scholarly journals Surface Wind Regionalization in Complex Terrain

2008 ◽  
Vol 47 (1) ◽  
pp. 308-325 ◽  
Author(s):  
P. A. Jiménez ◽  
E. García-Bustamante ◽  
J. F. González-Rouco ◽  
F. Valero ◽  
J. P. Montávez ◽  
...  
Keyword(s):  
Complex Terrain ◽  
Large Scale ◽  
Mesoscale Model ◽  
Surface Wind ◽  
Principal Component ◽  
Meridional Wind ◽  
Northern Spain ◽  
Sea Level Pressure ◽  
Topographic Features ◽  
Wind Variability

Abstract Daily wind variability in the Comunidad Foral de Navarra in northern Spain was studied using wind observations at 35 locations to derive subregions with homogeneous temporal variability. Two different methodologies based on principal component analysis were used to regionalize: 1) cluster analysis and 2) the rotation of the selected principal components. Both methodologies produce similar results and lead to regions that are in general agreement with the topographic features of the terrain. The meridional wind variability is similar in all subregions, whereas zonal wind variability is responsible for differences between them. The spectral analysis of wind variability within each subregion reveals a dominant annual cycle and the varying presence of higher-frequency contributions in the subregions. The valley subregions tend to present more variability at high frequencies than do higher-altitude sites. Last, the influence of large-scale dynamics on regional wind variability is explored by studying connections between wind in each subregion and sea level pressure fields. The results of this work contribute to the characterization of wind variability in a complex terrain region and constitute a framework for the validation of mesoscale model wind simulations over the region.

scholarly journals Summertime Surface Wind Variability over Northeastern North America at Multidecadal to Centennial Time Scales via Statistical Downscaling

2020 ◽  
Vol 33 (5) ◽  
pp. 1969-1990
Author(s):  
Etor E. Lucio-Eceiza ◽  
J. Fidel González-Rouco ◽  
Elena García-Bustamante ◽  
Jorge Navarro ◽  
Cristina Rojas-Labanda ◽  
...  
Keyword(s):  
North America ◽  
Time Scales ◽  
Statistical Downscaling ◽  
Large Scale ◽  
Surface Wind ◽  
Meridional Wind ◽  
Similar Amount ◽  
Coupled Modes ◽  
Northeastern North America ◽  
Wind Variability

AbstractThe variability of the surface zonal and meridional wind components over northeastern North America during June–October is analyzed through a statistical downscaling (SD) approach that relates the main wind and large-scale circulation modes. An observational surface wind dataset of 525 sites over 1953–2010 provides the local information. Twelve global reanalyses provide the large-scale information. The large-to-local variability of the wind field can be explained, to a large extent, in terms of four coupled modes of circulation explaining a similar amount of variance. The SD method is mostly sensitive to the number of retained modes and subregionally to the large-scale information variable, but not to the reanalysis source. The SD methodological uncertainty based on the use of multiple configurations is directly related to the variability of the wind, similar in relative terms for both components. With an adequate choice of parameters the SD estimates provide more realistic variances than the reanalysis wind, although their correlations with respect to observations are lower than the latter. Additionally, while these different SD estimations are very similar on the reanalysis used, the various reanalysis wind fields show noticeable differences, especially in their variances. The wind variability is reconstructed back to 1850, making use of century-long reanalyses and two additional SLP gridded datasets, which allows estimating the variability at decadal to multidecadal time scales. Recent negative (significant) trends in the zonal component do not stand out in the multidecadal context, but they are consistent with a global stilling process, and are partially attributable to changes in the large-scale dynamics.

