Northwestern Wind Research Articles

Geomorphological Processes and Environmental Interpretation at Espalmador islet (Western Mediterranean)

This study presents a sedimentological and stratigraphical description of the Pleistocene deposits cropping out in Espalmador islet (Illes Pitiüses). Four major sedimentary facies including the succession of aeolian, marine, colluvial and edaphic environments are described. The sedimentological and stratigraphical analysis of these deposits allows the reconstruction of the coastal Pleistocene environmental and geomorphological history of the Espalmador islet. The coastal relief and the fluctuations of the sea level mainly control the Pleistocene coastal landscape evolution on Espalmador. Episodes of aeolian activity and dune formation related to a predominant northwestern wind direction can be linked to periods of low sea level where a high amount of marine sediment is exposed on the shelf platform.

Cyclonic activity over northeastern Africa at 8.5–6.7 cal kyr B.P., based on lacustrine records in the Faiyum Oasis, Egypt

During African Humid Period in the Holocene when the summer Intertropical Convergence Zone migrated to its northernmost position, the Qarun Lake in the Faiyum Oasis in Egypt was fed with regular inflows from the Nile River and rainfall brought by the Mediterranean winter circulation. Finely-laminated lake sediments, dated at 8.5–6.7 cal kyr B.P., were examined in terms of lithology, geochemistry, microfossils (diatom, pollen) and magnetic susceptibility. Based on the inferred geographical derivation of pollen, the environmental affiliation of diatom taxa and geochemistry of lake sediments, wind trajectories were distinguished, related to two main atmospheric circulation phases. During the earlier phase (8.50–7.83 cal kyr B.P.) there were northwestern wind trajectories followed by southern ones and during the later phase (7.83–6.70 cal kyr B.P.), the northern winds were followed by northwestern and southern ones. Northwestern and northern winds brought winter rainfall and caused water turbulence in the lake, and the southern winds were associated with regional aridification. This scenario of atmospheric circulation in northeastern Africa extends significantly our understanding of key modes of climatic variability and wind trajectories in the Early to Middle Holocene (Greenlandian to Northgrippian) transition.

Atmospheric Precipitations, Hailstone and Rainwater, as a Novel Source of Streptomyces Producing Bioactive Natural Products.

A cultivation-dependent approach revealed that highly diverse populations of Streptomyces were present in atmospheric precipitations from a hailstorm event sampled in February 2016 in the Cantabrian Sea coast, North of Spain. A total of 29 bioactive Streptomyces strains isolated from small samples of hailstone and rainwater, collected from this hailstorm event, were studied here. Taxonomic identification by 16S rRNA sequencing revealed more than 20 different Streptomyces species, with their closest homologs displaying mainly oceanic but also terrestrial origins. Backward trajectory analysis revealed that the air-mass sources of the hailstorm event, with North Western winds, were originated in the Arctic Ocean (West Greenland and North Iceland) and Canada (Labrador), depending on the altitude. After traveling across the North Atlantic Ocean during 4 days the air mass reached Europe and precipitated as hailstone and rain water at the sampling place in Spain. The finding of Streptomyces species able to survive and disperse through the atmosphere increases our knowledge of the biogeography of genus Streptomyces on Earth, and reinforces our previous dispersion model, suggesting a generalized feature for the genus which could have been essential in his evolution. This unique atmospheric-derived Streptomyces collection was screened for production of bioactive secondary metabolites. Analyses of isolates ethyl acetate extracts by LC-UV-MS and further database comparison revealed an extraordinary diversity of bioactive natural products. One hundred molecules were identified, mostly displaying contrasted antibiotic and antitumor/cytotoxic activities, but also antiparasitic, antiviral, anti-inflammatory, neuroprotector, and insecticide properties. More interestingly, 38 molecules not identified in natural products databases might represent new natural products. Our results revealed for the first time an extraordinary diversity of Streptomyces species in the atmosphere able to produce an extraordinary repertoire of bioactive molecules, thus providing a very promising source for the discovery of novel pharmaceutical natural products.

