{"title":"U-Net Kalman Filter (UNetKF): An Example of Machine Learning-Assisted Data Assimilation","authors":"Feiyu Lu","doi":"10.1029/2023MS003979","DOIUrl":"https://doi.org/10.1029/2023MS003979","url":null,"abstract":"<p>Machine learning techniques have seen a tremendous rise in popularity in weather and climate sciences. Data assimilation (DA), which combines observations and numerical models, has great potential to incorporate machine learning and artificial intelligence (ML/AI) techniques. In this paper, we use U-Net, a type of convolutional neutral network (CNN), to improve the localized error covariances for the Ensemble Kalman Filter (EnKF) algorithm. Using a 2-layer quasi-geostrophic model, U-Nets are trained using data from EnKF DA experiments. The trained U-Nets are then successfully implemented in U-Net Kalman Filter (UNetKF) experiments to predict localized error covariances that possess adaptive localization and some state-dependent features of the model error covariances. UNetKF is compared to traditional 3-dimensional variational (3DVar), ensemble 3DVar (En3DVar) and EnKF methods. The performance of UNetKF can match or exceed that of 3DVar, or En3DVar and EnKF for small to moderate ensemble sizes. We also demonstrate that trained U-Nets can be transferred to a higher-resolution model for UNetKF implementation, which again performs competitively to 3DVar and EnKF, particularly for small ensemble sizes.</p>","PeriodicalId":14881,"journal":{"name":"Journal of Advances in Modeling Earth Systems","volume":"17 4","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023MS003979","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143784301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"4D-Var Using Hessian Approximation and Backpropagation Applied to Automatically Differentiable Numerical and Machine Learning Models","authors":"Kylen Solvik, Stephen G. Penny, Stephan Hoyer","doi":"10.1029/2024MS004608","DOIUrl":"https://doi.org/10.1029/2024MS004608","url":null,"abstract":"<p>Constraining a numerical weather prediction (NWP) model with observations via 4D variational (4D-Var) Data assimilation (DA) is often difficult to implement due to the need to develop and maintain a software-based tangent linear model and adjoint model. One of the most common 4D-Var algorithms uses an incremental update procedure, which has been shown to be an approximation of the Gauss-Newton method. Here we demonstrate that when using a forecast model that supports flexible automatic differentiation, an efficient and in some cases more accurate alternative approximation of the Gauss-Newton method can be applied by combining backpropagation of errors with a Hessian approximation. This approach can be used with either a conventional physical model implemented with automatic differentiation or a machine learning (ML) based surrogate model. We test the new approach on a variety of Lorenz-96 and quasi-geostrophic models. The results indicate potential for a deeper integration of modeling, DA, and new technologies in a next-generation of operational forecast systems that leverage weather models designed to support flexible, on-the-fly automatic differentiation.</p>","PeriodicalId":14881,"journal":{"name":"Journal of Advances in Modeling Earth Systems","volume":"17 4","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024MS004608","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143784302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Quantifying Fire-Driven Dust Emissions Using a Global Aerosol Model","authors":"Robert Wagner, Kerstin Schepanski","doi":"10.1029/2024MS004466","DOIUrl":"https://doi.org/10.1029/2024MS004466","url":null,"abstract":"<p>Vegetation fires have become increasingly recognized as a potential entrainment mechanism for mineral dust. However, the global importance of this emission pathway remains largely unknown. Based on previous LES investigations, we developed a parameterization that relates the dust emission potential of wildfires to observational data of the fire radiative power and further soil-surface conditions. It was implemented into the aerosol-climate model ICON-HAM and simulations with and without the new emission pathway were conducted for the 10-year period 2004–2013. Fire-dust emissions can account for around 230 (190–255) Tg yr<sup>−1</sup>, which represents around 18 (15–21) % of the total global dust emissions. These additional emissions originate largely from regions that are typically not known as significant sources of mineral dust. Locally, wildfires can enhance the presence of atmospheric dust particles and on the Southern hemisphere might even surpass other forms of dust emission. Highly dust active fire regions are identified in areas where burning grasslands create suitable emission conditions together with emissive soil types despite rather weak fires, for example, in Eastern Europe or the Central US. Fire-dust emissions are subject to a strong seasonal cycle, mainly driven by the fire activity, following the hemispheric warm and dry seasons. Multi-year comparisons with (dust) AOD observations revealed improvements due to the additional fire-dust emissions, particularly in the most fire-active regions on the Southern hemisphere. Nevertheless, further research and improvements of the parameterization are required to better classify the source areas and their variation with the changing climate and land use conditions.</p>","PeriodicalId":14881,"journal":{"name":"Journal of Advances in Modeling Earth Systems","volume":"17 4","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024MS004466","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143778399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hugh Morrison, Jason A. Milbrandt, Mélissa Cholette
