Correlation assessment and monitoring of the potential pollutants in the surface sediments of Pyeongchang River, Korea

The study provides a baseline for the assessment of the organic and inorganic pollution specially, heavy metal contamination in the surface sediments of Pyeongchang River,South Korea.The assessment of the study areas was done with respect to metal pollution load,ecological risk and geoaccumulated risk.Based upon the used indices,a priority index(P_index) was used to rank the utmost contaminated sites.Though the concentrations of mercury in all sediments were below the guideline, the significant enriched contamination was observed by all applied indices.As expected,the values of pollution load index（PLI）,ecological risk index（RI） and geoaccumulation risk index(I_geo) demonstrated lower heavy metal contamination in upstream areas compared to the downstream. Admittedly,sediments were unpolluted to slightly-polluted according to PLI while high to extremely high ecological risks were observed in several sediment samples.Furthermore,all the samples were uncontaminated as per I_geo.After simplification of I_geo,the P_index,showed the utmost contaminated sediments with a value of 2.537.Notably,protective measures should be taken to the highly contaminated areas which are prioritized by P_index Admittedly,the maximum concentrations of total organic carbon,total nitrogen,inorganic nitrogen,total phosphorous,inorganic phosphorous,calcium, magnesium,sodium and potassium were significantly observed as 7.8×10⁴,3,185,36,1,032,3.7, 1,5163,2,881,669 and 4,076mg/kg accordingly.     

A 30,000 yr record of land–ocean interaction in the eastern Gulf of Guinea

A 30,000 yr dinocyst and pollen record from the eastern equatorial Atlantic (off Cameroon) has been investigated in order to identify land–ocean linkages during the last deglacial transition. A strong correlation between the abundance of Brigantedinium spp. and the Ca/Fe ratio during the last glacial period suggests enhanced marine productivity in association with cool seawater temperatures and nutrient input linked to coastal upwelling and/or a proximal river mouth. Dry conditions are recorded on the adjacent continent with a significant representation of open vegetation indicators and the Afromontane taxon Podocarpus. After 17 cal ka BP these indicators register a sharp decline as a result of a climatic transition from the dry/cooler conditions of the last glacial period to the wetter/warmer conditions of the deglaciation. Simultaneously, dinocysts show a significant shift from dominant heterotrophs to an increasing abundance of autotrophs, reflecting warmer conditions. Significant changes are observed during the Younger Dryas, with a return to drier conditions and higher salinities. The start of the Holocene is marked by very low-salinity conditions, reflecting optimal monsoonal conditions over west equatorial Africa. The end of the African Humid Period is observed between 6 and 5 cal ka BP, followed by significant fluctuations in both terrestrial and oceanic proxies.     

A comparison of regional monsoon variability using monsoon indices

The present study aims to (a) examine meteorological basis for construction of regional monsoon indices and (b) explore the commonality and differences among tropical regional monsoons, especially the teleconnection and monsoon–ENSO relationship. We show that the area-averaged summer precipitation intensity is generally a meaningful precipitation index for tropical monsoons because it represents very well both the amplitude of annual cycle and the leading mode of year-to-year rainfall variability with a nearly uniform spatial pattern. The regional monsoon circulation indices can be defined in a unified way (measuring monsoon trough vorticity) for seven tropical monsoon regions, viz.: Indian, Australian, western North Pacific, North and South American, and Northern and Southern African monsoons. The structures of the tropical monsoons are commonly characterized by a pair of upper-level double anticyclones residing in the subtropics of both hemispheres; notably the winter hemispheric anticyclone has a barotropic structure and is a passive response. Two types of upper-level teleconnection patterns are identified. One is a zonal wave train emanating from the double anticyclones downstream along the westerly jets in both hemispheres, including Indian, Northern African and Australian monsoons; the other is a meridional wave train emanating from the double anticyclones polewards, such as the South American and western North Pacific monsoons. Over the past 55 years all regional summer monsoons have non-stationary relationship with ENSO except the Australian monsoon. The regional monsoon–ENSO relationship is found to have common changing points in 1970s. The relationships were enhanced for the western North Pacific, Northern African, North American and South American summer monsoons, but weakened for the Indian summer monsoon (with a recovery in late 1990s). Regardless the large regional differences, the monsoon precipitations over land areas of all tropical monsoon regions are significantly correlated with the ENSO, suggesting that ENSO drives global tropical monsoon rainfall variability. These results provide useful guidance for monitoring sub-seasonal to seasonal variations of the regional monsoons currently done at NCEP and for assessment of the climate models’ performances in representing regional and global monsoon variability.     

