Joan Romero

Simulation and validation of land surface temperature algorithms for MODIS and AATSR data

A database of global, cloud-free, atmospheric radiosounding profiles was compiled with the aim of simulating radiometric measurements from satellite-borne sensors in the thermal infrared. The objective of the simulation was to use Terra/Moderate Resolution Imaging Spectroradiometer (MODIS) and Envisat/Advanced Along Track Scanning Radiometer (AATSR) data to generate split-window (SW) and dual-angle (DA) algorithms for the retrieval of land surface temperature (LST). The database contains 382 radiosounding profiles acquired from land surfaces, with an almost uniform distribution of precipitable water between 0 and 5.5 cm. Radiative transfer calculations were performed with the MODTRAN 4 code for six different viewing angles between 0 and 65. The resulting radiance spectra were integrated with the response filter functions of MODIS bands 31 and 32 and AATSR channels at 11 and 12 μm. Using the simulation database, SW algorithms adapted for MODIS and AATSR data, and DA algorithms for AATSR data were developed. Both types of algorithms are quadratic in the brightness temperature difference, and depend explicitly on the land surface emissivity. These SW and DA algorithms were validated with actual ground measurements of LST collected concurrently with MODIS and AATSR observations in a large, flat and thermally homogeneous area of rice crops located close to the city of Valencia, Spain. The results were not bias and had a standard deviation of around ± 0.5 K for SW algorithms at the nadir of both sensors; the SW algorithm used in the forward view resulted in a bias of 0.5 K and a standard deviation of ± 0.8 K. The least accurate results were obtained in the DA algorithms with a bias close to -2.0 K and a standard deviation of almost ± 1.0 K.

Spanish Mediterranean Huertas: Theory And Reality In The Planning And Management Of Peri-urban Agriculture And Cultural Landscapes

Huertas are distinctive peri-urban agricultural landscapes. Only a few of these spaces remain in Europe. This paper focuses on two of them: the Spanish Mediterranean Huertas of Valencia and Murcia. Despite their cultural, historical and natural value, Huertas face an uncertain future. They are threatened by several confluent processes: a decrease of cultivated land, pollution, infrastructure plans, urban sprawl, profitability loss, low guarantee of generational renewal and abandonment of material heritage. These changes can be explained, as we argue, by analyzing the failure of political planning and management at the metropolitan level. We claim that the conservation of Huertas demands territorial planning at the appropriate scale and a new culture of water, territory and landscape. For traditional Huertas to be kept alive and have a multifunctional character, farmers should be the stewards of such privileged areas. But, in some cases, they will be expected to perform a social role different from the traditional food production activities. A cultural shift is required to conceive the territory not only as a resource and physical support of human activities, but also as an identity frame of reference, collective heritage, culture, history and legacy.