Usando a altura do ponto de inflexão no perfil do vento para a obtenção de perfis adimensionais acima da floresta amazônica

The most turbulent vortices that populate the forest-atmosphere interface have canopy height length scales. These vortices are mainly responsible for turbulent exchanges between inside and above canopy region. Thus, we used the vertical wind profiles obtained by 10 anemometers installed inside and above the forest canopy of the Rebio-Jarú experimental site, in the Amazon Rainforest. A third degree polynomial function was developed to better fit the wind profile and therefore estimate the inflection point height of the vertical wind profile (zi) a length scale associated with wind shear (Ls), and the wind speed at height zi. These length and velocity scales were used to obtain better fits for the dimensional wind profiles and turbulence statistical moments. Three dimensionless profile models were compared using friction velocity, wind velocity in zi and wind velocity at canopy height. It was observed that the dimensionless profiles using the velocity and shear calculated at zi provided support for the elaboration of more realistic parameterization of the turbulent exchange processes that occur both at the forest-atmosphere interface and inside the canopy.

Download Full-text

Determining Meaningful Differences for SMACEX Eddy Covariance Measurements

Journal of Hydrometeorology ◽

10.1175/jhm458.1 ◽

2005 ◽

Vol 6 (6) ◽

pp. 805-811 ◽

Cited By ~ 13

Author(s):

D. W. Meek ◽

J. H. Prueger ◽

W. P. Kustas ◽

J. L. Hatfield

Keyword(s):

Standard Deviation ◽

Eddy Covariance ◽

Wind Velocity ◽

Standard Error ◽

Friction Velocity ◽

Vertical Wind ◽

Sensible Heat ◽

Significant Difference ◽

Multiple Comparison Procedures ◽

Vertical Wind Velocity

Abstract Two eddy covariance instrument comparison studies were conducted before and after the Soil Moisture–Atmosphere Coupling Experiment (SMACEX) field campaign to 1) determine if observations from multiple sensors were equivalent for the measured variables over a uniform surface and to 2) determine a least significant difference (LSD) value for each variable to discriminate between daily and hourly differences in latent and sensible heat and carbon dioxide fluxes, friction velocity, and standard deviation of the vertical wind velocity from eddy covariance instruments placed in different locations within the study area. The studies were conducted in early June over an alfalfa field and in mid-September over a short grass field. Several statistical exploratory, graphical, and multiple-comparison procedures were used to evaluate each daily variable. Daily total or average data were used to estimate a pooled standard error and corresponding LSD values at the P = 0.05 and P = 0.01 levels using univariate procedures. There were no significant sensor differences in any of the daily measurements for either intercomparison period. Hourly averaged data were used to estimate a pooled standard error and corresponding LSD values at the P = 0.05 and P = 0.01 levels using mixed model procedures. Sensor differences for pre- and post-intercomparisons were minimal for hourly and daily values of CO2, water vapor, sensible heat, friction velocity, and standard deviation for vertical wind velocity. Computed LSD values were used to determine significant daily differences and threshold values for the variables monitored during the SMACEX campaign.

Download Full-text

Wind Profile Satellite Observation Requirements and Capabilities

Bulletin of the American Meteorological Society ◽

10.1175/bams-d-18-0202.1 ◽

2020 ◽

Vol 101 (11) ◽

pp. E2005-E2021

Author(s):

Ad Stoffelen ◽

Angela Benedetti ◽

Régis Borde ◽

Alain Dabas ◽

Pierre Flamant ◽

...

Keyword(s):

Wind Profile ◽

Weather Prediction ◽

Regional Scale ◽

Vertical Wind Shear ◽

Satellite Observation ◽

Vertical Wind ◽

Molecular Scattering ◽

Turbulence Regime ◽

Wind Profiles ◽

Globally Distributed

AbstractThe Aeolus mission objectives are to improve numerical weather prediction (NWP) and enhance the understanding and modeling of atmospheric dynamics on global and regional scale. Given the first successes of Aeolus in NWP, it is time to look forward to future vertical wind profiling capability to fulfill the rolling requirements in operational meteorology. Requirements for wind profiles and information on vertical wind shear are constantly evolving. The need for high-quality wind and profile information to capture and initialize small-amplitude, fast-evolving, and mesoscale dynamical structures increases, as the resolution of global NWP improved well into the 3D turbulence regime on horizontal scales smaller than 500 km. In addition, advanced requirements to describe the transport and dispersion of atmospheric constituents and better depict the circulation on climate scales are well recognized. Direct wind profile observations over the oceans, tropics, and Southern Hemisphere are not provided by the current global observing system. Looking to the future, most other wind observation techniques rely on cloud or regions of water vapor and are necessarily restricted in coverage. Therefore, after its full demonstration, an operational Aeolus-like follow-on mission obtaining globally distributed wind profiles in clear air by exploiting molecular scattering remains unique.

