Characteristics and variations of the picophytoplankton community in the Arctic Ocean

Picophytoplankton are responsible for much of the carbon fixation process in the Arctic Ocean, and they play an im- portant role in active microbial food webs. The climate of the Arctic Ocean has changed in recent years, and picophytoplankton, as the most vulnerable part of the high-latitude pelagic ecosystem, have been the focus of an increasing number of scientific studies. This paper reviews and summarizes research on the characteristics of picophytoplankton in the Arctic Ocean, including their abundance, biomass, spatial distribution, seasonal variation, commtmity structure, and factors influencing their growth. The impact of climate change on the Arctic Ocean picophytoplankton community is discussed, and future research directions are considered.     

ENSO signals and their spatial-temporal variation characteristics recorded by the sea-level changes in the northwest Pacific margin during 1965-2005

Sea-level is closely linked to the Earth's climate and its change is important as a metric for global and regional climate change. Identifying, extracting, and revealing such information through detailed analysis is the prerequisite for understanding the mechanisms of sea-level change. The monthlyaverage tide-change records reported and examined in this paper are from 10 tide gauge stations distributed in the northwest margin of the Pacific Ocean, registered during the period 1965-2005. In particular, we ha...     

Is climate change causing the increasing narwhal (Monodon monoceros) catches in Smith Sound, Greenland?

This paper evaluates recent changes in narwhal ( Monodon monoceros ) catches in Siorapaluk, the northernmost community in Greenland, in consideration of the effects of changing climate and uncertainty of stock delineation. The catch statistics show a significant increase in narwhal catches by hunters in Siorapaluk after 2002, which does not appear to be a result of increased effort. Hunters attribute the increase to changed sea-ice conditions providing access by boat to Smith Sound as early as June and July. This indicates that climate change is likely to have a considerable impact on narwhal hunting in northern Greenland. Traditional ecological knowledge and scientific surveys suggest that narwhal in Smith Sound constitute an independent stock. The absence of scientific recommendations for this stock has been seen as an opportunity to increase quotas in West Greenland. Scientific management recommendations are urgently needed to allow the authorities to assign sustainable quotas for this stock. The development of collaborative management agreements and locally based monitoring are recommended to ensure local acceptance of regulations, and to allow rapid responses to climate change.     

Synchronizing seismic networks with ambient noise

The technique of retrieving Green's functions by pairwise correlation of a random wavefield is used to estimate the stability of the timing system of a seismic network. The method is demonstrated with data from a network consisting of stations with four independent clocks and GPS-receivers. For a two years period, daily measurements of the timing error of each of the four systems are obtained. These measurements can be used to correct the timing of the data in periods without GPS reception. The accuracy of this method can exceed the precision of the internal station clocks already after a single day of uncorrected drift.     

Minimum on the light curve of the classical symbiotic star AS 338 in 1999

We present our UBVRI photometry and spectroscopy of AS 338 performed in 1999–2000. Another eclipse of the hot component in this symbiotic binary system, the deepest one ever observed, occurred in September 1999. The U brightness declined by ～2^m, the Hβflux decreased by a factor of ～2.3, and the [O III]γ5007 flux did not change. The hot component is eclipsed at orbital phases ?≈0.045–0.057. The U-B color index begins to appreciably fluctuate during an eclipse of the hot component and its circumstellar envelope. About 100 days after a strong outburst of 1995, the mean UBV brightness of AS 338 declined linearly in the ensuing five years at the same rate in all bands (ΔU/Δt≈10^?3 mag/day). The brightness of the outer, uneclipsed parts of the circumstellar envelope also decreased, which is attributable to a reduction in the luminosity of the hot component against the rise in its temperature. The appearance of He II lines has not yet been recorded, though the optical brightness of AS 338 has already dropped by ～2^m after the outburst.     

