Made available in DSpace on 2014-06-11T19:32:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2002-11Bitstream added on 2014-06-13T20:04:09Z : No. of bitstreams: 1 lunardi_ma_dr_botfca.pdf: 2616577 bytes, checksum: 3ce9de8aa359098429c03603153b828c (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Este experimento foi conduzido, dentro e fora de ambiente protegido, durante o período de 21/04 a 03/11/2000, na área experimental do Departamento de Recursos Naturais da Faculdade de Ciências Agronômicas, UNESP, Campus de Botucatu, São Paulo (latitude 22° 51’ S, longitude 48° 26’ W e altitude de 786 m). O objetivo foi avaliar o efeito do Polietileno de Baixa Densidade com 150 mm de espessura, difusor de luz (PEBD150d), no saldo de energia de ondas longas, assim como no desenvolvimento do pimentão vermelho (Capsicum annuum L.) híbrido Elisa e indicadores de produção da cultura. Os modelos de estimativa do saldo de ondas longas foram obtidos por meio de regressão linear entre os valores medidos deste parâmetro climático, pressão de vapor e temperatura do ar e solo. Os resultados mostraram que em condições de ambiente protegido houve aumento de produção da cultura, em relação ao ocorrido no campo, e significante diferença na transmissividade da energia líquida pela cobertura. Houve redução do fluxo de calor no solo, velocidade do vento, número de horas de insolação, consumo de água, radiação direta e refletida. Contrariamente, a radiação solar difusa teve aumento de 158 %, confirmando o alto efeito difusor do PEBD150d. Os testes dos modelos de estimativa obtidos mostraram alto coeficiente de determinação (r2 > 0,90), tanto para o ambiente protegido como no campo. / This experiment was carried out under field and protected environment conditions in the experimental area of the Natural Resources Department of the Faculty of Agricultural Sciences – UNESP, Campus of Botucatu, São Paulo State, Brazil, from April 21st to November 3rd, 2000. The objective was to assess the effect of the light diffuser polyethylene with 150 μm thickness (PEBD150d), on the long wave radiation estimate, as well as on growth and yield index of the hybrid Elisa of red pepper (Capsicum annuum L.). The long wave radiation models was obtained by linear regression of measured values of this climatic parameter and water vapor pressure, air and soil temperature. The results showed that the protected environmental condition provided gains of yield in relation to field and significant difference in the long wave transmission though the coverage. There was reduction of the heat flux from soil, wind speed, number of hours of sunshine, water consumption, reflected and direct radiation. The diffuse solar radiation had an increment of 158 %, confirming the higher diffuse effect of PEBD150d. The tests of the estimating models obtained for long wave presented high determination coefficient for both environmental conditions (r2 > 0.90).

Orientador: João Francisco Escobedo / Este experimento foi conduzido, dentro e fora de ambiente protegido, durante o período de 21/04 a 03/11/2000, na área experimental do Departamento de Recursos Naturais da Faculdade de Ciências Agronômicas, UNESP, Campus de Botucatu, São Paulo (latitude 22° 51' S, longitude 48° 26' W e altitude de 786 m). O objetivo foi avaliar o efeito do Polietileno de Baixa Densidade com 150 mm de espessura, difusor de luz (PEBD150d), no saldo de energia de ondas longas, assim como no desenvolvimento do pimentão vermelho (Capsicum annuum L.) híbrido Elisa e indicadores de produção da cultura. Os modelos de estimativa do saldo de ondas longas foram obtidos por meio de regressão linear entre os valores medidos deste parâmetro climático, pressão de vapor e temperatura do ar e solo. Os resultados mostraram que em condições de ambiente protegido houve aumento de produção da cultura, em relação ao ocorrido no campo, e significante diferença na transmissividade da energia líquida pela cobertura. Houve redução do fluxo de calor no solo, velocidade do vento, número de horas de insolação, consumo de água, radiação direta e refletida. Contrariamente, a radiação solar difusa teve aumento de 158 %, confirmando o alto efeito difusor do PEBD150d. Os testes dos modelos de estimativa obtidos mostraram alto coeficiente de determinação (r2 > 0,90), tanto para o ambiente protegido como no campo. / Resumo: This experiment was carried out under field and protected environment conditions in the experimental area of the Natural Resources Department of the Faculty of Agricultural Sciences - UNESP, Campus of Botucatu, São Paulo State, Brazil, from April 21st to November 3rd, 2000. The objective was to assess the effect of the light diffuser polyethylene with 150 μm thickness (PEBD150d), on the long wave radiation estimate, as well as on growth and yield index of the hybrid Elisa of red pepper (Capsicum annuum L.). The long wave radiation models was obtained by linear regression of measured values of this climatic parameter and water vapor pressure, air and soil temperature. The results showed that the protected environmental condition provided gains of yield in relation to field and significant difference in the long wave transmission though the coverage. There was reduction of the heat flux from soil, wind speed, number of hours of sunshine, water consumption, reflected and direct radiation. The diffuse solar radiation had an increment of 158 %, confirming the higher diffuse effect of PEBD150d. The tests of the estimating models obtained for long wave presented high determination coefficient for both environmental conditions (r2 > 0.90). / Doutor

