scholarly journals Padrões temporais da precipitação e variabilidade da vegetação sobre a bacia do rio Iriri em anos de ocorrência do El Niño Oscilação Sul (Temporal patterns of precipitation and vegetation variability over Iriri River basin during El Niño/Southern Oscilation)

2019 ◽  
Vol 12 (3) ◽  
pp. 789
Author(s):  
Jefferson Inayan Souto ◽  
Ariadne Reinaldo Trindade ◽  
Paulo Amador Tavares ◽  
Norma Ely Santos Beltrão ◽  
Altem Nascimento Pontes
Keyword(s):  
High Resolution ◽  
River Basin ◽  
El Niño ◽  
El Nino ◽  
Rainy Period ◽  
La Nina ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Very High

Este estudo investiga a evolução temporal do regime pluviométrico para a bacia do rio Iriri, e sua relação com o ciclo de crescimento da vegetação. Dados de precipitação baseados na técnica do CPC Morphing (CMORPH) e dados de índice de vegetação por diferença normalizada (NDVI) pelos sensores AVHRR (Advanced Very High Resolution Radiometer) e MODIS (Moderate Resolution Imaging Spectroradiometer) são analisados para o período de junho de 2009 a maio de 2014. Os resultados confirmam que o ciclo anual de precipitação da bacia do rio Iriri é caracterizado por uma variação intra-sazonal, que é ressoada na cobertura vegetal no decorrer dos meses. Durante o ano com ocorrência de La Niña, os excedentes mais extremos de precipitação mensal foram observados no meio da estação chuvosa (novembro a abril). Embora no período menos chuvoso os totais de precipitação possam não ser os mais altos, o NDVI varia de forma senoidal em decorrência da sazonalidade da região. Épocas chuvosas podem ser distinguidas das estações chuvosas que não sofrem influência de mecanismos de precipitação, examinando seus padrões de pico mensais. Além disso, foi identificado através do NDVI, que o período menos chuvoso pouco influência no índice vegetativo durante a ocorrência dos fenômenos do El Niño Oscilação Sul (ENOS). Estes resultados podem ter implicações importantes para compreensão da dinâmica dos recursos hídricos e provisões naturais para uma bacia composta por áreas protegidas.  A B S T R A C TThis study investigates the temporal evolution of the precipitation regime for the Iriri river basin, and its relation with the vegetation growth cycle. Precipitation data based on CPC Morphing (CMORPH) and normalized differential vegetation index (NDVI) data by AVHRR (Advanced Very High Resolution Radiometer) and MODIS (Moderate Resolution Imaging Spectroradiometer) are analyzed for the period June 2009 to May 2014. The results confirm that the annual precipitation cycle of the Iriri River basin is characterized by an intra-seasonal variation, which is resounded in the vegetation cover during the months. During the year with the occurrence of La Niña, the most extreme surpluses of monthly precipitation were observed in the middle of the rainy season (November to April). Although in the less rainy period precipitation totals may not be higher, the NDVI varies in sinusoidal form due to the seasonality of the region. Rainy seasons can be distinguished from rainy seasons that are not influenced by precipitation mechanisms by examining their monthly peak patterns. In addition, it was identified through the NDVI, that the less rainy period had little influence on the vegetative index during the occurrence of El Niño Southern Oscillation (ENSO) phenomena. These results may have important implications for understanding the dynamics of water resources and natural provisions for a basin composed of protected areas.Keywords: Climatology, remote sensing, vegetation. 

scholarly journals Análisis de la respuesta productiva ante la variabilidad climática en tipos de vegetación exótica y nativa del Desierto Sonorense

2021 ◽  
Vol 20 (1) ◽  
pp. e2021203
Author(s):  
Sofía Choza-Farías ◽  
Jose Raúl Romo-Leon ◽  
Alejandro E. Castellanos-Villegas
Keyword(s):  
El Niño ◽  
El Nino ◽  
La Niña ◽  
Cenchrus Ciliaris ◽  
La Nina ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Para Determinar

