Accuracy of the accuracy of offshore winds by WRF and CFD models on the Mutsu Ogawahara site

This article is2021Year11Held in the month43"Mutsu -Ogawahara site on the Mutsu Ogawara site" announced at the symposiumWRFWhenCFDA part of the accuracy verification of the offshore style by model is re -edited.

1. At the beginning

The doppler rider (hereinafter referred to as the rider) is a remote sensing device that irradiates laser light and receives the reflected light of micro particles in the atmosphere, and can remotely measure the wind direction and wind speed based on the movement speed.1That's right. Riders can observe the wind conditions in the sky and oceans that exceed the altitude of the windmill, so it is highly expected to use the utilization in wind development.

Riders have the characteristic of indispensable weather conditions under the weather conditions that have few fine particles in the atmosphere, under meteorological conditions, where there are few fine particles in the atmosphere. It is a very useful method if it is possible to make up for these missing data using the simulation results of the numerical models used in the wind status survey. Therefore, in this paper, as an initial analysis related to the interpolation of the missing data associated with the rider observation,Nedo"Implanted offshore window development support project (establishment of offshore style survey methods)"[1]Using the research results at Numutsu Ogawara Port, we tried to verify the accuracy of the air conditioning simulation using a numerical model. 

2. Target areas and weather observations

For the analysis of this research, on landST.A1And in -houseST.Bof2Point (figure)1Observed on the vertical doppler rider, on the sea surface50250mI used high wind speed and wind direction. The wind direction of this site is on the border of the coastline that extends north -south, and the sea octage (0-180°; Sea breeze) and land sector (180-360°Because it can be roughly divided into land wind)[2], Analyzed by wind direction sector. again,ST.BTemperature (2The altitude) and the sea surface temperature are measured, and the air stability is stable based on these observations (Stable) And unstable ()Unstable)of2An analysis in the case was also implemented (table)1)。


 Figure 1 Overview of observation points and observation elements

Table 1 Category of air stability in ST.B


3. Numeric model

In this study, the Meso -feeling modelWRF[3]WhenCFDmodelMascot[4]Using the numerical model ofST.BI guessed the offshore style. table2Table of calculation settings for each model3According to the input method of the observed value4Shows some calculation patterns.

Table 2 Calculation settings for numerical models (above: Meso Model WRF, Bottom: CFD model Mascot)

Table 3 Calculation patterns of the numerical model conducted in this study by entering observed values

WRFThe calculation does not require an observation value in the analysis area, but it is also possible to correct the calculation value after calculation. Therefore, in this study, there is no correction.WRFEstimated value (WRF-RAW) In addition to)1.6kmAreasST.A1With the wind status observation valueWRF-RAWMethod to correct (WRF-VECC) I tried.

on the other hand,MascotFor calculation1Use the wind status measurement value at the point as the input value. In this study, assuming that offshore style is estimated from the coast,ST.A1Is input value of the wind situationST.BIs estimated. In addition, in order to examine the impact of the input altitude on the estimated values, the altitude assuming a breeze mast.59mMAS-059M) And a windmill hub -equivalent altitude120mMAS-120m)of2I used the type input value.

Four. Overview of the breeze observation results

WatersST.BAnd landST.A1Wind speed vertical profile observed at the point (figure)2)WhenST.B120mThe average period of the period (table (table)4) Is shown.

Figure 2 Observation values ​​for wind speed vertical profiles on land (ST.A) and offshore (ST.B)
Left → Right: All samples, stability, unstable
Above → Bottom: All wind direction, land breeze, sea breeze
The stability classification referred to the observation values ​​of the sea.

Table 4 Average wind speed and sample number (ST.B 120m high) by air stability and wind direction (ST.B 120m high)

Advanced150mIn the higher level2While the wind speed at the point is well matched, there is a wind speed difference in the lower layer, and as the approach to the ground surface (sea surface), the land. < It is characteristic that it is offshore. It is presumed that the wind speed difference in this lower layer is caused by the difference between the ground surface roughness between the ground surface and the sea surface. Among them, the air stability of the sea is particularly noticeable during land breeze, and when the wind flies from the land to the sea, the air stability becomes unstable when heat is supplied from the sea. It is thought that the wind will increase the wind as the vertical mixing will increase.

Sea breezeST.BFocusing on the observation value (when stable), the vertical vertical shear of the wind speed is large.70mTo high, higher (approx.)70180mIt gets smaller in high)SThe profile is distorted in shape. Therefore, in this condition, the air in the sea windmill, which is located in the sky, is the altitude of the wind (approx.120mIt can be said that it is difficult to estimate the wind velocity vertical profile in the high).