The European wind from observational and simulated databases

2020 ◽  
Author(s):  
Elena García-Bustamante ◽  
Jorge Navarro ◽  
Jesús Fidel González-Rouco ◽  
E. Etor Lucio- Eceiza ◽  
Cristina Rojas-Labanda ◽  
...  
Keyword(s):  
Wind Field ◽  
Mesoscale Model ◽  
Surface Wind ◽  
Wrf Model ◽  
Horizontal Resolution ◽  
Spatial And Temporal Variability ◽  
Model Simulations ◽  
Wind Variability ◽  
Observational Database ◽  
Wind Velocities

<p>The New European Wind Atlas (https://map.neweuropeanwindatlas.eu) is developed based on the simulated wind field over Europe from a mesoscale model coupled to a microscale component through a statistical downscaling approach. The simulation that provides mesoscale inputs within the model chain has been decided upon a careful sensitivity analysis of potential model configurations. In order to accomplish model resolutions of 3 km over Europe, the broader European domain is partitioned into a set of 10 partially overlapping tiles. The wind field is simulated with the WRF model over these tiles and finally blended into a single domain. The wind outputs from a reference simulation is evaluated on the basis of its comparison with an observational database specifically compiled and quality controlled for the purpose of validating the wind atlas over the complete European domain. The observational database includes surface wind observations at ca. 4000 sites as well as 16 masts datasets. The observational dataset of surface wind (WISED) is informative about the spatial and temporal variability of the wind climatology, punctuated with singular masts that provide information of wind velocities at height. The validation of the mesoscale simulation aims at investigating the ability of the high-resolution simulation to reproduce the observed intra-annual variability of daily wind within the entire domain.</p><p>Observed and simulated winds are higher at the British, North Sea and Baltic shores and lowlands. Correlations are typically over 0.8. Surface wind variability tends to be overestimated in the northern coasts and underestimated elsewhere and inland. Mast wind variability tends to be overestimated except for some southern sites. Seasonal differences seem minor in these respects. Biases and RMSE can help identifying if systematic errors in specific tiles take place.</p><p>Therefore, performing model simulations of a high horizontal resolution over the broader European domain is possible. We can learn about the variability of surface and height wind both from observations and model simulations. Model observations are not perfect, but observations also present uncertainties. Good quality wind data, both at the surface and in masts are a requisite for robust evaluation of models. European wide features of wind variability can be recognized both in observations and simulations.</p>

Analysis of the long-term surface wind variability over complex terrain using a high spatial resolution WRF simulation

2012 ◽  
Vol 40 (7-8) ◽  
pp. 1643-1656 ◽  
Author(s):  
Pedro A. Jiménez ◽  
J. Fidel González-Rouco ◽  
Juan P. Montávez ◽  
E. García-Bustamante ◽  
J. Navarro ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Complex Terrain ◽  
High Spatial Resolution ◽  
Surface Wind ◽  
Wind Variability

scholarly journals Surface Wind Regionalization over Complex Terrain: Evaluation and Analysis of a High-Resolution WRF Simulation

2010 ◽  
Vol 49 (2) ◽  
pp. 268-287 ◽  
Author(s):  
Pedro A. Jiménez ◽  
J. Fidel González-Rouco ◽  
Elena García-Bustamante ◽  
Jorge Navarro ◽  
Juan P. Montávez ◽  
...  
Keyword(s):  
Complex Terrain ◽  
Dynamical Downscaling ◽  
Surface Wind ◽  
Wrf Model ◽  
Spatial Dimension ◽  
Weather Research And Forecasting ◽  
Observational Period ◽  
Spatiotemporal Resolution ◽  
Wind Variability ◽  
Spatial Coverage

Abstract This study analyzes the daily-mean surface wind variability over an area characterized by complex topography through comparing observations and a 2-km-spatial-resolution simulation performed with the Weather Research and Forecasting (WRF) model for the period 1992–2005. The evaluation focuses on the performance of the simulation to reproduce the wind variability within subregions identified from observations over the 1999–2002 period in a previous study. By comparing with wind observations, the model results show the ability of the WRF dynamical downscaling over a region of complex terrain. The higher spatiotemporal resolution of the WRF simulation is used to evaluate the extent to which the length of the observational period and the limited spatial coverage of observations condition one’s understanding of the wind variability over the area. The subregions identified with the simulation during the 1992–2005 period are similar to those identified with observations (1999–2002). In addition, the reduced number of stations reasonably represents the spatial wind variability over the area. However, the analysis of the full spatial dimension simulated by the model suggests that observational coverage could be improved in some subregions. The approach adopted here can have a direct application to the design of observational networks.