La introducción de zacate buffel (Cenchrus ciliaris) para incrementar la producción de forraje ha provocado modificaciones en grandes extensiones de terreno del Desierto Sonorense. Aunado a lo anterior, nuestro conocimiento acerca de la influencia de fenómenos climáticos, como El Niño, sobre la dinámica de productividad en la vegetación, es limitado. El presente trabajo pretende analizar la actividad fotosintética/productiva de la vegetación del Desierto Sonorense en sitios con matorral subtropical y praderas de buffel para determinar diferencias entre fases del fenómeno El Niño Oscilación del Sur (ENSO acrónimo en inglés). Se establecieron sitios de estudio en comunidades vegetales con y sin buffel. Se adquirieron imágenes satelitales del “Moderate Resolution Imaging Spectroradiometer (MODIS)” para derivar el Índice de Vegetación de Diferencia Normalizada (NDVI, acrónimo en inglés) en compuestos de 16 días. Se obtuvo información acerca de las diferentes fases de El Niño desde 2001 hasta 2017. Los resultados sugieren actividad productiva mayor durante la fase Neutra que durante las fases El Niño o La Niña. También, el matorral subtropical presenta mayor actividad productiva que las praderas de buffel en cualquiera de las combinaciones estación-fase analizadas, excepto en La Niña durante el verano

scholarly journals Inter-calibration of polar imager solar channels using SEVIRI

2013 ◽  
Vol 6 (2) ◽  
pp. 3215-3247 ◽  
Author(s):  
J. F. Meirink ◽  
R. A. Roebeling ◽  
P. Stammes
Keyword(s):  
High Resolution ◽  
Spectral Response ◽  
Calibration Method ◽  
Infrared Imager ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Aqua Satellite ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Direct Inter ◽  
Very High

Abstract. Accurate calibration of satellite imagers is a prerequisite for using their measurements in climate applications. Here we present a method for the inter-calibration of geostationary and polar-orbiting imager solar channels based on regressions of collocated near-nadir radiances. Specific attention is paid to correcting for differences in spectral response between instruments. The method is used to calibrate the solar channels of the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on the geostationary Meteosat satellite with corresponding channels of the Moderate Resolution Imaging Spectroradiometer (MODIS) on the polar-orbiting Aqua satellite. The SEVIRI operational calibration is found to be stable during the years 2004 to 2009 but off by −8, −6, and +3.5% for channels 1 (0.6 μm), 2 (0.8 μm), and 3 (1.6 μm), respectively. These results are robust for a range of choices that can be made regarding data collocation and selection, as long as the viewing and illumination geometries of the two instruments are matched. Uncertainties in the inter-calibration method are estimated to be 1% for channel 1 and 1.5% for channels 2 and 3. A specific application of the method is the inter-calibration of polar imagers using SEVIRI as a transfer instrument. This offers an alternative to direct inter-calibration, which in general has to rely on high-latitude collocations. Using this method we have tied MODIS-Terra and Advanced Very High Resolution Radiometer (AVHRR) instruments on National Oceanic and Atmospheric Administration (NOAA) satellites 17 and 18 to MODIS-Aqua for the years 2007 to 2009. While reflectances of the two MODIS instruments differ less than 2% for all channels considered, deviations of an existing AVHRR calibration from MODIS-Aqua reach −3.5 and +2.5% for the 0.8 and 1.6 μm channels, respectively.

scholarly journals Inter-calibration of polar imager solar channels using SEVIRI

2013 ◽  
Vol 6 (9) ◽  
pp. 2495-2508 ◽  
Author(s):  
J. F. Meirink ◽  
R. A. Roebeling ◽  
P. Stammes
Keyword(s):  
High Resolution ◽  
Spectral Response ◽  
Calibration Method ◽  
Infrared Imager ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Aqua Satellite ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Direct Inter ◽  
Very High

