S. V. Cuadra

Climate change impact on precipitation for the Amazon and La Plata basins

We analyze the local and remote impacts of climate change on the hydroclimate of the Amazon and La Plata basins of South America (SA) in an ensemble of four 21st century projections (1970–2100, RCP8.5 scenario) with the regional climate model RegCM4 driven by the HadGEM, GFDL and MPI global climate models (GCMs) over the SA CORDEX domain. Two RegCM4 configurations are used, one employing the CLM land surface and the Emanuel convective schemes, and one using the BATS land surface and Grell (over land) convection schemes. First, we find considerable sensitivity of the precipitation change signal to both the driving GCM and the RegCM4 physics schemes (with the latter even greater than the first), highlighting the pronounced uncertainty of regional projections over the region. However, some improvements in the simulation of the annual cycle of precipitation over the Amazon and La Plata basins is found when using RegCM4, and some consistent change signals across the experiments are found. One is a tendency towards an extension of the dry season over central SA deriving from a late onset and an early retreat of the SA monsoon. The second is a dipolar response consisting of reduced precipitation over the broad Amazon and Central Brazil region and increased precipitation over the La Plata basin and central Argentina. An analysis of the relative influence on the change signal of local soil-moisture feedbacks and remote effects of Sea Surface Temperature (SST) over the Niño 3.4 region indicates that the former is prevalent over the Amazon basin while the latter dominates over the La Plata Basin. Also, the soil moisture feedback has a larger role in RegCM4 than in the GCMs.

Cultivating C4 crops in a changing climate: sugarcane in Ghana

Over the next few decades, it is expected that increasing fossil fuel prices will lead to a proliferation of energy crop cultivation initiatives. The environmental sustainability of these activities is thus a pressing issue—particularly when they take place in vulnerable regions, such as West Africa. In more general terms, the effect of increased CO2 concentrations and higher temperatures on biomass production and evapotranspiration affects the evolution of the global hydrological and carbon cycles. Investigating these processes for a C4 crop, such as sugarcane, thus provides an opportunity both to extend our understanding of the impact of climate change, and to assess our capacity to model the underpinning processes. This paper applies a process-based crop model to sugarcane in Ghana (where cultivation is planned), and

Análise de sensibilidade dos coeficientes genéticos do modelo Canegro/DSSAT.

A analise de sensibilidade dos coeficientes geneticos utilizados na simulacao de produtividade da cana de acucar pelo modelo Canegro/DSSAT (CD) foi realizada com o objetivo de identificar quais parâmetros tem maior relevância na calibracao do modelo. O CD faz uso de 20 parâmetros que tem como objetivo capturar as diferencas entre as cultivares de cana-de-acucar. A analise de sensibilidade foi desenvolvida variando um parâmetro por vez dentro de um determinado intervalo e mantendo os demais constantes. Foram simulados o peso seco do colmo, indice de area foliar de folhas verdes e peso seco de sacarose ao final de cada ciclo de cultivo em um periodo de vinte anos, entre 1995 e 2014, considerando tres datas de plantio, 01 de agosto, 01 de setembro e 01 de outubro. As simulacoes foram feitas para o municipio de Pelotas – RS e os resultados foram avaliados pelo desvio padrao (D). Os resultados mostram que os coeficientes geneticos de maior sensibilidade na simulacao do peso seco do colmo foram PARCEmax (D ≈ 6 t.ha-1) e STKPFmax (D ≈ 5 t.ha-1). Para a simulacao de peso seco de sacarose os coeficientes geneticos de maior sensibilidade tambem foram PARCEmax (D ≈ 3,5 t.ha-1) e STKPFmax (D ≈ 3 t.ha-1). Para a simulacao do indice de area foliar maximo os coeficientes geneticos mais sensiveis foram LFMAX (D ≈ 2 cm2.cm-2), TT_POPGROWTH (D ≈ 1,4 cm2.cm-2) e Mxlfarea (D ≈ 1 cm2.cm-2). Os resultados tambem mostram que as diferencas na data de plantio tem influencia na sensibilidade dos coeficientes geneticos.

Parametrization of Models and Use of Estimated Global Solar Radiation Data in the Irrigated Rice Yield Simulation

The objective of this study was to evaluate the use of estimated global solar radiation data in the simulations of potential yield of irrigated rice. Global solar radiation was estimated by four empirical models, based on air temperature, and a meteorological satellite derivated. The empirical models were calibrated and validated for 10 sites, representative of the six rice regions of the State of Rio Grande do Sul Brazil. To evaluate the impact of the radiation estimates on irrigated rice yield simulations, the CERES-Rice model, calibrated for four cultivars, was used. The estimates of global solar radiation of the empirical models based on the air temperature showed deviations, from the observed values, of 20 to 30% and the estimated by satellite deviations of more than 30%. The global solar radiation data estimated by the Hargreaves and Samani, Donatelli and Campbell and derived satellite (PowerNasa) type air temperature-based empirical models can be used as input data in simulation models of crop growth, development and productivity of irrigated rice.

SIMULAÇÃO DO BALANÇO DE ENERGIA COM OS ESQUEMAS BATS E CLM SOBRE A AMÉICA DO SUL

In the present work two simulations with the land surfaceschemes BATS (RegBATS) and CLM (RegCLM) coupled in the RegCM3are evaluated. The larger differences between RegCLM and RegBATS arefound in the Amazon region, when the RegCLM reduces the excessiveevapotranspirantion simulated by the RegBATS during the wet season.In contrast, in the dry season RegCLM overestimates the sensible heatingtransfer, increasing the air temperature.