scholarly journals Using Sun Glint to Check the Relative Calibration of Reflected Spectral Radiances

2005 ◽  
Vol 22 (10) ◽  
pp. 1480-1493 ◽  
Author(s):  
Gunnar Luderer ◽  
James A. Coakley ◽  
William R. Tahnk
Keyword(s):  
Surface Wind ◽  
Tropical Rainfall Measuring Mission ◽  
Surface Wind Speed ◽  
High Gain ◽  
Atmospheric Composition ◽  
Marine Aerosols ◽  
Linear Relationships ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer

Abstract Observations of sunlight reflected from regions of sun glint are used to check the relative calibration of spectral radiances obtained with imaging radiometers. Reflectances at different wavelengths for sun-glint regions are linearly related. Provided that the atmosphere is reasonably transparent at the wavelengths, the aerosol burden is reasonably light, 0.64-μm optical depth less than 0.2; the particles constituting the aerosol are reasonably large, as is the case for marine aerosols; and the solar zenith angle is less than about 35°, the linear relationships between reflectances at different wavelengths are rather insensitive to the factors that govern the reflectances themselves. The relationships are remarkably insensitive to atmospheric composition, surface wind speed and direction, illumination, and viewing geometry. The slopes and offsets of the linear relationships are used to assess the relative accuracies of the calibrations of the different channels. Such assessments would appear to be attractive for checks on the in-flight performance of aircraft-borne imaging radiometers. Here, observations of reflectances at 0.64, 0.84, 1.6, and 2.1 μm for regions of sun glint obtained with the Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) instruments are shown to be consistent with each other. Observations of the 0.64- and 1.6-μm reflectances for the Tropical Rainfall Measuring Mission (TRMM) Visible and Infrared Scanner (VIRS) instrument are shown to be inconsistent with the MODIS observations, the VIRS 1.6-μm gain appearing to be too low by 9%. The 0.64-, 0.84-, and 1.6-μm reflectances obtained with the NOAA-16 and NOAA-17 Advanced Very High Resolution Radiometers (AVHRRs) for December 2002 are shown to be inconsistent with each other and inconsistent with the MODIS observations. Based on observations of the extensive ice sheets of Antarctica, the NOAA-16 0.64-μm gain is found to be too low by 5% and that for the 0.84-μm reflectance is too low by 12%; the NOAA-17 0.64-μm gain is found to be accurate (within 2%), but the 0.84-μm gain is too low by 15%. With the gains adjusted, the 0.64- and 0.84-μm reflectances obtained for regions of sun glint with the AVHRRs are consistent with each other and consistent with the Terra and Aqua MODIS observations. These results suggest that the gain for the NOAA-16 AVHRR 1.6-μm reflectance is accurate (within 1%) and that for the NOAA-17 AVHRR is too low by 5%. All of the observations were made with the AVHRR in the low-reflectance (high gain) mode. The accuracy of these assessments is expected to be about 5%.

scholarly journals Determination of enhancement ratios of HCOOH relative to CO in biomass burning plumes by the Infrared Atmospheric Sounding Interferometer (IASI)

2017 ◽  
Vol 17 (18) ◽  
pp. 11089-11105 ◽  
Author(s):  
Matthieu Pommier ◽  
Cathy Clerbaux ◽  
Pierre-Francois Coheur
Keyword(s):  
Southeast Asia ◽  
Biomass Burning ◽  
Surface Wind ◽  
Geographic Location ◽  
Surface Wind Speed ◽  
Weather Forecasts ◽  
Atmospheric Sounding ◽  
Agricultural Burning ◽  
Moderate Resolution ◽  
Moderate Resolution Imaging Spectroradiometer

