Dinâmica do microclima e fluxo de calor sensível armazenado no dossel vegetativo da caatinga no semiárido do Brasil

Abstract

In this study, we used the data of Cariri Experiment collected in native caatinga region in the municipality of São João do Cariri, Paraíba state, in the coordinates of 7º22'45.1 "S and 36º31'47.2" Wwith altitude of 458 m. Microclimate measurements were taken at two stages in the period from 01 to 13 January 2002 (rainy period) and 07 to 19 September 2002 (dry Period). The objective of this work was the microclimate characterization and behavior of the sensible heat flux stored in the canopy. The microclimate study involved the measurement of the following meteorological variables: precipitation; radiation; solar radiation; air temperature in the canopy and out of the canopy; heat flow in non-vegetated and vegetated soil and air relative humidity. We compared the average during the experimental period by analysis of variance and descriptive statistics. The results for the variables studied during the experimental period and submitted to statistical analyzes revealed significant effect from 1% by F test. The average net radiation was higher during the dry season when compared to the rainy season with average of 163.20 Wm-2 and 44.26 Wm-2, respectively. At night the net radiation was negative while during the day was positive. The global solar radiation during the rainy season was lower than in the dry season with an average of 208.27 Wm-2 and 265.49 Wm-2, respectively. At nighttime the net radiation was negative while during the day was positive. The air temperature inside of the canopy are higher than the temperature of the air outside the canopy in both periods. The heat flow in the medium soil was higher in non-vegetated soil when compared to vegetated soil in the rainy season with an average of 26.79 Wm-2 and 6.52 Wm-2, respectively in both periods studied. For the dry period showed average of 30.50 Wm-2 to non-vegetated soil 3.88 Wm-2 to vegetated soil. The relative humidity in the rainy season was higher than in the dry season with averages of 79.60% and 62.73%, respectively. The sensible heat flux stored in the canopy revealed no significant effect of 5% between the dry and rainy season by F test, with an average of -0.011 Wm-2 in the rainy season and -0.017 Wm-2 in the dry season.