The east-west oriented cloud bands in the tropics are called the Inter-tropical Con-vergence Zones (ITCZ). Till recently, the ITCZ has been assumed to have a simple vertical structure with convergence near the surface boundary layer and divergence near the tropopause. Recent work has shown that the ITCZ can have a complex ver-tical structure with multi-level ows. This complex structure has a profound impact on the mass, momentum and energy budget in the ITCZ. This thesis addresses the factors that govern the shallow meridional circulation that occurs in the ITCZ and the mechanisms that govern the abrupt poleward transition and the gradual poleward migration . The shallow meridional circulation forms when the boundary layer ow that con-verges in the ITCZ, rises above the boundary layer and diverges in the lower tropo-sphere. The ow above the boundary layer is in the direction opposite to the direction of the ow within the boundary layer. Some authors have argued that this is caused by the reversal of pressure gradients just above the boundary layer in response to strong sea surface temperature gradients. This hypothesis neglects the eect of plan-etary rotation on the ow and was found to be insucient to explain the formation of shallow meridional circulation. In the east Pacic ocean, the shallow circulation forms only to the south of the ITCZ when the ITCZ forms away from the equator, while it is absent when the ITCZ forms close to the equator. The aqua-planet simulations of the equatorial and the o-equatorial ITCZ were conducted using Community Atmosphere Model (CAM 3.0). The model used the Eulerian dynamical core with T42 horizontal resolution and 26 levels in vertical. Each simulation was run for 3 years and analysis of last six months was presented. The simulations reproduced the contrast in the vertical structure of the equatorial and o-equatorial ITCZ. The shallow circulation was simulated with-out the reversal of pressure gradients and the SST gradients were weakest when the shallow circulation was simulated. We have proposed a new mechanism for the exis-tence of shallow meridional circulation in the ITCZ. We have argued that, in Earth's atmosphere, the mean horizontal ow generally occurs in the direction perpendicular to the direction of applied pressure gradient due to the action of Coriolis force. If the local rotational eects of the ow (relative vorticity) cancels the action of the Coriolis force, then a ow along the pressure gradient is possible. We demonstrated that this condition was satised only to the south of the ITCZ when it forms away from the equator. The ITCZ is characterized by the maximum mass convergence in the boundary layer. The mass convergence is mainly caused by the deceleration of poleward ow in the boundary layer. When the ITCZ forms close to the equator, the ow in the boundary layer is a resultant of vector addition of three forces, a pressure gradient force in the north-south direction (i.e., the ow towards low pressure), a Coriolis force which acts in the east-west direction( perpendicular to the direction of the ow), and surface friction which opposes the resultant ow. When the ITCZ forms away from the equator a three way balance does not capture the dynamics of ow. As the poleward ow is accelerated towards low pressure, it has to advect a considerable amount of zonal momentum with it which acts to retard the poleward ow. This eect of advection of zonal momentum has to be included in the force balance to obtain an accurate estimate of the ow and associated convergence. The ITCZ acts like a heat engine. The energy is gained near the surface, some energy is transported towards pole while some is utilized in driving the meridional circulation. The rest is rejected near the tropopause. The transport within the troposphere occurs through the vertical or horizontal advection of the energy due to vertical and horizontal motions respectively. Our analysis of the ITCZ suggests that; a large amount of transport occurs through horizontal motions that was neglected in the previous studies. The detailed analysis suggests that the latent energy in the form of mass of water vapor is exported out of the ITCZ at dierent levels in association with the multilevel ows. The equatorial and the o-equatorial ITCZ are dierent because, evaporation is larger in the o-equatorial ITCZ when compared to the equatorial ITCZ. The ITCZ shows a strong sub-seasonal variability in its location in the Indian Ocean and the west Pacic Ocean during boreal summer. There are two favorable locations, one near the equator and another away from the equator, for formation of the ITCZ. The equatorial ITCZ either propagates abruptly or gradually to the o-equatorial location. A detailed analysis of moisture and momentum budget of the simulated abrupt and gradual propagations enabled us to separate the role of thermo-dynamic and dynamic processes. We found that, if the equatorial ITCZ would propa-gate abruptly or gradually to the o-equatorial location is decided by the availability of the water vapor in the boundary layer between the two locations of the ITCZ, i.e., by the thermodynamic processes. But, such a transition to the o-equatorial location is allowed only when the constraints imposed by the re-adjustment in the circulation are satised. In simple terms, these constraints emerge due to two processes. 1. The Earth (lower boundary of the atmosphere) spins at maximum eective radius near the equator. As a result, the atmosphere gains maximum angular momentum near the equator (`zonal momentum' in Cartesian co-ordinates) . The ITCZ is one of the primary avenues to transport the zonal momentum from the lower troposphere to the upper troposphere. When the favorable location of ITCZ is near the equator, the location of ITCZ and the location where atmosphere gains maximum zonal momentum are coincident. The ITCZ and associated meridional circulation transports the zonal momentum upwards which is then transported polewards. As the favorable location of ITCZ moves away from the equator, the two locations are die rent. As a result, the atmospheric ow has to re-adjust so that the zonal momentum is transported from the equator to the favorable location of the ITCZ which then transports it upwards and polewards. In summary, this thesis proposes a new mechanism for the generation of shallow meridional circulation, the abrupt transition and the gradual propagations of the ITCZ.