlation/ regression analysis is used to find the influence paths through the related anomalous mid-and low-level tropospheric circulations over the oceanic region and East Eurasia, including the western North Pacific summer monsoon (WNPSM). Among the three phenomena, El Niño Modoki has the strongest relationship with the WNPSM. When two or three phenomena coexist with either positive or negative phase, the influences exerted by one phenomenon on summer climate in different regions of China may be enhanced or weakened by other phenomena. In 1994 when both El Niño Modoki and IOD are prominent without El Niño, a strong WNPSM is associated with severe flooding in southern China and severe drought in the Yangtze River Valley (YRV). The 500 hPa high systems over China are responsible for heat waves in most parts of China. In 1983 when a strong negative phase of El Niño Modoki is accompanied by moderate El Niño and IOD, a weak WNPSM is associated with severe flooding in the YRV and severe drought in southern China. The 500 hPa low systems over China are responsible for the cold summer in the YRV and northeastern China. For rainfall, the influence path seems largely through the low-level tropospheric circulations including the WNPSM. For temperature, the influence path seems largely through the mid-level tropospheric circulations over East Eurasia/western North Pacific Ocean.
Summer upwelling in the South China Sea and its role in regional climate variations
Journal of Geophysical Research, 2003
Vietnam coast and the offshore spread of cold water are investigated using a suite of new satellite measurements. In summer, as the southwesterly winds impinge on Annam Cordillera-a north-south running mountain range on the east coast of Indochina-a strong wind jet occurs at its southern tip offshore east of Saigon, resulting strong wind curls that are important for ocean upwelling off the coast. In July and August an anticyclonic ocean eddy develops to the southeast advecting the cold coastal water offshore into the open South China Sea (SCS). The center of this cold filament is located consistently north of the wind speed maximum, indicating that open-ocean upwelling helps to cool the ocean surface. Corroborating evidence for the cold filament is found in ocean color observations that reveal a collocated tongue of high chlorophyll concentration. The development of this cold filament disrupts the summer warming of the SCS and causes a pronounced semi-annual cycle in SST. Moreover, the cold filament is an important player in interannual variability in the summer SCS. In 1998, the cold filament and mid-summer cooling never took place, giving rise to a strong basin-wide surface warming. Interannual SST variance has a local maximum over the cold filament, which is much greater than the variance over the adjacent Indian and western Pacific Oceans. A cold filament index is constructed, which displays significant lagged correlation with SST in the eastern equatorial Pacific and Indian Oceans, indicative of a teleconnection from El Nino.