CONDITIONS OF FORMING FOR THERAPEUTIC MUD IN THE VOEVODA BAY (AMUR BAY, JAPAN SEA)

The water dynamics and distribution of the sea grass Zostera marina are investigated as factors of the curative mud forming in the Voevoda Bay. The water currents are measured directly. The closed circulation is formed in the middle part of the bay by prevailing winds: anticyclonic by northwestern wind and cyclonic by southeastern wind. Zostera marina distribution is researched by divers. Its highest biomass is observed on the shallows where projective coating is 100 % and mean biomass is 3 kg/m 2 (wet weight). Bottom sediments and depth of the acoustic basement are mapped using seismoacoustic method. The maximal thickness of the curative mud layer is found in the internal part of the bay (Melkovodnaya Bight) where it reaches 15 meters.

Millennial mode of variability of sea ice conditions in the Okhotsk Sea during the last glaciation (MIS 4–MIS 2)

Coarse fraction (CF) content, grain-size distribution, roundness of CF, gravels and pebbles, and examination of surface of pebbles were studied in core LV28-44-4, recovered from the eastern Okhotsk Sea (OS). The age model of the studied core was based on the AMS 14C data, tephrochronology, δ18O benthic foraminifera record, and correlation of peaks of productivity proxies with long-lasted Dansgaard-Oeschger (DO) interstadials. The results show that sea ice was the main transport agent for CF (ice-rafted debris, IRD) in the eastern OS. Published mineralogical studies of clastic material of the OS indicated that the coast of western Kamchatka was the main source of IRD in the eastern OS. We found 19 peaks of IRD, which mostly coincided with DO stadials. The distribution of CF indicates a different pattern of IRD supply during MIS 4, 3, and 2. Comparison of IRD records in the eastern and central parts of the OS allow us to reconstruct millennial changes in ice and wind modes for MIS 4–MIS 2. Significant strengthening of northeastern and eastern winds during DOSs of MIS 3 and of northern and north-western winds during MIS 2 were observed.

Stability mechanisms of barchan dunes: A case study of Hexi Desert area in Gansu Province

Barchan dunes, an important type of dunes, are distributed on the edge of oases. Research of stability mechanisms of barchan dunes is of great importance to the determination of regulation of aeolian sand movement on the edge of oases. However, the stability of barchan dunes remains an unresolved scientific issue. In this paper, the stability mechanisms of the top of barchan dunes in Hexi desert area of Gansu Province were analyzed. The results showed that: (1) in Hexi desert area of Gansu Province, patches of barchan dunes were distributed downwind on the edge of desert. The distribution areas were flat sandy-clay or sandy-gravel beaches. The lowlands among the dunes were wide and had the prominent prevailing wind. (2) The prevailing northwestern wind caused the highest point and sand ridge line of the dunes to coincide, and the dunes to move forward and become lower. The southeastern wind (opposite to the prevailing wind) caused the highest point and sand ridge line of the dunes to separate, the leeward slope to be eroded by wind and the dunes to rise. (3) The higher the barchan dunes were, the longer the two flanks were, and the smaller the angle was. (4) The wide flat beaches were vital to the formation of barchan dunes and a chain of barchan dunes. The largely prevailing wind was the key factor for the stability of barchan dunes and a chain of barchan dunes. The opposite wind and the corridor effect of the two flanks were key factors for the increase of barchan dunes in size and height. The speed and distribution frequency of the prevailing and opposite winds were factors restraining the height of barchan dunes and a chain of barchan dunes here.

Late‐Holocene wind‐field evolution at the southern Baltic coast as revealed by GPR data from the Mrzeżyno dunefield, NW Poland

