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

Abstract

A better descriptions of the atmospheric boundary layer (ABL) properties in Amazonia, such as its time evolution is necessary, especially for studies involving weather forecast and climatic simulation. The objective of this work was integrate and comparing data of the ABL characteristics made by different techniques in RaCCI/LBA experiment, held in southwestern Amazonia pasture site during the dry-to-wet seasons of 2002. For daytime it was possible to observe that there is an abrupt growth of the Convective Boundary Layer (CBL) between 08 and 11 Local Time (LT) with a stationary pattern between 14 and 17 LT. The maximum heights at late afternoon were around 1500 m. The onset of the Nocturnal Boundary Layer (NBL) occurs before the sunset (18 LT) and its height is very stable during the whole night (typical values around 180-250 m). The erosion of the NBL lasts for 2 hours and it is complete at 08 LT.

Characteristics of Water Vapor Turbulence Profiles in Convective Boundary Layers During the Dry and Wet Seasons Over Darwin

“…During the daytime, solar heating of the surface drives convective mixing in the atmospheric boundary layer; this is also called the convective boundary layer (CBL). Its thickness is quite variable both in space and time, ranging from tens of meters to 4 km or more (e.g., McGrath-Spangler & Denning, 2013;Neves & Fisch, 2015;this work). Turbulence is ubiquitous throughout the CBL and plays an important role in redistributing trace gases, aerosols, heat, and momentum.…”

“…In order to evaluate and improve turbulence parameterizations in weather and climate models, high resolution and accurate measurements of profiles of turbulence throughout the CBL are needed. Vertical profiles of turbulent motion have been studied using various types of instruments including in situ aircraft measurement (Albrecht et al, 1995;Andrews et al, 2004;Lenschow et al, 1980;Stull et al, 1997;Vogelmann et al, 2012;Williams & Hacker, 1992), radiosonde soundings (Cooper & Eichinger, 1994;Frehlich & Sharman, 2010;Garcia-Carreras et al, 2015;Neves & Fisch, 2015;Wilson et al, 2011), wind profiling radars (Angevine et al, 1994;Cohn, 1995;Dehghan et al, 2014;Ecklund et al, 1988;McCaffrey, Bianco, Johnston, et al, 2016;Strauch et al, 1984;White et al, 1991), and tall towers (Businger et al, 1971;Kaimal & Gaynor, 1983;van Ulden & Wieringa, 1996;Wilczak & Tillman, 1980). Even though tall towers can take measurements continuously for long periods of time, their vertical coverage is limited to the lowest portion of the CBL due to their limited height.…”

Aerosol measurement methods to quantify spore emissions from fungi and cryptogamic covers in the Amazon

“…These diurnal patterns might be driven by spore emission patterns, boundary layer dynamics (daytime dilution vs. nighttime concentration), or a combination of both. During convective daytime hours, the boundary layer top is located much higher than during nighttime, which results in a dilution of the local emissions during the day and elevated concentrations during the night (Neves and Fisch, 2015). However, in our case the most important driver for the diurnal pattern of the coarse-mode particles might be the release pattern of the fungus, as the measuring device was located in close vicinity to the releasing fungus.…”