Abstract. Formic acid (HCOOH) concentrations are often underestimated by models, and its chemistry is highly uncertain. HCOOH is, however, among the most abundant atmospheric volatile organic compounds, and it is potentially responsible for rain acidity in remote areas. HCOOH data from the Infrared Atmospheric Sounding Interferometer (IASI) are analyzed from 2008 to 2014 to estimate enhancement ratios from biomass burning emissions over seven regions. Fire-affected HCOOH and CO total columns are defined by combining total columns from IASI, geographic location of the fires from Moderate Resolution Imaging Spectroradiometer (MODIS), and the surface wind speed field from the European Centre for Medium-Range Weather Forecasts (ECMWF). Robust correlations are found between these fire-affected HCOOH and CO total columns over the selected biomass burning regions, allowing the calculation of enhancement ratios equal to 7.30  ×  10−3 ± 0.08  ×  10−3 mol mol−1 over Amazonia (AMA), 11.10  ×  10−3 ± 1.37  ×  10−3 mol mol−1 over Australia (AUS), 6.80  ×  10−3 ± 0.44  ×  10−3 mol mol−1 over India (IND), 5.80  ×  10−3 ± 0.15  ×  10−3 mol mol−1 over Southeast Asia (SEA), 4.00  ×  10−3 ± 0.19  ×  10−3 mol mol−1 over northern Africa (NAF), 5.00  ×  10−3 ± 0.13  ×  10−3 mol mol−1 over southern Africa (SAF), and 4.40  ×  10−3 ± 0.09  ×  10−3 mol mol−1 over Siberia (SIB), in a fair agreement with previous studies. In comparison with referenced emission ratios, it is also shown that the selected agricultural burning plumes captured by IASI over India and Southeast Asia correspond to recent plumes where the chemistry or the sink does not occur. An additional classification of the enhancement ratios by type of fuel burned is also provided, showing a diverse origin of the plumes sampled by IASI, especially over Amazonia and Siberia. The variability in the enhancement ratios by biome over the different regions show that the levels of HCOOH and CO do not only depend on the fuel types.

scholarly journals Estudo da dinâmica espaço-temporal do bioma Pantanal por meio de imagens MODIS

2008 ◽  
Vol 43 (10) ◽  
pp. 1371-1378 ◽  
Author(s):  
Marcos Adami ◽  
Ramon Morais de Freitas ◽  
Carlos Roberto Padovani ◽  
Yosio Edemir Shimabukuro ◽  
Mauricio Alves Moreira
Keyword(s):  
Vegetation Index ◽  
Tropical Rainfall Measuring Mission ◽  
Shuttle Radar Topography Mission ◽  
Enhanced Vegetation Index ◽  
Tropical Rainfall ◽  
Modis Evi ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer

O objetivo deste trabalho foi avaliar dados multitemporais, obtidos pelo sensor "moderate resolution imaging spectroradiometer" (MODIS), para o estudo da dinâmica espaço-temporal de duas sub-regiões do bioma Pantanal. Foram utilizadas 139 imagens "enhanced vegetation index" (EVI), do produto MOD13 "vegetation index", dados de altimetria oriundos do "shuttle radar topography mission" (SRTM) e dados de precipitação do "tropical rainfall measuring mission" (TRMM). Para a redução da dimensionalidade dos dados, as imagens MODIS-EVI foram amostradas com base nas curvas de nível espaçadas em 10 m. Foram aplicadas as técnicas de análise de autocorrelação e análise de agrupamentos aos dados das amostras, e a análise de componentes principais na área total da imagem. Houve dependência tanto temporal quanto espacial da resposta espectral com a precipitação. A análise de agrupamentos apontou a presença de dois grupos, o que indicou a necessidade da análise completa da área. A análise de componentes principais permitiu diferenciar quatro comportamentos distintos: as áreas permanentemente alagadas; as áreas não inundáveis, compostas por vegetação; as áreas inundáveis com maior resposta de vegetação; e áreas com vegetação ripária.

scholarly journals DINÂMICA DE FOGO NO PARQUE ESTADUAL DO ARAGUAIA, ZONA DE TRANSIÇÃO AMAZÔNIA-CERRADO

2018 ◽  
Vol 44 ◽  
pp. 85
Author(s):  
Laís Fernandes De Souza Neves ◽  
Beatriz Schwantes Marimon ◽  
Liana Oighenstein Anderson ◽  
Sandra Mara Alves da Silva Neves
Keyword(s):  
Tropical Rainfall Measuring Mission ◽  
Burned Area ◽  
Tropical Rainfall ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer

