Three years of greenhouse gas column-averaged dry air mole fractions retrieved from satellite – Part 2: Methane

Carbon dioxide (CO2) and methane (CH4) are the two most important anthropogenic greenhouse gases. SCIAMACHY on ENVISAT is the first satellite instrument whose measurements are sensitive to concentration changes of the two gases at all altitude levels down to the Earth's surface where the source/sink signals are largest. We have processed three years (2003–2005) of SCIAMACHY near-infrared nadir measurements to simultaneously retrieve vertical columns of CO2 (from the 1.58 µm absorption band), CH4 (1.66 µm) and oxygen (O2 A-band at 0.76 µm) using the scientific retrieval algorithm WFM-DOAS. We show that the latest version of WFM-DOAS, version 1.0, which is used for this study, has been significantly improved with respect to its accuracy compared to the previous versions while essentially maintaining its high processing speed (~1 min per orbit, corresponding to ~6000 single measurements, and per gas on a standard PC). The greenhouse gas columns are converted to dry air column-averaged mole fractions, denoted XCO2 (in ppm) and XCH4 (in ppb), by dividing the greenhouse gas columns by simultaneously retrieved dry air columns. For XCO2 dry air columns are obtained from the retrieved O2 columns. For XCH4 dry air columns are obtained from the retrieved CO2 columns because of better cancellation of light path related errors compared to using O2 columns retrieved from the spectrally distant O2 A-band. Here we focus on a discussion of the XCH4 data set. The XCO2 data set is discussed in a separate paper (Part 1). For 2003 we present detailed comparisons with the TM5 model which has been optimally matched to highly accurate but sparse methane surface observations. After accounting for a systematic low bias of ~2% agreement with TM5 is typically within 1–2%. We investigated to what extent the SCIAMACHY XCH4 is influenced by the variability of atmospheric CO2 using global CO2 fields from NOAA's CO2 assimilation system CarbonTracker. We show that the CO2 corrected and uncorrected XCH4 spatio-temporal pattern are very similar but that agreement with TM5 is better for the CarbonTracker CO2 corrected XCH4. In line with previous studies (e.g., Frankenberg et al., 2005b) we find higher methane over the tropics compared to the model. We show that tropical methane is also higher when normalizing the CH4 columns with retrieved O2 columns instead of CO2. In consistency with recent results of Frankenberg et al. (2008b) it is shown that the magnitude of the retrieved tropical methane is sensitive to the choice of the spectroscopic line parameters of water vapour. Concerning inter-annual variability we find similar methane spatio-temporal pattern for 2003 and 2004. For 2005 the retrieved methane shows significantly higher variability compared to the two previous years, most likely due to somewhat larger noise of the spectral measurement

Evaporation of the soil water in response to the amount of straw and evaporative demand.

Título em português: Evaporação da água do solo em resposta à quantidade de palha e à demanda evaporativa

BLAST: a Loosely Schema-aware Meta-blocking Approach for Entity Resolution

Identifying records that refer to the same entity is a fundamental step for data integration. Since it is prohibitively expensive to compare every pair of records, blocking techniques are typically employed to reduce the complexity of this task. These techniques partition records into blocks and limit the comparison to records co-occurring in a block. Generally, to deal with highly heterogeneous and noisy data (e.g. semi-structured data of the Web), these techniques rely on redundancy to reduce the chance of missing matches. Meta-blocking is the task of restructuring blocks generated by redundancy-based blocking techniques, removing superfluous comparisons. Existing meta-blocking approaches rely exclusively on schema-agnostic features. In this paper, we demonstrate how “loose” schema information (i.e., statistics collected directly from the data) can be exploited to enhance the quality of the blocks in a holistic loosely schema-aware (meta-)blocking approach that can be used to speed up your favorite Entity Resolution algorithm. We call it Blast (Blocking with Loosely-Aware Schema Techniques). We show how Blast can automatically extract this loose information by adopting a LSH-based step for e ciently scaling to large datasets. We experimentally demonstrate, on real-world datasets, how Blast outperforms the state-of-the-art unsupervised meta-blocking approaches, and, in many cases, also the supervised one

Three Years of Greenhouse Gas Column-Averaged Dry Air Mole Fractions Retrieved from Satellite - Part 2: Methane

Abstract. Carbon dioxide (CO2) and methane (CH4) are the two most important anthropogenic greenhouse gases. SCIAMACHY on ENVISAT is the first satellite instrument whose measurements are sensitive to concentration changes of the two gases at all altitude levels down to the Earth's surface where the source/sink signals are largest. We have processed three years (2003-2005) of SCIAMACHY nearinfrared nadir measurements to simultaneously retrieve vertical columns of CO2 (from the 1.58µm absorption band), CH4 (1.66µm) and oxygen (O2 A-band at 0.76µm) using the scientific retrieval algorithm WFM-DOAS.We show that the latest version of WFM-DOAS, version 1.0, which is used for this study, has been significantly improved with respect to its accuracy compared to the previous versions while essentially maintaining its high processing speed (1 min per orbit, corresponding to 6000 single measurements, and per gas on a standard PC). The greenhouse gas columns are converted to dry air column-averaged mole fractions, denoted XCO2 (in ppm) and XCH4 (in ppb), by dividing the greenhouse gas columns by simultaneously retrieved dry air columns. For XCO2 dry air columns are obtained from the retrieved O2 columns. For XCH4 dry air columns are obtained from the retrieved CO2 columns because of better cancellation of light path related errors compared to using O2 columns retrieved from the spectrally distant O2 Aband. Here we focus on a discussion of the XCH4 data set. The XCO2 data set is discussed in a separate paper (Part 1). For 2003 we present detailed comparisons with the TM5 model which has been optimally matched to highly accurate but sparse methane surface observations. After accounting for a systematic low bias of 2% agreement with TM5 is typically within 1¿2%. We investigated to what extent the SCIAMACHY XCH4 is influenced by the variability of atmospheric CO2 using global CO2 fields from NOAA¿s CO2 assimilation system CarbonTracker. We show that the CO2 corrected and uncorrected XCH4 spatio-temporal pattern are very similar but that agreement with TM5 is better for the CarbonTracker CO2 corrected XCH4. In line with previous studies (e.g., Frankenberg et al., 2005b) we find higher methane over the tropics compared to the model. We show that tropical methane is also higher when normalizing the CH4 columns with retrieved O2 columns instead of CO2. In consistency with recent results of Frankenberg et al. (2008b) it is shown that the magnitude of the retrieved tropical methane is sensitive to the choice of the spectroscopic line parameters of water vapour. Concerning inter-annual variability we find similar methane spatio-temporal pattern for 2003 and 2004. For 2005 the retrieved methane shows significantly higher variability compared to the two previous years, most likely due to somewhat larger noise of the spectral measurements.JRC.H.2-Air and Climat

