Abstract The global thermohaline circulation, driven by density contrasts in seawater, plays a fundamental role in global climate regulation. Within this system, the Atlantic meridional overturning circulation (AMOC) governs large-scale heat redistribution between hemispheres. However, anthropogenic forcing in the Anthropocene threatens to weaken the AMOC, with profound consequences for regional climates and ecosystems. In this study, we applied a global atmospheric circulation model coupled with a dynamic global vegetation model to evaluate two sea surface temperature scenarios: a control case and an anomaly experiment based on Manabe and Stouffer. The simulations revealed pronounced precipitation anomalies, including substantial reductions in rainfall during several months that typically belong to the wet season and enhanced rainfall during months historically associated with the dry season in parts of the Amazon, linked to a displacement of the intertropical convergence zone (ITCZ). Additional impacts included surface cooling in the Amazon, warming in central Brazil, and weakening of the South Atlantic subtropical high, which enhanced frontal system penetration in southeastern Brazil. Vegetation dynamics indicated an expansion of tropical forests into Caatinga regions, where Caatinga is a semiarid dense shrubland ecosystem in Northeast Brazil, reflecting strong biosphere–climate feedbacks. Moreover, the reorganization of Hadley cell circulation confirmed large-scale atmospheric adjustments. Altogether, these results suggest that AMOC weakening may substantially reshape rainfall regimes, temperature patterns, pressure systems, and vegetation cover across Brazil. Significance Statement The Atlantic meridional overturning circulation (AMOC) is a critical component of Earth’s climate system, redistributing heat and regulating precipitation patterns across continents. Our modeling experiments reveal that AMOC weakening could profoundly alter Brazil’s climate, producing large shifts in seasonal rainfall regimes, marked changes in hydroclimatic variability, and substantial shifts in vegetation cover. These findings highlight the interconnectedness of oceanic and terrestrial systems, showing that large-scale circulation changes in the Atlantic can cascade into regional hydroclimatic and ecological transformations. Understanding these mechanisms is crucial for anticipating future climate resilience and for guiding adaptation strategies in tropical regions under anthropogenic pressure.
Over the past century, groundwater overexploitation has triggered severe land subsidence in coastal megacities like Tianjin, China. However, with policy changes such as enforced extraction restrictions and large-scale water diversion, the downward trend has now been reversed, unexpectedly leading to strange phenomena. Long-term monitoring in Tianjin (2013-23) reveals a complex spatiotemporal pattern where areas of persistent land subsidence coexist with zones of recent uplift, following shifts in groundwater policy. The mechanisms governing this transition, particularly the lagged, nonelastic nature of the uplift, remain poorly quantified. The decade-long leveling data and field experiments were integrated to elucidate the differential hydromechanical response of layered soils. Especially, the field experiments reveal distinct deformation mechanisms: Sand layers exhibit primarily elastoplastic behavior, whereas clay layers are dominated by viscoplastic deformation. These contrasting responses, combined with variations in layer thickness, lead to spatially heterogeneous ground movement. These insights inform the development of a 3D visco-elasto-plastic hydromechanical coupling model, explicitly incorporating state-dependent parameters to capture hysteresis and inelasticity. The validated model not only reproduces the observed decadal deformation field but also enables a quantitative, scenario-based risk assessment for critical infrastructure, projecting differential displacement under various groundwater management futures. SIGNIFICANCE STATEMENT: This study reveals how policies restricting groundwater extraction in coastal cities can unexpectedly cause ground uplift alongside subsidence, creating new risks for infrastructure like railways and tunnels. By analyzing a decade of data from Tianjin, China, we show that rising groundwater levels lead to uneven ground movement some areas lift while others sink due to differing soil properties. Our predictive model helps cities anticipate these shifts, enabling proactive protection of critical infrastructure. This work is vital for urban planners and policymakers seeking to balance water resource management with public safety, especially as global coastal cities face similar challenges from climate adaptation strategies.
