Ice Nucleating Particles in Northern Greenland: annual cycles, biological contribution and parameterizations

Sze, Kevin Cheuk Hang; Wex, Heike; Hartmann, Markus; Skov, Henrik; Maßling, Andreas; Villanueva, Diego; Stratmann, Frank

doi:10.5194/acp-2022-761

Cited by 4 publications

(4 citation statements)

References 36 publications

(42 reference statements)

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“…INP data are available at https://doi.org/10. 1594/PANGAEA.953838 (Sze et al, 2023a) and https://doi.org/10. 1594/PANGAEA.953839 (Sze et al, 2023b).…”

Section: Competing Interestsmentioning

confidence: 99%

Ice-nucleating particles in northern Greenland: annual cycles, biological contribution and parameterizations

et al. 2023

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Abstract. Ice-nucleating particles (INPs) can initiate ice formation in clouds at temperatures above −38 ∘C through heterogeneous ice nucleation. As a result, INPs affect cloud microphysical and radiative properties, cloud lifetime, and precipitation behavior and thereby ultimately the Earth's climate. Yet, little is known regarding the sources, abundance and properties of INPs, especially in remote regions such as the Arctic. In this study, 2-year-long INP measurements (from July 2018 to September 2020) at Villum Research Station in northern Greenland are presented. A low-volume filter sampler was deployed to collect filter samples for offline INP analysis. An annual cycle of INP concentration (NINP) was observed, and the fraction of heat-labile INPs was found to be higher in months with low to no snow cover and lower in months when the surface was well covered in snow (> 0.8 m). Samples were categorized into three different types based only on the slope of their INP spectra, namely into summer, winter and mix type. For each of the types a temperature-dependent INP parameterization was derived, clearly different depending on the time of the year. Winter and summer types occurred only during their respective seasons and were seen 60 % of the time. The mixed type occurred in the remaining 40 % of the time throughout the year. April, May and November were found to be transition months. A case study comparing April 2019 and April 2020 was performed. The month of April was selected because a significant difference in NINP was observed during these two periods, with clearly higher NINP in April 2020. In parallel to the observed differences in NINP, also a higher cloud-ice fraction was observed in satellite data for April 2020, compared to April 2019. NINP in the case study period revealed no clear dependency on either meteorological parameters or different surface types which were passed by the collected air masses. Overall, the results suggest that the coastal regions of Greenland were the main sources of INPs in April 2019 and 2020, most likely including both local terrestrial and marine sources.

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“…INP data are available at https://doi.org/10. 1594/PANGAEA.953838 (Sze et al, 2023a) and https://doi.org/10. 1594/PANGAEA.953839 (Sze et al, 2023b).…”

Section: Competing Interestsmentioning

confidence: 99%

Ice-nucleating particles in northern Greenland: annual cycles, biological contribution and parameterizations

et al. 2023

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“…Significant progress has been made during the last years regarding the characterization of local Arctic ice-nucleating particles (INPs) (Creamean et al, 2018(Creamean et al, , 2019(Creamean et al, , 2022Zeppenfeld et al, 2019;Wex et al, 2019;Hartmann et al, 2021;Li et al, 2022;Sze et al, 2022). In a remote environment such as the Arctic where particle concentrations are generally low, local production of biogenic INPs contributes significantly to the INP population in summer (Creamean et al, 2018;Wex et al, 2019) and influence ice nucleation in the lower troposphere.…”

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confidence: 99%

Annual cycle of aerosol properties over the central Arctic during MOSAiC 2019–2020 — light-extinction, CCN, and INP levels from the boundary layer to the tropopause

