Coastal Alaska communities from the Yukon-Kuskokwim Delta northward will see more of their buildings exposed to flooding by 2100 if they continue developing at the same location, according to new research.
Abstract
The Australian summer monsoon (ASM) influences the tropical hydro-climate of Northern Australia during the extended summer months (October–April). Despite advances in understanding the ASM, climate models vary widely in their depiction and projections of its future behavior remain uncertain. This study investigates the moist static energy (MSE) budget and examines the gross moist stability (GMS) evolution throughout the monsoon cycle using two reanalysis data sets. We then assess the ability of Atmospheric Modeling Intercomparison Project (AMIP) simulations of climate models to reproduce not only the monsoon seasonal cycle of rainfall but the associated mechanisms revealed by the budget analysis. The budget analysis shows a strong influence of the regions to the north and west of our study area for the import of moisture and export of energy into and away from the ASM. We find that models reproduce this influence qualitatively, but not quantitatively. As in previous studies, we identify two major regimes of the GMS associated with the absence (higher GMS) or presence (lower GMS) of convection. Whilst climate models are able to distinguish the two regimes, they significantly overestimate the GMS in convectively active periods, owing largely to profile of ascent that is too top heavy. Models with more realistic precipitation do not consistently offer more accurate representations of dynamic processes, as evaluated by the MSE budget and GMS. This highlights limitations in assessing models based solely on single variables. To enhance the generalizability of these findings, future studies should employ models without prescribed sea surface temperatures.
As the world transitions to greener sources of energy, demand for the metals used in these new technologies is increasing. But how do you grow the mining industry while still holding the line on carbon emissions?
Abstract
Dust emission fluxes during wind soil erosion are usually estimated using a dust concentration vertical gradient, by assuming a constant dust flux layer between the surface and the dust measurement levels. Here, we investigate the existence of this layer during erosion events recorded in Iceland and Jordan. Size-resolved dust fluxes were estimated at three levels between 2 and 4 m using the eddy-covariance method. Dust fluxes were found mainly constant only between the two upper levels in Iceland, the lower dust flux being often stronger and richer in coarse particles, while dust fluxes in Jordan were nearly constant across all levels. The wind dynamics could not explain the absence of a constant dust flux layer in Iceland. We show that the presence of stationary dust source patches in Iceland, related to surface humidity, created a non-uniform dust layer near the surface, named dust roughness sublayer (DRSL), where individual plumes behind each patch interact but do not fully mix. The lowest dust measurement level was probably located within this sublayer while the upper ones were located above, such that there the emitted dust became spatially well-mixed. This explains near the surface in Iceland, the more intermittent dust concentration, its low correlation with the dust concentrations above, and the richer dust flux in coarse particles due to their lower deposition contribution. Our findings highlight the importance of estimating dust fluxes above a dust blending height whose characteristics depend on the dust source patchiness caused by surface humidity or the presence of sparse non-erosive elements.
Abstract
A significant and striking seesaw pattern of winter surface air temperature (SAT) has emerged, featuring pronounced warming Arctic and cooling Eurasian (referred to as WACE). This study investigates the subseasonal SAT modes across the mid- and high-latitudes of Eurasia and their possible mechanisms based on daily reanalysis data from 1979 to 2022. Our results reveal that Eurasian winter SAT exhibits two distinct subseasonal modes, characterized by a correlated southeastward propagation of temperature and geopotential height anomalies (GHAs) in the middle and lower troposphere. Notably, the subseasonal SAT anomalies with eight phases constrained by the hydrostatic equilibrium, originate from the GHAs in the Arctic stratosphere and then transfer to the East Asia. The sixth phase of the transmitted subseasonal SAT mode is proved to be the key transition phase from the WACE pattern to its counterpart. Further analysis indicates that the strength of the transmitted subseasonal SAT mode is controlled by the tripolar sea surface turbulent heat flux anomalies over the north Atlantic.
