Typical Mountain Research Articles

Macedonian Architecture From 19th Century in The Village of Leshok, Republic of Macedonia

INTRODUCTION: The old rural architecture in Macedonia is insufficiently studied and in many villages is in the process of extinction, especially in Western Macedonia where there are many villages whose inhabitants have emigrated.
 OBJECTIVES: The objective of this research is the folk architecture of the house in the village of Leshok, near Tetovo, and getting acquainted with the other types of objects that are part of the rural-economic yard and are inextricably linked to the daily work, life and customs of the peasant from this region.
 MATERIAL AND METHODS: For analysis of the traditional architecture of the houses in the village of Leshok from the late 19th and early 20th centuries, 10 typical houses with different structure and location are chosen, which are identified and displayed by the Google Earth search engine.
 RESULTS: The basic characteristics of the architecture of the village house in Leshok are explained, where the economic yard together with the economic objects are included. The functional solutions of the foundations of houses from the end of the 19th and the beginning of the 20th century are shown, the constructions used in the house of Leshok are described, as well as the materials that were used for their construction. In the end we get acquainted with the interior and the design of the premises in the old Macedonian house.
 CONCLUSION: Leshok belongs to the group of mountain villages of compact type. The configuration of the terrain, the dead riverbed, dictated the way of construction, where the houses are placed one above the other and each has a clear view of the valley. In that way, the basic architectural features of the Leshok house are formed. It is a typical mountain house built of stone and wood, on two floors and with an open veranda.

Spatio-Temporal Differentiation of Trade-Offs and Synergies of Ecosystem Services in Typical Mountain Areas of China

Mountain area accounts for a high proportion of the land area in China, and it is the focal area to solve the contradiction of imbalanced regional development, as well as an important source of ecosystem services. Therefore, this area has been facing long-term pressure and challenges in economic development and ecological protection. In this paper, we selected a rocky desertification mountain area, an active mountain area of new tectonic movement and a typical northern earth-rock mountain area, as Qian-Gui karst Mountain area, Hengduan Mountain area and Taihang Mountain area, as examples to represent three main types of mountain areas. Three representative types of ecosystem services, including NPP (Net Primary Productivity) as a support service, water conservation as a regulation service, and agricultural produce as a supply service, were incorporated into this study. Linear regression, correlation analysis and other methods were then used to investigate the spatial-temporal characteristics of the trade-offs and synergies in each of the three kinds of mountain areas during 1990-2015 in China. The analysis yielded three main conclusions for the three mountainous areas. (1) The agricultural produce supply service decreased relatively, while the support and regulation services of NPP and hydrological regulation increased significantly. (2) There was a synergistic relationship between NPP and the hydrological regulation services in the three mountainous areas. The synergistic relation in Qian-Gui karst Mountain area became enhanced, while those in Hengduan and Taihang Mountain areas became weakened, and the former was weakened to a greater extent. There was a trade-off between NPP, the hydrological regulation service and the agricultural produce supply service among the three mountainous areas. In particular, the trade-off between NPP and the agricultural produce supply service in Qian-Gui karst Mountain area became weaker, while those in Hengduan and Taihang Mountain areas were enhanced, and the latter was enhanced to a greater degree. (3) Significant spatial differentiation was evident in the trade-offs and synergies of ecosystem services among the three mountain areas.

Quantitative Attribution of Runoff Attenuation to Climate Change and Human Activity in Typical Mountainous Areas: An Enlightenment to Water Resource Sustainable Utilization and Management in North China

The influence of climate change and human activities on hydrological elements has increased along with increasing dependence on water resources. Therefore, quantitative attribution of hydrological elements has received wide attention. In this study, the double mass curve (DMC) is used to assess the abrupt change point of the hydrological data series, based on which the periods with/without large-scale human activities causing runoff attenuation are separated. The land use transition matrix is then employed to analyze the land use types at different historical stages, and the sensitivities of the runoff attenuation to different land use/cover change (LUCC) categories are quantified. A soil and water assessment tool (SWAT) model that considers the underlying surface is constructed with six designed scenarios of different climate and LUCC conditions. Taking three typical mountainous basins in North China as the study area, the quantitative contributions of climate change and human activities to the water resources are identified. The results of the study have brought enlightenment to the water resource sustainable utilization and management in North China, and the methodologies can be transferred to runoff attribution analysis in water shortage areas.

