Erosion of the nocturnal boundary layer in the central Amazon during the dry season

Rayonil Gomes Carneiro,Alice Henkes,Camilla Kassar Borges,Gilberto Fisch

doi:10.1590/1809-4392201804453

Abstract

ABSTRACT In this study, the erosion of the nocturnal boundary layer (NBL) was analyzed in the central Amazon during the dry season of 2014, using data from the GoAmazon 2014/5 Project and high-resolution model outputs (PArallelized Les Model - PALM). The dataset consisted of in situ (radiosonde) and remote sensing instruments measurements (Ceilometer, Lidar, Wind Profiler, microwave radiometer, and SODAR). The results showed that the NBL erosion occurred, on average, two hours after sunrise (06:00 local time), and the sensible heat flux provided more than 50% of the sensible heating necessary for the erosion process to occur. After the erosion, the convective phase developed quickly (175.2 m h-1). The measurements of the remote sensors showed that the Ceilometer, in general, presented satisfactory results in relation to the radiosondes for measuring the height of the planetary boundary layer. The PALM simulations represented well the NBL erosion, with a small underestimation (≈ 20 m) at the beginning of this phase. In the final phase of NBL erosion and in the initial stage of the development of the convective boundary layer (CBL), the model presented satisfactory results, with heights of CBL ranging from 800 m to 1,650 m, respectively.

Highlights

The daily cycle of the planetary boundary layer (PBL) responds to surface heating due to solar radiation (Stull 1988)
It was measured that 72% of the available energy was converted into latent heat flux (LE), with a maximum observed at 12:00 local time (LT), and an average of 350.3 W m-2
This study showed that the erosion phase of the nocturnal boundary layer (NBL) occurred two hours after sunrise during the dry season (IOP2 of Project GOAmazon 2014/15) in the central Brazilian Amazon

Summary

Introduction

The daily cycle of the planetary boundary layer (PBL) responds to surface heating due to solar radiation (Stull 1988). It consists of a convective phase during the day, the convective boundary layer (CBL) and a stable phase during the night, the nocturnal boundary layer (NBL). Because of this variation throughout the day, the determination of the daily cycle of the height of the PBL has been the focus of much research (Santos et al 2007; Englberger and Dörnbrack 2017; Ramos et al 2018). The erosion of the NBL occurs when the atmosphere passes from

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Discussion

Conclusion