Abstract
Gravity waves (GW) transport momentum flux (MF) and energy across the lower, middle and upper atmosphere. Global Navigation Satellite System (GNSS) radio occultation (RO) is one of the measuring techniques used onboard satellites to provide vertical temperature profiles with global and permanent coverage. These retrievals may be applied in the study of GW. Most of the analysis methods provide absolute GWMF but are missing its net direction. This happens because the procedures can deduce the orientation but not the propagation sign of GW and hence the full direction of MF. We apply here a method that allows the net calculation with four close in space and time RO soundings (quartets). We use about 10,000 daily retrievals from 1 March 2022 to 28 February 2023 to study the seasonal and latitudinal characteristics of net GWMF in the height interval from 20 to 35 km. About 600 quartets were found. The calculated zonal MF and drag exhibited negative minima at middle and high latitudes during winter in the Southern Hemisphere. This well-known characteristic is usually mainly assigned to orographic sources. A similar intensity in zonal MF and drag is found during the same season at low latitudes. Meridional components are generally less significant. Besides finding the correct sign of the GWMF and the corresponding forcing on the mean flow, the quartets method also allows the determination of the horizontal and vertical wavelengths, the amplitude and sign of the vertical wave phase velocity and the intrinsic frequencies. The global statistics of these parameters are shown and each one exhibits a similar distribution shape across latitude bands. Large differences in the frequency of cases in vertical phase velocity sign appear only at low and high positive latitudes. The most even distribution of GW intrinsic frequency is found at low latitudes. We estimate that absolute MF calculations by methods assuming only upward GW propagation may produce a bias not larger than 40%. The increase of satellite measuring devices achieved in the last years due to the release of new missions led to a high spatial and temporal density of profiles that may allow the attainment of net GWMF climatologies over a seasonal time scale and about 4,000 km latitude bands but this performance may be even improved if the amount of retrievals continues to rise.
Abstract
The cloud properties and governing processes in Southern Ocean marine boundary layer clouds have emerged as a central issue in understanding the Earth's climate sensitivity. While our understanding of Southern Ocean cloud feedbacks have evolved in the most recent climate model intercomparison, the background properties of simulated summertime clouds in the Southern Ocean are not consistent with measurements due to known biases in simulating cloud condensation nuclei concentrations. This paper presents several case studies collected during the Capricorn 2 and Marcus campaigns held aboard Australian research vessels in the Austral Summer of 2018. Combining the surface-observed cases with MODIS data along forward and backward air mass trajectories, we demonstrate the evolution of cloud properties with time. These cases are consistent with multi-year statistics showing that long trajectories of air masses over the Antarctic ice sheet are critical to creating high droplet number clouds in the high latitude summer Southern Ocean. We speculate that secondary aerosol production via the oxidation of biogenically derived aerosol precursor gasses over the high actinic flux region of the high latitude ice sheets is fundamental to maintaining relatively high droplet numbers in Southern Ocean clouds during Summer.
Abstract
The cool season (November–March) of 2022–2023 was exceptional in the western United States (US), with the highest precipitation totals in ≥128 years in some areas. Recent precipitation extremes and expectations based on thermodynamics motivate us to evaluate the evidence for an anthropogenic intensification of western US cool-season precipitation to date. Over cool seasons 1951–2023, trends in precipitation totals on the wettest cool-season days were neutral or negative across the western US, and significantly negative in northern California and parts of the Pacific Northwest, counter to the expected net intensification effect from anthropogenic forcing. Multiple reanalysis data sets indicate a corresponding lack of increase in moisture transports into the western US, suggesting that atmospheric circulation trends over the North Pacific have counteracted the increases in atmospheric moisture expected from warming alone. The lack of precipitation intensification to date is generally consistent with climate model simulations. A large ensemble of 648 simulations from 35 climate models suggests it is too soon to detect anthropogenic intensification of precipitation across much of the western US. In California, the 35-model median time of emergence for intensification of the wettest days is 2080 under a mid-level emissions scenario. On the other hand, observed reductions of precipitation extremes in California and the Pacific Northwest are near the lower edge of the large ensemble of simulated trends, calling into question model representation of western US precipitation variability.
Abstract
This manuscript investigates the impact of land-surface heterogeneity on atmospheric processes by comparing 92 large-eddy simulation cases over the Southern Great Plains, leveraging high-resolution spatially heterogeneous and homogeneous land-surface fields. Utilizing the HydroBlocks land-surface model for detailed surface data and the Weather Research and Forecasting model for atmospheric simulations, this study emphasizes the significant role land-surface details play in atmospheric dynamics, particularly in cloud formation and boundary-layer development. The analysis focuses on the comparison of turbulent kinetic energy and liquid water path between heterogeneous and homogeneous surface conditions, revealing a strong correlation between surface heterogeneity and enhanced atmospheric activity. Furthermore, the study underscores that the most influential land-surface characteristics on the atmosphere are encapsulated within the largest spatial scales, suggesting a potential simplification for incorporating sub-grid scale land-surface features into global models. The findings advocate for a more formal coupling between the sub-grid land and atmosphere in Earth system models to improve the accuracy of weather and climate predictions, particularly for processes such as cloud formation and boundary-layer dynamics that are sensitive to surface conditions. This work lays foundational insights for future parameterization schemes in global models, highlighting the importance of land-surface details on atmospheric modeling.