Ansmann

Ohneiser

Engelmann

et al. 2023

Preprint

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Abstract. Continuous height-resolved observations of aerosol profiles over the central Arctic throughout a full year were performed for the first time. Such measurements covering aerosol layering features are required for an adequate modeling of Arctic climate conditions, especially with respect to a realistic consideration of cloud formation and here, in particular, of ice nucleation processes. MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) offered this favorable opportunity to monitor aerosol and clouds over the central Arctic over all four seasons, from October 2019 to September 2020. In this article, a summary of MOSAiC lidar observations aboard the icebreaker Polarstern of tropospheric aerosol products is presented. Particle optical properties, i.e., light-extinction profiles and aerosol optical thickness (AOT), and estimates of cloud-relevant aerosol properties (cloud condensation nucleus, CCN, and ice-nucleating particle concentrations, INPs) are discussed, separately for the lowest part of the troposphere (near the surface at 250 m height), within the lower free troposphere (2000 m height), and regarding INPs also near the tropopause (cirrus level, 8–10 km height). In situ observations of the particle number concentration and INPs aboard Polarstern are included in the study. Strong differences between summer and winter aerosol conditions were found. During the winter months (Arctic haze period) a strong decrease of the aerosol light extinction coefficient (532 nm) with height up to about 4–5 km height was found with values of 20–100 Mm-1 close to the surface and an order of magnitude less at 1500–2000 m height. Lofted aged wildfire smoke layers caused a re-increase of the aerosol concentration from the middle troposphere up to stratospheric heights and were continuously observable from October 2019 to May 2020. In summer (June to August 2020), much lower particle extinction coefficients, frequently as low as 1–5 Mm-1, were observed. Aerosol removal, controlled by cloud scavenging processes (widely suppressed in winter, very efficient in summer) in the lowermost 1–2 km of the atmosphere, seem to be the main reason for the strong differences between winter and summer aerosol conditions. In line with this pronounced annual cycle in the aerosol optical properties, CCN concentrations (0.2 % supersaturation level) ranged from 50–500 cm-3 in the atmospheric boundary layer (ABL) in winter and 1–40 cm-3 in summer. In the lower free troposphere, however, the CCN level was roughly constant throughout the year with values mostly from 30–100 cm-3. A strong contrast between winter to summer was also given in terms of ABL INPs which control ice production in low-level clouds. INP concentration of 0.01–0.2 L-1 prevailed in the ABL in winter at typical ice-nucleating cloud temperatures of -25 °C and assuming soil dust as the main INP type, and were roughly 2 orders of magnitude lower in the ABL in summer at typical cloud top temperatures of -10 °C. In the summer ABL, marine aerosol (biogenic components) is most probably the main INP type, continental INP contributions (e.g., soil dust INPs) are suppressed by efficient wet removal during long-range transport. A strong reduction in the INP population was also found in the lower free troposphere at 2000 m height from winter to summer (2 orders of magnitude), mostly due to the change in the prevailing ice-nucleation temperatures. Estimated INP concentration accumulated from 0.004–0.02 L-1 during the winter months. The highlight of the MOSAiC lidar studies was the detection of a persistent wildfire smoke layer in the upper troposphere and lower stratosphere from October 2019 to May 2020. The smoke particles (organic aerosol) triggered continuously cirrus formation at INP concentrations mostly from 1–20 L-1 close to the tropopause during the entire winter period.

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“…Furthermore, we reduce the amount of INPs available across all simulations by a factor of 10 3 (INP factor: 0.001). Observational studies show that INPs are important for controlling cloud phase (Carlsen & David, 2022;Creamean et al, 2022;Sze et al, 2023) and that climate models overestimate the amount of activated INPs in regions with the most frequent MPCs. This is especially pronounced over the Southern Ocean and the Arctic, where model INP concentration can be orders of magnitude too high (Vergara-Temprado et al, 2018;Vignon et al, 2021;Li et al, 2022).…”

Section: Implementation Of Observational Constraints In Noresm2mentioning

confidence: 99%

Realistic representation of mixed-phase clouds increases future climate warming

Höfer

Hahn

Shaw

et al. 2023

Preprint

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Clouds are the main source of uncertainties when projecting climate change. Mixed-phase clouds (MPCs) that contain ice and supercooled-liquid particles are especially hard to constrain, and climate models neither agree on their phase nor their spatial extent. This is problematic, as models that underestimate contemporary supercooled-liquid in MPCs will underestimate future warming. Furthermore, it has recently been shown that supercooled-liquid water in MPCs is not homogeneously-mixed, neither vertically nor horizontally. However, while there have been attempts at observationally constraining MPCs to constrain uncertainties in future warming, all studies only use the phase of the interior of MPCs. Using novel satellite observations, and contrary to current knowledge, we show that MPCs are more liquid at the cloud top globally. We use these observations to constrain, for the first time, the cloud top phase in addition to the interior of MPCs in a global climate model, leading to +1C more 21st century warming in NorESM2 SSP5-8.5 climate projections. We anticipate that the difference between cloud top and interior phase in MPCs is an important new target metric for future climate model development, because similar MPC-related biases in future warming are likely present in many climate models.

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Ice Nucleating Particles in Northern Greenland: annual cycles, biological contribution and parameterizations

Cited by 4 publications

References 36 publications

Ice-nucleating particles in northern Greenland: annual cycles, biological contribution and parameterizations

Ice-nucleating particles in northern Greenland: annual cycles, biological contribution and parameterizations

Annual cycle of aerosol properties over the central Arctic during MOSAiC 2019–2020 — light-extinction, CCN, and INP levels from the boundary layer to the tropopause

Realistic representation of mixed-phase clouds increases future climate warming

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