Patterns and Controls of the Latent and Sensible Heat Fluxes in the Brazilian Pampa Biome

Atmosphere

Luis Gustavo Gonçalves de Gonçalves¹  Tamíres Zimmer²  Alecsander Mergen²  Vanessa de Arruda Souza²  Gustavo Pujol Veeck²  Gisele Cristina Dotto Rubert²  Débora Regina Roberti²  Tiago Bremm²  Anderson Ruhoff³ 

[1] Centro de Previsão de Tempo e Estudos Climáticos (CPTEC), Instituto Nacional de Pesquisas Espaciais (INPE), Cachoeira Paulista 12630-000, SP, Brazil;Departamento de Física, Universidade Federal de Santa Maria (UFSM), Santa Maria 97105-900, RS, Brazil;Instituto de Pesquisas Hidráulicas, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre 91501-970, RS, Brazil;

关键词: energy balance;    evapotranspiration;    surface conductance;    aerodynamic conductance;    grassland;   

DOI  :  10.3390/atmos13010023

来源: DOAJ

【 摘 要 】

Energy and water exchange between the surface and the atmosphere are important drivers to Earth’s climate from local to global scale. In this study, the energy dynamic and the biophysical mechanisms that control the energy partitioning over a natural grassland pasture over the Brazilian Pampa biome are investigated using two micrometeorological sites located 300 km apart, in Southern Brazil. The latent heat flux, LE, was the main component of the energy balance in both autumn-winter (AW) and spring-summer (SS) periods. Annually, approximately 60% of the available energy is used for evapotranspiration (ET). However, the Bowen ratio presents seasonal variability greater in AW than SS. Global radiation, Rg, is the atmospheric variable controlling LE and sensible heat flux, H. Hysteresis curves in the daily cycle were observed for ET and surface conductance, Cs, regarding the environmental variables, net radiation, vapor pressure deficit, and air temperature. Among the variables analyzed in the Pampa biome, surface conductance and evapotranspiration respond more strongly to the vapor pressure deficit. The hysteresis cycles formed by ET and conductance show a substantial biophysical control in the ET process. The results obtained here allowed a comprehension of the biophysical mechanisms involved in the energy partition process in natural grassland. Therefore, this study can be used as a base for research on land-use changes in this unique ecosystem of the Pampa biome.

【 授权许可】

Unknown