scholarly journals Modes of Vertical Thermodynamic and Wind Variability over the Maritime Continent

2016 ◽  
Author(s):  
Jennie Bukowski ◽  
Derek J. Posselt ◽  
Jeffrey S. Reid ◽  
Samuel A. Atwood
Keyword(s):  
Temporal Variability ◽  
Large Scale ◽  
Principal Component ◽  
Structure Functions ◽  
Dimensional Subspace ◽  
Radiosonde Data ◽  
Spatial And Temporal Variability ◽  
Convective Systems ◽  
Wind Variability ◽  
Wind Profiles

Abstract. The Maritime Content (MC) is an exceedingly complex region, both from the perspective of its meteorology and its aerosol characteristics. Convection in the MC is ubiquitous, and assumes a wide variety of forms under the influence of an evolving large scale dynamic and thermodynamic context. Understanding the interaction between convective systems and their environment, both individually and in the aggregate, requires knowledge of the dominant patterns of spatial and temporal variability. To this end, radiosonde observations from 2008–2016 are examined from three sounding release sites within the MC for the purpose of exploring the dominant vertical temperature, humidity, and wind structures in the region. Principal Component Analysis is applied to the vertical atmospheric column to transform patterns present in radiosonde data into canonical thermodynamic and wind profiles for the MC. Both rotated and non-rotated principal components are considered, and the emerging structure functions reflect the fundamental vertical modes of short-term tropical variability. The results indicate that while there is tremendous spatial and temporal variability across the MC, the primary modes of vertical thermodynamic and wind variability in the region can be represented in a lower-dimensional subspace. In addition, the vertical structures are very similar among different sites around the region, though different structures may manifest more strongly at one location than another. The results indicate that, while very different meteorology may be found in various parts of the MC at any given time, the processes themselves are remarkably consistent. The ability to represent this variability using a limited number of structure functions facilitates analysis of co-variability between atmospheric structure and convective systems, and also enables future systematic model-based ensemble analysis of cloud development, convection, and precipitation over the MC.

Reproducibility of Surface Wind and Tracer Transport Simulations over Complex Terrain Using 5-, 3-, and 1-km-Grid Models

2020 ◽  
Vol 59 (5) ◽  
pp. 937-952 ◽  
Author(s):  
Tsuyoshi Thomas Sekiyama ◽  
Mizuo Kajino
Keyword(s):  
Complex Terrain ◽  
Mesoscale Model ◽  
Meteorological Data ◽  
Surface Wind ◽  
Weather Conditions ◽  
Radioactive Cesium ◽  
Model Resolution ◽  
Tracer Transport ◽  
Mountainous Areas ◽  
Sampling System

AbstractThe reproducibility of surface wind and tracer transport simulations from high-resolution weather and transport models was studied over complex terrain in wintertime in Japan. The horizontal grid spacing was varied (5-, 3-, and 1-km grids), and radioactive cesium (Cs-137) from the Fukushima nuclear power plant was used as a tracer. Fukushima has complex terrain, such as mountains and valleys. The model results were validated by observations collected from the national networks of the automated meteorological data acquisition system and the hourly air pollution sampling system. The reproducibility depended on the model resolution, topographic complexity, and synoptic weather conditions. Higher model resolution led to higher reproducibility of surface winds, especially in mountainous areas when the Siberian winter monsoon was disturbed. In contrast, the model improvement was negligible or nonexistent over plain/coastal areas when the synoptic field was steady. The statistical scores of the tracer transport simulations often deteriorated as a result of small errors in the plume locations. However, the higher-resolution models advantageously performed better transport simulations in the mountainous areas because of the lower numerical diffusion and higher reproducibility of the mass flux. The reproducibility of the tracer distribution in the valley of the Fukushima mountainous region was dramatically improved with increasing model resolution. In the range of mesoscale model resolutions (commonly 1–10 km), it was concluded that a higher-resolution model is definitely recommended for tracer transport simulations over mountainous terrain.

