Analysis of the Atmospheric Flow in a Coastal Area in Northeast Brazil Using in Situ and Ground Base Remote Sensing Wind Data

The coastal area in the northeast Brazil receives the trade winds coupled with the sea breeze circulation. In addition, there is also a topographic barrier (cliff) around 40-50 m that make the wind profile very turbulent. The spatial winds variatiosn have been investigated using data (10 min average) from an 70 m tower (6 levels of aerovane wind measurements) and a minisodar (ASC model 400 - 4500 MHz) colocated nearby (less than 50 m of distance) for a period of 60 days during the dry season (the period with the strongest winds). The surface winds (both in situ and ground base remote sensing measurements) followed the Monin-Obhukov Theory and logaritmic wind profile as the atmospheric stability is mostly neutral due to the high winds (typically between 8-10 m/s). An intercomparion between the tower and minisodar at 70 m height showed differences less than 0.5 m/s for the windspeed and 3 degrees for the direction (considering more than 6000 pairs of values) and there is no influence of daytime/nighttime conditions. The daily cycle of the windprofile up to 200 m (measurements derived from the minisodar) was studied combining 6 h profiles (0-6, 6-12, 12-18 and 18-24 Local Time (GMT-3 hours). The presence of the sea breeze can be observed for the afternoon times (profile 12-18 LT) as there is a reduction of the windspeed (around 2.0 m/s) from the levels 100-180 m. The direction did not change as the trade winds are the major synoptic system and it is very persistent. The meridional component (perpendicular to the shore coast) presented the largest differences with positive and negative fluctuations depending on the time of the day (daytime or nighttine conditions). The vertical velocity presented values lower than 1.0 m/s and there is a vertical dependency of the turbulence intensity. This is an ongoing project that merges observational data, numerical simulations (using LES and/or CFD) and wind tunnel essays that analyzed the spatial variation of the atmospheric flow at the Alcantara Space Center.