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Atmosphere

Unlocking Hawai’i’s Weather Secrets: The Surprising Role of Pacific Meridional Mode in Rainfall Variability

El Nino-Southern Oscillation (ENSO) is known to have a significant impact on climate across the Pacific, including Hawai’i, and adjacent continents. However, atmospheric scientists have now revealed that the Pacific Meridional Mode (PMM), another climate pattern that operates in the eastern Pacific Ocean, plays a major role in the variability of rainfall in Hawai’i.

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Hawai’i, a tropical paradise known for its lush landscapes and rich biodiversity, is also prone to varying levels of rainfall throughout the year. While El Niño-Southern Oscillation (ENSO) has long been recognized as a significant driver of climate variability across the Pacific, new research reveals that another crucial climate pattern, the Pacific Meridional Mode (PMM), plays a vital role in shaping Hawai’i’s rainfall patterns.

Led by University of Hawai’i at Manoa atmospheric scientists, this groundbreaking study published in the Journal of Climate sheds light on the impact of PMM on spring rainfall, particularly for Maui and the Big Island. According to Dr. Pao-Shin Chu, co-author and Hawaii State Climatologist, “Our study suggests that although El Niño emerges as the primary driver of winter rainfall variability in Hawai’i, the Pacific Meridional Mode has a pivotal role in spring rainfall.”

The PMM operates in two distinct states: positive and negative. During the positive state, weaker trade winds prevail, accompanied by increased sea surface temperatures. Conversely, stronger trade winds and cooler surface temperatures are observed during the negative state.

Researchers Bo-Yi Lu and Dr. Chu employed diagnostic analyses using actual weather data, sea surface observations, and weather model-generated information to understand how these PMM patterns influence rainfall variations across Hawai’i.

Their findings indicate that a positive PMM state in spring leads to increased rainfall throughout the islands as cold fronts move through. This phenomenon is particularly pronounced on the windward sides of the islands, where the increased rainfall can exacerbate the risk of flooding. The leeward sides, however, tend to experience an increase in extreme rainfall events.

Interestingly, whether the positive PMM state occurs in winter or spring, the result is an elevated risk of floods on the leeward sides of the Hawaiian Islands. Conversely, a negative PMM state corresponds with reduced daily rainfall over windward sides, potentially worsening drought occurrences.

As Hawai’i’s population grows, so does the demand for water resources. This increased pressure underscores the need to comprehend the intricate relationship between rainfall and climate variability. As Dr. Chu emphasizes, “This uncertainty in interannual rainfall, together with the increasing demand for water, requires us to better understand the relationship between rainfall and climate variability.”

By shedding light on the pivotal role of PMM in Hawai’i’s rainfall patterns, this research aims to empower communities with climate and weather information, ultimately contributing to more informed decision-making for disaster preparedness and resource management.

Acid Rain

Rising Soil Nitrous Acid Emissions Accelerate Global Ozone Pollution

Ozone pollution is a global environmental concern that not only threatens human health and crop production, but also worsens global warming. While the formation of ozone is often attributed to anthropogenic pollutants, soil emissions are revealed to be another important source.

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The article highlights a critical aspect of environmental degradation: the rising soil nitrous acid (HONO) emissions driven by climate change and fertilization, which accelerate global ozone pollution. A team of researchers from The Hong Kong Polytechnic University has examined global soil HONO emissions data from 1980 to 2016 and incorporated them into a chemistry-climate model. Their findings reveal that soil HONO emissions contribute significantly to the increase in the ozone mixing ratio in air, which has negative impacts on vegetation.

The researchers found that soil HONO emissions have increased from 9.4 Tg N in 1980 to 11.5 Tg N in 2016, with a 2.5% average annual rise in the global surface ozone mixing ratio. This increase may lead to overexposure of vegetation to ozone, affecting ecosystem balance and food crop production. Moreover, ozone damage reduces vegetation’s capacity to absorb carbon dioxide, further aggravating greenhouse gas emissions.

The study emphasizes that soil HONO emissions are influenced by nitrogen fertiliser usage and climate factors like soil temperature and water content. Emissions hotspots cluster in agricultural areas worldwide, with Asia being the largest emitter (37.2% of total).

Interestingly, regions with lower pollution levels are more affected by ozone formation due to higher volatile organic compound concentrations and lower nitrogen oxide levels. This implies that as global anthropogenic emissions decrease, the impact of soil HONO emissions on ozone levels may increase.

To mitigate this issue, Prof. Tao Wang recommends considering soil HONO emissions in strategies for reducing global air pollution. The research team developed a robust parameterisation scheme by integrating advanced modelling techniques and diverse datasets, which can facilitate more accurate assessments of ozone production caused by soil HONO emissions and their impact on vegetation.

