Journal: npj Climate and Atmospheric Science

Abbreviation

npj Clim Atmos Sci

Publisher

Springer

Journal Volumes

ISSN

2397-3722

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2023 - 20254
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Publications 1 - 4 of 4
  • Drought characteristics in Mediterranean under future climate change
    Item type: Journal Article
    Essa, Yassmin H.; Hirschi, Martin; Thiery, Wim; et al. (2023)
    npj Climate and Atmospheric Science
    The present work aims to address the physical properties of different drought types under near-future climates in the Mediterranean. To do so, we use a multi-model mean of the bias-adjusted and downscaled product of five Earth System Models participating in the Coupled Model Intercomparison Project—phase6 (CMIP6), provided by Inter-Sectoral Impact Model Intercomparison Project (ISIMIP), under four shared socioeconomic pathways (SSP1–2.6, SSP2–4.5, SSP3–7.0, and SSP5–8.5) for the period 2021–2060, to estimate the Standardized Precipitation Evapotranspiration Index (SPEI) at 1-, 6-, and 12-month time scales, and address the meteorological, agricultural, and hydrological drought, respectively. Additionally, SPEI is calculated from the bias-adjusted CMIP6 historical simulations and the reanalysis ‘WFDE5’ for 1980–2014 as a historical and reference period. The comparison of the CMIP6 with WFDE5 reveals a consistently increasing tendency for drought occurrences in the Mediterranean, particularly for agricultural and hydrological drought time scales. Nonetheless, an overestimation in historical trend magnitude is shown by the CMIP6 with respect to WFDE5. The projection results depict drought frequencies ranging between 12 and 25% of the studied period 2021–2060, varying with regions and climate scenarios. The tendency to increase the drought frequency is more pronounced in the southern than northern Mediterranean countries. Drought severity is remarkable in the aggregated time scales; consequently, more pressure is foreseen in the food and water sectors. Drought seasonality reveals a higher tendency for drought occurrences in summer (autumn) months for the meteorological (agricultural) droughts. The driving factor(s) for drought occurrence strongly depends on regional climate characteristics.
  • Carbon uptake of an urban green space inferred from carbonyl sulfide fluxes
    Item type: Journal Article
    Soininen, Jesse; Kohonen, Kukka-Maaria; Rantala, Pekka; et al. (2025)
    npj Climate and Atmospheric Science
    With several cities worldwide pursuing carbon neutrality in the upcoming decades, there is an increasing interest in quantifying cities’ anthropogenic carbon emissions using atmospheric observations. The challenge with both in-situ and remote sensing methods is, however, that the observations include both anthropogenic and biogenic signals. To reduce uncertainties in anthropogenic emission estimations, it is critical to partition biogenic fluxes of carbon dioxide (CO2) from the observed data. In this study, we, for the first time, examine the suitability of carbonyl sulfide (COS), a proxy for photosynthesis, on partitioning biogenic CO2 uptake from the ecosystem exchange measured with the eddy covariance (EC) technique over an urban area in Helsinki, Finland. The urban vegetation acts as a clear sink for COS whereas anthropogenic processes show minimal COS emissions within the source area of the measured net carbon flux. We show that two different COS flux-based methods are able to produce the dynamics of photosynthesis by an independent light-response curve-based estimation. Together with commonly used soil and vegetation respiration proxy, we removed biogenic signals from the urban net CO2 exchange and demonstrated that together with CO2 fluxes, COS flux can successfully be used to get realistic estimations of anthropogenic carbon emissions using the EC method.
  • Stratocumulus adjustments to aerosol perturbations disentangled with a causal approach
    Item type: Journal Article
    Fons, Emilie Annette Simone; Runge, Jakob; Neubauer, David; et al. (2023)
    npj Climate and Atmospheric Science
    A large fraction of the uncertainty around future global warming is due to the cooling effect of aerosol-liquid cloud interactions, and in particular to the elusive sign of liquid water path (LWP) adjustments to aerosol perturbations. To quantify this adjustment, we propose a causal approach that combines physical knowledge in the form of a causal graph with geostationary satellite observations of stratocumulus clouds. This allows us to remove confounding influences from large-scale meteorology and to disentangle counteracting physical processes (cloud-top entrainment enhancement and precipitation suppression due to aerosol perturbations) on different timescales. This results in weak LWP adjustments that are time-dependent (first positive then negative) and meteorological regime-dependent. More importantly, the causal approach reveals that failing to account for covariations of cloud droplet sizes and cloud depth, which are, respectively, a mediator and a confounder of entrainment and precipitation influences, leads to an overly negative aerosol-induced LWP response. This would result in an underestimation of the cooling influence of aerosol-cloud interactions.
  • Record-high Antarctic Peninsula temperatures and surface melt in February 2022: a compound event with an intense atmospheric river
    Item type: Journal Article
    Gorodetskaya, Irina V.; Durán-Alarcón, Claudio; González-Herrero, Sergi; et al. (2023)
    npj Climate and Atmospheric Science
    The Antarctic Peninsula (AP) experienced a new extreme warm event and record-high surface melt in February 2022, rivaling the recent temperature records from 2015 and 2020, and contributing to the alarming series of extreme warm events over this region showing stronger warming compared to the rest of Antarctica. Here, the drivers and impacts of the event are analyzed in detail using a range of observational and modeling data. The northern/northwestern AP was directly impacted by an intense atmospheric river (AR) attaining category 3 on the AR scale, which brought anomalous heat and rainfall, while the AR-enhanced foehn effect further warmed its northeastern side. The event was triggered by multiple large-scale atmospheric circulation patterns linking the AR formation to tropical convection anomalies and stationary Rossby waves, with an anomalous Amundsen Sea Low and a record-breaking high-pressure system east of the AP. This multivariate and spatial compound event culminated in widespread and intense surface melt across the AP. Circulation analog analysis shows that global warming played a role in the amplification and increased probability of the event. Increasing frequency of such events can undermine the stability of the AP ice shelves, with multiple local to global impacts, including acceleration of the AP ice mass loss and changes in sensitive ecosystems.
Publications 1 - 4 of 4