All dunes within a dunefield usually show a similar response to the wind regime. However, in the late‐Holocene coastal dunefield in NW Poland the surface topography suggests that slipface orientation may vary significantly with distance from the coast, which is rarely reported in the literature. The dunefield was stabilized with forest in the mid‐19th century, preserving a unique record of atmospheric circulation in the South Baltic region at the end of the Little Ice Age. To elucidate the Holocene processes occurring along the study site a pseudo‐3D GPR data set was collected. Six grids of parallel GPR lines combined with 400 m of GPR profiles (2D) were collected across the dunefield and displayed using GOCAD for interpretation and geostatistical analysis. The geophysical data revealed that the larger dunes almost entirely consist of steeply laminated facies. Most importantly the pseudo‐3D data, supported by geostatistical estimates of strata dip directions, revealed the existence of three zones parallel to the coastline with the mean dip direction almost perpendicular to the coast in the northern coastal strip and almost parallel to it in the southern part. Spreads of the dip directions in pseudo‐3D GPR data sets recorded on the stoss slopes of dunes and crests suggested initial deposition on transverse dunes, which later were transformed into barchanoid dunes. This can probably be linked to changes in the wind regime, i.e. reduction in velocity of the northern and northwestern winds leading to reduced sediment supply from the coast. While the data provide a new interpretation of Holocene dunefield dynamics at this site, they also suggest that the minimum number of pseudo‐3D GPR grids required to establish general trends using geostatistical analysis should be at least 10, with even more data needed at larger, or more complex dunefields.

Atmospheric electrical field measurements near a fresh water reservoir and the formation of the lake breeze

In order to access the effect of the lakes in the atmospheric electrical field, measurements have been carried out near a large man-made lake in southern Portugal, the Alqueva reservoir, during the ALqueva hydro-meteorological EXperiment 2014. The purpose of these conjoint experiments was to study the impact of the Alqueva reservoir on the atmosphere, in particular on the local atmospheric electric environment by comparing measurements taken in the proximity of the lake. Two stations 10 km apart were used, as they were located up- and down-wind of the lake (Amieira and Parque Solar, respectively), in reference to the dominant northwestern wind direction. The up-wind station shows lower atmospheric electric potential gradient (PG) values than the ones observed in the down-wind station between 12 and 20 UTC. The difference in the atmospheric electric PG between the up-wind and the down-wind station is ~30 V/m during the day. This differential occurs mainly during the development of a lake breeze, between 10 and 18 UTC, as a consequence of the surface temperature gradient between the surrounding land and the lake water. In the analysis presented, a correlation is found between the atmospheric electric PG differences and both wind speed and temperature gradients over the lake, thus supporting the influence of the lake breeze over the observed PG variation in the two stations. Two hypotheses are provided to explain this observation: (1) The air that flows from the lake into the land station is likely to increase the local electric conductivity through the removal of ground dust and the transport of cleaner air from higher altitudes with significant light ion concentrations. With such an increase in conductivity, it is expected to see a reduction of the atmospheric electric PG; (2) the resulting air flow over the land station carries negative ions formed by wave splashing in the lake's water surface, as a result of the so-called balloelectric effect. These negative ions will form a space-charge density (SCD) that can reduce the atmospheric electric PG. A formulation is derived here in order to estimate the local SCD.

Assessment of PM2.5 and PM10 over Guwahati in Brahmaputra River Valley: Temporal evolution, source apportionment and meteorological dependence

Temporal evolution, source apportionment and transport pathways of particulate matter (PM2.5 and PM10) are analysed over Guwahati, located in the Brahmaputra River Valley (BRV), as a function of meteorological dynamics. During the study period (July 2013–June 2014), the mean PM2.5 and PM10 mass concentrations were found to be 52 ± 37 and 91 ± 60 μg m−3, respectively, both exhibiting higher concentrations during December–March and very low during summer. The annual mean ratio of PM2.5/PM10 was 0.57 ± 0.11, varying from 0.24 to 0.86, suggesting dominance of anthropogenic vs natural emissions during winter and spring, respectively. Diurnal variation reveals higher PM concentrations during morning (∼9:00 local time (LT)) and evening (∼23:00 LT) and lowest around ∼14:00 to 17:00 LT due to influence of dilution processes and higher mixing-layer height over the region. Bivariate plots and Conditional Bivariate Probability Function (CBPF) analysis showed that the highest PM2.5 and PM10 concentrations are mostly associated with weak northwestern winds (<1.5 ms−1) in all seasons except spring, when the highest PM10 are for southwestern winds above 4–6 ms−1, indicating dust transport from SW Asia. Analysis reveals that the local emissions, transported aerosols, along with seasonally-changed air masses, meteorology and boundary-layer dynamics control the concentrations, evolution and fractions of PM over BRV. The turbid air masses transported over Guwahati mostly from western and southwestern directions contribute to higher PM concentrations, either carrying anthropogenic pollution from Indo-Gangetic Plains or locally and LRT dust from BRV and western India, respectively.

