scholarly journals A Comparison between a Generalized Beta–Advection Model and a Classical Beta–Advection Model in Predicting and Understanding Unusual Typhoon Tracks in Eastern China Seas

2015 ◽  
Vol 30 (3) ◽  
pp. 771-792 ◽  
Author(s):  
Jing Huang ◽  
Jun Du ◽  
Weihong Qian
Keyword(s):  
Tropical Cyclones ◽  
Large Scale ◽  
Eastern China ◽  
China Seas ◽  
Key Factors ◽  
Decomposition Approach ◽  
Left Turn ◽  
Meteorological Field ◽  
Eastern China Seas ◽  
Typhoon Tracks

Abstract A total of 163 tropical cyclones (TCs) occurred in the eastern China seas during 1979–2011 with four types of tracks: left turning, right turning, straight moving, and irregular. The left-turning type is unusual and hard to predict. In this paper, 133 TCs from the first three types have been investigated. A generalized beta–advection model (GBAM) is derived by decomposing a meteorological field into climatic and anomalous components. The ability of the GBAM to predict tracks 1–2 days in advance is compared with three classical beta–advection models (BAMs). For both normal and unusual tracks, the GBAM apparently outperformed the BAMs. The GBAM’s ability to predict unusual TC tracks is particularly encouraging, while the BAMs have no ability to predict the left-turning and right-turning TC tracks. The GBAM was also used to understand unusual TC tracks because it can be separated into two forms: a climatic-flow BAM (CBAM) and an anomalous-flow BAM (ABAM). In the CBAM a TC vortex is steered by the large-scale climatic background flow, while in the ABAM, a TC vortex interacts with the surrounding anomalous flows. This decomposition approach can be used to examine the climatic and anomalous flows separately. It is found that neither the climatic nor the anomalous flow alone can explain unusual tracks. Sensitivity experiments show that two anomalous highs as well as a nearby TC played the major roles in the unusual left turn of Typhoon Aere (2004). This study demonstrates that a simple model can work well if key factors are properly included.

Heat budget responses of the eastern China seas to global warming in a coupled atmosphere-ocean model

2019 ◽  
Vol 79 (2) ◽  
pp. 109-126
Author(s):  
D Tian ◽  
J Su ◽  
F Zhou ◽  
B Mayer ◽  
D Sein ◽  
...  
Keyword(s):  
Global Warming ◽  
Heat Budget ◽  
Eastern China ◽  
Ocean Model ◽  
China Seas ◽  
Eastern China Seas

scholarly journals The Climatological Analysis of Typhoon Tracks, Steering Flow, and the Pacific Subtropical High in the Vicinity of Taiwan and the Western North Pacific

Atmosphere ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 543
Author(s):  
Chih-wen Hung ◽  
Ming-Fu Shih ◽  
Te-Yuan Lin
Keyword(s):  
Tropical Cyclones ◽  
Large Scale ◽  
Subtropical High ◽  
Boreal Summer ◽  
The South ◽  
The West ◽  
Steering Flow ◽  
The Pacific ◽  
Typhoon Season ◽  
Typhoon Tracks

Taiwan frequently suffers from typhoon hits in the boreal summer and fall. The location of Taiwan makes it vulnerable to the pathways of typhoons mainly determined by the position of the Pacific subtropical high. In order to clarify the linkage between typhoon invasion and associated large-scale environments from a climatological perspective, this study counts the historical typhoon invasion days for each month in the typhoon season to establish analyzed cases and then categorizes them with statistical thresholds. Besides, the categorized cases with less typhoon invasion are further sorted to distinguish different movements of tropical cyclones. Therefore, corresponding composites are applied for each category. The results reveal that when the subtropical high retreats eastward, the accompanying steering flow guides typhoons to make an early recurvature toward Japan and South Korea. While the subtropical high further extends its property to the west covering Taiwan, the steering flow on the south transfers typhoons moving westward to the South China Sea. However, when the subtropical high lies in areas between the above two scenarios, the steering flow along the periphery of the subtropical high continuously sends typhoons toward Taiwan and the vicinity, which greatly increases the threat to the island.

scholarly journals Satellite views of seasonal and inter-annual variability of phytoplankton blooms in the eastern China seas over the past 14 yr (1998–2011)

2013 ◽  
Vol 10 (1) ◽  
pp. 111-155 ◽  
Author(s):  
X. Q. He ◽  
Y. Bai ◽  
D. L. Pan ◽  
C.-T. A. Chen ◽  
Q. Chen ◽  
...  
Keyword(s):  
Yellow Sea ◽  
Annual Variation ◽  
Bohai Sea ◽  
Eastern China ◽  
Chlorophyll Concentration ◽  
The Yellow Sea ◽  
China Seas ◽  
Phytoplankton Blooms ◽  
The Changjiang Estuary ◽  
Eastern China Seas