Download Full-text

Comparing Abnormalities in Onshore and Offshore Vertical Wind Profiles

10.5194/wes-2019-40 ◽

2019 ◽

Author(s):

Mathias Møller ◽

Piotr Domagalski ◽

Lars Roar Sætran

Keyword(s):

Wind Turbines ◽

Wind Profile ◽

Similarity Theory ◽

Internal Boundary Layer ◽

Vertical Wind ◽

Internal Boundary ◽

Data Series ◽

Local Maxima ◽

The North ◽

Wind Profiles

Abstract. Understanding the vertical wind profile is paramount for design & operation of wind turbines. It is needed not only for extrapolation of the wind velocity to hub height but also for structural load calculations, to name the most obvious issues. As wind turbines grow in size and development transitions offshore, issues such as shallow surface layers, low-level jets and internal boundary layers are raising questions to the applicability of the commonly used Monin-Obukhov similarity theory to accurately describe the vertical wind development to modern wind turbine hub heights. In this study the 10-minute averaged vertical wind profile up to a minimum elevation of 100 m is analyzed through measurements collected from seven sites which represent a span of conditions. Three sites are located offshore in the North/Baltic Sea with varying fetch, two onshore by the Norwegian coast, one further onshore by the Danish coast, and one is an inland forested site in Sweden. Through analysis of data series ranging from 8 months to several years depending on the site, the wind profile has been quantitatively categorized according to the number of exhibited local maxima which are not possible within Monin-Obukhov similarity theory. The results reveal that the occurrence of local maxima scales inversely to the roughness length, causing 65–75 % abnormal profiles offshore which decreases as the location transitions from offshore to coastal to further inland, and is lowest at the forested site. The results indicate that issues in predicting the vertical wind profile are most prevalent offshore, where very stable inflections cause severe deviations which may be related to an offshore internal boundary layer. These findings suggest that there is evident need of an improved vertical wind profile description in order to improve the accuracy of power predictions and load calculations, especially at offshore and coastal sites.

Download Full-text

Observing and Modeling the Vertical Wind Profile at Multiple Sites in and above the Amazon Rain Forest Canopy

Advances in Meteorology ◽

10.1155/2017/5436157 ◽

2017 ◽

Vol 2017 ◽

pp. 1-8 ◽

Cited By ~ 6

Author(s):

Raoni Aquino Silva de Santana ◽

Cléo Quaresma Dias-Júnior ◽

Roseilson Souza do Vale ◽

Júlio Tóta ◽

David Roy Fitzjarrald

Keyword(s):

Forest Structure ◽

Forest Floor ◽

Amazon Basin ◽

Forest Canopy ◽

Wind Profile ◽

Vertical Wind ◽

Average Height ◽

Dense Forest ◽

Amazon Rain Forest ◽

Input Variables

We analyzed the vertical wind profile measured at six experimental tower sites in dense forest in the Amazon Basin and examined how well two simple models can reproduce these observations. In general, the vertical wind profile below the canopy is strongly affected by the forest structure. From the forest floor to 0.65h (where h = 35 m is the average height of the forest canopy for sites considered), the wind profile is approximately constant with height with speeds less than 1 ms−1. Above 0.65 to 2.25h, the wind speed increases with height. Testing these data with the Yi and Souza models showed that each was able to reproduce satisfactorily the vertical wind profile for different experimental sites in the Amazon. Using the Souza Model, it was possible to use fewer input variables necessary to simulate the profile.

Download Full-text

The Horizontal and Vertical Wind Profiles of the Subtropical and Polar Jet for January 1–7, 1956 and the Variation of the Equivalent Barotropic Level

Tellus ◽

10.3402/tellusa.v11i4.9327 ◽

1959 ◽

Vol 11 (4) ◽

pp. 441-451 ◽

Cited By ~ 1

Author(s):

Hessam Taba

Keyword(s):

Vertical Wind ◽

Wind Profiles

Download Full-text

The impact of geolocation uncertainty on GEDI tropical forest canopy height estimation and change monitoring

Science of Remote Sensing ◽

10.1016/j.srs.2021.100024 ◽

2021 ◽

pp. 100024

Author(s):

David P. Roy ◽

Herve B. Kashongwe ◽

John Armston

Keyword(s):

Tropical Forest ◽

Forest Canopy ◽

Canopy Height ◽

Height Estimation ◽

The Impact ◽

Change Monitoring ◽

Tropical Forest Canopy

Download Full-text

Using GEDI Waveforms for Improved TanDEM-X Forest Height Mapping: A Combined SINC + Legendre Approach

Remote Sensing ◽

10.3390/rs13152882 ◽

2021 ◽

Vol 13 (15) ◽

pp. 2882

Author(s):

Hao Chen ◽

Shane R. Cloude ◽

Joanne C. White

Keyword(s):

High Resolution ◽

Forest Canopy ◽

Test Site ◽

Convergent Series ◽

Canopy Height ◽

Ecosystem Dynamics ◽

Sinc Function ◽

Vertical Profiles ◽

Legendre Series ◽

Vertical Profiling

In this paper, we consider a new method for forest canopy height estimation using TanDEM-X single-pass radar interferometry. We exploit available information from sample-based, space-borne LiDAR systems, such as the Global Ecosystem Dynamics Investigation (GEDI) sensor, which offers high-resolution vertical profiling of forest canopies. To respond to this, we have developed a new extended Fourier-Legendre series approach for fusing high-resolution (but sparsely spatially sampled) GEDI LiDAR waveforms with TanDEM-X radar interferometric data to improve wide-area and wall-to-wall estimation of forest canopy height. Our key methodological development is a fusion of the standard uniform assumption for the vertical structure function (the SINC function) with LiDAR vertical profiles using a Fourier-Legendre approach, which produces a convergent series of approximations of the LiDAR profiles matched to the interferometric baseline. Our results showed that in our test site, the Petawawa Research Forest, the SINC function is more accurate in areas with shorter canopy heights (<~27 m). In taller forests, the SINC approach underestimates forest canopy height, whereas the Legendre approach avails upon simulated GEDI forest structural vertical profiles to overcome SINC underestimation issues. Overall, the SINC + Legendre approach improved canopy height estimates (RMSE = 1.29 m) compared to the SINC approach (RMSE = 4.1 m).

Download Full-text