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

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Autor/in:
Erscheinungsjahr:
2022
Medientyp:
Text
Schlagworte:
  • Nepal
  • Rolwaling Himal
  • Landforms
  • Meteorology
  • Speed
  • Weather information services
  • Wind speed
  • Automated weather stations
  • Central himalayas
  • Complex terrains
  • Diurnal wind
  • Himalayas
  • Local wind
  • Valley wind day
  • Valley wind system
  • Valley winds
  • Wind systems
  • boundary layer
  • complex terrain
  • diurnal variation
  • mountain region
  • spatiotemporal analysis
  • topographic effect
  • valley
  • wind direction
  • wind field
  • wind velocity
  • Topography
  • automated weather station
  • Central Himalayas
  • diurnal wind
  • local wind
  • valley wind
  • valley wind days
  • valley wind system
Beschreibung:
  • 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 (Formula presented.)), 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 (Formula presented.) around noon during the VWDs. Wind directions followed a 180 (Formula presented.) 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. © 2022 by the authors.
Lizenz:
  • info:eu-repo/semantics/openAccess
Quellsystem:
Forschungsinformationssystem der UHH
Interne Metadaten
Quelldatensatz
oai:www.edit.fis.uni-hamburg.de:publications/586ef5d0-2607-479c-a87c-523bae12cb17