A recorrência de incêndios é presente no Cerrado como parte de sua evolução. No entanto, houve um aumento na frequência de incêndios nas últimas décadas devido ao seu uso para desmatamentos, na agricultura e para manutenção de pastagens. Alterações nos estoques de carbono acima do solo na vegetação e alteração na composição de espécies devido as queimadas foram observadas em muitos locais, incluindo o Parque Estadual do Araguaia (PEA), localizado no Cerrado da região sul da Amazônia, mas os padrões dos incêndios nesta área ainda não foram quantificados. Portanto, o objetivo deste estudo é caracterizar a dinâmica espaço-temporal dos incêndios ocorridos entre 2000 e 2013 neste Parque. Os dados de área queimada do produto Moderate Resolution Imaging Spectroradiometer (MODIS) Burned Area - MOD45 e os de precipitação, do satélite Tropical Rainfall Measuring Mission (TRMM) foram utilizados. Identificamos os picos de ocorrência de incêndios florestais, as áreas mais afetadas e os anos mais críticos, relacionando a área queimada com a precipitação pluviométrica mensal. Durante os 14 anos de estudo 633.625 hectares foram atingidos pelo fogo, área que corresponde a quase três vezes o tamanho do PEA. As maiores áreas atingidas por incêndios florestais foram registradas em 2007, 2010 e 2012. Observamos ainda um crescimento exponencial de incêndios quando a precipitação mensal foi inferior a 150 mm, com picos de incêndios nos meses de agosto e setembro. O PEA é uma unidade de proteção integral onde deveriam ser adotadas estratégias de gestão do fogo, principalmente nas florestas sazonalmente inundáveis.

scholarly journals ANÁLISE DA INFLUÊNCIA DA PRECIPITAÇÃO NA DINÂMICA DE FOCOS DE INCÊNDIO NO PARQUE NACIONAL DAS SEMPRE VIVAS-MG

2017 ◽  
Vol 15 ◽  
pp. 121-138
Author(s):  
Tereza Beatriz Oliveira Soares ◽  
Fernanda Cristina Resende ◽  
Guilherme Augusto Verola Mataveli ◽  
Gabriel Pereira ◽  
Bernardo Machado Gotijo
Keyword(s):  
Tropical Rainfall Measuring Mission ◽  
Tropical Rainfall ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer

Incêndios florestais ocorrem em diversas regiões do Brasil e do mundo, principalmente nas estações secas, atingindo, por muitas vezes, grandes extensões de terra. Devido à necessidade de preservação de áreas nativas dos diversos biomas brasileiros, as Áreas Protegidas foram criadas e destinadas à conservação dos recursos naturais. As Unidades de Conservação sofrem diferentes tipos de pressão, sendo a ocorrência de incêndios florestais descontrolados uma das ameaças contínuas que podem colocar seus objetivos em risco. Tendo isso em vista, esse artigo apresenta a análise da distribuição dos focos de incêndio no Parque Nacional das Sempre Vivas-MG, no período que compreende os anos de 2000 a 2014, e a verificação da influência da precipitação na incidência dos incêndios florestais, ou seja, se os anos mais secos coincidem com os anos de maior número de focos. Para tanto, empregaram-se produtos de focos de calor do Moderate Resolution Imaging Spectroradiometer (MODIS), produtos MOD14A1 e MYD14A1, e dados de precipitação do Tropical Rainfall Measuring Mission (TRMM) produto 3B43V6, para verificação da influência das chuvas na incidência de queimadas. Como resultado, constata-se que à medida que a precipitação decai, o número de focos começa a se elevar, evidenciando o quanto as variáveis são relacionadas.

