STATISTICAL ANALYSIS OF RELATIONSHIP BETWEEN VARIATIONS IN BEACH MORPHOLOGY AND NORTH PACIFIC SEA LEVEL PRESSURE

Author(s):  
Masayuki BANNO ◽  
Nobuhito MORI ◽  
Yoshiaki KURIYAMA
2015 ◽  
Vol 120 (1) ◽  
pp. 27-45 ◽  
Author(s):  
Ruiqiang Ding ◽  
Jianping Li ◽  
Yu-heng Tseng ◽  
Cheng Sun ◽  
Yipeng Guo

2021 ◽  
Vol 21 (10) ◽  
pp. 7499-7514
Author(s):  
Lixia Zhang ◽  
Laura J. Wilcox ◽  
Nick J. Dunstone ◽  
David J. Paynter ◽  
Shuai Hu ◽  
...  

Abstract. Air pollution is a major issue in China and one of the largest threats to public health. We investigated future changes in atmospheric circulation patterns associated with haze events in the Beijing region and the severity of haze events during these circulation conditions from 2015 to 2049 under two different aerosol scenarios: a maximum technically feasible aerosol reduction (MTFR) and a current legislation aerosol scenario (CLE). In both cases greenhouse gas emissions follow the Representative Concentration Pathway 4.5 (RCP4.5). Under RCP4.5 with CLE aerosol the frequency of circulation patterns associated with haze events increases due to a weakening of the East Asian winter monsoon via increased sea level pressure over the North Pacific. The rapid reduction in anthropogenic aerosol and precursor emissions in MTFR further increases the frequency of circulation patterns associated with haze events, due to further increases in the sea level pressure over the North Pacific and a reduction in the intensity of the Siberian high. Even with the aggressive aerosol reductions in MTFR periods of poor visibility, represented by above-normal aerosol optical depth (AOD), still occur in conjunction with haze-favorable atmospheric circulation. However, the winter mean intensity of poor visibility decreases in MTFR, so that haze events are less dangerous in this scenario by 2050 compared to CLE and relative to the current baseline. This study reveals the competing effects of aerosol emission reductions on future haze events through their direct contribution to pollutant source and their influence on the atmospheric circulation. A compound consideration of these two impacts should be taken in future policy making.


2015 ◽  
Vol 12 (2) ◽  
pp. 403-447
Author(s):  
N. Tim ◽  
E. Zorita ◽  
B. Hünicke

Abstract. Detecting the atmospheric drivers of the Benguela Upwelling Systems is essential to understand its present variability and its past and future changes. We present a statistical analysis of an ocean-only simulation driven by observed atmospheric fields over the last decades with the aim of identifying the large-scale atmospheric drivers of upwelling variability and trends. The simulation is found to reproduce well the seasonal cycle of upwelling intensity, with a maximum in the June-to-August season in North Benguela and in the December-to-February season in South Benguela. The statistical analysis of the interannual variability of upwelling focuses on its relationship to atmospheric variables (sea level pressure, 10 m-wind, wind stress). The relationship between upwelling and the atmospheric variables differ somewhat in the two regions, but generally, the correlation patterns reflect the common atmospheric pattern favoring upwelling: southerly wind/wind stress, strong subtropical anticyclone, and an ocean-land sea level pressure gradient. In addition, the statistical link between upwelling and large-scale climate variability modes was analyzed. The El Niño Southern Oscillation and the Antarctic Oscillation exert some influence on austral summer upwelling velocities in South Benguela. The decadal evolution and the long-term trends of upwelling and of ocean-minus-land air pressure gradient do not agree with Bakun's hypothesis that anthropogenic climate change should generally intensify coastal upwelling.


2021 ◽  
Author(s):  
Abdulhaleem H. Labban ◽  
Adel M. Awad

Abstract Objectively, Saharan cyclones have been detected for the period from 1967 to 2019 using mean sea level pressure (SLP); their tracks have been specified from nearest neighbor cyclonic positions and classified into long/short tracks depending on the area of influence of the cyclones. Additionally, the detected long tracks have been objectively classified into five main routes directed generally eastward, northeastward and northward, accounting for approximately 41.6%, 19.7% and 30.4% of the total long tracks, respectively. Mainly for long tracks, three cyclogenesis areas, where more than 99% of cyclones are generated, were identified, with more than 61% generated in the Atlas region. Moreover, four far cyclolysis areas were identified, where approximately 74% of these cyclones terminated, with more than 66% of them terminating in the eastern study region. Furthermore, statistical analysis indicated that Saharan cyclones are commonly generated in the spring and summer, with ~35.3% and 46.3%, respectively. However, the highest numbers occur in spring in the northern Saharan and in summer in the southern Saharan, with ~49.1% and 57.7%, respectively. Temporally, the monthly distribution indicates that most of the cyclones moving along the five main routes are generated in warm months, namely, May to August. Approximately 85% of these cyclones have a lifespan of three days, while only 1% span more than five days.


2011 ◽  
Vol 24 (4) ◽  
pp. 1170-1183 ◽  
Author(s):  
Sang-Wook Yeh ◽  
Yune-Jung Kang ◽  
Yign Noh ◽  
Arthur J. Miller

Abstract This paper examines characteristic changes in North Pacific sea surface temperature (SST) variability during the boreal winter (December–February) for two subperiods (1956–88 and 1977–2009) during which the 1976/77 and the 1988/89 climate transitions occurred. It is found that the Pacific decadal oscillation (PDO)-like SST variability plays a dominant role in the 1976/77 climate transition, while both the North Pacific Gyre Oscillation (NPGO)-like and PDO-like SST variability contribute to the 1988/89 climate transition. Furthermore, the leading mode changes from PDO-like SST variability during the period 1956–88 to NPGO-like SST variability during the period 1977–2009, indicative of an enhancement of NPGO-like SST variability since 1988. Changes in sea level pressure across the 1976/77 climate transition project strongly onto the Aleutian low pressure system. But sea level pressure changes across the 1988/89 climate transition project primarily onto the North Pacific Oscillation, which is associated with remote changes in the Arctic Oscillation over the polar region as well. This contributes to enhancing the NPGO-like SST variability after 1988. The authors also analyze the output from an ensemble of Tropical Ocean and Global Atmosphere (TOGA) experiments in which the observed SSTs are inserted only at grid points in the tropics between 20°S and 20°N. The results indicate that the changes in the North Pacific atmosphere in the 1976/77 climate transition are mostly due to the tropics, whereas those in the 1988/89 climate transition are not.


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