Water conservancy projects enhanced local resilience to floods and droughts over the past 300 years at the Erhai Lake basin, Southwest China

As a typical mountain area at the Yunnan-Guizhou Plateau in Southwest China, the Erhai Lake Basin has uneven precipitation (frequent droughts and floods), affected by the Southwest Monsoon in Asia and significant vertical zonal differences determined by local topography. Though with such harsh physical environment, this area sustained development in ancient times and has been considered a typical resilience case in many studies. With extensive investigation of various historical archives, this paper explores the situation and changes of water management in the Erhai Basin during the past 300 years, and aims to identify local factors in maintaining resilience to water stresses. Findings indicate that various strong and smart social regulations (governance, institutions, plans, management, motivations, orders, donations, dedication, etc.) enabled a wise development of many water conservancy projects that set up an effective irrigation system at the flat basin center. Lots of stream dams, sluice gates and terraced croplands jointly further enabled water storage, drainage and irrigation at the surrounding hillside areas. Additionally, by adopting drought-resistant and cold-resistant crops, agriculture production kept increasing and successfully fed the growing population. The complex but systematically developed river canal system, with its dams, reservoirs, and sluice gates, as well as adaptive cropping strategies, together maintained and enhanced the resilience of local communities to hydrological hazards. Over the 300 years of the study period, the changing water environment and the developing water conservancy projects showed a resilience loop, which offers a simple but valuable perspective on building human-water resilience in face of current and future water crises in this region and beyond.

The Influences of Livelihood and Land Use on the Variation of Forest Transition in a Typical Mountainous Area of China

As one of the countries which has been experiencing a forest transition, China provides important insights into and theoretical and empirical knowledge of forest transition. In this study, through the framework of Sustainable Livelihood Analysis (SLA) and questionnaire surveys, we examined forest transition, farmers’ land-use activities and livelihood changes in Chicheng county, a typical mountainous area in Northern China, during 1975–2018. Most villages of Chicheng county experienced forest transition during the period of 2003–2005, but some villages experienced forest transition in 2010–2015. Forest transition variation over time was influenced by land use and livelihood changes. Livelihood resources, policy and institutional constraints and livelihood strategies had significant influences on land use and then caused variation in forest transition characteristics. The process of “livelihood–land use–forest transition” was the key to achieving and maintaining forest transition, and the interaction between livelihood and land use was a negative feedback relationship between society and ecology. The dominant path of forest transition in Chicheng county was the “economic development path”. Moreover, the “intensive agriculture path of small-scale farmers” enhanced the “economic development path”, and the “forest scarcity path” promoted both of the above two paths. This implies that the feedback and interactions between society and ecology should be taken into account so as to achieve a sustainable human and environmental system.

Experiment using semi-natural meadow vegetation for restoration of river revetments: A case study in the upper reaches of the Yangtze River

