Spatial representativeness of ground-based solar radiation measurements-Extension to the full Meteosat disk

Abstract

The spatial representativeness of a point measurement of surface solar radiation (SSR) of its larger-scale surrounding, e.g., collocated grid cell, is a potential source of uncertainty in the validation of climate models and satellite products. Here we expand our previous study over Europe to the entire Meteosat disk, covering additional climate zones in Africa, the Middle east, and South America between −70• to 70• East and −70• to 70• North. Using a high-resolution (0.03 [2001][2002][2003][2004][2005], we quantify the spatial subgrid variability in grids of 1 • and 3• resolution and the spatial representativeness of 887 surface sites with respect to site-centered surroundings of variable size. In the multiannual mean the subgrid variability is the largest in some mountainous and coastal regions but varies seasonally due to changes in the Intertropical Convergence Zone location. The absolute mean representation errors at the surface sites with respect to surroundings of 1 • and 3• are on average 1-2% (3 W m −2 ) and 2-3% (4 W m −2 ), respectively. The majority of sites are found to be representative within the in situ measurement accuracy. We show that their site-specific representativeness can be reliably approximated by the subgrid variability in a fixed grid (1 • ). The subgrid variability in turn is only moderately reduced when computed from coarser grid data, typically the only data available in areas not covered by the 0.03• resolved Meteosat disk. Together, this paves the way to a fully global assessment of site-specific spatial representativeness.

Evaluation of Radiation Components in a Global Freshwater Model with Station-Based Observations

“…The median E MAE for S↓ from this study is about three times higher (10 to 15 Wm −2 , Figure 6) than those of Hakuba et al [26]. Obviously, due to the heterogeneity of land surface characteristics, the representativeness of downward and upward radiation fluxes differs fundamentally.…”

“…In contrast to the downward components, which show a reasonable representativeness of station measurements at the grid cell level [26], upward measurements have a small footprint and thus a high uncertainty in terms of representativeness for the grid cell.…”

Trends of surface solar radiation in unforced CMIP5 simulations

“…Note that point data (ground‐based measurements) are compared with grid box means (CMIP5, CERES); thus, differences may be rather an upper limit. We are, however, not aware of any dedicated quantitative study comparing temporal variability at a measurement site and averaged over its larger surrounding (for spatial representativeness see Hakuba et al [, ]).…”

The Global Energy Balance Archive (GEBA) version 2017: a database for worldwide measured surface energy fluxes

“…More recently, with the advent of high-quality TOA satellite observations from the Clouds and the Earth's Radiant Energy System (CERES) program, CERES rather than ERBE data have been combined with GEBA data to improve the quantification of the atmospheric shortwave absorption (Hakuba et al, 2014b). To estimate potential uncertainties induced by the scale mismatch between the gridded 1 • TOA satellite data from CERES and the surface point observations from GEBA, the representativeness of the GEBA sites for their larger-scale surroundings has been thoroughly assessed (Hakuba et al, 2013(Hakuba et al, , 2014a. Based on the collocated GEBA and CERES observations, the atmospheric shortwave absorption over Europe has been estimated by Hakuba et al (2014b) at 23 % of the TOA insolation.…”