Abstract. The eastern China seas are one of the largest marginal seas in the world, where high primary productivity and phytoplankton blooms are often observed. However, to date, little is known about the spatial and temporal variability of phytoplankton blooms in these areas due to the difficulty of the monitoring of bloom events by field measurement. In this study, 14-yr time series of satellite ocean color data from the Sea-Viewing Wide Field-of-view Sensor (SeaWiFS) and the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Aqua satellite have been used to investigate the seasonal and inter-annual variability and long-term changes of phytoplankton blooms in the eastern China seas. We validated and calibrated the satellite-derive chlorophyll concentration in the eastern China seas based on extensive data sets from two large cruises. Overestimation of satellite-derive chlorophyll concentration caused by high water turbidity was found to be less than 10 μg L−1. This level can be used as a safe threshold for the identification of a phytoplankton bloom in a marginal sea with turbid waters. Annually, blooms mostly occur in the Changjiang Estuary and along the coasts of Zhejiang. The coasts of the northern Yellow Sea and Bohai Sea also have high-frequency blooms. The blooms have significant seasonal variation, with most of the blooms occurring in the spring (April–June) and summer (July–September). This study revealed a doubling in bloom intensity in the Yellow Sea and Bohai Sea during the past 14 yr (1998–2011), yet surprisingly, there has been no decadal increase or decrease of bloom intensity in despite of significant inter-annual variation in the Changjiang Estuary. The time series in situ datasets show that both the nitrate and phosphate concentrations increase more than twofold from 1998 to 2005. This might be the reason for the doubling of bloom intensity in the Yellow Sea and Bohai Sea. In addition, the ENSO and PDO can affect the inter-annual variation of bloom intensity in the eastern China seas.

scholarly journals Satellite views of the seasonal and interannual variability of phytoplankton blooms in the eastern China seas over the past 14 yr (1998–2011)

2013 ◽  
Vol 10 (7) ◽  
pp. 4721-4739 ◽  
Author(s):  
X. He ◽  
Y. Bai ◽  
D. Pan ◽  
C.-T. A. Chen ◽  
Q. Cheng ◽  
...  
Keyword(s):  
Yellow Sea ◽  
Bohai Sea ◽  
Eastern China ◽  
The Yellow Sea ◽  
China Seas ◽  
Phytoplankton Blooms ◽  
Chl A ◽  
The Past ◽  
Eastern China Seas

Abstract. The eastern China seas are some of the largest marginal seas in the world, where high primary productivity and phytoplankton blooms are often observed. However, little is known about their systematic variation of phytoplankton blooms on large spatial and long temporal scales due to the difficulty of monitoring bloom events by field measurement. In this study, we investigated the seasonal and interannual variability and long-term changes in phytoplankton blooms in the eastern China seas using a 14 yr (1998–2011) time series of satellite ocean colour data. To ensure a proper satellite dataset to figure out the bloom events, we validated and corrected the satellite-derived chlorophyll concentration (chl a) using extensive in situ datasets from two large cruises. The correlation coefficients between the satellite retrieval data and the in situ chl a on the logarithmic scale were 0.85 and 0.72 for the SeaWiFS and Aqua/MODIS data, respectively. Although satellites generally overestimate the chl a, especially in highly turbid waters, both the in situ and satellite data show that the overestimation of satellite-derived chl a has an upper limit value (10 μg L−1), which can be used as a threshold for the identification of phytoplankton blooms to avoid the false blooms resulting from turbid waters. Taking 10 μg L−1 as the threshold, we present the spatial-temporal variability of phytoplankton blooms in the eastern China seas over the past 14 yr. Most blooms occur in the Changjiang Estuary and along the coasts of Zhejiang, with a maximal frequency of 20% (about 73 days per year). The coasts of the northern Yellow Sea and the Bohai Sea also have high-frequency blooms (up to 20%). The blooms show significant seasonal variation, with most occurring in spring (April–June) and summer (July–September). The study also revealed a doubling in bloom intensity in the Yellow Sea and Bohai Sea during the past 14 yr. The nutrient supply in the eastern China seas might be a major controlling factor in bloom variation. The time series in situ nutrient datasets show that both the nitrate and phosphate concentrations increased more than twofold between 1998 and 2005 in the Yellow Sea. This might be the reason for the doubling of the bloom intensity index in the Yellow Sea and Bohai Sea. In contrast, there has been no significant long-term increase or decrease in the Changjiang Estuary, which might be regulated by the Changjiang River discharge. These results offer a foundation for the study of the influence of phytoplankton blooms on the carbon flux estimation and biogeochemical processes in the eastern China seas.

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