Mixed-species vegetation, such as that in semi-natural meadows, is increasingly adopted in urban green infrastructure to enhance habitat quality and aesthetic value; however, little is known regarding the consequences of using meadow mixes in river revetments. In the present study, 20 herbaceous species that naturally occur in habitats with infrequent and periodic inundation were mix-planted in hydrology-induced and disturbed revetments along the mainstream of the Yangtze River in the typical mountain city of Chongqing, China. The experimental meadow communities exhibited persistence under the constraints imposed by the prevailing hydrological conditions and disturbances, such as the extremely high soil wetness variability between periodical inundation on seedlings, the drought during the summer, and the transition between runoff washout and quick drainage. All planted species survived under the changing hydrological conditions, while the semi-natural meadow maintained good growth and visual landscape quality. Meadow mixes were significantly superior in species richness, abundance and structural diversity over the existing homogeneous community dominated by invasive liana Humulus scandens. Community data suggest that species richness has increased by more than 60% in the meadow mix over the existing vegetation. The meadow communities resisted invasion by indigenous weeds and colonising species that spread through wind-dispersal and hydrochorous transport from the upstream catchment. We therefore recommend prioritising taxonomically diverse meadows for river revetments wherever possible. This study provides a valid framework that can be used to inform future vegetation restoration schemes in river revetments affected by complex hydrological variation and disturbances. The methodology is applicable to a broad range of vegetative revetment structures.

Spatial-temporal Variations and the Regulators of Nitrate Status in Shallow Groundwater of the Typical Mountainous Agricultural Watershed in the Upper Reaches of the Yangtze River

Shallow groundwater is the main drinking water supply for the mountainous area in the upper reaches of the Yangtze River, while its quality is often degraded by nitrate (NO3--N) pollution due to intensive agricultural production activities. In the present study, we selected a mountainous agricultural watershed in the upper reaches of the Yangtze River to investigate the land use, management, and hydrogeological conditions, aiming to clarify the spatial-temporal variations in NO3--N concentration of shallow groundwater, thereby exploring the key regulators. The results showed that the NO3--N concentrations of the groundwater ranged from 0.40 to 12.51 mg ·L-1in the study area, and the exceeding ratio was nearly 30%. On an average, NO3--N concentrations for the wet season were higher than that for the dry season, indicating great variations in NO3--N concentration across different seasons. In addition, the spatial variations of NO3--N concentration in groundwater were also significant among different sub-catchment, which was mainly due to variations in the groundwater table depth and land uses. Furthermore, the significant correlations between the NO3--N concentrations and concentrations of Cl-, NH4+-N, DOC, and SO42- in the shallow groundwater were also explored in this study, suggesting that the NO3--N concentrations were likely to depend on the chemical factors of the shallow groundwater in the study area. Overall, our current study highlights that the characterization of spatial-temporal variations of NO3--N status in shallow groundwater and illustration of key regulators are essential to mitigate NO3--N pollution and prevent quality degradation of shallow groundwater in mountainous rural areas of the upper Yangtze River watershed.

Expansion of Juniperus sibirica Burgsd. as a response to climate change and associated effect on mountain tundra vegetation in the Northern Urals

Shrub expansion into arctic and alpine tundra is one of the prominent vegetation changes currently underway. We studied the expansion of shrub vegetation into high elevation tundra in the Kvarkush Range of the Northern Ural mountains, Russia. Age structure analysis of the dominant shrub Juniperus sibirica Burgsd. seems to support ongoing upslope advance of shrubs, a process particularly active in the second half of the 20th century. We found a close connection between the expansion of shrub vegetation and the general change in climatic conditions of the cold season (months with mean air temperature below 0°C from November to March). In general, the greatest influence on the distribution of J. sibirica is exerted by the climate conditions of the beginning (November–January) and the end (March) of the cold season. With increasing elevation, the correlation coefficients between the establishment of J. sibirica shrubs and the precipitation of the beginning of the cold season increased, and reached maximum values at the top elevation level of the study area. However, the upwards shift of J. sibirica into typical mountain tundra does not lead to changes in the ecological structure of vegetation at this stage, but simply a decrease in the area of mountain tundra.