The study focuses on the scale dependence of surface energy fluxes in topographically diverse landscapes, where variations in soil moisture and vegetation types significantly influence evapotranspiration processes. Land-atmosphere interaction plays a major role in atmospheric processes in the Qinghai-Tibet Plateau (QTP) region, and the inability of current land-atmosphere models to capture the landscape-scale heterogeneity in the latent heat flux introduces uncertainties in these models. To address this issue, the remote sensing-based fine-scale energy balance modeling [Mapping Evapotranspiration at High Resolution with Internalized Calibration (METRIC)] was combined here with topographical analysis [2D FFT spectral analysis and Landscape Unit Mapping Program (LUMP) hillslope discretization] to identify a representative elementary area (REA) for latent heat flux. A scale dependence analysis within a 1-10-km range is performed, and two flux aggregation methods are proposed: the mechanistic approach to define REA, which identifies optimal aggregation areas for latent heat through window size variations, and the landscape-explicit approach, which upscales latent heat based on hillslope elements of dominant quasi-periodic topographic features. It was established that the representative elementary area for latent heat at QTP is in the 2-4-km range. Moreover, REA is formed by characteristic topographical patterns that can be defined through regularity and repetition, which can be seen in representative hillslopes. Benchmark simulations conducted with the METRIC model indicate that ignoring topographical influences results in the absence of REA. The landscape-explicit approach may offer greater interpretability and predictive capability for future land-atmosphere model development as it considers topographic effects on lateral water redistribution and surface energy transfer.
The northeastern Sylhet region of Bangladesh has faced severe flooding, leading to tragic consequences such as loss of life, displacement, and economic challenges. This study evaluates the impact of flooding on various land uses in the region from 2018 to 2022. Flood-affected areas were identified using Sentinel-1 SAR images in Google Earth Engine (GEE), and land use was analyzed with the Dynamic World dataset of Sentinel-2 images. The study found that cropland has been significantly impacted, with two-thirds affected by floods from 2018 to 2022, and 84% in 2023, causing economic hardship. In 2018, 27% of vegetation coverage was affected, decreasing in subsequent years but rising to 30% during the 2022 flood. In 2018, about 47.83 km2 of built-up area was impacted, increasing to 128.135 km2 in 2022. The total affected population (TAP) in Sylhet district increased from 27% in 2021 to 43% in 2022, while Sunamganj exhibited the highest vulnerability, with TAP rising from 65% in 2021 to 74% in 2022. These findings highlight the increasing severity of flood events, likely driven by climate change and inadequate infrastructure, and emphasize the urgent need for integrated flood management strategies to protect the population and environment in Sylhet.
At 2020 UTC 16 March 2024, the Sundhnuksg & imath;gar crater row located north of the town of Grindav & imath;k on the Reykjanes Peninsula, Iceland, erupted. Forty minutes after the start of the eruption, a significant rain shower started 20 km downwind of the eruption site to the west of the Keflav & imath;k International Airport. Since there was no precipitation over the peninsula prior to the eruption and the precipitation event started shortly after the eruption and downwind from the volcano, we were led to believe that it was linked to the eruption. In the style of a mystery novel, we sought to elucidate the mechanism linking the eruption and the rain shower. Two different mechanisms were initially investigated: 1) the volcano heat and moisture led to convection and 2) the volcanic ash created condensation nuclei. Using radar data, ground-based measurements, and model soundings, it was found that the eruption could not be directly responsible for the precipitation event through either of these mechanisms. As such, another process had to be involved, namely, that the eruption acted as an obstacle to the atmospheric flow causing precipitation. SIGNIFICANCE STATEMENT: Shortly after a volcano in southwest Iceland erupted, an unforecasted heavy rain shower started west of the Keflav & imath;k International Airport, the main airport deserving Reykjavik, Iceland. Such a heavy shower could have disrupted the airport activities and might have been a hazard to landing and departing aircraft should it have occurred over the airport. We investigated how the volcano caused the rainstorm as the rain started shortly after and downwind of the eruption. The uncovered process proved to be unexpected, justifying this publication: It appears that the eruption acted as an obstacle that wind had to leap over, and this sudden ascending motion quickly produced significant precipitation downwind.
