scholarly journals Spatial variability of snow precipitation and accumulation in COSMO–WRF simulations and radar estimations over complex terrain

2018 ◽  
Author(s):  
Franziska Gerber ◽  
Nikola Besic ◽  
Varun Sharma ◽  
Rebecca Mott ◽  
Megan Daniels ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Small Scale ◽  
Hydro Power ◽  
Near Surface ◽  
Avalanche Forecasting ◽  
Precipitation Patterns ◽  
Flow Interactions ◽  
Wide Variability ◽  
High Precipitation ◽  
Snow Precipitation

Abstract. Snow distribution in complex alpine terrain and its evolution in the future climate is important in a variety of applications including hydro-power, avalanche forecasting and fresh water resources. However, the relative importance of processes such as cloud-dynamics and pure particle-flow interactions is still barely known and models are essential to investigate these processes. Here, we present very high resolution Weather Research and Forecasting model (WRF) simulations, which are initialized by 2.2 km resolution Consortium for Small-scale Modeling (COSMO) reanalysis (COSMO–WRF). To assess the ability of COSMO–WRF to represent spatial snow precipitation patterns, they are validated against operational weather radar measurements. Estimated WRF precipitation is generally higher than estimated radar precipitation, most likely due to an overestimation of orographic precipitation in the model. The high precipitation also leads to a higher spatial variability in the model at the scale of 10 km. Overall, an autocorrelation and scale analysis of radar and WRF precipitation patterns show that WRF captures the variability relative to the domain wide variability of precipitation patterns down to the scale of few kilometers, but misses quite substantial variability on the smallest scales of a few 100 meters. However, differences of precipitation between 2830 m above sea level and the ground indicate that near-surface processes are active in the model.

scholarly journals Spatial variability in snow precipitation and accumulation in COSMO–WRF simulations and radar estimations over complex terrain

2018 ◽  
Vol 12 (10) ◽  
pp. 3137-3160 ◽  
Author(s):  
Franziska Gerber ◽  
Nikola Besic ◽  
Varun Sharma ◽  
Rebecca Mott ◽  
Megan Daniels ◽  
...  
Keyword(s):  
High Resolution ◽  
Spatial Variability ◽  
Complex Terrain ◽  
Small Scale ◽  
Near Surface ◽  
Precipitation Patterns ◽  
Simulated Precipitation ◽  
Precipitation Processes ◽  
Snow Distribution ◽  
Snow Precipitation

Abstract. Snow distribution in complex alpine terrain and its evolution in the future climate is important in a variety of applications including hydropower, avalanche forecasting and freshwater resources. However, it is still challenging to quantitatively forecast precipitation, especially over complex terrain where the interaction between local wind and precipitation fields strongly affects snow distribution at the mountain ridge scale. Therefore, it is essential to retrieve high-resolution information about precipitation processes over complex terrain. Here, we present very-high-resolution Weather Research and Forecasting model (WRF) simulations (COSMO–WRF), which are initialized by 2.2 km resolution Consortium for Small-scale Modeling (COSMO) analysis. To assess the ability of COSMO–WRF to represent spatial snow precipitation patterns, they are validated against operational weather radar measurements. Estimated COSMO–WRF precipitation is generally higher than estimated radar precipitation, most likely due to an overestimation of orographic precipitation enhancement in the model. The high precipitation amounts also lead to a higher spatial variability in the model compared to radar estimates. Overall, an autocorrelation and scale analysis of radar and COSMO–WRF precipitation patterns at a horizontal grid spacing of 450 m show that COSMO–WRF captures the spatial variability normalized by the domain-wide variability in precipitation patterns down to the scale of a few kilometers. However, simulated precipitation patterns systematically show a lower variability on the smallest scales of a few hundred meters compared to radar estimates. A comparison of spatial variability for different model resolutions gives evidence for an improved representation of local precipitation processes at a horizontal resolution of 50 m compared to 450 m. Additionally, differences of precipitation between 2830 m above sea level and the ground indicate that near-surface processes are active in the model.

scholarly journals The Importance of Near-Surface Winter Precipitation Processes in Complex Alpine Terrain

2019 ◽  
Vol 20 (2) ◽  
pp. 177-196 ◽  
Author(s):  
Franziska Gerber ◽  
Rebecca Mott ◽  
Michael Lehning
Keyword(s):  
Winter Precipitation ◽  
Snow Accumulation ◽  
Windward Side ◽  
Leeward Side ◽  
Small Scale ◽  
Orographic Precipitation ◽  
Near Surface ◽  
Simulated Precipitation ◽  
Snow Precipitation ◽  
Precipitation Enhancement