Influence of rain pattern on flood control in mountain creek areas: a case study of northern Zhejiang

Mountain creek areas are a type of flood-prone area, and the flood control in these areas has not been well understood. This study aims to evaluate the impact of rain patterns on the water level and the establishment of flood control standard in mountain creek areas by conducting a case study. The case study was performed on a typical mountain creek area, called Shiliqu watershed in Hangzhou, China. A MIKE11 model was first established to analyze the required flood control standard through investigating the river level impacted by two rain patterns (the designed rainstorm and the typhoon Fitow). The results show that the designed rainstorm pattern and the typhoon Fitow rain pattern have the single-peak and multi-peak profile, respectively. The peak rainfall value of the designed rainstorm pattern is much higher than that of the typhoon Fitow. However, the large fluctuations under the typhoon Fitow rain pattern causes multi-level overtopping which threats the safety of the flood control. Also, the typhoon Fitow could have a greater influence on the water level of the tributaries of the river than that of the mainstream. The selection of rain pattern on the design of flood control standard in mountain creek areas is discussed.

Tree Growth Variability of Pinus heldreichii at Tree-Line Locations in Kosovo

It is well-known that tree growth at the upper treeline is controlled by low temperatures and limited seasonal growth. The study’s objective was to investigate the climate warming effects on Bosnian pine (BP; Pinus heldreichii Christ.) growth during the 20th century. We hypothesized that, like all the other drought-stressed conifers growing on tree-line locations, BP responds significantly to climate factors that control their growth. Three natural forest stands of BP were selected in Prevalla, Decan and Koritnik. The cores were taken from 98 dominant and co-dominant BP trees at breast height with no sign of human interference. The tree-ring widths were measured at 0.001 mm precision, with a LINTAB 6 (RINNTECH, Heidelberg) system and TSAP-Win Scientific software. A set of three BP tree-ring width chronologies were developed by trees spread on a typical mountain slope at elevations ranging from 1815 to 1945 m above sea level. The tree-ring chronologies from three sites showed significant correlation and this agreement decreased with the distance between sites. The length of the master chronologies varies among sites ranging from 176 years (Koritnik) to 541 years (Decani). The tree growth was controlled by a common climatic signal (local temperatures) and drought during midsummer across the investigated sites. These results confirm the assumption that tree growth at tree-line sites is controlled by low temperatures and drought conditions during the midsummer.

NET PRIMARY PRODUCTIVITY OF A MOUNTAIN FOREST ECOSYSTEM AS AFFECTED BY CLIMATE AND TOPOGRAPHY

Response of terrestrial ecosystems to changing climate has become an issue of central importance for land managers and policymakers. Climate extremes and trends have a strong control on productivity of semi-arid mountain ecosystems. Located in a transition zone from continental type climate to relatively mild Black Sea type climate in Turkey, the Ilgaz Mountains with their rich biodiversity, provide a unique opportunity to evaluate vulnerability of a typical semi-arid mountain ecosystem to climate change. Therefore, we evaluated spatio-temporal variation of annual net primary productivity (NPP) of Ilgaz Mountains predicted by Moderate Resolution Imaging Spectroradiometer (MODIS), as affected by topography and climate between 2000 and 2010. The annual MODIS NPP ranged from 500 to 912 g.m-2.y-1. Elevation, slope aspect, and vegetation type were significantly correlated with MODIS NPP The MODIS NPP was highly sensitive to droughts, and the mean MODIS NPP generally decreased across the study pixels in the study period. The response of MODIS NPP to climate was highly site- and time-specific. Multiple interactions among climate, plant composition, and topography were the principal determinants of the temporal pattern as well as drought sensitivity of MODIS NPP to climate between 2000 and 2010. Quality control charts showed that MODIS NPP decreased sharply in 2003 and 2007 droughts. The results obtained in this study contributed to our understanding of the interactions among climate, topography, and vegetation composition in a typical mountain ecosystem.