The possibility of including the remaining windmills in the tourist offer of Vojvodina

At the end of the eighteenth and in the early nineteenth century, Dutch, Hungarian, Slovak and Serbian builders built more than 280 windmills in Vojvodina. As the most advanced facilities for grinding grain, windmills used the drive energy of the northern and the northwestern winds and facilitated the lives of the people of that time. Two centuries later, based on a field research carried out in Vojvodina in the period from 2012 to 2014, it was determined that eleven windmills still physically exist. Despite the fact that most of them are protected by law, these important monuments of folk architecture are in very poor condition and have lost their function. The aim of this paper is to point to the examples of good practice and the inclusion of windmills in the tourist offer of European countries as well as the possibility for the revitalization of the remaining windmills in Vojvodina as important cultural and historical monuments and an integral part of the history, culture and heritage of our country - as a chance to enrich the tourist offer of Vojvodina.

Role of downwelling/upwelling in formation/destruction of hypoxia in the bottom waters of the Amur Bay (Japan Sea)

Downwelling/upwelling influence on hypoxia at the bottom of the Amur Bay is determined on the data of oceanographic surveys conducted aboard RV Impulse in August 2012 and RV Malachite in August 2013 coupled with the data of monitoring oceanographic station in the bay. The hypoxia develops in the period of downwelling circulation driven by southern and southeastern winds and relaxes in conditions of upwelling induced by northern and northwestern winds.

Wind dispersal results in a gradient of dispersal limitation and environmental match among discrete aquatic habitats.

Directional dispersal by wind and other dispersal agents may generate spatial patterns in passively dispersing metacommunities which cannot be detected by classical eigenvector methods based on Euclidean distances. We analysed zooplankton communities (Rotifera, Cladocera, Copepoda) in a cluster of soda pans distributed over a short spatial scale of 18 km and tested explicitly for directional signals in their spatial configuration. The study area is exposed to a prevailing northwestern wind direction. By applying asymmetric eigenvector maps (AEM), we were able to identify corresponding directionality in the spatial structure of communities. Furthermore, the match between community composition and environmental conditions exhibited a spatial pattern consistent with the prevailing wind corridor, with best match found downwind the dominant wind direction. We also found that classical eigenvector methods based on Euclidean distances underestimated the role of spatial processes in our data. Our study furthermore shows that dispersal limitation may constrain community assembly in highly mobile organisms even at spatial scales below 5 km.

Improvement of PM10 prediction in East Asia using inverse modeling

Aerosols from anthropogenic emissions in industrialized region in China as well as dust emissions from southern Mongolia and northern China that transport along prevailing northwestern wind have a large influence on the air quality in Korea. The emission inventory in the East Asia region is an important factor in chemical transport modeling (CTM) for PM10 (particulate matters less than 10 ㎛ in aerodynamic diameter) forecasts and air quality management in Korea. Most previous studies showed that predictions of PM10 mass concentration by the CTM were underestimated when comparing with observational data. In order to fill the gap in discrepancies between observations and CTM predictions, the inverse Bayesian approach with Comprehensive Air-quality Model with extension (CAMx) forward model was applied to obtain optimized a posteriori PM10 emissions in East Asia. The predicted PM10 concentrations with a priori emission were first compared with observations at monitoring sites in China and Korea for January and August 2008. The comparison showed that PM10 concentrations with a priori PM10 emissions for anthropogenic and dust sources were generally under-predicted. The result from the inverse modeling indicated that anthropogenic PM10 emissions in the industrialized and urbanized areas in China were underestimated while dust emissions from desert and barren soil in southern Mongolia and northern China were overestimated. A priori PM10 emissions from northeastern China regions including Shenyang, Changchun, and Harbin were underestimated by about 300% (i.e., the ratio of a posteriori to a priori PM10 emission was a factor of about 3). The predictions of PM10 concentrations with a posteriori emission showed better agreement with the observations, implying that the inverse modeling minimized the discrepancies in the model predictions by improving PM10 emissions in East Asia.