This study examines climate conditions that modulate crop yield using a satellite vegetation color index in the highlands of South Africa 27 degrees-30 degrees S, 24 degrees-29 degrees E. A monthly time series is formulated (1982-2022) which exhibits large seasonality (brown winters, green summers). Correlations with detrended national maize yield exceed 0.70 in austral summer. The January-March vegetation index exhibits significant negative correlation with east Pacific and west Indian sea surface temperatures at lead times from 0 to 6 months. Persistent 3-5-yr cycles are associated with tilting of the ocean thermocline and El Ni & ntilde;o-Southern Oscillation (ENSO), a link that has strengthened with time. Green minus brown composites exhibit a cyclonic circulation near Windhoek and a midlatitude anticyclone. Together these induce easterly winds (3 m s-1) that supply moisture from the Mozambique Channel. The composites show a southward shift of upwelling in the Benguela Current and a slowing and warming of the Agulhas Current. Long-term simulations by the CMIP6 ensemble predict more rain in the east and warm temperatures (+0.04 degrees C yr-1) in the west. Yet, outcomes suggest that adaptation to climate change is underway and that South Africa's crop yields may continue to rise (+0.1 t ha-1 yr-1) and ensure regional food security.
Wildfire activity in the southwestern United States has intensified in recent decades, driven by the complex interactions of climatic variability, vegetation patterns, and human impacts. This study examines wildfire dynamics in Arizona and New Mexico using data from 1984 to 2021 to evaluate how antecedent moisture and aridity conditions influ-ence fire activity across conifer forests, shrublands, and grasslands. The findings reveal distinct, ecosystem-specific responses to climate: In conifer forests, prolonged drought and rising vapor pressure deficits drive larger and more severe wildfires, underscoring the increasing influence of aridity. In shrublands and grasslands, wildfire risk is often tied to antecedent wet periods that stimulate fine-fuel growth, followed by warm, dry conditions that promote fire spread. The spread of invasive grasses has further heightened fire risk in shrubland and desert ecosystems by enhancing fuel connectivity and transforming fire-climate dynamics in historically fuel-limited regions. As the climate continues to warm and precipitation patterns shift, the spatial and temporal patterns of wildfire activity are expected to remain dynamic, posing significant challenges for fire management and planning. Additionally, the ongoing expansion of the wildland-urban interface will amplify the social and ecological consequences of wildfires, regardless of whether conditions trend wetter or drier. This study highlights the need for adaptive management strategies that incorporate short-term climatic influences into fire-risk assessments while addressing the unique ecological and societal contexts of the region. By advancing understanding of fire-climate-vegetation interactions, this research provides critical insights for mitigating future wildfire impacts in the Southwest.
The temperate climate region of southeastern Australia (SEA) suffers from large periodic wildfires. We investigated how land-atmosphere (L-A) interactions could affect wildfires in the SEA region by applying the forest fire danger index (FFDI) using climate variables from the European Centre for Medium-Range Weather Forecasts reanalysis 5. We calculated FFDI95, which is the number of days exceeding the 95th percentile of daily FFDI during the study period of 1980-2021. The FFDI95 was verified by correlation with the burned areas obtained from satellite data and fire records (r = 0.66, p value < 0.05). We found that FFDI95 in the temperate climate region of SEA increased significantly during the fire season (austral summer) throughout the study period. Using the FFDI95 area averaged over the study region, correlation and composite difference analyses were conducted along with land and atmospheric variables after removing the long-term trend and El Ni & ntilde;o-Southern Oscillation variability. During the prefire season (austral spring), significantly reduced soil moisture enhances heat transfer through sensible heat flux, thus raising the temperature from the surface to the lower troposphere. Thermal expansion results in increased atmospheric thickness and strengthened anticyclonic circulation in the midtroposphere. During the fire season, a thicker troposphere, including the intensification of anticyclonic circulation and subsidence, may promote hot and dry conditions, thus intensifying wildfires. The physical processes related to the variations in land conditions and the corresponding responses of the atmosphere indicate that L-A interactions can amplify wildfires in SEA. Significance Statement: Rising temperatures caused by climate change have increased the risk of wildfires. We focused on the physical processes that amplify wildfire risk in southeastern Australia (SEA) regarding the interactions between land and the atmosphere. We propose a plausible process as follows: With a soil moisture deficit, surface to lower-troposphere temperatures may increase by more sensible heat transfer from drier land. The warming troposphere expands thermally; therefore, atmospheric pressure increases in the midtroposphere. Consequently, high temperatures and low humidity at the surface and in the lower troposphere could be induced by adiabatic warming, and hot and dry conditions promote the danger of wildfires in SEA.
