Breeze Potential Along the Brazilian Northern and Northeastern Coast

ABSTRACT The breeze potential along the Brazilian northern and northeastern coast was studied using wind data from the Climate Forecast System Reanalysis for the period between 1980 and 2010. March and September were considered, which are representative of the rainy and dry (or less rainy) periods, respectively. The Brazilian northern and northeastern coast is composed by meridionally oriented coastlines (Amapá State coast and eastern coast of Northeast Brazil) and a zonally oriented coastline (Brazilian northern coast east of Marajó Island). Along the meridionally oriented coastlines, the breeze potential was mainly related to the zonal wind and extended inland over 1 - 2° from the shore. The daily zonal wind cycle maximum (minimum), which represents the land (sea) breeze potential, occurred at ~0700 UTC (~1900 UTC). Along the zonally oriented coastline, the breeze potential was mainly related to the meridional wind and extended inland and offshore over 2 - 3° from the shore. At the shore, the daily meridional wind cycle maximum (minimum), which represents the land (sea) breeze potential, occurred at ~1000 UTC (~2200 UTC). Phase propagation occurred from the shore inland in March and September and also offshore in September. In general, for the entire Brazilian northern and northeastern coast, the breeze potential frequency was higher in September (20 - 25 days per month). In March, while the frequency slightly decreased over the meridionally oriented coastlines (to 15 - 20 days per month), the frequency sharply decreased over the zonally oriented coastlines to 5 - 10 days per month in landside coastal areas and vanished in seaside coastal areas. Higher frequency was generally related to lower interannual variability, and there was significant correlation between the interannual variability of the frequency and oceanic indices, along specific coastal areas. The features of the breeze potential areas obtained in this study complement the results from others and provide a more complete depiction of breeze features along the entire Brazilian northern and northeastern coast.

摘要 本研究采用1980至2010年的气候预报系统再分析（Climate Forecast System Reanalysis）风速数据，对巴西北部及东北部沿海的海风潜势（breeze potential）开展了研究。本研究选取3月和9月作为代表月份，分别对应雨季与旱季（或少雨期）。巴西北部及东北部沿海的海岸线可分为两类：一类为经向走向的海岸线（包括阿马帕州海岸与巴西东北部东海岸），另一类为纬向走向的海岸线（马拉若岛以东的巴西北部海岸）。在经向走向海岸沿线，海风潜势主要与纬向风相关，且可从岸内向内陆延伸1~2个纬度。代表陆（海）风潜势的日纬向风周期峰值（谷值）出现在协调世界时（Coordinated Universal Time）约0700时（约1900时）。在纬向走向海岸线沿线，海风潜势主要与经向风相关，且可从岸内向内陆及向海侧延伸2~3个纬度。在岸线位置，代表陆（海）风潜势的日经向风周期峰值（谷值）出现在协调世界时约1000时（约2200时）。相位传播现象在3月和9月均从岸线向内陆发生，且在9月还会向海侧传播。总体而言，整个巴西北部和东北部沿海的海风潜势出现频次在9月更高，可达每月20~25天。在3月，经向走向海岸沿线的频次略有下降，降至每月15~20天；而纬向走向海岸沿线的频次则大幅下降：陆侧沿海区域降至每月5~10天，海侧沿海区域则无海风潜势出现。较高的潜势频次通常对应较低的年际变率，且在特定沿海区域，频次的年际变率与海洋指数间存在显著相关性。本研究所得的海风潜势区域特征补充了现有相关研究成果，为完整刻画巴西北部和东北部沿海的海风特征提供了更为全面的描述。