Seasonal variation of mountain-valley wind circulation and surface layer parameters over the mountainous terrain of the northeastern region of India

Barman, Nilamoni; Borgohain, Arup; Kundu, Shyam Sundar; Kumar, Nishant

doi:10.1007/s00704-020-03491-y

Cited by 11 publications

(6 citation statements)

References 42 publications

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“…Furthermore, the lower rate of parasitism in spring and summer compared to winter could arise because of the impact of the subtropical monsoon in the northeast region of Bangladesh which brings heavy rainfall (on average 695.33 mm during wet and hot summer months) (Fick & Hijmans, 2017 ). Additionally, our low altitude study area (altitude = 10 m) receives water from the adjacent Meghalaya Hills (altitude = 1961 m), which often experience one of the highest average rainfalls in the world (Barman et al., 2021 ; Deb et al., 2013 ; Murata et al., 2007 ). As a consequence, the study area is frequently flooded (Murata et al., 2007 ).…”

Section: Discussionmentioning

confidence: 99%

Cooler and drier conditions increase parasitism in a subtropical damselfly population

Paul,

Rayhan,

Herberstein

et al. 2024

Ecology and Evolution

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Host–parasite interactions are impacted by climate, which may result in variation of parasitism across landscapes and time. Understanding how parasitism varies across these spatio‐temporal scales is crucial to predicting how organisms will respond to and cope under a rapidly changing climate. Empirical work on how parasitism varies across climates is limited. Here, we examine the variation of parasitism across seasons and identify the likely climatic factors that explain this variation using Agriocnemis femina damselflies and Arrenurus water mite ectoparasites as a host–parasite study system. We assessed parasitism in a natural population in Sylhet, Bangladesh which is located in subtropical climate between 2021 and 2023. We calculated prevalence (proportion of infected individuals) and intensity (the number of parasites on an infected individual) of parasitism across different seasons. Parasite prevalence and intensity were greater during cooler seasons (autumn and winter) compared to hotter seasons (spring and summer). Mean temperature and precipitation were negatively correlated with parasite prevalence, whereas only mean precipitation was negatively correlated with parasite intensity. Tropical, subtropical and mediterranean regions are predicted to experience extreme climatic events (extreme temperature, less precipitation and frequent drought) as a consequence of anthropogenic climate change, and our finding suggests that this might alter patterns of parasitism in aquatic insects.

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Section: Discussionmentioning

confidence: 99%

Cooler and drier conditions increase parasitism in a subtropical damselfly population

Paul,

Rayhan,

Herberstein

et al. 2024

Ecology and Evolution

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“…It has a unique periodic pattern, with an up-slope ow in the day and the down-slope ow in the nighttime. During the pre-monsoon season, the wind direction is constrained to the southeast (90º-180º) direction, the wind speed also increased in comparison to the winter season (Barman et al 2021). In the monsoon, the wind direction is restricted to the south direction (180º-270º) in the day, indicating the superposition of the mountain-valley wind circulation.…”

Section: Seasonal Wind Direction and Speedmentioning

confidence: 99%

“…In the monsoon, the wind direction is restricted to the south direction (180º-270º) in the day, indicating the superposition of the mountain-valley wind circulation. In the post-monsoon season, wind direction ranges from the northeast (45º) to the west direction (300º), indicating mountain-valley wind circulation over the station (Barman et al 2021).…”

Section: Seasonal Wind Direction and Speedmentioning

confidence: 99%

“…The evaporation/condensation processes have a signi cant impact on aerosol formation and size distribution (Levin et al 2010;Sakamoto et al 2016). Barman et al (2021) demonstrated that mountain-valley wind movements have an impact on the meteorological parameters throughout the year except for the monsoon season. The region's recent rapid socioeconomic development may have accelerated anthropogenic aerosol emissions.…”

Section: Introductionmentioning

confidence: 99%

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Observation and model simulation of aerosol optical properties and size distribution over the hilly terrain of Northeast India