Abstract
Deep tropical oceanic convection (TOC) is a prevailing component of the tropical atmosphere and plays a significant role in modulating global weather and climate. Despite its importance, prediction challenges remain, partly attributed to a lack of understanding of how TOC relates to its near-storm environments. Prior studies suggest location-dependent relationships between TOC structure and associated environments, necessitating targeted regional studies. The NASA 2017 Convective Processes Experiment (CPEX) and 2021 CPEX—Aerosols & Winds (CPEX-AW) field campaigns collected high-resolution measurements of convective storms and their environments in the Gulf of Mexico, Caribbean, and western Atlantic basins, providing a rare opportunity to investigate near-storm environmental relationships with 3-D TOC structure where in situ non-tropical cyclone-related deep TOC research is comparatively lacking. Collocated CPEX and CPEX-AW airborne observations from the multi-wavelength Airborne Precipitation Radar, Doppler Aerosol Wind Lidar, and dropsondes revealed large near-storm environmental variability across TOC of similar convective type (i.e., isolated, organized) and within individual convective systems. However, trends still emerged amongst the large environmental variability. Horizontal TOC structure was most consistently linked to planetary boundary layer and mid-tropospheric near-storm environments, with organized TOC being associated with generally greater relative humidity (RH) and vertical speed shear than isolated TOC. TOC intensity was linked to upper tropospheric (i.e., above melting level) near-storm environments, with isolated TOC intensity most consistently associated with upper tropospheric CAPE and organized TOC intensity associated with upper tropospheric RH. Mesoscale low-level convergence was also linked to greater organized TOC intensity, motivating further research using these unique data sets.
Abstract
Odhisa, a state of India, bore the disastrous consequences of two consequent Tropical Cyclones (TCs), TC 04B and TC 05B (Odisha 1999 supercyclone), which formed over the Bay of Bengal and experienced landfall in October 1999, with a time gap of fewer than two weeks, over the same region. It is suggested that the first TC, TC 04B, provided an “ocean-like situation” over the coastal land region, thus delivering the appropriate land conditions that would facilitate the intensification of the following second tropical cyclone, TC 05B; a clear illustration of the “Brown Ocean effect.” Two Weather Research Forecasting (WRF) simulations were conducted, with the control and experimental runs differing solely in the following aspect: the initial cyclonic vortex corresponding to the first TC at the initial time was removed in the experimental run, whereas it was retained in the control run. Both simulations were analyzed to reveal the “Brown Ocean Effect” role. The experimental run result indicates that the minimum central sea level pressure of the second TC was 35 hPa higher than the second TC simulation in the control run. The heavy rainfall associated with TC 04B led to increased soil moisture conditions, providing the second TC (TC 05B) with the necessary conditions for its intensification by the “Brown Ocean Effect.” The results of this study appear to strongly suggest that the “Brown Ocean Effect” could provide one of the main reasons for the extraordinary intensities associated with the 1999 Odisha supercyclone.
Abstract
Ammonia (NH3) from animal feeding operations (AFOs) is an important source of reactive nitrogen in the US, but despite its ramifications for air quality and ecosystem health, its near-source evolution remains understudied. To this end, Phase I of the Transport and Transformation of Ammonia (TRANS2Am) field campaign was conducted in the northeastern Colorado Front Range in summer 2021 and characterized atmospheric composition downwind of AFOs during 10 research flights. Airborne measurements of NH3, nitric acid (HNO3), and a suite of water-soluble aerosol species collected onboard the University of Wyoming King Air research aircraft present an opportunity to investigate the sensitivity of particulate matter (PM) formation to AFO emissions. We couple the observations with thermodynamic modeling to predict the seasonality of ammonium nitrate (NH4NO3) formation. We find that during TRANS2Am northeastern Colorado is consistently in the NH3-rich and HNO3-limited NH4NO3 formation regime. Further investigation using the Extended Aerosol Inorganics Model reveals that summertime temperatures (mean: 23°C) of northeastern Colorado, especially near the surface, inhibit NH4NO3 formation despite high NH3 concentrations (max: ≤114 ppbv). Finally, we model spring/autumn and winter conditions to explore the seasonality of NH4NO3 formation and find that cooler temperatures could support substantially more NH4NO3 formation. Whereas NH4NO3 only exceeds 1 μg m−3 ∼10% of the time in summer, modeled NH4NO3 would exceed 1 μg m−3 61% (88%) of the time in spring/autumn (winter), with a 10°C (20°C) temperature decrease relative to the campaign.