Aplicación de la teoría de redes para el modelado de una red de drenaje de una cuenca: caso de estudio departamento del Quindío Colombia

Background: The hydrographic network of the basins of the department of Quindio, located in Colombia, South America, suffers from pollution due to industries such as tanneries, mining, food processing, among others. Goals: Represent a hydrographic network of a basin employing a graph and study its most representative measures of centrality; as a case study, we considered the hydrologic network of the basins of the department of Quindio. Methods: The theory of networks and the analysis of centrality measures such as degree distribution, PageRank, and eccentricity; also, topological measures such as density and assortativity. Results: The study provided a different approach to research on the properties of river networks. The grade distribution shows a network with input grades of one, two, and three, while the output grade is only one or zero, consistent with a typical mountain basin. Measurements such as density and assortativity showed a low-density network with no defined connection patterns. The centrality of PageRank and eccentricity highlighted the leading causes and the most important rivers according to the way the hydrographic network is connected. Conclusions: The study concluded that by using network theory, we obtained a global vision of the network, understanding its structure and allowing us to visualize which areas of the network are vulnerable. PageRank’s centrality allowed us to identify well-monitored nodes in the network and those that need care; this same distribution highlighted zones in the network that are more prone to contamination. Finally, the eccentricity determined the center of the network (sector of “La Maria”) as one of the network’s most vulnerable areas.

Psychological Influences on Bus Travel Mode Choice: A Comparative Analysis between Two Chinese Cities

Psychological factors give an important influence on the behavior of travel mode choice, but the effects vary from different cities. To identify and explain the differences, this study makes a comparative analysis between two Chinese cities, Chongqing and Chengdu: a typical mountain city and a typical plain city. The sample is obtained by questionnaires containing 401 and 450 valid records of the two cities, respectively. The model used in this study is established based on the framework of the theory of planned behavior. The main work of this study has three aspects: (1) define the measured variables based on the combination of bus travel characteristics and the theory of planned behavior; (2) verify the model validity in both two cities; (3) make a comparative analysis on the two cities. According to the results, the validity of the theory framework and measured variables is verified; the perceived behavioral control plays the most important role in affecting the behavior of traveling by bus in both two cities; significant differences between the two cities are presented and explained.

LoRa System for Search and Rescue: Path-Loss Models and Procedures in Mountain Scenarios

Typical mountain Search and Rescue (SaR) operations require the localization of the persons involved in accidents in harsh environments. ARVA and RECCO are the current standards for the localization in snowy environments although their radio range is limited to some tens of meters. In this article, we prove by experimental results that the long-range (LoRa) low-power wide-area network (LPWAN) technology is very promising for SaR applications due to its extended radio range. A LoRa-based system for SaR operations is presented and analyzed. The localization of the persons is obtained through an algorithm based on path-loss (PL) measurements. Radio PL models of body-worn LoRa devices in harsh mountain environments are derived by measurements. We observed that although the communication range of LoRa decreases from kilometers to hundreds of meters in the tested environments, at least 50% of the transmitted packets can be received at distances about five times greater than those achievable with golden standard technologies such as ARVA. The performances of the considered localization algorithm are analyzed on the basis of the collected data. The achievable accuracy is in the order of meters around the true position for a relatively large number of available PL measurements. Finally, we propose and detail a LoRa-based system for SaR operations.

A study on the forecast calculating method of the density of rainfall debris flow in Southwestern of China

Density is the most important parameter of debris flow. This work looks into the typical debris flow and mountain torrent occurred in Longmen Mountains in the past 20 years and compares the calculation results of the density using various methods. It shows that the mean deviations of result are in the range of 20–30%, and the static model is only suitable to the occurred debris flow event but not the forecast. Based on the analysis of typical rainfall debris flow, the influence factors of density are revealed; it shows that the density is controlled by the form conditions and the soil-water coupling process of debris flow. A function is introduced to describe the activity of material source, which defined by volume and relative elevation of materials, and the watershed area. The forecast model is established by the relationship between the density and its influence factors. When the new method is applied to the Longmen mountain area and the upper basin of the Minjiang River, although there are still few discretization errors, the results still can explain nearly 95% of the evolution trend, which shows that the new method is not compromised by regional differences.