Abstract In this study, near-surface snow and graupel dynamics from formation to deposition are analyzed using WRF in a large-eddy configuration. The results reveal that a horizontal grid spacing of ≤50 m is required to resolve local orographic precipitation enhancement, leeside flow separation, and thereby preferential deposition. At this resolution, precipitation patterns across mountain ridges show a high temporal and spatial variability. Simulated and observed event-mean snow precipitation across three mountain ridges in the upper Dischma valley (Davos, Switzerland) for two precipitation events show distinct patterns, which are in agreement with theoretical concepts, such as small-scale orographic precipitation enhancement or preferential deposition. We found for our case study that overall terrain–flow–precipitation interactions increase snow accumulation on the leeward side of mountain ridges by approximately 26%–28% with respect to snow accumulation on the windward side of the ridge. Cloud dynamics and mean advection may locally increase precipitation on the leeward side of the ridge by up to about 20% with respect to event-mean precipitation across a mountain ridge. Analogously, near-surface particle–flow interactions, that is, preferential deposition, may locally enhance leeward snow precipitation on the order of 10%. We further found that overall effect and relative importance of terrain–flow–precipitation interactions are strongly dependent on atmospheric humidity and stability. Weak dynamic stability is important for graupel production, which is an essential component of solid winter precipitation. A comparison to smoothed measurements of snow depth change reveals a certain agreement with simulated precipitation across mountain ridges.

scholarly journals Understanding Spatial Variability of NO2 in Urban Areas Using Spatial Modelling and Data Fusion Approaches

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 179
Author(s):  
Said Munir ◽  
Martin Mayfield ◽  
Daniel Coca
Keyword(s):  
Data Fusion ◽  
Spatial Variability ◽  
Urban Areas ◽  
Road Traffic ◽  
Dispersion Model ◽  
Low Cost ◽  
Spatial Modelling ◽  
City Centre ◽  
Small Scale ◽  
The City

Small-scale spatial variability in NO2 concentrations is analysed with the help of pollution maps. Maps of NO2 estimated by the Airviro dispersion model and land use regression (LUR) model are fused with measured NO2 concentrations from low-cost sensors (LCS), reference sensors and diffusion tubes. In this study, geostatistical universal kriging was employed for fusing (integrating) model estimations with measured NO2 concentrations. The results showed that the data fusion approach was capable of estimating realistic NO2 concentration maps that inherited spatial patterns of the pollutant from the model estimations and adjusted the modelled values using the measured concentrations. Maps produced by the fusion of NO2-LCS with NO2-LUR produced better results, with r-value 0.96 and RMSE 9.09. Data fusion adds value to both measured and estimated concentrations: the measured data are improved by predicting spatiotemporal gaps, whereas the modelled data are improved by constraining them with observed data. Hotspots of NO2 were shown in the city centre, eastern parts of the city towards the motorway (M1) and on some major roads. Air quality standards were exceeded at several locations in Sheffield, where annual mean NO2 levels were higher than 40 µg/m3. Road traffic was considered to be the dominant emission source of NO2 in Sheffield.

Small-scale spatial variability of particle concentrations and traffic levels in Montreal: a pilot study

2005 ◽  
Vol 338 (3) ◽  
pp. 243-251 ◽  
Author(s):  
Audrey Smargiassi ◽  
Mary Baldwin ◽  
Charles Pilger ◽  
Rose Dugandzic ◽  
Michael Brauer
Keyword(s):  
Pilot Study ◽  
Spatial Variability ◽  
Small Scale

scholarly journals Large Temperature Fluctuations due to Cold-Air Pool Displacement along the Lee Slope of a Desert Mountain

2017 ◽  
Vol 56 (4) ◽  
pp. 1083-1098 ◽  
Author(s):  
Matthew E. Jeglum ◽  
Sebastian W. Hoch ◽  
Derek D. Jensen ◽  
Reneta Dimitrova ◽  
Zachariah Silver
Keyword(s):  
Low Frequency ◽  
Temperature Fluctuations ◽  
Atmospheric Modeling ◽  
Large Temperature ◽  
Complex Flow ◽  
Near Surface ◽  
Cold Air ◽  
Flow Interactions ◽  
Initial Drop ◽  
Program Temperature

