Despite extensive implementation of best management practices to mitigate external nutrient runoff, numerous New Hampshire lakes are continuing to experience diminished water quality, likely due to internal phosphorus loading (IPL). This remobilization of legacy nutrients can lead to more frequent and prolonged cyanobacteria blooms and exacerbate the process of eutrophication. This is the case for Lake Kanasatka, Moultonborough, NH, where IPL contributes to nearly 25% of its total phosphorus budget, with that percentage increasing towards 50% by the end of summer as the hypolimnion reaches anoxia, accelerating dissolutive release. Cyanobacteria blooms at Lake Kanasatka have become more prevalent in recent years, heightened around fall turnover when bioavailable phosphate is upwelled into the epilimnion, with blooms lasting up to 83 days. With Lake Kanasatka receiving an aluminum sulfate treatment in early 2024, we are compiling a comprehensive biogeochemical profile of the water column from April to October with a focus on the fractionation of phosphorus into its organic, inorganic, and reactive forms to understand how treatment affects the different forms and bioavailability of this critical nutrient. In addition, we are conducting a comparison to the interconnected upstream waterbody, Wakondah Pond, to better understand the influence of IPL on the efficacy of treatment, and establish if Wakondah Pond is a possible source of external nutrients. Wakondah Pond has exhibited similar seasonal patterns and serves as a control to compare the Lake Kanasatka post-treatment results against. Evaluating both waterbodies will provide broader insight on the water quality and biogeochemical dynamics of the watershed and determine what future management and conservation efforts are needed. With only two other New Hampshire lakes receiving an aluminum sulfate treatment since 1984, it is important to analyze seasonal trends in nutrient loading along with consistent monitoring to better understand the longevity of treatment and its impact on water quality.

We describe a new capability of the Wang-Sheeley-Arge (WSA) model to routinely derive the coronal separatrix web (S-web) as a standard data product. We use one Carrington rotation (CR) to demonstrate this tool, in which we derive the global coronal magnetic field and S-web using a sequence of synchronic photospheric field maps from the Air Force Data Assimilative Photospheric Flux Transport (ADAPT) model. We also derive a time series that quantitatively relates the in situ observed solar wind at ACE with the squashing factor ($Q$) derived at the model-determined source region of the solar wind, where high $Q$ indicates the source region proximity to a magnetic separatrix or quasi-separatrix layer (QSL) in the corona. We demonstrate that all intervals of high $Q$, including one associated with a pseudostreamer, correlate with times when the charge state and abundance measurements at L1 are enhanced and highly structured. This is predicted to occur for solar wind originating from the open-closed boundary, where closed field plasma with escapes out into the solar wind via interchange reconnection with open fields. Further, we relate $Q$ to expansion factor ($f_s$) and coronal hole boundary distance ($\theta_b$, DCHB), which are longstanding parameters used to empirically derive solar wind speed. We demonstrate that $Q$, though related to $f_s$ and DCHB, is a separate metric of the coronal magnetic field topology and a unique probe of solar wind formation. We conclude by highlighting the novel capabilities of this tool, and we discuss future uses for space weather forecasting.

A document by Suma Bhanu Battula. Click on the document to view its contents.

Existing comparative studies on conceptual hydrological model structures have generally focused on streamflow, with less attention to evapotranspiration (ET). Studies have shown that an appropriate ET representation in conceptual models is crucial for obtaining reliable hydrological simulations and predictions, especially under climate change and for ungauged basins. To address this gap, we investigated 30 conceptual models in terms of how they represent ET process and their ability on reproducing two state-of-the-art ET products (PML-V2 and FLUXCOM-X-BASE) in 507 catchments across different climates and landscapes. We found significant differences in ET simulation performance between models with different ET representations. Models employing a linear-relationship between ET from soil and soil moisture storage generally outperformed those that equate ET from soil directly with potential ET (PET). For each catchment, at least one model could well reproduce at least one ET product. Models’ performance in the ET simulation varied with climatic and vegetation characteristics. In humid catchments with summer-dominated rainfall or mild rainfall seasonality, a concise linear-type ET representation could effectively replicate ET products. Adding parameter(s) controlling the long-term ratio between ET and PET could further improve performance. In humid winter-rainfall-dominated catchments, explicitly representing an interception evaporation (Ei) component and constraining Ei by the interception capacity or storage was critical for reproducing ET products. In some arid catchments, considering the contribution of lower storage to ET generation was necessary to reproducing ET products. This study provides insights into how to appropriately represent the conversion process from PET and precipitation to ET in various climates.

A document by Walter N Meier. Click on the document to view its contents.