Five. Vehicle estimation result by numerical models

5.1 A vertical profile estimation value by each numerical model

Velidal vertical profile estimated by each numerical model (figure)3) And the frequency of the wind tate (figure)4) Is shown. Considering the effects of the terrain, etc., this result was only for the sea breeze.

WRFof2The vertical shear of the wind speed estimated by the case is unstableWRF-RAWWhenWRF-VECCBoth are well consistent with the tendency of the observation value, but in a stableWRF-VECCShows a tendency similar to the observed value. This result is an observed valueWRFBy using togetherWRFIt suggests that you can estimate the air conditioner than a single unit. on the other hand,Mascotof2The shea in the case is uniform regardless of air stability. this is,MascotHowever, it means that the vertical shear caused by air stability cannot be reproduced in order not to consider thermodynamic action.

Estimated value of wind direction appearing frequency (figure)4) If you look at)WRFYou can see that it reproduces the vertical vertical via (vertical wind direction) with good accuracy.MascotIs accurately reproduced the frequency of input altitude wind tube, but it shows the same appearance frequency in the entire altitude, and cannot be represented by wind direction via. The wind direction beer seen near the surface of the ground is not only thermodynamic effects but also by Corioli, and does not consider these meteorological effects.MascotThen there is no characteristics of wind direction via.

 Figure 3 Estimated results by each numerical model in ST.B (wind speed vertical profile during sea breeze)
Left → Right: Observation value, WRF-RAW, WRF-VECC, MAS-059M, MAS-120m


Figure 4 Estimated results by each numerical model in ST.B (frequency of wind tip appearance in stable)
Left → Right: Observation value, WRF-RAW, WRF-VECC, MAS-059M, MAS-120m

5.2 Wind speed estimation results of each numerical model (ST.B 120m)

figure5,ST.BIn120mAverage error of each numerical model estimated value for high period average wind speedBIAS [%]Is shown.

Fig. 5 Each numerical model period Average error of the average period wind speed BIAS [%] (ST.B 120m high)
Left → Right: All wind direction, land wind, sea breeze. The deficit indicates the average error when all samples are targeted.

WRF-RAWThe estimated value is for all the samplesBiasBut-0.4%By the time, throughout the periodST.BWe estimate the wind situation in accurate accuracy. This value is on the Mutsu Ogawahara Port siteNEOWINS[5]ofWRFResults verified under the same conditions as calculation(+12.9%[6]Obviously improved compared to. This is the researchWRFRegarding calculations, because the ground roughness has been changed to a higher value than the default value, so near the coastlineWRFBecause the overestimation of wind speed has been significantly reduced[10]It is considered.

MAS-120mThen, the error is small in both wind direction sectors and conditions of air stability (in all samples)-0.8%) You can see. on the other hand,MAS-059MThen in all samplesBiasLarge negative value (same)-14.4%) Is seen, and this underestimated is mainly due to the trend of land sector. This is considered to be due to the fact that the vertical shea at the input point has not been sufficiently reproduced in the model, and it is an estimated altitude.MascotSuch an error may occur due to different input altitudes.

 6. Summary

1)Comparing the air and track and field wind observation values, the more the wind speed of the sea approached the ground surface (sea surface), the more prominent the air stability was unstable. again,

2)Advanced120mPeriod average wind speedBiasIf you look at it as an index,WRFEstimated values ​​(no correction) and altitude on land120mEntered the observation valueMascotThe accuracy of the calculation value is antagonistic, both±1%It was within it.

3) MascotIt turns out that the estimated accuracy depends greatly on the input value observation altitude. It is important to use an input value observed at an altitude close to the estimated altitude in order to minimize the effects of the frequency of wind tube and the errors of vertical shea due to altitude.



[1] Osawa / Shimada / Kogaki / Iwashita / Kasaya / Araki / Imamura,2020NedoAbout implantable offshore wind firms development ⽀ ⽀ ⽀ ⽀ 上 上 (((((. First42 Winding energy usage Symposium proposal.

[2] KONAGAYA M., OHSAWA T., INOUE, T., T., T., KATO, KATO, Kawamoto, Kawamoto, Kawamoto, K. , SOLA, 17, 225-228.

[3] Skamarock, W. C., Klemp, J. B., J. B., J., GILL, D. O., Barker, D. M., Wang, Powers, J. G. 475+str, 1-96.

[4] Ishihara / Yamaguchi / Fujino / Nippon2002: Ninlinium wind situation predictive modelMascotDevelopment and its application. First24Winding energy usage Symposium proposal.

[5] NEDO, offshore style mapNeowins, url:

[6] Kohana, Osawa, Mito, Kato, Inoue, Kawamoto, Watanabe,2018: Comparison of offshore estimation values ​​in near waters using multiple wind -fashion simulations. First40 Winding energy usage Symposium proposal.