AbstractLarge temperature fluctuations (LTFs), defined as a drop of the near-surface temperature of at least 3°C in less than 30 min followed by a recovery of at least half of the initial drop, were frequently observed during the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) program. Temperature time series at over 100 surface stations were examined in an automated fashion to identify and characterize LTFs. LTFs occur almost exclusively at night and at locations elevated 50–100 m above the basin floors, such as the east slope of the isolated Granite Mountain (GM). Temperature drops associated with LTFs were as large as 13°C and were typically greatest at heights of 4–10 m AGL. Observations and numerical simulations suggest that LTFs are the result of complex flow interactions of stably stratified flow with a mountain barrier and a leeside cold-air pool (CAP). An orographic wake forms over GM when stably stratified southwesterly nocturnal flow impinges on GM and is blocked at low levels. Warm crest-level air descends in the lee of the barrier, and the generation of baroclinic vorticity leads to periodic development of a vertically oriented vortex. Changes in the strength or location of the wake and vortex cause a displacement of the horizontal temperature gradient along the slope associated with the CAP edge, resulting in LTFs. This mechanism explains the low frequency of LTFs on the west slope of GM as well as the preference for LTFs to occur at higher elevations later at night, as the CAP depth increases.

Experiments on wind-driven heat exchange processes over melting snow

2021 ◽  
Author(s):  
Michael Haugeneder ◽  
Tobias Jonas ◽  
Dylan Reynolds ◽  
Michael Lehning ◽  
Rebecca Mott
Keyword(s):  
Snow Cover ◽  
Surface Wind ◽  
Infrared Camera ◽  
Snow Accumulation ◽  
Internal Boundary ◽  
Small Scale ◽  
Snow Melt ◽  
Two Dimensional ◽  
Atmospheric Conditions ◽  
Near Surface

<p>Snowmelt runoff predictions in alpine catchments are challenging because of the high spatial variability of t<span>he snow cover driven by </span>various snow accumulation and ablation processes. In spring, the coexistence of bare and snow-covered ground engages a number of processes such as the enhanced lateral advection of heat over partial snow cover, the development of internal boundary layers, and atmospheric decoupling effects due to increasing stability at the snow cover. The interdependency of atmospheric conditions, topographic settings and snow coverage remains a challenge to accurately account for these processes in snow melt models.<br>In this experimental study, we used an Infrared Camera (VarioCam) pointing at thin synthetic projection screens with negligible heat capacity. Using the surface temperature of the screen as a proxy for the air temperature, we obtained a two-dimensional instantaneous measurement. Screens were installed across the transition between snow-free and snow-covered areas. With IR-measurements taken at 10Hz, we capture<span> the dynamics of turbulent temperature fluctuations</span><span> </span>over the patchy snow cover at high spatial and temporal resolution. From this data we were able to obtain high-frequency, two-dimensional windfield estimations adjacent to the surface.</p><p>Preliminary results show the formation of a stable internal boundary layer (SIBL), which was temporally highly variable. Our data suggest that the SIBL height is very shallow and strongly sensitive to the mean near-surface wind speed. Only strong gusts were capable of penetrating through this SIBL leading to an enhanced energy input to the snow surface.</p><p>With these type of results from our experiments and further measurements this spring we aim to better understand small scale energy transfer processes over patch snow cover and it’s dependency on the atmospheric conditions, enabling to improve parameterizations of these processes in coarser-resolution snow melt models.</p>

scholarly journals Cryoconite hole connectivity on the Wright Lower Glacier, McMurdo Dry Valleys, Antarctica

2016 ◽  
Vol 62 (234) ◽  
pp. 714-724 ◽  
Author(s):  
SHELLEY MACDONELL ◽  
MARTIN SHARP ◽  
SEAN FITZSIMONS
Keyword(s):  
Spatial Variability ◽  
Drainage System ◽  
Chloride Content ◽  
Mcmurdo Dry Valleys ◽  
Hydrological Connectivity ◽  
Dry Valleys ◽  
Near Surface ◽  
Cryoconite Hole ◽  
Transfer Method ◽  
Surface Ice

ABSTRACTCryoconite holes can be important sources and stores of water and nutrients on cold and polythermal glaciers, and they provide a habitat for various forms of biota. Understanding the hydrological connectivity of cryoconite holes may be the key to understanding the transport of nutrients and biological material to the proglacial areas of such glaciers. This paper aims to characterize and explain spatial variability in the connectivity of ice-lidded cryoconite holes on a small, piedmont glacier in the McMurdo Dry Valleys through geochemical analysis of cryoconite hole waters. Solute concentrations in both surface and near-surface ice and cryoconite holes, vary greatly along the glacier centerline, and all sample types displayed similar spatial patterns of variability. Using chloride as a tracer, we estimated variations in cryoconite hole connectivity along the glacier centerline. We found that a previously used mass transfer method did not provide reliable estimates of the time period for which cryoconite hole waters had been isolated from the atmosphere. We attribute this to spatial variability in both the chloride content of the surface ice and surface ablation rates. The approach may, however, be used to qualitatively characterize spatial variations in the hydrological connectivity of the cryoconite holes. These results also suggest that ice-lidded cryoconite holes are never truly isolated from the near-surface drainage system.