The intensity of Galactic cosmic rays (GCRs) is affected by solar wind structures such as coronal mass ejections (CMEs), their interplanetary counterparts (ICMEs), and stream interaction regions (SIRs), giving rise to temporal decreases in the cosmic ray intensity, which can be recorded with neutron monitor data, these variations observed at the Earth surface can be a valuable tool to analyze and predict space weather phenomena. However, some of these decrements cannot be linked to significant structures in the local interplanetary medium. In other words, we may have events not detected at L1 close enough to Earth to affect neutrons. They might be significant even though Wind or ACE does not detect them. In this work, we look for this type of decrements during the beginnings of solar cycle 24 using heliospheric imagers onboard STEREO, allowing us to observe the region between the Sun and Earth in a manner that was never followed by imaging cameras continuously, allowing us to determine enhancements in density observed by heliospheric imagers may explain previously unexplained cosmic ray decreases.

This paper introduces the basics of asymmetrical spectral band fitting and discusses the resolution of overlapping Gaussian shapes. We study how to fit overlapping bands with asymmetric Gaussian shapes. First, we derive an equation for an Asymmetric Gaussian shape. We then use this equation to derive a resolvability basis for the resolution of two nearby Gaussian bands. The so called Master Equation is then used to fit these two overlapping bands. We identify regions of the fitting space where the Asymmetric Gaussian fit is likely to be Optimal, Sub Optimal and Not Optimal. We then demonstrate the use of the Asymmetric Gaussian to fit four overlapping bands, and show how this is relevant to the olivine spectral complex at 1 μm. The limitations of the asymmetric band fitting method and a critical assessment of three commonly used numerical minimization and fitting methods are also provided.

• Arctic phytoplankton net primary production can be predicted for multiple years, largely due to the Arctic shelves. • This predictability is driven by ocean temperatures, which are an important limit on phytoplankton growth and maintain predictability. • Phytoplankton net primary production predictability in the Arctic may increase in the near future (2030s) relative to the 2010s.

A document by Suma Bhanu Battula. Click on the document to view its contents.

In this work, a team of globally distributed space science researchers come together to voice their perspectives on space weather research globally and locally. We highlight the importance of studying Heliophysics and space weather research efforts and discuss the challenges the field faces in different parts of the world. We emphasize the importance of focusing on local matters, emphasizing that space weather science can look and mean different things in various parts of the world. Local stories and regional challenges are often lost in chasing the broadly defined issues by the community. We highlight this issue and the importance of global voices, focusing on three different regions: India, Africa, and Latin America. The regions are demographically and culturally distinct, and each region offers a unique perspective on space weather research. We then discuss these challenges in terms of data, software, and technological infrastructure, diving into the guidelines and vision of the globally united space weather research community. This leads to a discussion of shared global challenges and an offering of solutions in today's digital world incorporating open science initiatives. Lastly, we describe what emerging technologies such as artificial intelligence and augmented/virtual reality can offer the space weather community, taking inspiration from other fields.

Peatlands are critical to global biogeochemical cycles because their large accumulations of organic carbon (OC) and nitrogen (N). Broadscale peatland depth maps are needed to assess stocks of OC and N. We used a large peat-core dataset (n=7,111) to assess which environmental variables control peat depth across the extratropical northern hemisphere, testing climatic variables, topography, mineral soil texture and peatland extent. We find that no single environmental variable can accurately predict peat depth. Rather, analyses with multiple regression models show that greater peat depth is linked to a combination of low potential evapotranspiration, warm summers, and limited intra-annual climatic seasonality. At broad scales, the environmental controls of peatland extent are different from controls on peatland depth. This supports the use of methods that treat peatland extent separately from depth when quantifying peat OC stocks. We evaluate different upscaling methods for peat depth mapping and find that random forest machine learning works better than geographically weighted regression or thematic upscaling because the random forest method is more robust with clustered and spatially variable peat depth data. Consistent with earlier studies, we estimate total northern peat stocks of 400±150 Pg OC and 10±7 Pg N. A large part of this peat, containing ca. 50-100 Pg OC, is stored below the 0-3 m depth interval used for global soil OC inventories. Future peatland mapping efforts should target high-resolution maps of individual peatland basins. Such maps will enable more focused studies into the processes that constrain vertical peat accumulation across space and time.

A document by Jack Sheehan. Click on the document to view its contents.

jabbrv-ltwa-all.ldf jabbrv-ltwa-en.ldf Previous attempts to explain the distribution of Neodymium (Nd) and its isotopes in the ocean, a tracer for past global Meridional Overturning Circulation (MOC) changes, primarily focused on a top-down approach using reversible scavenging. This approach assumes that Nd is supplied to the ocean through terrestrial sources at the surface, and reversible particulate scavenging and sinking of Nd on particles explains observations of linearly increasing dissolved Nd concentrations with depth. Here, we explore a conceptually different model: the bottom-up hypothesis and irreversible scavenging. A benthic flux (BF) is assumed to be the sole source of marine Nd at the seafloor; vertical diffusion leads to upward transport and adsorption onto particles, with a constant adsorption coefficient (kp) as the only loss term. This model is explored in a simple one-dimensional (vertically resolved) version and a three-dimensional global general circulation numerical model. Results indicate that the observed distribution of Nd in the ocean is well reproduced globally using a constant BF of 20 pmol cm-2 yr -1 and irreversible scavenging. Our results suggest that bathymetry and lateral transport play important roles in determining Nd water column distribution in the pelagic ocean.