Barman

Kundu

Borgohain

2023

Preprint

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The aerosol optical properties are studied at northeast India's high-altitude station. The aerosol total scattering at the station is influenced by the mountain valley wind circulation. The backward trajectory shows the pre-monsoon season is a transition period when the air mass transportation alters the direction from northwest to south direction. The dominance of biomass burning and other emissions over long-range transportation of particles contributed strongly to the aerosol loading, which caused the higher range of scattering Ångström exponent (α450−700 nm > 1.5) in the pre-monsoon, monsoon, and post-monsoon seasons. The α450−700 nm varies from 1.47 to 1.88, indicating that the fine aerosol particles with a radius of < 0.5 µm have dominance at the station. To estimate the backscatter fraction (bf) and Asymmetry Parameter (g), theoretical approximation (Sviridenkov 2017 and Kokhanovsky 2006) and model simulation (MieTab and Mieplot) are utilized. The bf and g are found to be in the range of 0.11–0.13 and 0.68 to 0.74, after comparison of this value with the model simulated particle size, observed that the radius varies from \(\approx\) 0.17 µm − 0.21 µm. The bf decreased from winter to monsoon season, while the g values enhanced, demonstrating a negative correlation. The bf value decreased owing to the less backscatter and higher forward scatter for bigger particles from winter to monsoon. Thus, the g values were smaller for higher bf values and associated with smaller aerosol particles and vice-versa.

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“…They found that the consistency of winds is generally high during nighttime and low during the shift between the up-and down-valley flows. Barman et al [40] conducted seasonal analyses on the MVWS and surface layer parameters in the northeastern mountain regions of India. They found strong influences of incoming solar radiation and synoptic air flows on evaporation, heating, and thus, the energy budget of the valley that drives the MVWS.…”

Section: Introductionmentioning

confidence: 99%

Spatio-Temporal Analysis of Valley Wind Systems in the Complex Mountain Topography of the Rolwaling Himal, Nepal

Jentsch

Weidinger

2022

Atmosphere

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The diurnal, seasonal, and spatio-temporal characteristics of local wind systems in a steep mountain valley in Nepal are analyzed with the identification of valley wind days (VWDs). Distributed across the Rolwaling Himal valley in Nepal between 3700 and 5100 m a.s.l. at eight automated weather stations (AWSs), meteorological data between October 2017 and September 2018 were examined. VWDs were classified by means of ERA5 reanalysis data and in situ observations, employing established thresholds using precipitation, solar radiation, air pressure, and wind speed data at different pressure levels. Thus, overlying synoptic influences are highly reduced and distinctive diurnal patterns emerge. A strong seasonal component in near-surface wind speed and wind direction patterns was detected. Further analyses showed the diurnal characteristics of slow (approximately 0.5–0.9 m s−1), but gradually increasing wind speeds over the night, transitional periods in the morning and evening, and the highest averaged wind speeds of approximately 4.3 m s−1 around noon during the VWDs. Wind directions followed a 180∘ shift with nocturnal katabatic mountain winds and inflowing anabatic valley winds during the daytime. With AWSs at opposing hillsides, slope winds were clearly identifiable and thermally driven spatio-temporal variations throughout the valley were revealed. Consequently, varying temporal shifts in wind speed and direction along the valley bottom can be extracted. In general, the data follow the well-known schematic of diurnal mountain–valley wind systems, but emphasize the influence of monsoonal seasonality and the surrounding complex mountain topography as decisive factors.

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Seasonal variation of mountain-valley wind circulation and surface layer parameters over the mountainous terrain of the northeastern region of India

Cited by 11 publications

References 42 publications

Cooler and drier conditions increase parasitism in a subtropical damselfly population

Cooler and drier conditions increase parasitism in a subtropical damselfly population

Observation and model simulation of aerosol optical properties and size distribution over the hilly terrain of Northeast India

Spatio-Temporal Analysis of Valley Wind Systems in the Complex Mountain Topography of the Rolwaling Himal, Nepal

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