Thermal internal boundary layer characteristics at a tropical coastal site as observed by a mini-SODAR under varying synoptic conditions

Atmospheric boundary layer observations are conducted at a coastal site during a transition phase from winter to summer season over the Indian peninsula. Thermal Internal Boundary Layer (TIBL) characteristics in presence of an off-shore and a weakly influenced on-shore synoptic wind are examined with the help of measurements carried out with a mini-SODAR (SOund Detection And Ranging), tethered balloon, and tower-based micrometeorological measurements. Influence of the changing synoptic scale conditions on turbulent characteristics of TIBL is discussed. Mini-SODAR data showed the development and decay of sea and land breeze. It is seen that the characteristics of TIBL over the coastal land after sea breeze onset are similar to that of a shallow convective boundary layer (CBL) commonly found over plain land. Inside the TIBL, a maximum wind speed was noted close to the surface due to the penetration of sea breeze. In the off-shore case, a distinct sea breeze circulation was observed unlike in the case of on-shore flow. In the presence of weak on-shore case, a ‘minor sea’ breeze is noted before the establishment of sea breeze and a reduction in the momentum fluxes gives rise to decrease in the turbulence intensity. Updraft in the sea breeze front was stronger during weak synoptic conditions. Influence of synoptic changes on the sea breeze-land breeze circulation such as onset, strength and duration of the sea-land breeze are also examined. This work was done while the first author was a visiting scientist at IGCAR, Kalpakkam, India.     

鄂尔多斯高原地下水流系统的多层结构循环模式—来自深孔中PACKER系统分层水头测定的证据

地下水流系统和循环模式分析是研究地下水形成机理的基础,对正确认识和评价地下水资源具有重要意义。鄂尔多斯高原在含水系统和众多地下水排泄区的控制下,形成了多个不同规模、不同循环深度、相互独立的地下水流系统。PACKER系统分层试验测定的不同深度水头的数据证明,鄂尔多斯高原地下水流系统存在托斯多层水流模式,区域性水流系统一般包含浅循环、中间循环和深循环3个循环系统。浅循环系统的发育深度在200m以内,深循环系统的发育深度大于400m。