scholarly journals Análise Ambiental da Ocorrência das Queimadas na Porção Nordeste do Cerrado

2017 ◽  
Vol 34 ◽  
pp. 31
Author(s):  
Fernanda Cristina Resende ◽  
Francielle Da Silva Cardozo ◽  
Gabriel Pereira
Keyword(s):  
Tropical Rainfall Measuring Mission ◽  
Tropical Rainfall ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer

Com a crescente demanda nos últimos anos por áreas agricultáveis ainda não exploradas, o bioma Cerrado se tornou um dos ambientes mais favoráveis para a expansão da fronteira agrícola. Uma das consequências consiste no desmatamento e no aumento do número de queimadas, ocasionando a degradação e supressão de extensas áreas de ecossistemas naturais do bioma. Neste contexto, o presente trabalho teve como objetivo principal analisar a distribuição espacial das áreas queimadas na porção nordeste do bioma Cerrado. Desta forma, foi realizado o mapeamento das áreas queimadas em imagens do sensor Moderate Resolution Imaging Spectroradiometer (MODIS), da plataforma Terra e Aqua, nos anos de 2012 a 2015 a partir do uso do Modelo Linear de Mistura Espectral (MLME). Os dados de precipitação do Tropical Rainfall Measuring Mission (TRMM) do produto 3B43 foram utilizados para verificar a influência das chuvas na ocorrência das queimadas. Além disso, analisou-se a ocorrência das queimadas com o uso e cobertura da terra, com as Unidades de Conservação (UC) e com os municípios da área de estudo. Foi verificado que as áreas mais atingidas por queimadas são de Savana, Savana Lenhosa e Gramíneas e os anos que apresentaram menores índices de precipitações também foram os anos que ocorreram maior incidência de queimadas. A unidade de conservação mais atingida foi a Estação Ecológica Uruçuí-Uma no Piauí, com uma média de 36,5% de sua área queimada e os municípios mais atingidos estão localizados principalmente nos estados do Piauí e Maranhão, apresentando em média metade de suas áreas queimadas.

scholarly journals The Thar, Rajputana desert unprecedented rainfall in 2006 and 2010: effect of climate change?

2011 ◽  
Vol 50 (4) ◽  
Author(s):  
Vadlamudi Brahmananda Rao ◽  
Egidio Arai ◽  
Sergio H. Franchito ◽  
Yosio E. Shimabukuro ◽  
S.S.V.S. Ramakrishna ◽  
...  
Keyword(s):  
Climate Change ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Tropical Rainfall Measuring Mission ◽  
Enhanced Vegetation Index ◽  
Tropical Rainfall ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer

En agosto de 2006 la región de Rajasthan registró lluvias excepcionalmente intensas que provocaron severas inundaciones. También, en la temporada del monzón de 2010 Rajasthan recibió fuertes lluvias, aunque no superiores a las de agosto de 2006. Pero los altos valores de precipitación en el año 2010 se produjeron durante toda la temporada del monzón. En el 2006 varias estaciones registraron lluvias intensas de alrededor de 125 mm en 24 horas. Un estudio reciente mostró que, en el futuro, eventos extremos similares tenderán a ocurrir en la India Central, que incluye una parte de Rajasthan. En este trabajo estos eventos son estudiados en el contexto de un probable cambio climatico sobre esta región usando datos de satélites. Para ello fueron usados los índices de vegetación NDVI (Normalized Difference Vegetation Index) y EVI (Enhanced Vegetation Index), derivados del MODIS (Moderate Resolution Imaging Spectroradiometer) y los datos de precipitación del satélite TRMM (Tropical Rainfall Measuring Mission) para 11 años (2000-2010). Ambos productos NDVI y EVI revelaron un crecimiento exuberante de la vegetación sobre el desierto de Rajputana en setiembre de 2006 y en agosto y septiembre de 2010. El análisis de los datos de precipitación y EVI confirmó el crecimiento de la vegetación en 2006 y 2010, mostrando la utilidad de los datos obtenidos por satélite en la captura de los cambios en esta región. En algunos estudios previos se ha señalado que la lluvia sobre la región Oeste de Rajasthan durante la temporada del monzón muestra una importante tendencia creciente. Así, en el futuro, el crecimiento de la vegetación en el desierto Rajputana parece ser muy posible.