Analysis of spatio-temporal variability of aerosol optical depth with empirical orthogonal functions in the Changjiang River Delta, China

This work aims to analyze the spatial and temporal variability of aerosol optical depth (AOD) from 2000 to 2012 in the Changjiang River Delta (CRD), China. US Terra satellite moderate resolution imaging spectroradiometer (MODIS) AOD and Angstrom exponent (α) data constitute a baseline, with the empirical orthogonal functions (EOFs) method used as a major data analysis method. The results show that the maximum value of AOD observed in June is 1.00±0.12, and the lowest value detected in December is 0.40±0.05. AOD in spring and summer is higher than in autumn and winter. On the other hand, the α-value is lowest in spring (0.86±0.10), which are affected by coarse particles. High α-value appears in summer (1.32±0.05), which indicate that aerosols are dominated by fine particles. The spatial distribution of AOD has a close relationship with terrain and population density. Generally, high AODs are distributed in the low-lying plains, and low AODs in the mountainous areas. The spatial and temporal patterns of seasonal AODs show that the first three EOF modes cumulatively account for 77% of the total variance. The first mode that explains 67% of the total variance shows the primary spatial distribution of aerosols, i.e., high AODs are distributed in the northern areas and low AODs in the southern areas. The second mode (7%) shows that the monsoon climate probably plays an important role in modifying the distribution of aerosols, especially in summer and winter. In the third mode (3%), this distribution of aerosols usually occurs in spring and winter when the prevailing northwestern or western winds could bring aerosol particles from the inland areas into the central regions of the CRD.

Impact of wind erosion on detecting active tectonics from geomorphic indexes in extremely arid areas: a case study from the Hero Range, Qaidam Basin, NW China

Geomorphologic analysis has been used widely to detect active tectonics in regions where fluvial incision is the major erosional process. In this paper, however, we assess the feasibility of utilizing these frequently-used geomorphic indexes (e.g., hypsometric curves, longitudinal channel profiles, normalized stream length-gradient (SLK) index) to determine active tectonics in extremely arid areas where wind erosion also plays an important role. The case study is developed on the Hero Range in the western Qaidam Basin, one of the driest regions on Earth with severe wind erosion since late Pliocene. The result shows that in the west and south sectors, as well as the western part of the east sector, of the Hero Range where fluvial incision prevails, these geomorphic indexes are good indicators of active faulting and consistent with the geological result based on study of fault traces, scarps, faulted Holocene fans and historical seismicity within the past four decades. In contrast, along the northeastern margin (the NE and the SE parts of the east sector) of the range where wind erosion is also important, the results from the geomorphic indexes show quite active tectonics, contrary with the geological evidence favoring weakly active tectonics. Moreover, the positive SLK anomaly lies oblique to the fault trace and the anticline axis but parallel to the wind direction. To reconcile the contradiction, we propose that wind erosion caused by northwestern winds has a tendency to make geomorphic indexes exhibit anomalous values that indicate higher activities, by way of (1) lowering the base-level to generate knickpoints on the longitudinal channel profiles and therefore positive SLK anomalies, and (2) lateral erosion of the mountain front making the hypsometric curves and even the longitudinal channel profiles more convex, and producing obvious slope breaks.

A study of urban pollution and haze clouds over northern China during the dusty season based on satellite and surface observations

