0000000000204748
AUTHOR
M.j. López García
A multi-temporal study of chlorophyll-a concentration in the Albufera lagoon of Valencia, Spain, using Thematic Mapper data
Abstract A multi-temporal study of chlorophyll-a concentration, has been made by means of Landsat-5 Thematic Mapper (TM) band 1 (0·45-0·52μm) in the Albufera of Valencia, a hypertrophic lagoon of shallow depth. The relationship between this parameter and satellite data was set up from in situ measurements and concurrent satellite data obtained in a campaign from 22 July 1985. This relation has been applied to images of different dates by using a simple procedure of correction, which is based on the use of selected surfaces whose ground reflectance is assumed to be constant with time. Good results were obtained and chlorophyll-a concentrations have been determined with an error of 20 per cen…
Efectos del ácido valproico sobre el desarrollo sexual
Introducción: La utilización del ácido valproico se ha relacionado enniñas y adolescentes con efectos adversos endocrinológicos: ganancia de peso e hiperandrogenismo. Además, enmujeres adultas se han descrito ovarios poliquísticos e hiperinsulinismo. En varones apenas se han estudiado losposibles efectos adversos endocrinológicos. Objetivos: El objetivo de este estudio fue evaluar los efectos del ácido valproico en el desarrollo puberal en chicas y en chicosepilépticos, en especial relación con su posible efecto hiperandrogénico. Material y métodos: Se incluyeron 23 chicas y 15 chicos (entre 8 y 16 años)epilépticos, tratados con ácido valproico, se compararoncon 15 niñas control y 10 niños …
Recent trends of SST in the Western Mediterranean basins from AVHRR Pathfinder data (1985-2007)
Climate change in the Mediterranean region cannot be understood without taking into account changes in the Mediterranean Sea, which is an important source of moisture and heat for the Mediterranean climate system. Many research papers have been published in the last two decades increasing our knowledge about long-term trends and inter-annual variability of temperature and salinity in the Western Mediterranean. Although recent changes have been better documented, there remain uncertainties because different results are obtained depending on the period of time analyzed or the geographic region selected. This paper analyses the regional, seasonal and decadal variability of sea surface temperat…
Mapping burns and natural reforestation using thematic Mapper data
Abstract Remote sensing techniques are specially suitable to detect and to map areas affected by forest fires. In this work, Landsat 5 Thematic Mapper (TM) data has been used to study a number of forest fires that occurred in the province of Valencia (Spain) and to monitor the vegetation regeneration over burnt areas. A reference area (non‐burnt forest) was established to assess the change produced by fire. The radiance in the thermal band (10.4–12.5 μm) and the normalized difference in reflectance between near 1R (0.76–0.90 μm) and middle IR (2.08–2.35 μm) were the most suitable parameters to map burnt areas. This index can also be used for monitoring vegetation regeneration in burnt areas…
An alternative simple approach to estimate atmospheric correction in multitemporal studies
Abstract Studies that use multitemporal images require the conversion of original digital data into the corresponding physical magnitudes. Atmospheric correction is one of the most important steps in this process, which is usually undertaken using atmospheric radiative transfer models. The main difficulty in these models is the need of atmospheric input data which are not usually available. An alternative approach to atmospheric correction is proposed in this Letter. It is based on the idea that the atmospheric effects over two or more dates can be determined in a relative way, by using the apparent reflectance values of surfaces whose ground reflectance can be considered unchangeable with …
Analysis of the heat-island effect of the city of Valencia, Spain, through air temperature transects and NOAA satellite data
The aim of this paper is to analyze the heat-island effect of the city of Valencia, Spain, by means of the traditional technique (transects of the air temperature measured from a car) and by means of NOAA satellite thermal images. The analysis includes the nights of 27 and 28 February 1988, on which a light radiative frost occurred. Satellite images were corrected for the emissivity effect by defining an effective emissivity, which was obtained from the emissivity values of the asphalt, walls and roofs of the buildings, and from the proportion of these elements in each pixel. By comparing air temperature values with corrected NOAA data, we have observed that the value of the heat-island eff…