{"title":"A Complete Three-Moment Representation of Ice in the Predicted Particle Properties (P3) Microphysics Scheme","authors":"Hugh Morrison, Jason A. Milbrandt, Mélissa Cholette","doi":"10.1029/2024MS004644","DOIUrl":"https://doi.org/10.1029/2024MS004644","url":null,"abstract":"<p>A new, complete three-moment bulk microphysics approach is proposed that includes the effects of all relevant microphysical processes on the evolution of ice particle size distribution (PSD) width. This extends the three-moment approach that was originally implemented in the Predicted Particle Properties (P3) scheme that assumed sedimentation and advection dominate and neglected the effects of most microphysical processes on PSD width. The new approach (FULL) is tested in idealized one-dimensional kinematic updraft and three-dimensional supercell simulations and compared to results using the original approach (ORIG). Although tendencies of the gamma PSD width parameter (<i>μ</i>) from several microphysical processes using FULL are large in magnitude relative to the sedimentation and advection tendencies, they have only minor impacts on the overall spatiotemporal patterns of <i>μ</i>; PSDs are narrower using FULL in regions with relatively narrow PSDs using ORIG and slightly wider in regions with relatively wide PSDs. The processes driving these impacts using FULL are ice-rain collection near convective cores and sublimation in the far forward flank, both leading to PSD narrowing, and broadening from aggregation in the near forward flank. A general theoretical expression is derived to explain whether a process broadens or narrows PSDs based in part on the ice particle mass-size relationship. However, the effects on bulk cloud and precipitation properties are limited, with only a 7%–8% decrease in mean surface precipitation using FULL compared to ORIG. Although overall impacts are modest in the tests conducted, the full approach improves physical realism with a negligible increase in computational cost.</p>","PeriodicalId":14881,"journal":{"name":"Journal of Advances in Modeling Earth Systems","volume":"17 4","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024MS004644","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143770076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Andrew R. Axelsen, Terence J. O’Kane, Courtney R. Quinn, Andrew P. Bassom
{"title":"Hyperbolicity and Southern Hemisphere Persistent Synoptic Events","authors":"Andrew R. Axelsen, Terence J. O’Kane, Courtney R. Quinn, Andrew P. Bassom","doi":"10.1029/2024MS004834","DOIUrl":"https://doi.org/10.1029/2024MS004834","url":null,"abstract":"<p>Predicting the occurrence of coherent blocking structures in synoptic weather systems remains a challenging problem that has taxed the numerical weather prediction community for decades. The underlying factor behind this difficulty is the so-called “loss of hyperbolicity” known to be linked with the alignment of dynamical vectors characterizing the growth and decay of flow instabilities. We introduce measures that utilize the close link between hyperbolicity, the alignment of Lyapunov vectors, and their associated growth and decay rates to characterize the dynamics of persistent synoptic events in the mid-troposphere of the Southern Hemisphere. These measures reveal a general loss of hyperbolicity that typically occurs during onset and decay of a given event, and a gain of hyperbolicity during the persistent mature phase. Facilitating this analysis in a high-dimensional system first requires the extraction of the relevant observed coherent structures, and the generation of a reduced-order model for constructing the tangent space necessary for dynamical analysis. We achieve this through the combination of principal component analysis and a non-parametric, temporally regularized, vector auto-regressive clustering method. Analysis of the primary blocking sectors reveals hyperbolic dynamics that are consistent between metastable states and whose dynamics span the tangent subspace defined by the leading physical modes. We show that these diverse synoptic features are manifest via common spatially dependent attractors as determined by tangent space dynamics. Our results are not only important for dynamical approaches applicable to high-dimensional multi-scale systems, but are also relevant for the development of modern operational ensemble numerical weather prediction systems.