Soil erosion is a widespread form of soil degradation in terrestrial ecosystems and plays a crucial role in the dynamics of soil carbon pools. Assessing soil erosion affected by climate and land-use changes is essential for evaluating future risks and impact on soil organic carbon (SOC) displacements. The phase 5 of the Coupled Model Intercomparison Project (CMIP5) simulations have provided the basis for most such assessments, but are gradually being superseded by more recent simulations from phase 6 of CMIP (CMIP6). However, a quantitative comparison of the differences between CMIP5 (RCP8.5) and CMIP6 [shared socioeconomic pathway (SSP) SSP5-8.5] models and their impacts on soil erosion and SOC simulations has not been conducted. Therefore, this study aims to compare changes in soil erosion in response to climate change and land-use change in China based on CMIP5 and CMIP6 simulations and assesses the impact of erosion on SOC stocks. Combining the effects of climate and land-use change, the CMIP5 ensemble model projects an increase in soil erosion rates over most of China, while CMIP6 models project an average soil erosion reduction of 39 t km-2 a-1 for the years 2031-50 compared to the reference period. Climate and land-use changes contribute to the increased soil erosion rate by 51.75% and-28.85%, respectively, based on CMIP5 and by 32.75% and-54.01%, respectively, based on CMIP6. The CMIP6 results demonstrate less rainfall erosivity due to climate change and more pronounced mitigating effects from beneficial land-use changes on soil erosion compared to CMIP5. However, the average change in SOC displacement rate is projected to be-0.02 t km-2 a-1 for CMIP6. The CMIP5 results suggest that soil erosion in areas other than the Tibetan Plateau will result in a rising rate of soil organic carbon displacement by 0.03 t km-2 a-1. Therefore, it is recommended that decision-makers consider multiple dimensions such as different models and influencing factors when updating impact studies for water and soil conservation.
Wildfires occur each summer in the boreal forests of Alaska, with an increasing frequency of extreme fi re seasons in recent decades. The wildfire season typically begins after the snow melts (i.e., snowoff) in April-May, which is trending toward earlier dates since 1959 (ranging from 2 to 4 days decade21 over Alaska). This study evaluates snowoff dates in Alaska and related synoptic-scale atmospheric drivers in spring over 1959-2020 to assess possible linkages with the summer wildfire season. Many of the largest fi re seasons followed regional snowoff dates in the earliest tercile accounting for 56%-95% of the total historical area burned by the region. Snowoff is best correlated with average daily maximum temperatures during April-May with weaker correlations thereafter. In some years, early snowoff and associated warm temperature anomalies persisted later into the summer influencing fi re danger indices. This occurred in many years with the largest area burned. More limited instances of persistent lower precipitation anomalies were also found. The persistent temperature anomalies primarily occurred during El Ni & ntilde;o conditions and the positive phase of the east Pacific/North Pacific pattern. Precipitation anomalies were most strongly associated with the Atlantic multidecadal oscillation. Blocking high pressure associated with these teleconnections was a likely driving mechanism, particularly for temperature persistence. The results indicated that the snowoff date and concurrent springtime synoptic climate conditions may provide predictability of fi re weather conditions during the wildfire season when this persistence occurs. These subseasonal surface-atmosphere linkages could be used to inform wildfire-related seasonal forecasts. SIGNIFICANCE STATEMENT: The purpose of this study is to understand how snowoff timing impacts seasonal wildfire activity in Alaska to inform wildfire-related forecasts needed for operational planning. Snowoff timing was found to directly impact fi re weather conditions only during the early season. However, early snowoff was correlated with sustained warm temperature anomalies during several large wildfire years. These conditions were linked with El Ni & ntilde;o and other teleconnections. Sustained dry conditions were most strongly associated with wildfire on the North Slope. Our results show that climate conditions during the spring snowoff period may serve as a potential predictor of summer temperature, precipitation, and wildfire in Alaska. These precursor relationships can therefore contribute to improvements in the seasonal prediction of wildfire danger.
