C. Badenas

Emissivity measurements of several soils and vegetation types in the 8–14, μm Wave band: Analysis of two field methods

Abstract The two variants of the box method (with one and two lids) has been rigorously analyzed. As a result of this analysis, a correction factor that takes into account the nonideality of the materials used for the box, as well as its geometry, has been derived A simple method for determining the effective downward atmospheric temperature that uses only the temperature measurement at the zenith also has been proposed. Finally, by using one of the two variants of the box method, 72 in situ emissivity measurements in the 8–14 pin wave-band region of typical vegetation, soils, and rocks of Europe and South America, has been obtained. The use of these data for the ernissivity correction of satellite thermal measurements has been analyzed, and emissivities for the Landsat Thematic Mapper band 6 and NOAA Advanced Very High Resolution Radiometer channels 4 and 5 have been derived.

Meteorological Processes Relevant to Forest Fire Dynamics on the Spanish Mediterranean Coast

Abstract The Valencian region on the Spanish east coast has experienced a significant increase in wildfires in the last 20 years, as have other areas in the Mediterranean basin. Experimental data and modeling results, obtained within several European Commission (EC) projects in southern Europe, indicate that specific mesometeorological circulations develop in these regions during the summer. Analysis of the available evidence further indicates that the resulting flows could be instrumental in the evolution of wildfires in this area. Three situations have been identified that cover the most likely interactions between the synoptic conditions and the regional winds, and their implications for the dynamics of fires in this region. These situations are 1) diurnal cycles of sea and land breezes with a thermal low developing over the Iberian Peninsula; 2) “ponientes,” that is, a Fohn effect producing westerly winds when a traveling low-pressure system crosses the Iberian Peninsula; and 3) combined cycles, when ...

A simple technique for estimating surface temperature by means of a thermal infrared radiometer

Abstract In this Letter we present a simple technique for estimating surface temperatures from data obtained by means of a thermal infrared radiometer. The technique is based simply on the use of a table and a graph, from which cmissivity and atmospheric effects are easily evaluated. The accuracy is better than a tenth of a degree when emissivity and atmospheric radiance arc known.

Some improvements on the processes to obtain accurate maps of sea surface temperature from AVHRR raw data transmitted in real time. Part 1: HRPT images

Abstract In this paper we have developed some improvements on the commonly used methodologies in order to obtain accurate maps of sea surface temperature (SST). These improvements permit us: (1) to calibrate without bias AVHRR channels including non-linear corrections; (2) to get geometrically corrected maps for the complete scan width of AVHRR (3000 km) with a subpixel accuracy; (3) to detect clouds over the sea; and (4) to make atmospheric and emissivity correction for all zenith angles from nadir to the outermost off-nadir view of AVHRR images (68.9 ) and for different types of atmospheres. The theoretical base of the improvements used is detailed in each section, and an example is also included in each section in order to better explain how they are applied in a practical situation. The methodologies developed here can be profitable for any user interested in accurate retrievals of SST such as meteorologists, climatologists and oceanographers.

Review and improvement of an algorithm for determining emissivity of a heterogeneous cavity in thermal infrared remote sensing

Abstract The algorithm for determination of effective emissivity of a cavity developed by Caselles and Sobrino ( Remote Sensing of Environment, 29, 135-146) has been proved to violate Kirchhoff s law, and to give low values of emissivity. In this paper a Kirchhoff s law-observing algorithm is developed, and comparison of the two algorithms is performed. Emissivity retrieved by our algorithm can be 1.5 times larger than emissivity calculated with the algorithm of Caselles and Sobrino. Although no significant difference is found between them for almost blackbodies (vegetated surfaces with large values of ground and vegetation emissivity), for other kind of terrestrial surfaces (bare soils and rocks) difference between the two algorithms can be up to 0.05 for a typical cavity.