Intercomparação entre quatro métodos de estimativa da altura da camada limite convectiva durante o experimento RaCCI - LBA (2002) em Rondônia - Amazônia

Abstract

Este trabalho tem como objetivo fazer uma comparação entre quatro diferentes métodos de estimativa da altura da Camada Limite Convectiva (CLC), utilizando dados obtidos pelo equipamento SODAR e por radiossondas, durante a campanha DRY - to - WET do experimento RaCCI - LBA (2002) em Rondônia. Os quatro métodos de estimativa utilizados foram os seguintes: o das Parcelas; do Número de Richardson; dos Perfis; e um método de medição direta através do SODAR. Os resultados mostraram que o Método das Parcelas superestimou as alturas da CLC (em 15% para às 08:00 HL e 14:00 HL e 30% nos demais horários), em quase todos os casos analisados, obtendo índices baixos do coeficiente de determinação (r²), quando comparado com os outros métodos. O Método do Número de Richardon e o Método dos Perfis apresentaram alturas muito semelhantes, com diferenças médias de menos de 50 m, alcançando um valor de r² igual a 0,97, durante o período de início da estação chuvosa. As medidas realizadas com o SODAR não se mostraram adequadas nas primeiras horas da manhã, indicando que o equipamento mediu a Camada Limite Residual (do dia anterior) e não a Camada Limite Convectiva rasa, em fase de desenvolvimento.

Observational analysis of the daily cycle of the planetary boundary layer in the central Amazon during a non-El Niño year and El Niño year (GoAmazon project 2014/5)

“…With these measurements, other derived quantities were computed and used in this study: altitude (m), geographic position (latitude and longitude), From these data, the potential temperature (θ ) and specific humidity (q) were extrapolated and their vertical profiles were used for the determination of e height of the PBL. At the CBL phase, the heights were identified by the vertical level where there was a systematic increase in potential temperature and a sudden reduction in specific humidity, and this method is called the profile method, as described in detail by Santos and Fisch (2007), Seidel et al (2010), and . However, at the NBL phase, the heights were determined by the height where the vertical θ gradient was null or less than a defined number (0.01 K m −1 ) starting from the surface.…”

The Daily Cycle of the Atmospheric Boundary Layer Heights over Pasture Site in Amazonia

“…The profile method has traditionally been used as an indicator of the height of the CBL [11]. According to [12], the parcel method has tendencies to overestimate CBL especially in areas with high incidence of solar radiation and superadiabatic gradients, which is the case of the pasture areas in the Amazon, and it showed a growth rate of 242.5 mm h-1 between 08 and 14 LT. The final height of the CBL by this method is 1595 ± 439 m at 17 LT after reaching a maximum about 1968 ± 421 m at 14 LT.…”

“…The measurements were made at Nossa Senhora Aparecida farm (10° 45' S, 62° 22' W; 293 m), Figure 1, a cleared/pasture area, which has been used in LBA´s micrometeorological field campaigns since the 90s [12]. The data-set was obtained during the RaCCI/LBA (Radiation, Cloud and Climate Interactions in the Amazonia/Large Scale Biosphere-Atmosphere Experiment in Amazonia) experiment, conducted from September 6 up to October 31, 2002, which occurred during the transition between the dry and rainy seasons.…”

Nocturnal Boundary Layer Erosion Analysis in the Amazon Using Large-Eddy Simulation during GoAmazon Project 2014/5

“…From the vertical profile of θ and q, the height of the PBL can be determined. During the CBL phase, the heights were identified by the vertical level where there was a systematic increase in potential temperature (∆θ/∆Z > 0) and a reduction in specific humidity (∆q/∆z < 0), called the profile method [22][23][24][25]. During the NBL phase, the heights were determined by the maximum distance from the surface where radiative night cooling occurs.…”

“…During the NBL phase, the heights were determined by the maximum distance from the surface where radiative night cooling occurs. Thus, these heights were measured from where the vertical θ gradient was null or less than a defined number (0.01 K m −1 ) starting from the surface [24,26].…”