Influence of climate shifts on decadal variations of surface solar radiation in Alaska

From past studies it has been known that the Pacific Decadal Oscillation (PDO) shifted toward a positive mode in 1976 and a new climate regime occurred that produced a warming of the mean annual and seasonal temperatures and associated increases in cloud cover and precipitation in the North Pacific including Alaska. In this study, this climate shift is examined with regard to the variations in surface solar radiation before and after 1976 during the period 1961–2005. The results show greatest changes occurring in the southeast region in winter with a significant rise of 1.67% y

Modelli fisici per la matematica: trisettori

Questo articolo presenta alcune macchine matematiche per la soluzione del classico problema della trisezione dell’angolo. Per esempio, tra gli strumenti scelti vi è quello riferito a Kempe, ma anche a Pascal e a Ceva. Lo studio di questi strumenti è stato svolto come primo passo per la costruzione di un percorso didattico laboratoriale per la scuola secondaria.This paper describes some mathematical machines for solving the well-known classical problem of angle trisection. For instance, we refer to Kempe’s trisector, as well as to Pascal and Ceva’s tools. The study of these machines was the first step of an educational project, aiming to propose laboratory sessions on this topic to secondary school student

Sensitivity to soil moisture by applying a model-based polarimetric decomposition to a time-series of airborne radar L-band data over an agricultural area

In this paper, the sensitivity to soil moisture variations over an agricultural area characterized by different vegetation covers has been investigated. The objectives of the study were identifying the correlation of one or more polarimetric parameters with soil moisture changes over time. In this respect, we assessed the possibility to separate three individual scattering mechanisms (i.e., surface, double-bounce, volume) offered by radar polarimetry. We apply a model-based polarimetric decomposition to a time-series of high-resolution SAR data collected at L-band by the NASA/JPL UAVSAR airborne radar over the Yucatan Lake region in Louisiana, USA. Thirteen flights were considered and five regions of interest characterized by different surface properties and vegetation covers were selected. The temporal evolution of different polarimetric parameters, obtained by applying the Freeman-Durden decomposition, is reported and discussed. The polarimetric features were compared not only to the NDVI variations derived from Sentinel-2 satellite, but also to precipitation data recorded by a nearby precipitation station as well as to the Soil Water Index derived from the ASCAT sensor onboard Metop satellites. The improved sensitivity of the polarimetric features with respect to the single backscattering coefficients at different polarizations was also assessed

Joint analysis of Sentinel-1 and SAOCOM data sensitivity to soil moisture content over an agricultural area

A joint analysis of C-band dual-pol Sentinel-1A data and L-band full-pol SAOCOM-1A data is presented to investigate their sensitivity to soil moisture over an agricultural area located near the city of Monte Buey in the Córdoba Province, Argentina. The temporal evolution of the backscattering coefficient σ0 at different polarizations is analyzed with respect to in-situ soil moisture measurements collected during a field campaign as well as data recorded by ground stations from a permanent network. Sensitivity to vegetation parameters is also discussed. The fully polarimetric electromagnetic model developed at Tor Vergata University is used to compare simulated and measured σ0 for corn fields