Low Level Jet Influence on the Nocturnal Boundary-layer Vertical Structure Above Caxiuanã Forest Reserve During Wet Season
Daniele
Santos
Nogueira, Universidade Federal do Pará - UFPA, holywod@interconect.com.br
(Presenting)
Leonardo
Deane de Abreu
Sá, Centro de Previsão de Tempo e Estudos Climáticos, Instituto Nacional de Pesquisas Espaciais (CPTEC-INPE)– Museu Paraense Emílio Goeldi (MPEG)., ldsa@museu-goeldi.br
Julia
Clarinda Paiva
Cohen, Universidade Federal do Pará - UFPA, jcpcohen@ufpa.br
In this work we investigate the occurrence of low level jet (LLJ) events in the nocturnal boundary-layer above the “Ferreira Penna Scientific Station”, in Caxiuanã Forest Reserve, which is located in the North-Eastern part of Amazonia. As LLJ we define a region of the wind velocity vertical profile located below 1 km height in which the strength of the wind is greater than 5 m/s and where there is a relative maximum value in such way that the wind velocity value decays at least 2 m/s both above and below the jet region. We use radiossonde data of wind velocity, potential virtual temperature, specific humidity and bulk Richardson number to show that LLJs actually separate the atmospheric boundary-layer in two regions with distinct mixing characteristics: a below LLJ well mixed layer and a above LLJ layer without mixing. These data were collected during April 2002 – Experiment of Milenio/LBA Project. At the height of the LLJ (between 200 and 400 m height) the wind velocity changes of direction and is north-easterly. The results have important implications for correct parameterization of forest-atmospheric exchange processes.