scholarly journals Influence of Straw Burning on Urban Air Pollutant Concentrations in Northeast China

2019 ◽  
Vol 16 (8) ◽  
pp. 1379 ◽  
Author(s):  
Zhenzhen Wang ◽  
Jianjun Zhao ◽  
Jiawen Xu ◽  
Mingrui Jia ◽  
Han Li ◽  
...  
Keyword(s):  
Northeast China ◽  
Arable Land ◽  
Pollution Index ◽  
Air Pollutant ◽  
Thermal Anomalies ◽  
Pollutant Concentrations ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Straw Burning ◽  
Moderate Resolution Imaging Spectroradiometer

Northeast China is China’s primary grain production base. A large amount of crop straw is incinerated every spring and autumn, which greatly impacts air quality. To study the degree of influence of straw burning on urban pollutant concentrations, this study used The Moderate-Resolution Imaging Spectroradiometer/Terra Thermal Anomalies & Fire Daily L3 Global 1 km V006 (MOD14A1) and The Moderate-Resolution Imaging Spectroradiometer/Aqua Thermal Anomalies and Fire Daily L3 Global 1 km V006 (MYD14A1) data from 2015 to 2017 to extract fire spot data on arable land burning and to study the spatial distribution characteristics of straw burning on urban pollutant concentrations, temporal variation characteristics and impact thresholds. The results show that straw burning in Northeast China is concentrated in spring and autumn; the seasonal spatial distributions of PM2.5, PM10 andAir Quality Index (AQI) in 41 cities or regions in Northeast China correspond to the seasonal variation of fire spots; and pollutants appear in the peak periods of fire spots. In areas where the concentration coefficient of rice or corn is greater than 1, the number of fire spots has a strong correlation with the urban pollution index. The correlation coefficient R between the number of burned fire spots and the pollutant concentration has a certain relationship with the urban distribution. Cities are aggregated in geospatial space with different R values.

scholarly journals A Climatological Assessment of Intense Desert Dust Episodes over the Broader Mediterranean Basin Based on Satellite Data

2021 ◽  
Vol 13 (15) ◽  
pp. 2895
Author(s):  
Maria Gavrouzou ◽  
Nikolaos Hatzianastassiou ◽  
Antonis Gkikas ◽  
Christos J. Lolis ◽  
Nikolaos Mihalopoulos
Keyword(s):  
Mediterranean Basin ◽  
Eastern Mediterranean ◽  
Mean Value ◽  
Early Spring ◽  
Dust Aerosol ◽  
Ozone Monitoring Instrument ◽  
Central Mediterranean ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer

A satellite algorithm able to identify Dust Aerosols (DA) is applied for a climatological investigation of Dust Aerosol Episodes (DAEs) over the greater Mediterranean Basin (MB), one of the most climatologically sensitive regions of the globe. The algorithm first distinguishes DA among other aerosol types (such as Sea Salt and Biomass Burning) by applying threshold values on key aerosol optical properties describing their loading, size and absorptivity, namely Aerosol Optical Depth (AOD), Aerosol Index (AI) and Ångström Exponent (α). The algorithm operates on a daily and 1° × 1° geographical cell basis over the 15-year period 2005–2019. Daily gridded spectral AOD data are taken from Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua Collection 6.1, and are used to calculate the α data, which are then introduced into the algorithm, while AI data are obtained by the Ozone Monitoring Instrument (OMI) -Aura- Near-UV aerosol product OMAERUV dataset. The algorithm determines the occurrence of Dust Aerosol Episode Days (DAEDs), whenever high loads of DA (higher than their climatological mean value plus two/four standard deviations for strong/extreme DAEDs) exist over extended areas (more than 30 pixels or 300,000 km2). The identified DAEDs are finally grouped into Dust Aerosol Episode Cases (DAECs), consisting of at least one DAED. According to the algorithm results, 166 (116 strong and 50 extreme) DAEDs occurred over the MB during the study period. DAEDs are observed mostly in spring (47%) and summer (38%), with strong DAEDs occurring primarily in spring and summer and extreme ones in spring. Decreasing, but not statistically significant, trends of the frequency, spatial extent and intensity of DAECs are revealed. Moreover, a total number of 98 DAECs was found, primarily in spring (46 DAECs) and secondarily in summer (36 DAECs). The seasonal distribution of the frequency of DAECs varies geographically, being highest in early spring over the eastern Mediterranean, in late spring over the central Mediterranean and in summer over the western MB.