</p>","PeriodicalId":14881,"journal":{"name":"Journal of Advances in Modeling Earth Systems","volume":"17 4","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024MS004834","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143749466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Unraveling Atmosphere and Surface Boundary Interactions Behind Extreme Tropical Rainfall: A Case Study in Indonesia Using Fully Coupled Atmosphere-Hydrology Simulations","authors":"Asrini Chrysanti, Sangyoung Son","doi":"10.1029/2024MS004730","DOIUrl":"https://doi.org/10.1029/2024MS004730","url":null,"abstract":"<p>This study investigates the interactions of ocean and land surface boundary conditions with the atmosphere during extreme rainfall associated with the flooding over South Kalimantan on January 10–18, 2021. The interactions are analyzed through a set of sensitivity tests that involve perturbations in ocean and soil surface conditions. Our results indicate that wet soil conditions alleviate inland rainfall propagation from the ocean by promoting deep convection through the modulation of background winds, while dryer soil weakens the convective rainfall and limits the convective initiation to localized regions. Additionally, flooded surfaces enhance wind flow, allowing moisture to spread over a broad area. Ocean surface feedback to rainfall only exhibits positive feedback over the ocean, while inland rainfall is more complex, driven primarily by wind dynamics. Under extreme synoptic conditions, background winds, forced by gravity waves and Madden-Julian Oscillation, play a more significant role in modulating rainfall propagation than land-sea breezes or diurnal temperature cycle. Ultimately, in an energy-controlled regime, atmospheric dynamics are found to be the dominant factors in the ocean-land-atmosphere interactions, with surface fluxes partitioning playing a secondary role.</p>","PeriodicalId":14881,"journal":{"name":"Journal of Advances in Modeling Earth Systems","volume":"17 4","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024MS004730","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143726861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On the Dependence of Simulated Convection on Domain Size in CRMs","authors":"A. M. Jenney, Z. Hu, W. M. Hannah","doi":"10.1029/2024MS004749","DOIUrl":"https://doi.org/10.1029/2024MS004749","url":null,"abstract":"<p>We present a heuristic model to explain the suppression of deep convection in convection-resolving models (CRMs) with a small number of grid columns, such as those used in super-parameterized or multi-scale modeling framework (MMF) general circulation models (GCM) of the atmosphere. Domains with few grid columns require greater instability to sustain convection because they force a large convective fraction, driving strong compensating subsidence warming. Updraft dilution, which is stronger for reduced horizontal grid spacing, enhances this effect. Thus, suppression of deep convection in CRMs with few grid columns can be reduced by increasing grid spacing. Radiative-convective equilibrium simulations using standalone CRM simulations with the System for Atmospheric Modeling (SAM) and using GCM-coupled CRM simulations with the Energy Exascale Earth System Model (E3SM)-MMF confirm the heuristic model results.</p>","PeriodicalId":14881,"journal":{"name":"Journal of Advances in Modeling Earth Systems","volume":"17 3","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024MS004749","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143707334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jakub L. Nowak, Ian C. D. V. Dragaud, Junhong Lee, Piotr Dziekan, Juan Pedro Mellado, Bjorn Stevens
{"title":"A First Look at the Global Climatology of Low-Level Clouds in Storm Resolving Models","authors":"Jakub L. Nowak, Ian C. D. V. Dragaud, Junhong Lee, Piotr Dziekan, Juan Pedro Mellado, Bjorn Stevens","doi":"10.1029/2024MS004340","DOIUrl":"https://doi.org/10.1029/2024MS004340","url":null,"abstract":"<p>The representation of subtropical stratocumulus and trade-wind cumulus clouds by preliminary versions of Integrated Forecasting System (IFS) and ICON km-scale global coupled climate models is explored. These models differ profoundly in their strategy to represent subgrid-scale processes. The IFS employs complex parameterizations, including eddy-diffusivity mass-flux and convection schemes. ICON applies a minimal set of paramaterizations, including the Smagorinsky-Lilly closure. Five-year simulations are performed and evaluated for their representation of cloud albedo, its variability with environmental parameters and the vertical structure of the atmospheric boundary layer in eight regions: four corresponding to canonical Atlantic and Pacific stratocumulus and four in their downstream trades. For stratocumulus, both models capture the albedo's mean, annual cycle, and its relationship with the parameters relevant for low cloudiness, including lower tropospheric stability. They simulate an expected thermodynamic vertical structure of a stratocumulus-topped boundary layer. ICON largely exhibits a lower cloud base and inversion height than IFS. We speculate the disagreement can be attributed to the contrasting treatment of subgrid mixing and cloud top entrainment. In the case of trade-wind cumulus, both models well differentiate the cloud amount, the character of annual cycles and parameter correlations, and the vertical structure from the upstream stratocumulus. The annual cycles and parameter correlations reflect the dry and wet periods. Both models overestimate mean albedo and underestimate the strength of trade-wind inversion. With an additional ICON run, we demonstrate the strong sensitivity of stratocumulus and the weaker response of trade-wind cumulus to the treatment of subgrid mixing.