Wind Speed Variation with the Distance from the Coast of Northern Shandong

Offshore wind speed of coastal areas in Shandong Province were assessed by numerical simulation with high resolution from a dynamical downscaling method in the present work,with the objective to reveal wind speed variation with the distance from the coast.The widely-used mesoscale numerical model system MM5 and CALMET meteorological wind field module in combination with NCEP/NCAR reanalysis data and surface/high weather observation data were jointly used to study wind speed variation with high spatial resolution of 1 km×1 km.The simulated period was from June 2009 to May 2010 and the integration time was 36 hours of daily simulation.Meanwhile,statistical analysis was 24 hours after the model output.Wind data of the same period at automatic weather stations and wind towers in coastal,sea,and island were used to analyze the 10 m and 70 m height relative error between numerical simulations and observations.Comparative analysis results show that the dynamical downscaling method could be used to better simulate the characteristics of the near surface wind field and the simulation results could be used to analyze the regional wind field features.The northern Shandong and Yantai wind speed profiles were studied based on the location of wind measurement sites and climate characteristics.Then,two wind speed profile's annual average,off-shore wind,and on-shore wind,and a cold wave process wind speed variation were analyzed.Results show that the mean wind speed of the Northern Shandong and Yantai wind speed profile attenuated significantly from the sea to the inland between sea from 10 km distance to the coast and inland from a 20～30 km distance to the coast.The wind speed gradually stabilized in addition to these areas.The wind speed variation with the distance from the coast was more significant at near the ground.The wind speed peaked at sea from the 10 km distance to the coast,where the wind speed decreased greatly towards inland direction and it did not change obviously towards the sea direction.Land wind speed was significantly lower than sea wind speed and annual average wind speed.Wind speed variation of cold wave on 24 December,2009,was highest at sea from the 10 km distance to the coast,but it decreased towards sea and inland direction along the wind speed profile.The wind speed reduction ratio was different on two wind speed profiles.In short,the wind speed attenuation ratio and range were largely differing at varying terrains,wind speed species,and heights.