title: Warming trends of perialpine lakes from homogenised time series of historical satellite and in-situ data.
abstract: The availability of more than thirty years of historical satellite data is a valuable source which could be used as an alternative to the sparse in-situ data. We developed a new homogenised time series of daily day time Lake Surface Water Temperature (LSWT) over the last thirty years (1986-2015) at a spatial resolution of 1km from thirteen polar orbiting satellites. The new homogenisation procedure implemented in this study corrects for the different acquisition times of the satellites standardizing the derived LSWT to 12:00 UTC. In this study, we developed new time series of LSWT for five large lakes in Italy and evaluated the product with in-situ data from the respective lakes. Furthermore, we estimated the long-term annual and summer trends, the temporal coherence of mean LSWT between the lakes, and studied the intra-annual variations and long-term trends from the newly developed LSWT time series. We found a regional warming trend at a rate of 0.017°Cyr-1annually and 0.032°Cyr-1during summer. Mean annual and summer LSWT temporal patterns in these lakes were found to be highly coherent. Amidst the reported rapid warming of lakes globally, it is important to understand the long-term variations of surface temperature at a regional scale. This study contributes a new method to derive long-term accurate LSWT for lakes with sparse in-situ data thereby facilitating understanding of regional level changes in lake's surface temperature.
authors.affiliation: Department of Sustainable Agro-Ecosystems and Bioresources, Research and Innovation Centre, Fondazione Edmund Mach (FEM), S. Michele all'Adige (Trento), Italy; Department of Biology, Chemistry and Pharmacy, Free University, Berlin, Germany. Electronic address: spareeth@gmail.com.
authors.forename: Sajid
authors.initials: S
authors.lastname: Pareeth
authors.affiliation: Optical Remote Sensing-Water group, Istituto per il Rilevamento Elettromagnetico dell'Ambiente IREA - CNR, Milan, Italy.
authors.forename: Mariano
authors.initials: M
authors.lastname: Bresciani
authors.affiliation: ARPA Lombardia, Lecco, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Buzzi
authors.affiliation: Department of Earth and Environmental Sciences, University of Milan-Bicocca, Milan, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Leoni
authors.affiliation: Institute of Earth Sciences, University of Applied Sciences and Arts of Southern Switzerland, Canobbio, Switzerland.
authors.forename: Fabio
authors.initials: F
authors.lastname: Lepori
authors.affiliation: Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Ludovisi
authors.affiliation: CNR - Institute for the Study of Ecosystems, Pallanza (VB), Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Morabito
authors.affiliation: Department of Biology, Chemistry and Pharmacy, Free University, Berlin, Germany; Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany.
authors.forename: Rita
authors.initials: R
authors.lastname: Adrian
authors.affiliation: mundialis GmbH & Co. KG, Bonn, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Neteler
authors.affiliation: Department of Sustainable Agro-Ecosystems and Bioresources, Research and Innovation Centre, Fondazione Edmund Mach (FEM), S. Michele all'Adige (Trento), Italy.
authors.forename: Nico
authors.initials: N
authors.lastname: Salmaso
keywords: Climate change; Homogenisation; LSWT; Perialpine lakes; Remote sensing; Trends