scholarly journals The Effects of Complex Terrain on Severe Landfalling Tropical Cyclone Larry (2006) over Northeast Australia

2008 ◽  
Vol 136 (11) ◽  
pp. 4334-4354 ◽  
Author(s):  
Hamish A. Ramsay ◽  
Lance M. Leslie
Keyword(s):  
Boundary Layer ◽  
Tropical Cyclone ◽  
Land Surface ◽  
Wind Field ◽  
Complex Terrain ◽  
Mesoscale Model ◽  
Surface Wind ◽  
Small Scale ◽  
Precipitation Pattern ◽  
Intense Storm

Abstract The interaction between complex terrain and a landfalling tropical cyclone (TC) over northeastern Australia is investigated using the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5). Severe TC Larry (in March 2006) made landfall over an area of steep coastal orography and caused extensive damage. The damage pattern suggested that the mountainous terrain had a large influence on the TC wind field, with highly variable damage across relatively small distances. The major aims in this study were to reproduce the observed features of TC Larry, including track, intensity, speed of movement, size, decay rate, and the three-dimensional wind field using realistic high-resolution terrain data and a nested grid with a horizontal spacing of 1 km for the finest domain (referred to as CTRL), and to assess how the above parameters change when the terrain height is set to zero (NOTOPOG). The TC track for CTRL, including the timing and location of landfall, was in close agreement with observation, with the model eye overlapping the location of the observed eye at landfall. Setting the terrain height to zero resulted in a more southerly track and a more intense storm at landfall. The orography in CTRL had a large impact on the TC’s 3D wind field, particularly in the boundary layer where locally very high wind speeds, up to 68 m s−1, coincided with topographic slopes and ridges. The orography also affected precipitation, with localized maxima in elevated regions matching observed rainfall rates. In contrast, the precipitation pattern for the NOTOPOG TC was more symmetric and rainfall totals decreased rapidly with distance from the storm’s center. Parameterized maximum surface wind gusts were located beneath strong boundary layer jets. Finally, small-scale banding features were evident in the surface wind field over land for the NOTOPOG TC, owing to the interaction between the TC boundary layer flow and land surface characteristics.

scholarly journals Multiscale Characteristics of Surface Winds in an Area of Complex Terrain in Northwest Utah

2016 ◽  
Vol 55 (7) ◽  
pp. 1549-1563 ◽  
Author(s):  
Matthew E. Jeglum ◽  
Sebastian W. Hoch
Keyword(s):  
Sierra Nevada ◽  
Complex Terrain ◽  
Large Scale ◽  
Surface Wind ◽  
Surface Winds ◽  
Thermally Driven ◽  
Primary Direction ◽  
Monthly Changes ◽  
Large Scale Flow ◽  
Baroclinic Zone

AbstractClimatological features of the surface wind on diurnal and seasonal time scales over a 17-yr period in an area of complex terrain at Dugway Proving Ground in northwestern Utah are analyzed, and potential synoptic-scale, mesoscale, and microscale forcings on the surface wind are identified. Analysis of the wind climatology at 26 automated weather stations revealed a bimodal wind direction distribution at times when thermally driven circulations were expected to produce a single primary direction. The two modes of this distribution are referred to as the “northerly” and “southerly” regimes. The northerly regime is most frequent in May, and the southerly regime is most frequent in August. January, May, and August constitute a “tripole seasonality” of the wind evolution. Although both regimes occur in all months, the monthly changes in regime frequency are related to changes in synoptic and mesoscale phenomena including the climatological position of the primary synoptic baroclinic zone in the western United States, interaction of the large-scale flow with the Sierra Nevada, and thermal low pressure systems that form in the Intermountain West in summer. Numerous applications require accurate forecasts of surface winds in complex terrain, yet mesoscale models perform relatively poorly in these areas, contributing to poor operational forecast skill. Knowledge of the climatologically persistent wind flows and their potential forcings will enable relevant model deficiencies to be addressed.