Shallow landslides are often triggered during rainfall events, which can increase subsurface soil water pressure and destabilize hillslopes. The likelihood of regional shallow landslide initiation is often assessed through a comparison of rainfall intensity and duration to pre-established thresholds. While informative for landslide warning, this exclusive focus on rainfall exceeding thresholds does not consider the meteorological conditions producing the rainfall. Here, we ask the question, are there common meteorological characteristics that lead to landslide-triggering precipitation? We develop a catalog of 18 post-1995 widespread, impactful shallow landslide events occurring within 13 storms across California, USA, where initiation time could be constrained to a <= 6-h window. We examine storm characteristics during the landslide initiation window using atmospheric reanalysis products, radar observations, and quantitative precipitation estimates. We fi nd that, while there are some common atmospheric characteristics across landslide events, they can occur under a range of atmospheric conditions. For example, all Northern California landslide events assessed are associated with moderate to strong atmospheric rivers (ARs), while Southern California landslides feature non-AR to strong AR conditions. The storm events evaluated herein share many characteristics of hydrologically important storms in California that did not necessarily result in landslides; thus, atmospheric characteristics alone may not be sufficient to determine whether landslides will occur. However, documenting the characteristics of landslide-triggering storms defines the conditions under which landslides tend to occur, provides analog events that can be useful in forecast applications, helps define future research directions relating to atmospheric conditions and landslides, and supports interdisciplinary research efforts.
With the importance of agriculture to the southern Great Plains (SGPs), accurate knowledge of growing season (GS) temperatures and precipitation is critical. Previous research into GS precipitation and temperature maxima leads to the development of the asynchronous difference index (ADI) which identified fi ed positive and negative ADI GSs (March-September). The goal of this research is to further investigate the ADI within a specific fi c agricultural region of the SGP, the winter wheat region, and to quantify the temporal evolution of temperature and precipitation during positive and negative ADI GSs. For this, Global Historical Climatology Network (GHCN) daily station data were analyzed across the GS (March-September) from 1900 to 2020. Results show that differences appear in the temperature and precipitation fi elds when comparing positive and negative GSs. Namely, positive (negative) ADI GSs show positive (negative) precipitation and negative (positive) temperature anomalies early in the GS, with these anomalies fl ipping in the later portion of the GS. Further, the results of this work show that the depicted changes in temperature and precipitation during positive and negative ADI GSs impact winter wheat yields. Overall, these results analyze the implications of positive and negative ADI GSs on the SGP climate, namely, the impact of the seasonal variability of daily maximum temperature and precipitation on agriculture.
