Albedo and estimates of net radiation for green beans under polyethylene cover and field conditions

This paper describes the albedo (r) and estimates of net radiation and global solar irradiance for green beans crop (Phaseolus vulgaris L.), cultivated in greenhouse with cover of polyethylene and field conditions, in Botucatu, SP, Brazil (22º 54' S; 48º 27' W; 850 m). The solar global irradiance (Rg) and solar reflected radiation (Rr) were used to estimate the albedo through the ratio between Rr and Rg. The diurnal curves of albedo were obtained for days with clear sky and partially cloudy conditions, for different phenological stages of the crop. The albedo ranged with the solar elevation, the environment and the phenological stages. The cloudiness range have almost no influence on the albedo diurnal amount. The estimation of radiation were made by linear regression, using the global solar irradiance (Rg) and net short-waves radiation (Rc) as independent variables. All estimates of radiation showed better adjustment for specific phenological periods compared to the entire crop growing cycle. The net radiation in the greenhouse has been estimated by the global solar irradiance measured at field conditions.

MODELING AND SIMULATION OF RELIEF INFLUENCE ON EUCALYPTUS FORESTS: INTERACTION BETWEEN SOLAR IRRADIANCE AND PRODUCTIVITY

ABSTRACT This study aimed to verify the differences in radiation intensity as a function of distinct relief exposure surfaces and to quantify these effects on the leaf area index (LAI) and other variables expressing eucalyptus forest productivity for simulations in a process-based growth model. The study was carried out at two contrasting edaphoclimatic locations in the Rio Doce basin in Minas Gerais, Brazil. Two stands with 32-year-old plantations were used, allocating fixed plots in locations with northern and southern exposure surfaces. The meteorological data were obtained from two automated weather stations located near the study sites. Solar radiation was corrected for terrain inclination and exposure surfaces, as it is measured based on the plane, perpendicularly to the vertical location. The LAI values collected in the field were used. For the comparative simulations in productivity variation, the mechanistic 3PG model was used, considering the relief exposure surfaces. It was verified that during most of the year, the southern surfaces showed lower availability of incident solar radiation, resulting in up to 66% losses, compared to the same surface considered plane, probably related to its geographical location and higher declivity. Higher values were obtained for the plantings located on the northern surface for the variables LAI, volume and mean annual wood increase, with this tendency being repeated in the 3PG model simulations.

Antecipando o futuro: a agenda política para a governança econômica global

Este artigo analisa a agenda política para a governança econômica global para os próximos cinqüenta anos. Segundo o autor, o grande crescimento populacional proveniente dos países pobres induzirá uma maior participação desses países na tomada de decisão no âmbito internacional, fomentando a troca de informações e experiências entre os países ricos e pobres. Por fim, há uma breve explanação de outras razões pelas quais os países emergentes deveriam ter maior voz na governança econômica global.

Unipolaridade, governabilidade global e intervenção unilateral anglo-americana no Iraque

As intervenções humanitárias (Bósnia 1995-2003, Somália 1992-1993, Kosovo 1999-2003) e de substituição de regimes ditatoriais (Haiti 1994, Afeganistão 2001-2003, Iraque 2003) na política internacional têm sido objeto de muitas controvérsias acadêmicas durante a última década. O presente artigo, à luz dos teóricos das relações internacionais e da ciência política, analisa a legitimidade dessas atitudes por meio do unilateralismo norte-americano.

Going Global: an organizational study of Brazilian foreign policy

This study analyzes the impact of globalisation on the organization and strategies outlined by the Brazilian Ministry of Foreign Affairs. The study intends to understand how countries from the periphery deal with new institutional challenges resulting from globalization, using the case of the Brazilian diplomatic service.

O Brasil na iniciativa BRIC: soft balancing numa ordem global em mudança?

As opções de política externa do Brasil são limitadas, tendo em conta os recursos materiais superiores das grandes potências establecidas. Soft balancing envolve estratégias institucionais, tais como a formação de coalizões ou ententes diplomáticas limitadas, como BRIC, para restringir o poder das grandes potências estabelecidas. Os países BRIC tinham constado dentre os precursores mais fortes de mudança da diplomacia mundial e por sua vez se beneficiam mais destas mudanças de poder global. Dentro da ordem global modelada pelas grandes potências por meio de instituições internacionais, aqueles jogadores que operam efetivamente dentro destas como inovadores, formadores de alianças e porta-vozes, e que ao mesmo tempo conservam soberania e independência têm o potencial de influir sustancialmente os resultados de políticas futuras.

When emergent countries reform global governance of climate change: Brazil under Lula

Due to its recent economic success, Brazil is considered an emerging country, but is it an emerging power concerning global environmental governance? This article argues that although Brazil has a sui generis profile, it can only be considered an emerging power in some environmental regimes, such as global climate change. Thus, international relations theory needs more analytical instruments to assess the impact of emerging powers in global environmental governance

Emerging global partnership: Brazil and China

The Lula era has witnessed a changing bilateral strategic partnership between China and Brazil, having the interlocutions between both countries became more substantial, comprehensive and influential. To enlarge the global impacts of the partnership, both countries should inject more regional and global components into their bilateral agenda. In doing so, both sides need to enhance the ties not only in terms of economic cooperation but also of social interaction

A União Europeia como potência global? As alterações do Tratado de Lisboa na política externa e de defesa

Este artigo aborda as alterações que o Tratado de Lisboa introduziu na política externa e de defesa, tendo em conta a gradual alteração do conceito estratégico da União Europeia que pretende transformá-la numa potência global. Começa por enquadrar a intervenção da União Europeia na política internacional, com a adoção de uma política externa e de segurança pelo Tratado de Maastricht. Em seguida, refere as inovações do Tratado de Lisboa nessa política, analisando os aspectos de maior relevo.

A Governança econômica global e os desafios do G-20 pós-crise financeira: análise das posições de Estados Unidos, China, Alemanha e Brasil

A crise financeira de 2008 teve impactos significativos no capitalismo global, sendo um de seus reflexos na estrutura da governança global a constituição e evolução do G-20. Neste contexto, o objetivo do artigo é analisar tais mudanças e, em especial, as posições de quatro dos principais atores nas cúpulas do G-20, a saber: Estados Unidos, China, Alemanha e Brasil.

The G-77, BASIC, and global climate governance: a new era in multilateral environmental negotiations

The G-77 has historically organized the participation of developing countries in multilateral environmental negotiations. This article analyses the impact of a new coalition of emerging powers - Brazil, China, India, and South Africa as BASIC - on the G-77's role in climate governance. While there are important benefits for both sides in their relationship, I argue that the G-77 is also disadvantaged in several concrete ways by the BASIC countries.