Interdecadal change of the controlling mechanisms for East Asian early summer rainfall variation around the mid-1990s

East Asian (EA) summer monsoon shows considerable differences in the mean state and principal modes of interannual variation between early summer (May–June, MJ) and late summer (July–August, JA). The present study focuses on the early summer (MJ) precipitation variability. We find that the interannual variation of the MJ precipitation and the processes controlling the variation have been changed abruptly around the mid-1990s. The rainfall anomaly represented by the leading empirical orthogonal function has changed from a dipole-like pattern in pre-95 epoch (1979–1994) to a tripole-like pattern in post-95 epoch (1995–2010); the prevailing period of the corresponding principal component has also changed from 3–5 to 2–3 years. These changes are concurrent with the changes of the corresponding El Nino-Southern Oscillation (ENSO) evolutions. During the pre-95 epoch, the MJ EA rainfall anomaly is coupled to a slow decay of canonical ENSO events signified by an eastern Pacific warming, which induces a dipole rainfall feature over EA. On the other hand, during the post-95 epoch the anomalous MJ EA rainfall is significantly linked to a rapid decay of a central Pacific warming and a distinct tripolar sea surface temperature (SST) in North Atlantic. The central Pacific warming-induced Philippine Sea anticyclone induces an increased rainfall in southern China and decreased rainfall in central eastern China. The North Atlantic Oscillation-related tripolar North Atlantic SST anomaly induces a wave train that is responsible for the increase northern EA rainfall. Those two impacts form the tripole-like rainfall pattern over EA. Understanding such changes is important for improving seasonal to decadal predictions and long-term climate change in EA.     

Evaluation of cloud and precipitation parameterization using a single-column model: A TWP-ICE case study

Cloud and precipitation parameterization schemes are evaluated, and their sensitivity to the method and/or parameters used to determine cloud physical processes is examined using a singlecolumn version of the Unified Model (SCUM). In the experiment for TWP-ICE, cloud fraction is overestimated (underestimated) in the upper (lower) troposphere due to the wet (dry) bias. The precipitation rate is well simulated during the active monsoon period, but overestimated during the suppressed monsoon and clear skies periods. In the moist convection scheme, trigger condition and entrainment process affect the lower tropospheric humidity through the impact on convective occurrence frequency and intensity, respectively. Strengthening the trigger condition and using the adaptive entrainment method alleviate the low-level dry bias. In the microphysics scheme, more large-scale precipitation is produced with prognostic rain, due to rain sedimentation considering vertical velocity of rain drop, than with diagnostic rain. Less ice/snow deposition with the prognostic two-ice category results in lower ice water content and upper-level cloud fraction than with the diagnostic splitting method for the twoice category. In the cloud macrophysics scheme, the prognostic cloud fraction and cloud/ice water content scheme produces a larger cloud fraction and more cloud/ice water content than the diagnostic scheme, mainly due to detrainment from moist convection (cloud source) that surpasses the effect of convective heating and drying (cloud sink). This affects temperature by influencing the radiative, convective, and microphysical processes. The experiment with combined modifications in cloud and precipitation schemes shows that interaction between modified moist convection and cloud macrophysics schemes results in more alleviation of the cold bias not only at the lower levels but also at the upper levels.     

Correlation between Rimjingang belt and Dabie-Sulu orogenic belt

The Dabic-Sulu orogenic belt in central-eastern China is considered as a high-pressure and ultrahighpressure metamorphic belt that demensions are comparatively large,and formed as a result of the colli...     

Beta Gyres in Global Analysis Fields

A three-component decomposition is applied to global analysis data to show the existence of a beta gyre, which causes Tropical Cyclone (TC) to drift from a large-scale environmental steering current. Analyses from the Global Data Assimilation and Prediction System (GDAPS) of the Korea Meteorological Adminis-tration (KMA), the Global Forecast System (GFS) of NCEP, and the Navy Operational Global Atmospheric Prediction System (NOGAPS) are used in this study. The structure of the beta gyre obtained in our anal...