The effects of various strategies aimed at simultaneously promoting environmental conservation and human development are closely related to sustainable development regionally and globally. However, although the effects of many such strategies have been evaluated by ecologists and sociologists separately, their ability to simultaneously meet these two anticipated goals (i.e., environmental conservation and human development) at the fine spatial scale remains unclear. To answer this fundamental but crucial question, incorporating household and forest change data, we concurrently estimated the ecological and socioeconomic effects of two world-renowned Payment for Ecosystem Services (PES) programs (i.e., the Nature Forest Conservation Program, the Grain to Green Program) and nature-based tourism in 30 protected areas across 8 provinces in China. Here we showed a trade-off between the ecological and economic effects of two PES programs, while synergistic effects exist in the ecological and economic benefits of tourism. Attributes of household and protected areas significantly influenced economic and environmental benefits as well. Our research provides new insights into the complex effects of PES programs and tourism, and crucial information to support their adequate and sustainable implementation in China and the rest of the world. Significance Statement This work answers a fundamental but crucial question, that is, whether the policies commonly advocated to incorporate environmental conservation and human development can yield positive effects both for conservation and economic development. Our evaluation is also timely to inform some shortness (i.e., negligible economic effects, or the lack of expected positive economic benefits) and provides new insights (e.g., the implication of households and protected-areas attributes in conservation and economic outcomes) of Payment for Ecosystem Services (PES) programs and the complex effects of instruments in the context of multiple policies, particularly given the upcoming 2030 deadline for achieving the Sustainable Development goals (SDGs). We expected that implications in this study can provide important lessons for these two instruments, other PES programs, and other conservation and development instruments to support their adequate and sustainable implementation in China and beyond and to contribute to the achievement of relevant SDGs in the remaining years.
Harmful algae and cyanobacteria blooms are increasing in frequency and intensity in freshwater systems due to anthropogenic impacts such as nutrient loading in watersheds and engineered alterations of natural waterways. There are multiple physical factors that affect the conditions in a freshwater system that contribute to optimal habitats for harmful algae and toxin -producing cyanobacteria. A growing body of research shows that climate change stressors also are impacting water -body conditions that favor harmful algae and cyanobacteria species over other phytoplankton. The overgrowth of these organisms, or a "bloom," increases the opportunity for exposure to toxins by humans, companion animals, livestock, and wildlife. As waters warm and precipitation patterns change over time, exposure to these blooms is projected to increase. Hence, it is important that states and tribes develop monitoring and reporting strategies as well as align governmental policies to protect their citizens and ecosystems within their jurisdiction. Currently, the policies and approaches taken to monitor and report on harmful algae and cyanobacteria blooms vary widely among states, and it is undetermined if any tribes have speci fi c policies on harmful algae blooms. This paper synthesizes research on algal blooms in inland freshwater systems of the United States. This review examines how climate change contributes to trends in bloom frequency or severity and outlines approaches that states and tribes may use to monitor, report, and respond to harmful algae and cyanobacteria blooms. SIGNIFICANCE STATEMENT: Inland bodies of freshwater supply drinking water for humans and animals, water for irrigating crops, habitats for aquatic species, places of cultural signi fi cance for Indigenous peoples, and other important functions. Many of these bodies of water have been polluted with runoff from industry, including agriculture, and already support harmful algal blooms during warm conditions. Hot extremes associated with climate change are expected to increase the occurrence and duration of harmful algal blooms, and in some places, initiate blooms where none have been recorded previously. These toxic blooms are harmful to people, companion animals, livestock, and wildlife. It is important to review the interconnections among biological, climate, and water systems to monitor blooms and alert the public about their toxin production.
Regional warming and associated changes in hydrologic systems pose challenges to water supply management in river basins of the western United States and call for improved understanding of the spatial and temporal variability of runoff. We apply a network of total width, subannual width, and delta blue intensity tree-ring chronologies in combination with a monthly water balance model to identify droughts and their associated precipitation P and temperature T footprints in the Truckee - Carson River basin (TCRB). Stepwise regression gave reasonably accurate reconstructions, from 1688 to 1999, of seasonal P and T (e.g., R 2 = 0.50 for May - September T ). These were disaggregated to monthly values, which were then routed through a water balance model to generate " indirectly " reconstructed runoff. Reconstructed and observed annual runoff correlate highly ( r = 0.80) from 1906 to 1999. The extended runoff record shows that twentiethcentury droughts are unmatched in severity in a 300 -yr context. Our water balance modeling reconstruction advances the conventional regression-based dendrochronological methods as it allows for multiple hydrologic components (evapotranspiration, snowmelt, etc.) to be evaluated. We found that imposed warming (3 degrees and 6 degrees C) generally exacerbated the runoff de fi - cits in past droughts but that impact could be lessened and sometimes even reversed in some years by compensating factors, including changes in snow regime. Our results underscore the value of combining multiproxy tree-ring data with water balance modeling to place past hydrologic droughts in the context of climate change.
