Influence of Thermodynamic State Changes on Surface Cloud Radiative Forcing in the Arctic: A Comparison of Two Approaches Using Data From AFLUX and SHEBA

Stapf, Johannes; Ehrlich, André; Wendisch, Manfred

doi:10.1029/2020jd033589

Cited by 12 publications

(4 citation statements)

References 49 publications

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“…The ACLOUD campaign and the Airborne measurements of radiative and turbulent FLUXes of energy and momentum in the Arctic boundary layer (AFLUX) campaign are both parts of Arctic Amplification: Climate Relevant Atmospheric and Surface Processes and Feedback Mechanisms (AC)3, which aims to observe clouds, aerosol particles, and some surface properties with two aircrafts, Polar 5 and Polar 6 in ACLOUD [22], and one aircraft, Polar5 in AFLUX [23]. The ACLOUD campaign was conducted from 23 May to 26 June 2017, which was exactly in the melting season.…”

Section: Aircraft Measurementsmentioning

confidence: 99%

Arctic Sea Ice Albedo Estimation from Fengyun-3C/Visible and Infra-Red Radiometer

Sun,

Guan

2024

Remote Sensing

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The sea ice albedo can amplify global climate change and affect the surface energy in the Arctic. In this paper, the data from Visible and Infra-Red Radiometer (VIRR) onboard Fengyun-3C satellite are applied to derive the Arctic sea ice albedo. Two radiative transfer models, namely, 6S and FluxNet, are used to simulate the reflectance and albedo in the shortwave band. Clear sky sea ice albedo in the Arctic region (60°~90°N) from 2016 to 2019 is derived through the physical process, including data preprocessing, narrowband to broadband conversion, anisotropy correction, and atmospheric correction. The results are compared with aircraft measurements and AVHRR Polar Pathfinder-Extended (APP-x) albedo product and OLCI MPF product. The bias and standard deviation of the difference between VIRR albedo and aircraft measurements are −0.040 and 0.071, respectively. Compared with APP-x product and OLCI MPF product, a good consistency of albedo is shown. And analyzed together with melt pond fraction, an obvious negative relationship can be seen. After processing the 4-year data, an obvious annual trend can be observed. Due to the influence of snow on the ice surface, the average surface albedo of the Arctic in March and April can reach more than 0.8. Starting in May, with the ice and snow melting and melt ponds forming, the albedo drops rapidly to 0.5–0.6. Into August, the melt ponds begin to freeze and the surface albedo increases.

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Section: Aircraft Measurementsmentioning

confidence: 99%

Arctic Sea Ice Albedo Estimation from Fengyun-3C/Visible and Infra-Red Radiometer

Sun,

Guan

2024

Remote Sensing

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“…In this paper, data obtained during low-level flight sections are analyzed, either below clouds or in cloud-free conditions. During AFLUX, low-level data spanning 6 h (corresponding to a horizontal distance of 1400 km) were gathered at an altitude below 100 m (average 73 m) (Stapf et al, 2021b). During ACLOUD, 16 h of measurements at an altitude of less than 250 m (average 80 m), covering a total distance of 3700 km, was collected (Stapf et al, 2019).…”

Section: Measurements and Radiative Transfer Simulationsmentioning

confidence: 99%

Effects of variable ice–ocean surface properties and air mass transformation on the Arctic radiative energy budget

Wendisch,

Stapf,

Becker

et al. 2023

Atmos. Chem. Phys.