Microclima e produção de videiras 'Niágara rosada' em cultivo orgânico sob cobertura plástica.

O uso de coberturas plásticas sobre vinhedos tem aumentado no Sul do Brasil, visando a atenuar limitações climáticas. Este estudo objetivou quantificar alterações micrometeorológicas causadas por cobertura plástica e seus efeitos no desenvolvimento e na produção de videiras ?Niágara Rosada?, em cultivo orgânico. O estudo foi realizado em Bento Gonçalves-RS, num vinhedo conduzido em sistema latada e submetido a dois ambientes: em céu aberto e coberto por plástico transparente (160μm) em arcos descontínuos. Nos dois ambientes, foram monitoradas radiação fotossinteticamente ativa (RFA) e temperatura do ar. Avaliaram-se fenologia, índice de área foliar (IAF), peso e diâmetro de bagas, teor de sólidos solúveis e acidez total titulável, incidência de doenças fúngicas e rendimento. A cobertura reduziu em um terço a RFA incidente (-34%) e aumentou as temperaturas máximas do ar (+3,1ºC). Ela acelerou o ciclo vegetativo das videiras até a maturação, mas retardou a queda de folhas. A cobertura promoveu incrementos de IAF, duração da área foliar e produção de uvas, de 12,3 para 27,1 t ha-1. Não foi observada incidência de doenças fúngicas no vinhedo coberto. Portanto, a cobertura plástica sobre vinhedos é uma alternativa importante na produção de uvas de mesa no Sul do Brasil, em cultivo orgânico

Fenologia e requerimento térmico de videira sob cobertura plástica.

O objetivo desse trabalho foi caracterizar a fenologia e o requerimento térmico da videira Vitis vinifera L., cv. Moscato Giallo sob cobertura plástica, nas condições da Serra Gaúcha.bitstream/CNPUV-2009-09/10531/1/cot093.pd

Produtividade de videiras Moscato Giallo sob cultivo protegido.

Este trabalho teve por objetivos avaliar a influência da cobertura plástica impermeável sobre o potencial e a estabilidade de produção, considerando a análise dos componentes de rendimento da cultivar Moscato Giallo (Vitis vinifera).bitstream/item/31569/1/cot101.pd

Anatomy, chlorophyll content and photosynthetic potential in grapevine leaves under plastic cover.

o presente trabalho avaliou a anatomia, o teor de clorofila e as respostas fotossintéticas em diferentes níveis de radiação solar em folhas de videiras cultivadas sob cobertura plástica. o experimento foi realizado em vinhedo com a cultivar Moscato Giallo, com e sem cobertura plástica. A avaliação da anatomia foliar foi realizada em 10 plantas, nas áreas coberta e descoberta. No estádio fenológico de mudança de cor das bagas, em cada área, foram coletadas seis folhas expostas à radiação solar e seis sombreadas, as quais foram fixadas e micrografadas (espessuras das epidermes adaxiais e abaxiais e dos parênquimas paliçádicos e lacunosos). O teor de clorofila e o potencial fotossintético foram avaliados na mudança de cor das bagas e após a colheita. A diminuição da radiação solar pela cobertura plástica propicia um incremento da espessura do parênquima paliçádico em folhas expostas e sombreadas. As epidermes adaxiais e abaxiais e o parênquima lacunoso não variam suas espessuras em função da diminuição de radiação solar. O teor de clorofila aumenta nas folhas das plantas cultivadas sob cobertura plástica. o potencial fotossintético das videiras não é afetado pela restrição de radiação solar da cobertura plástica devido à modificação na anatomia das folhas

Maize yield and rainfall on different spatial and temporal scales in Southern Brazil

This study aimed to establish relationships between maize yield and rainfall on different temporal and spatial scales, in order to provide a basis for crop monitoring and modelling. A 16-year series of maize yield and daily rainfall from 11 municipalities and micro-regions of Rio Grande do Sul State was used. Correlation and regression analyses were used to determine associations between crop yield and rainfall for the entire crop cycle, from tasseling to 30 days after, and from 5 days before tasseling to 40 days after. Close relationships between maize yield and rainfall were found, particularly during the reproductive period (45-day period comprising the flowering and grain filling). Relationships were closer on a regional scale than at smaller scales. Implications of the crop-rainfall relationships for crop modelling are discussed.Título em português: Rendimento de milho e chuva em diferentes escalas espaço-temporais no Sul do Brasil