</p>","PeriodicalId":14881,"journal":{"name":"Journal of Advances in Modeling Earth Systems","volume":"17 3","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024MS004340","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143689721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Mesoscale Eddy-Induced Sharpening of Oceanic Tracer Fronts","authors":"Yueyang Lu, Igor Kamenkovich","doi":"10.1029/2024MS004693","DOIUrl":"https://doi.org/10.1029/2024MS004693","url":null,"abstract":"<p>Oceanic fronts are ubiquitous and important features that form and evolve due to multiscale oceanic and atmospheric processes. Large-scale temperature and tracer fronts, such as those found along the eastward extensions of the Gulf Stream and Kuroshio currents, are crucial components of the regional ocean environment and climate. This numerical study examines the relative importance of large-scale currents and mesoscale currents (“eddies”) in the front formation and evolution. Using an idealized model of the double-gyre system on both eddy-resolving and coarse-resolution grids, we demonstrate that the effect of eddies is to sharpen the large-scale tracer front, whereas the large-scale current counteracts this effect and acts to create a broader front. The eddy-driven frontogenesis is further described in terms of a recently proposed framework of generalized eddy-induced advection, which represents all those eddy effects on tracers that are not due to eddy-induced mass fluxes and are traditionally parameterized by isopycnal diffusion. In this study the generalized advection is formulated using an effective eddy-induced velocity (EEIV), which is the speed at which eddies move large-scale tracer contours. The advantage of this formulation is that the frontal sharpening can be readily reproduced by EEIVs. A functional form of EEIV in terms of large-scale variables effectively represents the frontogenesis in a coarse-resolution simulation. This study shows promise for using an advective framework to parameterize eddy-driven frontogenesis in numerical models that are not eddy-resolving.</p>","PeriodicalId":14881,"journal":{"name":"Journal of Advances in Modeling Earth Systems","volume":"17 3","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024MS004693","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143689637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Lee, M. Jung, N. Carvalhais, M. Reichstein, M. Forkel, A. A. Bloom, J. Pacheco-Labrador, S. Koirala
{"title":"Spatial Attribution of Temporal Variability in Global Land-Atmosphere CO2 Exchange Using a Model-Data Integration Framework","authors":"H. Lee, M. Jung, N. Carvalhais, M. Reichstein, M. Forkel, A. A. Bloom, J. Pacheco-Labrador, S. Koirala","doi":"10.1029/2024MS004479","DOIUrl":"https://doi.org/10.1029/2024MS004479","url":null,"abstract":"<p>The spatial contribution to the global land-atmosphere carbon dioxide (CO<sub>2</sub>) exchange is crucial in understanding and projecting the global carbon cycle, yet different studies diverge on the dominant regions. Informing land models with observational data is a promising way to reduce the parameter and structural uncertainties and advance our understanding. Here, we develop a parsimonious diagnostic process-based model of land carbon cycles, constraining parameters with observation-based products. We compare CO<sub>2</sub> flux estimates from our model with observational constraints and Trends in Net Land-Atmosphere Carbon Exchange (TRENDY) model ensemble to show that our model reasonably reproduces the seasonality of net ecosystem exchange (NEE) and gross primary productivity (GPP) and interannual variability (IAV) of NEE. Finally, we use the developed model, TRENDY models, and observational constraints to attribute variability in global NEE and GPP to regional variability. The attribution analysis confirms the dominance of Northern temperate and boreal regions in the seasonality of CO<sub>2</sub> fluxes. Regarding NEE IAV, we identify a significant contribution from tropical savanna regions as previously perceived. Furthermore, we highlight that tropical humid regions are also identified as at least equally relevant contributors as semi-arid regions. At the same time, the largest uncertainty among ensemble members of NEE constraint and TRENDY models in the tropical humid regions underscore the necessity of better process understanding and more observations in these regions. Overall, our study identifies tropical humid regions as key regions for global land-atmosphere CO<sub>2</sub> exchanges and the inter-model spread of its modeling.</p>","PeriodicalId":14881,"journal":{"name":"Journal of Advances in Modeling Earth Systems","volume":"17 3","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024MS004479","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143689795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}