Datasets related to in‐land water for limnology and remote sensing applications: distance‐to‐land, distance‐to‐water, water‐body identifier and lake‐centre co‐ordinates

Abstract

Datasets containing information to locate and identify water bodies have been generated from data locating static‐water‐bodies with resolution of about 300 m (1/360∘) recently released by the Land Cover Climate Change Initiative (LC CCI) of the European Space Agency. The LC CCI water‐bodies dataset has been obtained from multi‐temporal metrics based on time series of the backscattered intensity recorded by ASAR on Envisat between 2005 and 2010. The new derived datasets provide coherently: distance to land, distance to water, water‐body identifiers and lake‐centre locations. The water‐body identifier dataset locates the water bodies assigning the identifiers of the Global Lakes and Wetlands Database (GLWD), and lake centres are defined for in‐land waters for which GLWD IDs were determined. The new datasets therefore link recent lake/reservoir/wetlands extent to the GLWD, together with a set of coordinates which locates unambiguously the water bodies in the database. Information on distance‐to‐land for each water cell and the distance‐to‐water for each land cell has many potential applications in remote sensing, where the applicability of geophysical retrieval algorithms may be affected by the presence of water or land within a satellite field of view (image pixel). During the generation and validation of the datasets some limitations of the GLWD database and of the LC CCI water‐bodies mask have been found. Some examples of the inaccuracies/limitations are presented and discussed. Temporal change in water‐body extent is common. Future versions of the LC CCI dataset are planned to represent temporal variation, and this will permit these derived datasets to be updated.

Global Climate

“…2) Lake surface temperature-L. Carrea In 2019, the worldwide averaged satellite-derived lake surface water temperature (LSWT) warmseason (June-August in the Northern Hemisphere [NH]; December-February 2018/19 in the Southern Hemisphere [SH]; and December-August 2018/19 for the tropical region of 23.5°N-23.5°S) anomaly was +0.025 ± 0.022°C compared with the 1996-2016 base period. The mean warming trend from 1995 to 2019 was 0.21 ± 0.02°C decade −1 , broadly consistent with previous analyses (Woolway et al 2017(Woolway et al , 2018Carrea et al 2019). On average, anomalies (with respect to the 1996-2016 baseline) in 2019 were less positive than in 2018 and in 2017, 0.23°C and 0.19°C less, respectively.…”

“…2.2.). The year 2018 was the warmest since records began in 1995 for European lakes over the June-August (JJA) period (similar to the finding for July-September [JAS] in Carrea et al 2019). The anomaly in Europe in 2019 was more moderately positive than in 2018, due to the contribution of cooler lakes in northern Europe and Ireland (see section 7f for details).…”

“…LSWT time series were derived from satellite observations from the series of Along Track Scanning Radiometers (ATSR) and the Advanced Very High Resolution Radiometers (AVHRR) on MetOp A and B platforms. The retrieval method of MacCallum and Merchant (2012) was applied on image pixels filled with water according to both the inland water dataset of Carrea et al (2015) and a reflectance-based water detection scheme. The satellite-derived LSWT data are spatial averages for each of a total of 927 lakes, for which high-quality temperature records were available through August 2019.…”

State of the Climate in 2016

“…LSWTs were retrieved during the day using the retrieval methods of MacCallum and Merchant (2012) on image pixels filled with water according to both the inland water dataset of Carrea et al (2015) and a reflectance-based water detection scheme (Xu 2006). The satellite temperatures represent mid-morning observations throughout the record.…”

Worldwide alteration of lake mixing regimes in response to climate change

“…Time series data were extracted for the grid point situated closest to the centre of each lake, defined as the maximum distance to land, calculated using the distance-to-land dataset of ref. 59.…”