31 Jul 2023
 | 31 Jul 2023
Status: this preprint is currently under review for the journal ESSD.

Shortwave and longwave components of the surface radiation budget measured at the Thule High Arctic Atmospheric Observatory, Northern Greenland

Daniela Meloni, Filippo Calì Quaglia, Virginia Ciardini, Annalisa Di Bernardino, Tatiana Di Iorio, Antonio Iaccarino, Giovanni Muscari, Giandomenico Pace, Claudio Scarchilli, and Alcide di Sarra

Abstract. The Arctic climate is influenced by the interaction of shortwave (SW) and longwave (LW) radiation with the atmosphere and the surface. The comprehensive evolution of the Surface Radiative Fluxes (SRF) on different time scales is of paramount importance to understanding the complex mechanisms governing the Arctic climate. However, only a few sites located in the Arctic region provide long-term time series of SRF allowing for capturing the seasonality of atmospheric and surface parameters and carrying out validation of satellite products and/or reanalyses.

This paper presents the daily and monthly SRF record collected at the Thule High Arctic Atmospheric Observatory (THAAO, 76.5° N, 68.8° W), in North-Western Greenland. The downwelling components of the SW (DSI) and the LW (DLI) irradiances have been measured at THAAO since 2009, while the collection of the upwelling SW (USI) and LW (ULI) irradiance was started in 2016, together with additional measurements, such as e.g., meteorological parameters and column water vapour. The datasets of DSI (Meloni et al., 2022a;, USI (Meloni et al., 2022b;, DLI (Meloni et al., 2022c;, ULI (Meloni et al., 2022d;, and near surface air temperature (Muscari et al., 2018;, can be accessed through the THAAO web site (

DSI is absent (solar zenith angle≥90°) from 29 October to 13 February, assuming maxima in June (monthly mean of 277.0 Wm-2), when it is about half of the total incoming irradiance. The USI maximum occurs in May (132.4 Wm-2) due to the combination of moderately high DSI values and high albedo. The shortwave surface albedo (A) assumes an average of 0.16 during summer, when the surface is free of snow. Differently, during months of snow-covered surface, when solar radiation allows estimating A, its values are greater than 0.6. A large interannual variability is observed in May and September, months characterized by rapidly changing surface conditions, which appear to be linked with air temperature anomalies.

DLI and ULI maxima occur in July and August, and minima in February and March. ULI is always larger than DLI and shows a wider annual cycle. ULI is well described by a fourth-order polynomial fit to the air temperature (R2>0.99 for monthly data and R2>0.97 for daily data).

The surface radiation budget (SRB) is positive from April to August, when absorption of solar radiation exceeds the infrared net cooling, with a maximum value of 153.2 Wm-2 in June. From November to February, during the polar night, the LW net flux varies between -34.5 and -43.0 Wm-2. In March and September, the negative LW net flux overcomes the positive SW contribution, producing a negative SRB.

THAAO measurements show clear evidence of the influence of several regional weather/climate events, which appear strongly linked with SRF anomalies. These anomalies are found for example during summer 2012, when a large ice melting event took place over Greenland, and during winter 2019–2020, extraordinarily cold in the Arctic region.

Daniela Meloni et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on essd-2023-162', Anonymous Referee #1, 25 Aug 2023
  • RC2: 'Comment on essd-2023-162', Anonymous Referee #2, 25 Aug 2023

Daniela Meloni et al.

Daniela Meloni et al.


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Short summary
Solar and infrared radiation are key factors in determing Arctic climate. Only few sites in the Arctic perform long-term measurements of the surface radiation budget. At the Thule High Arctic Atmospheric Observatory (THAAO, 76.5° N, 68.8° W), in Northern Greenland, solar and infrared irradiance measurements started in 2009. These data are of paramount importance to study the impact of the atmospheric (mainly clouds and aerosols) and surface (albedo) parameters on the surface radiation budget.