Discussion on position of China’s north-south transitional zone by comparative analysis of mountain altitudinal belts

The Qinling Mountains has always been regarded as an essential dividing line between the warm temperate zone and the subtropical zone in eastern China and plays a vital role in the geoecological pattern of China. However, there is controversy about the specific location of this geographical boundary in the academic community. As a product of the combined effects of zonal and non-zonal factors, the mountain altitudinal belts (MABs) can reflect both the horizontal zonality and the vertical zonality of vegetation distribution. Using the MAB information, we can not only profoundly understand the complex mountain system of Qinling-Daba Mountains but can also judge its nature as a geographical boundary more scientifically. Therefore, based on the comparative analysis of basal belt, dominant belt characteristics and belt structure characteristics of the MABs in Qinling-Daba Mountains, subtropical and temperate mountains, this paper analyzed the MAB differences and similarities among Qinling-Daba Mountains, subtropical and temperate typical mountains, to reveal the vegetation distribution characteristics in the north-south transitional zone. The results show that: (1) The MABs of the southern part of Qinling-Daba Mountains (southern slope of the Daba Mountains) are the same or similar to those of the Subtropical Mountains, and the MABs of the northern part of Qinling-Daba Mountains (northern slope of the Qinling Mountains) are similar to those of the temperate mountains. While it shows obvious transitional characteristics in the vast area between the northern slope of the Daba Mountains and the southern slope of the Qinling Mountains: the basal belts gradually transit from the evergreen broad-leaved forest belt (basal belt in subtropical mountains) to the evergreen and deciduous broad-leaved mixed forest belt, and the dominant belts also transit from the evergreen broad-leaved forest belt to the evergreen and deciduous broad-leaved mixed forest belt or the deciduous broad-leaved forest belt. (2) The transitional zone between the subtropical zone and the warm temperate zone is located between the northern slope of the Daba Mountains and the southern slope of the Qinling Mountains. The southern boundary of the transitional zone is along the northern slope of Shennongjia Mountain-the northern slope of Micang Mountain-Baishuijiang Nature Reserve, and the northern boundary is along the southern slope of Funiu Mountain-the southern slope of Taibai Mountain-Lianhua Mountain. Additionally, in the transitional zone, the average temperature in January is between -5°C and 1°C, the annual average temperature is between 10°C and 13°C except Hanzhong Basin and Hanshui Valley, and the accumulated temperature above 10°C ranges from 2000°C to 4000°C, the annual rainfall is about 800–1000 mm. The results provide a scientific basis for revealing the characteristics of China’s north-south transitional zone and scientific division of the boundary between the subtropical zone and warm temperate zone in China.

Contamination Identification of Trace Metals in Roadway Dust of a Typical Mountainous County in the Three Gorges Reservoir Region, China, and its Relationships with Socio-Economic Factors

Trace metal contamination in urban road dust has attracted global concern due to its potential risk to the urban environment and human health. Compared to big cities, relative studies in counties and small towns have not been well quantified. This research identified the trace metal contamination characteristics and possible sources in the road dust of a typical mountainous county and a town in the Three Gorges Reservoir region, southwest China, and their associations with major regional socio-economic factors. The trace metal concentrations were determined, and the contamination levels were assessed. Concentrations of Zn, Pb, and Cu were relatively high in both locations, and a significant accumulation of them was confirmed by the geo-accumulation method. Multivariate analysis and geographic information system (GIS) mapping were combined to explore the sources of trace metals in the investigated area. Anthropogenic activities predominantly affected the contamination levels of Zn, Pb, Cu, and Co, and traffic emission, agricultural activities, and fossil fuel combustion were their main sources. The significant accumulation of Zn should attract special concern for its wide use in industrial and agricultural activities. Population and vehicle density were the main factors that controlled the trace metal contamination levels in the roadway dust. Rapid urbanizing promoted trace metal accumulation in counties and towns. Therefore, it is urgent to make appropriate strategies for trace metal pollution mitigation in the process of urbanization.