Small-scale temporal and spatial variability in the erosion threshold and properties of cohesive intertidal sediments

2006 ◽  
Vol 26 (3) ◽  
pp. 351-362 ◽  
Author(s):  
T.J. Tolhurst ◽  
E.C. Defew ◽  
J.F.C. de Brouwer ◽  
K. Wolfstein ◽  
L.J. Stal ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Small Scale ◽  
Intertidal Sediments ◽  
Erosion Threshold ◽  
Temporal And Spatial Variability ◽  
Temporal And Spatial

scholarly journals Characteristics of Large-Scale Orographic Precipitation in a Linear Perspective

2011 ◽  
Vol 12 (1) ◽  
pp. 27-44 ◽  
Author(s):  
Michael Kunz
Keyword(s):  
Time Scales ◽  
Characteristic Time ◽  
Large Scale ◽  
Linear Perspective ◽  
Horizontal Wind ◽  
Small Scale ◽  
Orographic Precipitation ◽  
Observation Data ◽  
Horizontal Wind Speed ◽  
Precipitation Patterns

Abstract Simulations of orographic precipitation over the low mountain ranges of southwestern Germany and eastern France with two different physics-based linear precipitation models are presented. Both models are based on 3D airflow dynamics from linear theory and consider advection of condensed water and leeside drying. Sensitivity studies for idealized conditions and a real case study show that the amount and spatial distribution of orographic precipitation is strongly controlled by characteristic time scales for cloud and hydrometeor advection and background precipitation due to large-scale lifting. These parameters are estimated by adjusting the model results on a 2.5-km grid to observed precipitation patterns for a sample of 40 representative orography-dominated stratiform events (24 h) during a calibration period (1971–80). In general, the best results in terms of lowest rmse and bias are obtained for characteristic time scales of 1600 s and background precipitation of 0.4 mm h−1. Model simulations of a sample of 84 events during an application period (1981–2000) with fixed parameters demonstrate that both models are able to reproduce quantitatively precipitation patterns obtained from observations and reanalyses from a numerical model [Consortium for Small-scale Modeling (COSMO)]. Combining model results with observation data shows that heavy precipitations over mountains are restricted to situations with strong atmospheric forcings in terms of synoptic-scale lifting, horizontal wind speed, and moisture content.

scholarly journals The influence of water resources on transformation of spatial-functional structure of the territory of the municipality of Mali Zvornik and the possibilities for the construction of new hydro power plants

2010 ◽  
Vol 90 (3) ◽  
pp. 189-206 ◽  
Author(s):  
Mila Pavlovic ◽  
Rajko Golic ◽  
Dejan Sabic
Keyword(s):  
Water Resources ◽  
Power Plants ◽  
Hydraulic Engineering ◽  
Functional Structure ◽  
Hydropower Plant ◽  
Small Scale ◽  
Hydro Power ◽  
Hydropower Plants ◽  
Economic Revitalization ◽  
Hydro Power Plants

The territory of the municipality of Mali Zvornik is, from the aspect of morphology and spatial-functional structure, a heterogeneous area. It is located in the valley of the Drina River and in hilly-mountainous part of Podrinjske mountains. The area of the municipality is 184 km?, with 14076 inhabitants (2002). The importance of water resources for the development of the municipality, particularly of the hydropower plant (HPP) ?Zvornik?, is analyzed in this paper. Inadequate use of hydro-energetic potential, possibilities for construction of new hydropower plants and economic reasons for their construction are also emphasized. The priorities of the development of hydraulic engineering are defined in relation to morphological and hydrological conditions. They refer to increase of power of the HPP ?Zvornik? and construction of small-scale hydropower plants in hilly-mountainous part of municipality. Considering depopulation processes in the villages of Mali Zvornik, hydraulic engineering, together with agriculture, forestry, exploitation of mineral goods and tourism, can be one of the factors of demographic and economic revitalization of this area.

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