Future studies should explore mitigation strategies to optimise fertiliser use while maintaining agricultural productivity, such as deep fertiliser placement and the use of nitrification inhibitors.

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Atmosphere

Boosting Catalysts with Magnetic Fields: A Game-Changer for Efficient Production

Researchers proposed a novel strategy for using a magnetic field to boost the efficiency of single-atom catalysts — thus speeding up helpful reactions used for ammonia production and wastewater treatment.

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As scientists continue to push the boundaries of innovation, researchers at Tohoku University have made a groundbreaking discovery in the realm of electrocatalysis. They have successfully demonstrated that applying an external magnetic field can significantly enhance the performance of single-atom catalysts (SACs), leading to a staggering 2,880% improvement in oxygen evolution reaction magnetocurrent.

This revolutionary finding has far-reaching implications for various industries, particularly those involving ammonia production and wastewater treatment. Traditionally, electrocatalysis focused on tweaking the chemical composition and structure of catalysts. However, the introduction of magnetic-induced spin state modulation offers a new dimension for catalyst design and performance improvement.

By regulating the electronic spin state of the catalyst through an external magnetic field, researchers can precisely control the adsorption and desorption processes of reaction intermediates. This, in turn, reduces the activation energy of the reaction, allowing it to proceed more quickly. As explained by Hao Li of Tohoku University’s Advanced Institute for Materials Research (WPI-AIMR), “More efficient production processes can reduce costs, which may translate into lower prices for products such as fertilizers and treated water at the consumer level.”

The study employed advanced characterization techniques to confirm that the magnetic field causes a transition to a high spin state, which improves nitrate adsorption. Theoretical analysis also revealed the specific mechanics behind why this spin state transition enhances electrocatalytic ability.

In an experiment conducted with a Ru-N-C electrocatalyst exposed to an external magnetic field, researchers achieved a remarkable NH3 yield rate (~38 mg L-1 h-1) and a Faradaic efficiency of ~95% for over 200 hours. This represents a significant improvement compared to the same catalyst without the boost from an external magnetic field.

This groundbreaking work enriches our theoretical understanding of electrocatalysis by exploring the relationship between magnetic fields, spin states, and catalytic performance. The experimental results offer valuable insights for future research and development of new catalysts, paving the way for practical applications in electrochemical technologies.

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Ancient DNA

Chemists Recreate a Crucial Step in the Origin of Life

Chemists have demonstrated how RNA (ribonucleic acid) might have replicated itself on early Earth — a key process in the origin of life.

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The origin of life is one of humanity’s greatest mysteries. For centuries, scientists have sought to understand how the complex systems that govern our world emerged from the simple chemistry of the early Earth. A crucial step in this process is the replication of genetic material, which would have been carried by RNA (ribonucleic acid) molecules before DNA and proteins later took over.

Chemists at UCL and the MRC Laboratory of Molecular Biology have made a groundbreaking discovery that brings us closer to understanding how life began. They’ve successfully recreated the conditions under which RNA might have replicated itself on early Earth, a key process in the origin of life.

The researchers used three-letter “triplet” RNA building blocks in water and added acid and heat, which separated the double helix structure that normally prevents RNA strands from replicating. By neutralizing and freezing the solution, they created liquid gaps between the ice crystals where the triplet building blocks could coat the RNA strands and prevent them from zipping back together, allowing replication to occur.

By repeating this cycle of changes in pH and temperature, which could plausibly occur in nature, the researchers were able to replicate RNA over and over again. This process produced RNA strands long enough to have a biological function and play a role in the origin of life.

The study’s lead author, Dr James Attwater, emphasized that replication is fundamental to biology. “In one sense, it is why we are here,” he said. “But there’s no trace in biology of the first replicator.”

The researchers believe that early life was run by RNA molecules, and their findings provide a possible explanation for how this process could have occurred before life began several billion years ago.

While the study focuses solely on the chemistry, the conditions they created could plausibly mimic those in freshwater ponds or lakes, especially in geothermal environments where heat from inside the Earth has reached the surface. However, this replication of RNA could not occur in freezing and thawing saltwater, as the presence of salt interferes with the freezing process and prevents RNA building blocks from reaching the concentration required to replicate RNA strands.

The origin of life is likely to have emerged out of a combination of RNA, peptides, enzymes, and barrier-forming lipids that can protect these ingredients from their environment. The researchers are uncovering clues about how life began, and their findings bring us closer to understanding this fundamental mystery.
In recent years, teams led by Dr John Sutherland and Professor Matthew Powner have demonstrated how chemistry could create many of the key molecules of life’s origin, including nucleotides, amino acids and peptides, simple lipids and precursors to some of the vitamins, from simple molecular building blocks likely abundant on the early Earth.

The latest study was supported by the Medical Research Council (MRC), part of UK Research and Innovation (UKRI), as well as the Royal Society and the Volkswagen Foundation.

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