Abstract. Accurate calibration of satellite imagers is a prerequisite for using their measurements in climate applications. Here we present a method for the inter-calibration of geostationary and polar-orbiting imager solar channels based on regressions of collocated near-nadir reflectances. Specific attention is paid to correcting for differences in spectral response between instruments. The method is used to calibrate the solar channels of the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on the geostationary Meteosat satellite with corresponding channels of the Moderate Resolution Imaging Spectroradiometer (MODIS) on the polar-orbiting Aqua satellite. The SEVIRI operational calibration is found to be stable during the years 2004 to 2009, but offset by −8, −6, and +3.5 % for channels 1 (0.6 μm), 2 (0.8 μm), and 3 (1.6 μm), respectively. These results are robust for a range of choices that can be made regarding data collocation and selection, as long as the viewing and illumination geometries of the two instruments are matched. Uncertainties in the inter-calibration method are estimated to be 1 % for channel 1 and 1.5 % for channels 2 and 3. A specific application of our method is the inter-calibration of polar imagers using SEVIRI as a transfer instrument. This offers an alternative to direct inter-calibration, which in general has to rely on high-latitude collocations. Using this method we have tied MODIS-Terra and Advanced Very High Resolution Radiometer (AVHRR) instruments on National Oceanic and Atmospheric Administration (NOAA) satellites 17 and 18 to MODIS-Aqua for the years 2007 to 2009. While reflectances of the two MODIS instruments differ less than 2 % for all channels considered, deviations of an existing AVHRR calibration from MODIS-Aqua reach −3.5 and +2.5 % for the 0.8 and 1.6 μm channels, respectively.

scholarly journals Vegetative growth of grasslands based on hyper-temporal NDVI data from the Modis sensor

2016 ◽  
Vol 51 (7) ◽  
pp. 858-868
Author(s):  
Marcos Cicarini Hott ◽  
Luis Marcelo Tavares de Carvalho ◽  
Mauro Antonio Homem Antunes ◽  
Polyanne Aguiar dos Santos ◽  
Tássia Borges Arantes ◽  
...  
Keyword(s):  
Vegetative Growth ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
High Growth ◽  
Growth Index ◽  
Data Series ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Very High

Abstract: The objective of this work was to analyze the development of grasslands in Zona da Mata, in the state of Minas Gerais, Brazil, between 2000 and 2013, using a parameter based on the growth index of the normalized difference vegetation index (NDVI) from the moderate resolution imaging spectroradiometer (Modis) data series. Based on temporal NDVI profiles, which were used as indicators of edaphoclimatic conditions, the growth index (GI) was estimated for 16-day periods throughout the spring season of 2012 to early 2013, being compared with the average GI from 2000 to 2011, used as the reference period. Currently, the grassland areas in Zona da Mata occupy approximately 1.2 million hectares. According to the used methods, 177,322 ha (14.61%) of these grassland areas have very low vegetative growth; 577,698 ha (45.96%) have low growth; 433,475 ha (35.72%) have balanced growth; 39,980 ha (3.29%) have high growth; and 5,032 ha (0.41%) have very high vegetative growth. The grasslands had predominantly low vegetative growth during the studied period, and the NDVI/Modis series is a useful source of data for regional assessments.

Test of a Modified Infrared-Only ABI Cloud Mask Algorithm for AHI Radiance Observations

2016 ◽  
Vol 55 (11) ◽  
pp. 2529-2546 ◽  
Author(s):  
X. Zhuge ◽  
X. Zou
Keyword(s):  
Near Infrared ◽  
Extended System ◽  
Clear Sky ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Cloud Mask ◽  
Very High ◽  
Lower False Alarm Rate ◽  
Infrared Channel

AbstractAssimilation of infrared channel radiances from geostationary imagers requires an algorithm that can separate cloudy radiances from clear-sky ones. An infrared-only cloud mask (CM) algorithm has been developed using the Advanced Himawari Imager (AHI) radiance observations. It consists of a new CM test for optically thin clouds, two modified Advanced Baseline Imager (ABI) CM tests, and seven other ABI CM tests. These 10 CM tests are used to generate composite CMs for AHI data, which are validated by using the Moderate Resolution Imaging Spectroradiometer (MODIS) CMs. It is shown that the probability of correct typing (PCT) of the new CM algorithm over ocean and over land is 89.73% and 90.30%, respectively and that the corresponding leakage rates (LR) are 6.11% and 4.21%, respectively. The new infrared-only CM algorithm achieves a higher PCT and a lower false-alarm rate (FAR) over ocean than does the Clouds from the Advanced Very High Resolution Radiometer (AVHRR) Extended System (CLAVR-x), which uses not only the infrared channels but also visible and near-infrared channels. A slightly higher FAR of 7.92% and LR of 6.18% occurred over land during daytime. This result requires further investigation.