Analysis of the relationship between cross-cultural perceptions of landscapes and cultural ecosystem services in Genheyuan region, Northeast China

A major challenge today and in the future is to maintain or enhance the beneficial contributions of landscapes to the quality of life of people. Neglecting cultural ecosystem services (CES) in landscape planning can lead to loss of unique cultural landscapes and undermine the well-being of local communities. Despite a rapidly increasing body of literature on CES, little is known about the relationship between socio-cultural values and the non-material benefits of landscapes. To help fill this gap, we assessed the perceptions of people from different ethnic groups about the cultural ecosystem services of local landscapes. We took the Genheyuan National Wetland Park and the adjacent forest areas, a typical mountain forest-wetland ecosystem, as our case area. By combining surveys (250 semi-structured interviews and 26 local stakeholders in Focus Group Discussion) with structural equation modelling (SEM), we gained insights into the importance of landscapes to CES provision from the perspective of stakeholder diversity. Surprisingly, wetlands are perceived as playing more important roles than other landscape types in providing diverse CES, with a 1.25 times higher CES Diversity Index (CDI) than that of forests. Among all demographic factors, ethnicity is most significant in determining people’s perceptions, reflecting the spiritual cognition, manners, and customs of the ethnic groups. The perceptions of CES provided by landscapes are likely to increase if landscape characteristics are attached more to functions in order to meet fundamental human needs.

Biochemical evolution of dissolved organic matter during snow metamorphism across the ablation season for a glacier on the central Tibetan Plateau

The metamorphism of snow (snowmelt process) has a potential influence on chemical and physical process occurring within it. This study carried out a detailed study on the variation of dissolved organic matter (DOM) in different stages of snowmelt in a typical mountain glacier located at Tibetan Plateau through collecting four different surface snow/ice categories, i.e., fresh snow, fine firn, coarse firn, and granular ice during May to October in 2015. The dissolved organic carbon (DOC) was observed by lost 44% from fresh snow to fine firn and enriched 129% from fine firn to granular ice, reflecting the dynamic variability in DOC concentration during snow metamorphism. The absorbance properties of each snow category are positively correlated with DOC concentration. The result of excitation emission matrix fluorescence with parallel factor analysis (EEM-PARAFAC) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) highlighted the domination of lipid- and protein-like compounds in glacial-derived DOM. The molecular composition of the DOM also exhibited a new N-containing molecular formula (CHON classes) that was enriched during snow metamorphism. This study suggests that snow metamorphism could induce a loss of DOM as well as enrich and modify the DOM.

An Orographic‐Drag Parametrization Scheme Including Orographic Anisotropy for All Flow Directions

AbstractOrographic drag is an essential process for numerical weather predictions in complex terrain regions, which depends on the inflow direction. In this study, we define the orographic asymmetry vector (OAV) for a coarse grid as the normalized vector between the grid's center point and its center of mass, and the orographic asymmetry in a flow direction—which describes the inclination direction and the extent of the subgrid terrain—is calculated as the projection of OAV on this direction. Calculations of the effective orographic length (OL) and the model grid length λ are extended to all flow directions. A new orographic drag scheme, which considers the effect of orographic anisotropy in all directions, is then developed based on the OAV projection and the extended OL and λ for any given direction. Sensitivity tests of the orographic drag under the new scheme are conducted using a 5 m/s vertically uniform wind along different directions for four coarse grid points in typical mountain regions. The new scheme is shown to provide a more continuous transition of the orographic parameters and the resulting stress as a function of flow direction than piecewise transition of schemes with only eight directions. The predicted momentum flux profile of the new scheme is compared with mountain‐wave simulations obtained from the integrated modeling system IAP‐WRF (Institute of Atmospheric Physics‐Weather Research and Forecasting Model) for the Rocky Mountain. The new scheme is shown to predict an overall narrower stress scatter about the reference simulation than the old scheme.