This year (2023), the American Meteorological Society (AMS) started undertaking an organizationwide equity assessment to understand the experiences of members and staff with regard to inclusion, equity, justice, accessibility, and diversity at AMS.The equity assessment process will gather this information through a culture survey in mid-September and follow-up focus groups.The equity assessment process is being conducted with care and rigor.The AMS Council and leadership want a data-driven understanding that reflects a wide range of backgrounds and experiences, and they have set a goal of at least 50% of AMS members participating.The AMS Publications Commission strongly encourages all AMS publications enterprise stakeholders (readers, authors, reviewers, and editors) to participate when the survey is released in September.The American Meteorological Society has already adopted policies and practices that promote inclusion, equity, justice, accessibility, and diversity throughout all aspects of the Society's work.Inclusion is the active and deliberate pursuit of creating a society in which all are welcome, respected, valued, and able to participate and contribute.Equity means that people are supported with what they individually need to be successful.Justice is treating all fairly by dismantling barriers to opportunities, resources, and decision-making.Accessibility is providing equitable access to everyone along the continuum of human ability and experience.Diversity is the outcome of creating inclusive, equitable, accessible, and just organizations and systems.These values must be intentionally and actively fostered.Policies and practices that aim simply for neutrality with respect to bias ignore the systemic obstacles faced by individuals and communities who are underrepresented in the weather, water, and climate enterprise.Actively dismantling/reducing these obstacles is necessary to establish a culture of inclusion.Such efforts cannot be left to those already laboring under various forms of bias.Everyone has a role, especially those in positions of power and influence.All of these ideas apply to scientific publishing.The AMS Publications Commission commits to taking an active role in carrying out AMS policies on inclusion.We will make a substantive contribution through the parts of the scientific process for which we are responsible, and we will make inclusion a standard and central practice rather than an afterthought.
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In this paper, we introduce a novel strategy to robustly diagnose the onset and demise of the rainy season using daily observed rainfall over seven specific regions across Australia, as demarcated by the Natural Resource Management (NRM) agency of Australia. The methodology lies in developing an ensemble spread of the diagnosed onset and demise from randomly perturbing the observed daily time series of rainfall at synoptic scales to obtain a measure of the uncertainty of the diagnosis. Our results indicate that the spread of the ensemble in the diagnosis of the onset and demise dates of the rainy season is higher in the subtropical region than the tropical region. Secular change of earlier onset, later demise, longer length, and wetter season are also identified in many of these regions. The influence of the PDO at decadal scale, ENSO and Indian Ocean dipole at interannual scale, and MJO at intraseasonal scale also reveals significant influence on the evolution of the rainy season over these regions in Australia. Most important, the covariability of the onset date with the length of the season and seasonal rainfall anomaly of the season is highlighted as a valuable relationship that can be exploited for real-time monitoring and providing an outlook of the forthcoming rainy season, which could serve some of the NRM regions.
The pan-African Great Green Wall for the Sahara and the Sahel initiative (GGW) is a reforestation pro-gram to reverse the degradation of land. We investigate characteristics of mean precipitation due to proposed land-use changes to woody savannah with three hypothetical courses of the GGW, with an area between 0.8 and 1.25 million km2, and between the 100-and 400-mm isohyets. The global Model for Prediction Across Scales (MPAS) was applied for this in-vestigation, employing ensembles with 40 members for the rainy season from June to September and 50 members for August when precipitation is at its peak. In comparison with the observational reference, the results show that a wet bias on the order of 33% in the eastern Sahel and a moderate dry bias of 241% in the western Sahel are present in the MPAS simulations. Our simulations do not provide any significant evidence for GGW-induced changes in the characteristics of the summer precipitation, for positive changes within the Sahel supporting the forestation activities, or for potentially adverse changes in the neighboring regions. Changes are present at the regional scale, but they are not significant at the 5% level. Also, changes simulated for further hydrometeorological variables such as temperature, radiation fluxes, or runoff are comparatively small.
