Processing historical NOAA AVHRR data with precise geometric correction

We published a new article in MDPI Remote Sensing journal on new method to accurately process time series of AVHRR Local Area Coverage (LAC) data. You can read the entire paper here:

We developed a new workflow which can read all the AVHRR LAC level 1B  data over all the NOAA satellites, calibrate them, applied clock drift corrections, geometrically correct them using automated feature matching technique called SIFT and finally applied split window technique to the thermal bands to derive lake surface water temperature as a case study. We found that the SIFT based geometric correction followed by gcp filter using m.gcp.filter addon in GRASS GIS 7 is very efficient in performing image to image corrections on thousands of images.

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Speed up matrix median calculation in R

I decided to write this short post after wasting some hours to optimize my R code to make median calculation possible for some million of values. Hope it can help someone else. The problem is easy to explain and to solve. Median is a very expensive operation to compute as it implies ordination of values, therefore sometimes may considerably slow down the code running time.
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My example makes use of a list of matrices, like this:

pippo <- list(matrix(runif(100000),ncol=5),matrix(runif(100000),ncol=5),matrix(runif(100000),ncol=5),matrix(runif(100000),ncol=5),matrix(runif(100000),ncol=5),matrix(runif(100000),ncol=5),matrix(runif(100000),ncol=5),matrix(runif(100000),ncol=5),matrix(runif(100000),ncol=5),matrix(runif(100000),ncol=5))
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Landscape configuration and composition analysis with GRASS GIS 7

Landscape configuration and composition metrics summarize the structure of the landscape in a determined area and time. These metrics  are closely related to the occurring ecological patterns (e.g. species distribution) and processes (e.g. biogeochemical cycle). As a consequence they are often used as predictors in ecological modelling. Thereby, a researcher who wants to test whether or not the landscape structure has an influence on the studied ecological properties (i.e., species richness, ecosystem functioning, conservation status, energy flow, animal movements, species dispersion, etc), need a tool to derive them from a Land Use or Land Cover (LULC) map.
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Studying spatio-temporal changes in phytoplankton by means of remote sensing

The ocean is teeming with microscopic organisms called phytoplankton. Phytoplankton comprises two main groups: photosynthetic cyanobacteria and the single-celled algae that drift in the sunlit top layers of oceans. They provide food, directly or indirectly for virtually every other marine creature. They emit much of the oxygen that permeates our atmosphere and their fossilized remains, buried and compressed by geological forces, are transformed into oil. In addition, they play a huge role in the cycling of carbon dioxide from the atmosphere to the biosphere and back, cycling that helps to control Earth’s climate [1].air jordan 1

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When the Indian tiger pays a visit to villages!!!!!

In summer 2009, we conducted a field work in Kanha Tiger reserve, as part of the ground truthing exercise to study the effects of eco-tourism and to understand the zone of interaction around the park for better management. It was an afternoon on a scorching hot day, the open jeep on which we were exploring the core area, suddenly stopped. Sensing wildlife nearby, I started looking around. Everyone whispered Tiger! Tiger!; still I cannot see it. After few seconds, looking at where the cameras around me are zoomed, I realised that the mighty Tigress was resting right ahead on the track blocking us.Order nike air max

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Biological diversity is raising, for scale’s sake!

Estimating the current trend in direction of biological diversity (or ‘biodiversity’) is not as easy as it looks.
Like the assessment of CO2 concentration in the atmosphere, biological diversity status is key in understanding the amplitude of anthropogenic impact on natural systems and to inform policy.
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Roads – dangerous slopes for biodiversity

The street is a concrete jungle, Hector Lavoe echoed this in his famous latin song named Juanito Alimaña. This description falls short if we think about the current situation, where according to the World Health Organization, each year more than 1.27 million people die in traffic-related accidents and more than 90% of these deaths occur in developing countries.
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Processing ERA-Interim dataset in ncdf using GDAL and GRASS GIS

Processing big data efficiently has become a necessity of the hour in ecological and climate change research. Now there are enormous number of public data available online, which demands high level of processing capabilities too.  In this post I will show you how we can process ESA-Interim data which is global atmospheric reanalysis from 1979 to present developed by ECMWF.

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