This paper presents a multi-scale study on formation process of urban pollution and haze clouds as well as their interactions over northern China in spring using integrated satellite and surface observations. Several extreme haze events occurred in Beijing area in March 2013, but primary atmospheric pollutants in the urban pollution exhibited inconsistent variations with the widespread haze clouds observed by satellites. Two typical types of haze event were found in Beijing area. Type-1 haze pollution appeared in stagnant weather conditions, during which PM2.5 was <200 μg m−3 with a short duration within 1–2 days. By contrast, strong northwestern winds prevailed in type-2 haze events with durative and intense temperature inversion near surface. Meanwhile, PM2.5 concentration exceeded ∼400 μg m−3 in type-2 pollution, and the heavy pollution can last 3–5 days. Different from urban pollution, our results show that the thick haze clouds were dominated by mixing of floating dust and anthropogenic pollutants in the middle and upper part, accompanied by hygroscopic growth of fine particles. Elevated coarse dust particles were prevalent over northern China, which accounted for a predominant fraction in the columnar optical volume during all the haze events. Furthermore, comparison between satellite and surface observations indicates that haze clouds above surface had no significant direct contribution to the serious urban pollution. In addition, mixing of dust and anthropogenic pollutants at high altitudes regulates regional aerosol optical properties throughout the whole March.

SAR 위성영상 해상풍 추출 소프트웨어 비교

Comparative evaluation of offshore wind retreival software, which use the satellite images taken by Synthetic Aperture Radar sensor; SARTools of CLS-SOPRONO, France and SpaceEye of London Research and Development Corporation, Canada is carried out. For a reference satellite image, ENVISAT ASAR imagery of Jeollanam-do Wan-do area when the winter-time northwestern wind prevails is processed by CMOD_IFR2, CMOD4, CMOD5 algorithms. Wind speed difference and its relative ratio are calculated to evaluate uncertainty of software selection.

Chloritoid in the bottom sediments of the Akademichesky Ridge of Lake Baikal, an indicator of eolian transportation

We present results of study of Holocene and Late Pleistocene deposits recovered on the underwater Akademichesky Ridge in Lake Baikal. The change in mineral composition and grain size in the bottom sediment core is closely consistent with the change of major diatom complexes marking the Holocene–Late Pleistocene boundary. A high content of chloritoid (up to 14.6%) has been found among the heavy minerals of the sand fraction of Late Pleistocene clays. The concentration of chloritoid in Holocene mud is no higher than 1.2%. The source of chloritoid is chloritoid shales of the Anaya Formation (Upper Proterozoic), widespread in the watershed of the Primorsky Ridge in the upper reaches of the Lena and Anaya Rivers. Chloritoid was transported to the area of the Akademichesky Ridge by predominant western and northwestern winds, which is also evidenced from the absence of mechanical impacts on the surface of its grains. The high contents of chloritoid in the Late Pleistocene sediments are due to the more intense eolian transportation at that time as compared with the Holocene.

Proliferation of Amphidinium carterae (Gymnodiniales: Gymnodiniaceae) in Bahía de La Paz, Gulf of California

During a sampling on 15 December 2011 in Bahía de La Paz, a bloom of the benthic dinoflagellateAmphidinium carterae was detected. Its abundance ranged from 28.2 to 64.8 × 103 cells L–1. Cells of A. carterae varied in length from 18 to 28 µm and 13 to 18 µm in wide (n = 30). The presence of A. carterae and benthic species of diatoms and dinoflagellates at the surface could be an indicator of upwelling water generated by northwestern winds. Seawater temperature during the bloom was 20 °C. Also, new records of dinoflagellates for the Mexican coast of the Pacific are here reported: Amphidiniopsis hirsuta, Amphidiniopsis sp., Amylax buxus,Cochlodinium pulchellum, Cochlodinium virescens, Durinskia cf. baltica, Gyrodinium sp., Thecadinium sp., and Prorocentrum minimum var. triangulatum.

Atomic mercury distribution features in the surface air layer in the Sea of Japan in the fall of 2010

Presented are the results of mercury content measurements in the surface air layer in the Sea of Japan in the period from October 27 to November 11, 2010. It is revealed that the mercury content varied from 0.6 to 3.8 ng/m3. It is demonstrated that the mercury concentration distribution has geographical zoning and depends on the movement of air masses and on the closeness of anthropogenic sources. The maximum mercury concentration is detected in the central part of the sea at the southwestern and southern directions of the wind, that is associated with the industrial emissions of East Asia countries. The minimum mercury concentration corresponding to the concentration in the surface air layer of the Arctic, Atlantic Ocean (Northern Hemisphere), and the Sea of Okhotsk and Bering Sea was observed along the coast of Primorye at the northwestern wind direction.