scholarly journals Improved Simulation of Tropical Cyclone Responses to ENSO in the Western North Pacific in the High-Resolution GFDL HiFLOR Coupled Climate Model*

2016 ◽  
Vol 29 (4) ◽  
pp. 1391-1415 ◽  
Author(s):  
Wei Zhang ◽  
Gabriel A. Vecchi ◽  
Hiroyuki Murakami ◽  
Thomas Delworth ◽  
Andrew T. Wittenberg ◽  
...  
Keyword(s):  
High Resolution ◽  
Tropical Cyclone ◽  
El Niño ◽  
North Pacific ◽  
Western North Pacific ◽  
El Nino ◽  
Walker Circulation ◽  
La Niña ◽  
Sea Surface ◽  
La Nina

Abstract This study aims to assess whether, and the extent to which, an increase in atmospheric resolution of the Geophysical Fluid Dynamics Laboratory (GFDL) Forecast-Oriented Low Ocean Resolution version of CM2.5 (FLOR) with 50-km resolution and the High-Resolution FLOR (HiFLOR) with 25-km resolution improves the simulation of the El Niño–Southern Oscillation (ENSO)–tropical cyclone (TC) connections in the western North Pacific (WNP). HiFLOR simulates better ENSO–TC connections in the WNP including TC track density, genesis, and landfall than FLOR in both long-term control experiments and sea surface temperature (SST)- and sea surface salinity (SSS)-restoring historical runs (1971–2012). Restoring experiments are performed with SSS and SST restored to observational estimates of climatological SSS and interannually varying monthly SST. In the control experiments of HiFLOR, an improved simulation of the Walker circulation arising from more realistic SST and precipitation is largely responsible for its better performance in simulating ENSO–TC connections in the WNP. In the SST-restoring experiments of HiFLOR, more realistic Walker circulation and steering flow during El Niño and La Niña are responsible for the improved simulation of ENSO–TC connections in the WNP. The improved simulation of ENSO–TC connections with HiFLOR arises from a better representation of SST and better responses of environmental large-scale circulation to SST anomalies associated with El Niño or La Niña. A better representation of ENSO–TC connections in HiFLOR can benefit the seasonal forecasting of TC genesis, track, and landfall; improve understanding of the interannual variation of TC activity; and provide better projection of TC activity under climate change.

scholarly journals Differential Imprints of Distinct ENSO Flavors in Global Patterns of Very Low and High Seasonal Precipitation

2021 ◽  
Vol 3 ◽  
Author(s):  
Marc Wiedermann ◽  
Jonatan F. Siegmund ◽  
Jonathan F. Donges ◽  
Reik V. Donner
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Spatial Scales ◽  
La Niña ◽  
Seasonal Precipitation ◽  
Central Pacific ◽  
Regional Patterns ◽  
La Nina ◽  
Very High

The effects of El Niño's two distinct flavors, East Pacific (EP) and Central Pacific (CP)/Modoki El Niño, on global climate variability have been studied intensively in recent years. Most of these studies have made use of linear multivariate statistics or composite analysis. Especially the former assumes the same type of linear statistical dependency to apply across different phases of the El Niño–Southern Oscillation (ENSO), which appears not necessarily a justified assumption. Here, we statistically evaluate the likelihood of co-occurrences between very high or very low seasonal precipitation sums over vast parts of the global land surface and the presence of the respective EP and CP types of both, El Niño and La Niña. By employing event coincidence analysis, we uncover differential imprints of both flavors on very low and very high seasonal precipitation patterns over distinct regions across the globe, which may severely affect, among others, agricultural and biomass production or public health. We particularly find that EP periods exhibit statistically significant event coincidence rates with hydrometeorological anomalies at larger spatial scales, whereas sparser patterns emerge along with CP periods. Our statistical analysis confirms previously reported interrelations for EP periods and uncovers additional distinct regional patterns of very high/low seasonal precipitation, such as increased rainfall over Central Asia alongside CP periods that have to our knowledge not been reported so far. Our results demonstrate that a thorough distinction of El Niño and La Niña into their two respective flavors could be crucial for understanding the emergence of strong regional hydrometeorological anomalies and anticipating their associated ecological and socioeconomic impacts.

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