1. Wind velocity and turbulence measurements in tall masts in Estonia
Marko Kaasik1 , Steffen Noe2, Jakob Hoyer1, Sander Mirme1
1Institute of Physics, University of Tartu, Tartu, Estonia
2Institute of Agriculture and Environment, Estonian University of Life Sciences
Valgjärve:
Operational since 2015
58º05’50’’N, 26º40’41’’E
Mast foot 180 m a.s.l.
In hilly agricultural landscape with forest patches.
TV broadcasting mast equipped.
Metek Class A sonic anemometers and Rotronic HC2-S3 termperature-humidity sensors.
Kipp & Zonen CNR-4 radiometer (200 m).
Data flow:
HIRLAM mast verification system (FMI).
Estonian Air Quality Management System:
Järvselja:
Operational since 2014
58º16’38’’N, 27º18’35’’E
Mast foot 40 m a.s.l.
In flat, mostly forested landscape several kilometers in all directions, mixed forest, canopy height 30 – 35 m nearby.
Specially built mast for atmospheric and forest gas exchange measurements: eddy covariance, incl. CO2 etc. gas fluxes.
Metek Class A sonic anemometers.
Distance between these two masts is 43 km
a) Valgjärve
b) Järvselja
Probability density of wind directions and speeds (m/s) measured at 30 m height at Valgjärve (01. – ) and Järvselja ( ). The colour presents the density of horizontal wind vectors. The light to brownish colours mark the higher frequency of wind vectors with given speed and direction. Blue tones denote a low probability of wind vectors. The isolines visualize the wind probability density and are spred equally in steps of 0 to the maximum probability (Pm) with 0.1 Pm step.
Winds from southern to western sector dominate in both sites.
Winds at Järvselja, at the height of canopy level, are weaker than at open Valgjärve site.
Weak winds from NW at Valgjärve may be due to mast wake. No such an effect is visible at Järvselja.
Average wind speed profiles measured in Valgjärve and Järvselja masts. The logarithmic profile is a good fit for both sites. At Järvselja the logarithmic slope is bigger due to wind drag above the forest canopy.
Average turbulent kinetic energy density profiles at Valgjärve in time scales of 1 secoond and 30 minutes.
Acknowledgements
The “Environmental Conservation and Environmental Technology R&D Programme” project BioAtmos ( ).
The “Estonian Research Infrastructures Roadmap” project Estonian Environmental Observatory ( )).
Estonian Ministry of Education and Research, institutional research funding IUT20-11.
Estonian Ministry of Education and Research, base funding project “Biosphere-atmosphere interaction and climate research applying the SMEAR Estonia research infrastructure”, P
Comparison of wind speeds and directions measured at Valgjärve, height 30 m with those from closest station of national meteorological observation network Tõravere at distance 21 km. Half-hourly values from January to November 2015.