scholarly journals 250-m Aerosol Retrieval from FY-3 Satellite in Guangzhou

2021 ◽  
Vol 13 (5) ◽  
pp. 920
Author(s):  
Zhongting Wang ◽  
Ruru Deng ◽  
Pengfei Ma ◽  
Yuhuan Zhang ◽  
Yeheng Liang ◽  
...  
Keyword(s):  
Mixing Model ◽  
Blue Band ◽  
Aerosol Retrieval ◽  
Aerosol Distribution ◽  
Medium Resolution ◽  
Fine Spatial Resolution ◽  
Yearly Average ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer

Aerosol distribution with fine spatial resolution is crucial for atmospheric environmental management. This paper proposes an improved algorithm of aerosol retrieval from 250-m Medium Resolution Spectral Image (MERSI) data of Chinese FY-3 satellites. A mixing model of soil and vegetation was used to calculate the parameters of the algorithm from moderate-resolution imaging spectroradiometer (MODIS) reflectance products in 500-m resolution. The mixing model was used to determine surface reflectance in blue band, and the 250-m aerosol optical depth (AOD) was retrieved through removing surface contributions from MERSI data over Guangzhou. The algorithm was used to monitor two pollution episodes in Guangzhou in 2015, and the results displayed an AOD spatial distribution with 250-m resolution. Compared with the yearly average of MODIS aerosol products in 2015, the 250-m resolution AOD derived from the MERSI data exhibited great potential for identifying air pollution sources. Daily AODs derived from MERSI data were compared with ground results from CE318 measurements. The results revealed a correlation coefficient between the AODs from MERSI and those from the ground measurements of approximately 0.85, and approximately 68% results were within expected error range of ±(0.05 + 15%τ).

scholarly journals New generation geostationary satellite observations support seasonality in greenness of the Amazon evergreen forests

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hirofumi Hashimoto ◽  
Weile Wang ◽  
Jennifer L. Dungan ◽  
Shuang Li ◽  
Andrew R. Michaelis ◽  
...  
Keyword(s):  
Cloud Cover ◽  
Seasonal Patterns ◽  
Optical Remote Sensing ◽  
Amazon Forest ◽  
Evergreen Forests ◽  
Geostationary Satellites ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
New Generation

AbstractAssessing the seasonal patterns of the Amazon rainforests has been difficult because of the paucity of ground observations and persistent cloud cover over these forests obscuring optical remote sensing observations. Here, we use data from a new generation of geostationary satellites that carry the Advanced Baseline Imager (ABI) to study the Amazon canopy. ABI is similar to the widely used polar orbiting sensor, the Moderate Resolution Imaging Spectroradiometer (MODIS), but provides observations every 10–15 min. Our analysis of NDVI data collected over the Amazon during 2018–19 shows that ABI provides 21–35 times more cloud-free observations in a month than MODIS. The analyses show statistically significant changes in seasonality over 85% of Amazon forest pixels, an area about three times greater than previously reported using MODIS data. Though additional work is needed in converting the observed changes in seasonality into meaningful changes in canopy dynamics, our results highlight the potential of the new generation geostationary satellites to help us better understand tropical ecosystems, which has been a challenge with only polar orbiting satellites.

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