Climatic characteristics of the Jianghuai cyclone and its linkage with precipitation during the Meiyu period from 1961 to 2020
Ran Zhu and Lei Chen
Nat. Hazards Earth Syst. Sci., 24, 1937–1950, https://doi.org/10.5194/nhess-24-1937-2024, 2024
There is a positive correlation between the frequency of Jianghuai cyclone activity and precipitation during the Meiyu period. Its occurrence frequency has an obvious decadal variation, which corresponds well with the quasi-periodic and decadal variation in precipitation during the Meiyu period. This study provides a reference for the long-term and short-term forecasting of precipitation during the Meiyu period.
Tangible and intangible ex-post assessment of flood-induced damages to cultural heritage
Claudia De Lucia, Michele Amaddii, and Chiara Arrighi
Nat. Hazards Earth Syst. Sci. Discuss., https//doi.org/10.5194/nhess-2024-104,2024
Preprint under review for NHESS (discussion: open, 1 comment)
The work describes the flood damages to cultural heritage (CH) occurred in the event of September 2022 in Central Italy. Datasets related to flood impacts to cultural heritage are rare and this work aims at highlighting both tangible and intangible aspects and their correlation with physical characteristics of the flood, i.e., water depth and flow velocity. The results show that current knowledge and datasets are inadequate for risk assessment of CH.
No abstract is available for this article.
In-flight characterization of a compact airborne quantum cascade laser absorption spectrometer
Linda Ort, Lenard Lukas Röder, Uwe Parchatka, Rainer Königstedt, Daniel Crowley, Frank Kunz, Ralf Wittkowski, Jos Lelieveld, and Horst Fischer
Atmos. Meas. Tech., 17, 3553–3565, https://doi.org/10.5194/amt-17-3553-2024, 2024
Airborne in situ measurements are of great importance to collect valuable data to improve our knowledge of the atmosphere but also present challenges which demand specific designs. This study presents an IR spectrometer for airborne trace-gas measurements with high data efficiency and a simple, compact design. Its in-flight performance is characterized with the help of a test flight and a comparison with another spectrometer. Moreover, results from its first campaign highlight its benefits.
Direct high-precision radon quantification for interpreting high frequency greenhouse gas measurements
Dafina Kikaj, Edward Chung, Alan D. Griffiths, Scott D. Chambers, Grant Foster, Angelina Wenger, Penelope Pickers, Chris Rennick, Simon O'Doherty, Joseph Pitt, Kieran Stanley, Dickon Young, Leigh S. Fleming, Karina Adcock, and Tim Arnold
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-54,2024
Preprint under review for AMT (discussion: open, 0 comments)
We present a protocol to enhance confidence in reported atmospheric radon measurements, enabling direct comparisons between sites and integration with GHG measurements. Radon, a natural atmospheric tracer, provides an independent evaluation of transport model performance. The standardized approach ensures radon's use as a metric for model evaluation. Applicable beyond UK observatories, this protocol can benefit larger networks like ICOS or GAW, advancing atmospheric studies worldwide.
No abstract is available for this article.
Comprehensive Air Quality Model With Extensions, v7.20: Formulation and Evaluation for Ozone and Particulate Matter Over the US
Christopher A. Emery, Kirk R. Baker, Gary M. Wilson, and Greg Yarwood
Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2024-48,2024
Preprint under review for GMD (discussion: open, 0 comments)
We describe the Comprehensive Air quality Model with extensions (CAMx) and evaluate a model simulation during 2016 over nine U.S. climate zones. For ozone, the model statistically replicates measured concentrations better than most other past models and applications. For small inhalable particulates, the model replicates concentrations consistent with most other past models and applications subject to common uncertainties associated with sources, weather, and chemical interactions.
Development of the MPAS-CMAQ Coupled System (V1.0) for Multiscale Global Air Quality Modeling
David C. Wong, Jeff Willison, Jonathan E. Pleim, Golam Sarwar, James Beidler, Russ Bullock, Jerold A. Herwehe, Rob Gilliam, Daiwen Kang, Christian Hogrefe, George Pouliot, and Hosein Foroutan
Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2024-52,2024
Preprint under review for GMD (discussion: open, 0 comments)
This work describe how we linked meteorological Model for Prediction Across Scales – Atmosphere (MPAS-A) with the Community Multiscale Air Quality (CMAQ) air quality model to form a coupled modelling system. This could be used to study air quality or climate and air quality interaction in a global scale. This new model scales well on high performance computing environment and performs well with respect to ground surface networks in terms of ozone and PM2.5.