Changes in the Atlantic Meridional Overturning Circulation (AMOC) are believed to have affected the cycling of carbon isotopes (δ13C) in both the ocean and the atmosphere. However, understanding how AMOC changes δ13CDIC of Dissolved Inorganic Carbon (DIC) distributions in the ocean is limited, since models do not typically decompose the various processes that affect δ13CDIC. Here, a new decomposition is applied to idealized simulations of an AMOC collapse, both for glacial and preindustrial conditions. The decomposition explicitly calculates the preformed and regenerated components of δ13CDIC and separates between physical and biological effects. An AMOC collapse leads to a large and rapid decrease in δ13CDIC in the North Atlantic, which is due to, in about equal parts, accumulation of remineralized organic matter and changes in preformed δ13CDIC, both in glacial and preindustrial simulations. In the Pacific, Indian, and Southern Oceans δ13CDIC increases by a smaller magnitude. This increase is dominated by changes in preformed δ13CDIC in the glacial simulation and remineralized δ13CDIC in the preindustrial simulation. An extensive evaluation of the decomposition shows that its errors are small in most cases, especially for large basin-wide changes, whereas for small, local or global changes errors can be substantial. In contrast, approximations of the remineralized component based on Apparent Oxygen Utilization have large errors in most cases and are generally unreliable because they include contributions from oxygen disequilibrium.

The Atlantic Meridional Overturning Circulation (AMOC) impacts temperatures, ecosystems, and the carbon cycle. However, how AMOC affects the carbon cycle remains poorly understood, in part because the respective contributions of different physical and biological mechanisms that impact carbon storage in the ocean are not typically diagnosed in climate models. Here we explore modeled effects of an AMOC shutdown on Dissolved Inorganic Carbon (DIC) in the ocean by applying a new decomposition that explicitly calculates preformed and regenerated DIC components and separates physical and biological contributions. An extensive evaluation of the method in transient simulations finds that, in most cases, it is accurate and reliable, especially for basin-wide changes, whereas errors can be significant at global and local scales. In contrast, estimates of respired carbon based on Apparent Oxygen Utilization lead to large errors and are generally not reliable. In response to a shutdown of the AMOC, ocean carbon increases and then decreases, leading to opposite changes in atmospheric CO2. DIC changes are dominated by opposing changes in biological carbon storage. Whereas regenerated components increase in the Atlantic and dominate the initial increase in global ocean DIC, preformed components decrease in the other ocean basins and dominate the long-term DIC decrease. Biological disequilibrium is an important contribution to preformed carbon changes. Biological saturation carbon decreases in the Pacific, Indian, and Southern Oceans due to a decrease in surface alkalinity. The spatial patterns of the DIC components and their changes in response to an AMOC collapse are presented.

Heatwaves are becoming more frequent and intense, yet many countries remain inadequately prepared to manage their impacts. Existing heat risk plans and responses often fail to account for the complex interdependencies among the various causes and impact pathways of heatwaves. Effective planning requires a system-level understanding of these interdependencies to identify strategic entry points for action. This paper employs a participatory system mapping approach to explore the interconnections among causes, impacts, and response actions during the UK heatwave events of summer 2022. Cognitive maps were developed shortly after the events, incorporating input from 38 stakeholders across sectors involved in the heatwave response. These maps informed a forensic disaster analysis designed to provide a holistic understanding of the heatwave's causes, impacts, and adaptation measures. By analysing the interdependencies among these factors, we identified cascading effects and amplifiers that significantly intensified heat risk in the UK. Notably, we find that the primary heatwave impacts were often indirect, emerging or worsening due to cascading effects such as wildfires, drought, transportation disruptions, and the overburdening of first responders. In many cases, adaptation measures were reactive, addressing isolated, short-term impacts, while proactive, system-level approaches tackling interconnected impacts and root causes-such as vulnerable buildings, at-risk populations, and behavioural barriers-were largely absent. Additionally, we found notable variations in heat risk perceptions among groups. While individual sectors displayed a limited understanding of the broader heat risk system, a system-level perspective emerged through the aggregation of cognitive maps. The implications for adaptation research and policy are discussed.

A document by Mark B. Moldwin. Click on the document to view its contents.

In order to contribute to the deliberation of medium- to long-term local climate policies towards Carbon Neutral by 2050, which is a statutory goal in Japan, the CO2 emissions by prefecture before fiscal year 1990 for each sector such as manufacturing, residential households/businesses, and transportation (passenger/freight) were estimated.