Coupled Ocean–Atmosphere Interactions between the Madden–Julian Oscillation and Synoptic-Scale Variability over the Warm Pool

2005 ◽  
Vol 18 (12) ◽  
pp. 2004-2020 ◽  
Author(s):  
Crispian P. Batstone ◽  
Adrian J. Matthews ◽  
David P. Stevens
Keyword(s):  
Heat Flux ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Surface Wind ◽  
Principal Component ◽  
Ocean Model ◽  
Dominant Mode ◽  
Madden Julian Oscillation ◽  
Wind Variability ◽  
Eastern Hemisphere

Abstract A principal component analysis of the combined fields of sea surface temperature (SST) and surface zonal and meridional wind reveals that the dominant mode of intraseasonal (30 to 70 day) covariability during northern winter in the tropical Eastern Hemisphere is that of the Madden–Julian oscillation (MJO). Regression calculations show that the submonthly (30-day high-pass filtered) surface wind variability is significantly modulated during the MJO. Regions of increased (decreased) submonthly surface wind variability propagate eastward, approximately in phase with the intraseasonal surface westerly (easterly) anomalies of the MJO. Because of the dependence of the surface latent heat flux on the magnitude of the total wind speed, this systematic modulation of the submonthly surface wind variability produces a significant component in the intraseasonal latent heat flux anomalies, which partially cancels the latent heat flux anomalies due to the slowly varying intraseasonal wind anomalies, particularly south of 10°S. A method is derived that demodulates the submonthly surface wind variability from the slowly varying intraseasonal wind anomalies. This method is applied to the wind forcing fields of a one-dimensional ocean model. The model response to this modified forcing produces larger intraseasonal SST anomalies than when the model is forced with the observed forcing over large areas of the southwest Pacific Ocean and southeast Indian Ocean during both phases of the MJO. This result has implications for accurate coupled modeling of the MJO. A similar calculation is applied to the surface shortwave flux, but intraseasonal modulation of submonthly surface shortwave flux variability does not appear to be important to the dynamics of the MJO.

scholarly journals Temperature extremes in Europe: overview of their driving atmospheric patterns

2012 ◽  
Vol 12 (5) ◽  
pp. 1671-1691 ◽  
Author(s):  
C. Andrade ◽  
S. M. Leite ◽  
J. A. Santos
Keyword(s):  
Atmospheric Circulation ◽  
Large Scale ◽  
Principal Component ◽  
Temperature Extremes ◽  
Cold Night ◽  
Sea Level Pressure ◽  
Atmospheric Flow ◽  
Atlantic Sector ◽  
Driving Mechanisms ◽  
Large Scale Atmospheric Circulation

Abstract. As temperature extremes have a deep impact on environment, hydrology, agriculture, society and economy, the analysis of the mechanisms underlying their occurrence, including their relationships with the large-scale atmospheric circulation, is particularly pertinent and is discussed here for Europe and in the period 1961–2010 (50 yr). For this aim, a canonical correlation analysis, coupled with a principal component analysis (BPCCA), is applied between the monthly mean sea level pressure fields, defined within a large Euro-Atlantic sector, and the monthly occurrences of two temperature extreme indices (TN10p – cold nights and TX90p – warm days) in Europe. Each co-variability mode represents a large-scale forcing on the occurrence of temperature extremes. North Atlantic Oscillation-like patterns and strong anomalies in the atmospheric flow westwards of the British Isles are leading couplings between large-scale atmospheric circulation and winter, spring and autumn occurrences of both cold nights and warm days in Europe. Although summer couplings depict lower coherence between warm and cold events, important atmospheric anomalies are key driving mechanisms. For a better characterization of the extremes, the main features of the statistical distributions of the absolute minima (TNN) and maxima (TXX) are also examined for each season. Furthermore, statistically significant downward (upward) trends are detected in the cold night (warm day) occurrences over the period 1961–2010 throughout Europe, particularly in summer, which is in clear agreement with the overall warming.

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