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Abstract. Low-level airborne observations of the Arctic surface radiative energy budget are discussed. We focus on the terrestrial part of the budget, quantified by the thermal-infrared net irradiance (TNI). The data were collected in cloudy and cloud-free conditions over and in the vicinity of the marginal sea ice zone (MIZ) close to Svalbard during two aircraft campaigns conducted in the spring of 2019 and in the early summer of 2017. The measurements, complemented by ground-based observations available from the literature and radiative transfer simulations, are used to evaluate the influence of surface type (sea ice, open ocean, MIZ), seasonal characteristics, and synoptically driven meridional air mass transports into and out of the Arctic on the near-surface TNI. The analysis reveals a typical four-mode structure of the frequency distribution of the TNI as a function of surface albedo, the sea ice fraction, and surface brightness temperature. Two modes prevail over sea ice and another two over open ocean, each representing cloud-free and cloudy radiative states. Characteristic shifts and modifications of the TNI modes during the transition from winter to spring and early summer conditions are discussed. Furthermore, the influence of warm air intrusions (WAIs) and marine cold-air outbreaks (MCAOs) on the near-surface downward thermal-infrared irradiances and the TNI is highlighted for several case studies. It is concluded that during WAIs the surface warming depends on cloud properties and evolution. Lifted clouds embedded in warmer air masses over a colder sea ice surface, decoupled from the ground by a surface-based temperature inversion, have the potential to warm the surface more strongly than near-surface fog or thin low-level boundary layer clouds because of a higher cloud base temperature. For MCAOs it is found that the thermodynamic profile of the southward-moving air mass adapts only slowly to the warmer ocean surface.

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“…The comparison of the different CRE results is further hampered by the inconsistent consideration of the cloud impact on the thermodynamic profiles and on the surface albedo (Stapf et al, 2021a(Stapf et al, , 2020. Some studies applied the radiative-transfer approach, where the cloud-free state is simulated by only removing the cloud, neglecting adjustments of the thermodynamic profiles and the surface albedo between cloudy and cloud-free conditions (e. g., Intrieri et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

“…The resulting differences between the two approaches can be significant. Stapf et al (2021a) demonstrated that, due to the decreased surface temperature, the TIR CRE obtained during SHEBA would be up to 25 W m −2 lower in autumn if the measurement-based approach was used. In summer, no significant differences were found.…”

Section: Introductionmentioning

confidence: 99%

Airborne observations of the surface cloud radiative effect during different seasons over sea ice and open ocean in the Fram Strait

Becker

Ehrlich

Schäfer

et al. 2023

Preprint

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Abstract. This study analyzes the surface cloud radiative effect (CRE) obtained during airborne observations of three campaigns in the Arctic north-west of Svalbard. The surface CRE quantifies the potential of clouds to modify the radiative energy budget of the surface and is calculated by combining broadband radiation measurements during low-level flight sections in mostly cloudy conditions with radiative transfer simulations of cloud-free conditions. The significance of surface albedo changes due to the presence of clouds is demonstrated and this effect is considered in the cloud-free simulations. The observations are discussed with respect to differences of the CRE between sea ice and open ocean surfaces, and between the seasonally different campaigns. The results indicate that the CRE depends on both cloud, illumination, surface, and thermodynamic properties. The solar and thermal-infrared (TIR) component of the CRE are analyzed separately and in combination. The inter-campaign differences of the solar CRE are dominated by the seasonal cycle of the solar zenith angle, with the largest cooling effect in summer. The lower surface albedo causes a larger solar cooling effect over open ocean than over sea ice, which amounts to −259 W m−2 (−108 W m−2) and −65 W m−2 (−17 W m−2), respectively, during summer (spring). Independent of campaign and surface type, the TIR CRE is only weakly variable and shows values around 75 W m−2. In total, clouds show a cooling effect over open ocean during all campaigns. In contrast, clouds over sea ice exert a warming effect to the surface, which neutralizes during mid-summer. Given the seasonal cycle of the sea ice distribution, these results imply that clouds in the Fram Strait region cool the surface during the sea ice minimum in late summer, while they warm the surface during the sea ice maximum in spring.

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Influence of Thermodynamic State Changes on Surface Cloud Radiative Forcing in the Arctic: A Comparison of Two Approaches Using Data From AFLUX and SHEBA

Cited by 12 publications

References 49 publications

Arctic Sea Ice Albedo Estimation from Fengyun-3C/Visible and Infra-Red Radiometer

Arctic Sea Ice Albedo Estimation from Fengyun-3C/Visible and Infra-Red Radiometer

Effects of variable ice–ocean surface properties and air mass transformation on the Arctic radiative energy budget

Airborne observations of the surface cloud radiative effect during different seasons over sea ice and open ocean in the Fram Strait

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