Changes In Background Conditions Research Articles

Will typhoon over the western North Pacific be more frequent in the Blue Arctic conditions?

How would typhoon activity over the western North Pacific change for various scenarios of future global warming? Using the model projections of the Coupled Model Intercomparison Project phase 3 (CMIP 3) under the SRES A1B scenario, we generated summer (September) ice-free Arctic conditions, also referred to as Blue Arctic conditions, and then used the corresponding monthly sea surface temperature (SST) and a set of CO2 concentrations to drive an AGCM model to simulate the resulting changes in background conditions affecting typhoon activity over the western North Pacific. Our results show that, during typhoon season (June to October), atmospheric and ocean circulations over the western North Pacific would be significantly different from the present circulations. Changes in the vertical shear of zonal wind and outgoing longwave radiation (OLR) in the western North Pacific are favorable for westward and northward shift, respectively, of the location of typhoon genesis. Moreover, changes in the above fields over the key area may be conducive to less frequent typhoons. In addition, the tropical cyclone genesis potential index (GPI) over the western North Pacific would decrease (increase) east (west) of 150°E (140°E).

Enhanced western North Pacific tropical cyclone activity in May in recent years

The tropical cyclone (TC) power dissipation index (PDI) in May over the western North Pacific (WNP) region shows a remarkable increase from the pre-1999 years (1979–1999) to the post-1999 years (2000–2011). Both increased TC numbers and enhanced TC intensity contributed to the change in the PDI. The averaged TC number in May increased from 1.05 per year in the pre-1999 years to 1.75 per year in the post-1999 years. In particular, the number of intense typhoon goes up from 0.14 per year to 0.83 per year, implying a sharp increase of TC intensity. Examination of the large scale background circulation in May shows that the epochal increase of TC number is caused by a significant increase of the genesis potential index (GPI), which has increased by about 33 % from the first (1979–1998) to the second (1999–2011) epoch over the TC genesis region (110°E–160°E, 5°N–20°N). The higher TC intensity is related to the increased maximum potential intensity and reduced TC ambient vertical wind shear in the second epoch. These decadal changes in background conditions over the WNP are the results of the enhanced summer monsoon in May over the both South Asia and South China Sea.

Features of species composition and abundance of the nekton community in the upper epipelagic layer of the Northwest Pacific in early summer

The composition and structure of nekton in the upper epipelagic zone is considered based on the data of trawl surveys conducted in the Northwestern Pacific Ocean and adjacent waters in 2004–2009. Alterations in the nekton community during the early summer period, as well as peculiarities of its species composition and quantitative distribution that depend on changes in background conditions are described. In total, as many as 66 species of fish and 22 species of cephalopods were recorded in catches for the studied period. The lowest biodiversity was found in the near-shore waters (areas nos. 5, 7, and 9) and the highest one was in open oceanic waters (area no. 13). In 2004–2009, nekton biomass was formed mainly by mesopelagic species and their share amounted to 40–60% of the entire nekton community. Pacific salmon varied within 17–37% the total nekton biomass in various years. In general, for the period of studies, the mean biomass of nekton community was 2 431 000 tons, and in 2009, the total biomass approached this value.

El Niño and its relationship to changing background conditions in the tropical Pacific Ocean

This paper addresses the question of whether the increased occurrence of central Pacific (CP) versus Eastern Pacific (EP) El Niños is consistent with greenhouse gas forced changes in the background state of the tropical Pacific as inferred from global climate change models. Our analysis uses high‐quality satellite and in situ ocean data combined with wind data from atmospheric reanalyses for the past 31 years (1980–2010). We find changes in background conditions that are opposite to those expected from greenhouse gas forcing in climate models and opposite to what is expected if changes in the background state are mediating more frequent occurrences of CP El Niños. A plausible interpretation of these results is that the character of El Niño over the past 31 years has varied naturally and that these variations projected onto changes in the background state because of the asymmetric spatial structures of CP and EP El Niños.

Causation in biology: stability, specificity, and the choice of levels of explanation

This paper attempts to elucidate three characteristics of causal relationships that are important in biological contexts. Stability has to do with whether a causal relationship continues to hold under changes in background conditions. Proportionality has to do with whether changes in the state of the cause “line up” in the right way with changes in the state of the effect and with whether the cause and effect are characterized in a way that contains irrelevant detail. Specificity is connected both to David Lewis’ notion of “influence” and also with the extent to which a causal relation approximates to the ideal of one cause–one effect. Interrelations among these notions and their possible biological significance are also discussed.

Dynamic Influences on Smoking Relapse Process

This article describes a program of research applying Ecological Momentary Assessment (EMA) methods to study relapse to cigarette smoking, with a particular focus on the role of negative affect (NA) and self-efficacy (SE). Day-to-day changes in mood and stress did not predict lapse risk, but more proximal changes in affect were associated with lapses: Many lapses were marked by intense NA and by NA increases in the preceding hours. Individual differences in baseline SE predicted lapse risk, but daily SE was relatively stable during abstinence and did not influence lapse risk. However, lapses resulted in immediate drops in SE, and day-to-day changes in postlapse SE predicted progression to relapse, even after accounting for concurrent smoking. SE showed momentary drops associated with NA, but only among smokers with low baseline SE. Individual differences in baseline SE were only expressed situationally under conditions of NA. The findings highlight the importance of dynamic changes in background conditions and in immediate states as important influences on lapses and relapse and also suggest the importance of considering person by situation interactions.