Rapid report of the 8 January 2022 ​MS 6.9 Menyuan earthquake,Qinghai, China

The M_S 6.9 Menyuan earthquake in Qinghai Province, west China is the largest earthquake by far in 2022. The earthquake occurs in a tectonically active region, with a background b-value of 0.87 within 100 ?km of the epicenter that we derived from the unified catalog produced by China Earthquake Networks Center since late 2008. Field surveys have revealed surface ruptures extending 22 ?km along strike, with a maximum ground displacement of 2.1 ?m. We construct a finite fault model with constraints from InSAR observations, which showed multiple fault segments during the Menyuan earthquake. The major slip asperity is confined within 10 ?km at depth, with the maximum slip of 3.5 ?m. Near real-time back-projection results of coseismic radiation indicate a northwest propagating rupture that lasted for ～10 ?s. Intensity estimates from the back-projection results show up to a Mercalli scale of IX near the ruptured area, consistent with instrumental measurements and the observations from the field surveys. Aftershock locations (up to January 21, 2022) exhibit two segments, extending to ～20 ?km in depth. The largest one reaches M_S 5.3, locating near the eastern end of the aftershock zone. Although the location and the approximate magnitude of the mainshock had been indicated by previous studies based on paleoearthquake records and seismic gap, as well as estimated stressing rate on faults, significant surface-breaching rupture leads to severe damage of the high-speed railway system, which poses a challenge in accurately assessing earthquake hazards and risks, and thus demands further investigations of the rupture behaviors for crustal earthquakes.     

The Reference Manure Concept for Transformation Tests of Veterinary Medicines and Biocides in Liquid Manure

Veterinary medicines and biocides are frequently applied in animal houses of livestock husbandry. Due to these application patterns, they reach liquid manure. So far these substances are not transformed during manure storage, they enter soil by the application of manure as organic fertilizer. Therefore, biodegradability of veterinary medicines and biocides in manure is in the focus of regulatory procedures of environmental risk assessment. Since the representative and reproducible sampling of manures from high volume tanks is considered impossible due to high matrix variabilities, the reference manure concept was developed to utilize liquid bovine and pig manures for reproducible laboratory testing. Accordingly, excrement samples of cattle and pigs individually kept at experimental and conventional animal houses were taken. Tap water was added to matrix characterized excrements in order to prepare bovine and pig reference manures of 10 and 5% dry substance contents, respectively. Subsequently, the long‐term transformation of selected ¹⁴C‐labeled test substances was investigated under strictly anaerobic conditions. The application of different batches of bovine or pig reference manures indicated that extrapolation of transformation rates within the same animal species was possible. However, results cannot be transferred from bovine to pig manure because of substance specific interactions with the different manure matrices. The dependency of metabolic dynamics on different dry substance contents (2.5, 5, 10%) was additionally investigated in both manure matrices. These tests clearly showed that the dry substance content of the reference manure is one of the most relevant factors affecting the transformation of veterinary medicines and biocides. In contrast to highly variable tank manures, the reference manure concept allows for the exact adjustment of this parameter to guarantee reproducible laboratory testing.     

国家经济增速与国家竞争力/影响力的时空关系

经济发展速度一直是各国家经济发展水平的重要测度指标,但国家经济增速与国家竞争/影响力之间的关系及可能的阈值需要进行深入地研究,尤其是在中国经济增速下滑的背景下,迫切需要阐释经济增速下降是否影响国家竞争力/影响力。在评述既有研究进展的基础上,采用时空分析路径,探讨国家经济发展速度与国家竞争力/影响力的时空关系。首先,从历史的角度分析了15世纪以来世界权力中心的演变路径,考察了英国、美国等世界权力中心的国家经济增速变化,总结其发展规律,考察国家影响力与国家经济增速之间的对应关系。然后着眼于空间视角,考察目前国家经济增速与国家竞争力的空间分异,尤其是考察两者之间关系的分异关系,总结主要特征与规律。研究发现国家经济增速与国家影响力之间并非存在严格的线性关系,但国家影响力的培育与强化仍需要一定的经济增速进行支撑,而国家经济增速与国家竞争力之间呈现逆向的对应关系,经济高速增长的国家往往竞争力较低,竞争力较高的国家往往有较低的经济增速甚至负增长。     

Radiative forcing by contrails

A parametric study of the instantaneous radiative impact of contrails is presented using three different radiative transfer models for a series of model atmospheres and cloud parameters. Contrails are treated as geometrically and optically thin plane parallel homogeneous cirrus layers in a static atmosphere. The ice water content is varied as a function of ambient temperature. The model atmospheres include tropical, mid-latitude, and subarctic summer and winter atmospheres. Optically thin contrails cause a positive net forcing at top of the atmosphere. At the surface the radiative forcing is negative during daytime. The forcing increases with the optical depth and the amount of contrail cover. At the top of the atmosphere, a mean contrail cover of 0.1% with average optical depth of 0.2 to 0.5 causes about 0.01 to 0.03 Wm⁻² daily mean instantaneous radiative forcing. Contrails cool the surface during the day and heat the surface during the night, and hence reduce the daily temperature amplitude. The net effect depends strongly on the daily variation of contrail cloud cover. The indirect radiative forcing due to particle changes in natural cirrus clouds may be of the same magnitude as the direct one due to additional cover.