Sublimation of SnowLundquist, Jessica D.; Vano, Julie; Gutmann, Ethan; Hogan, Daniel; Schwat, Eli; Haugeneder, Michael; Mateo, Emilio; Oncley, Steve; Roden, Chris; Osenga, Elise; Carver, Liz
doi: 10.1175/bams-d-23-0191.1pmid: N/A
AbstractSnow is a vital part of water resources, and sublimation may remove 10%–90% of snowfall from the system. To improve our understanding of the physics that govern sublimation rates, as well as how those rates might change with the climate, we deployed an array of four towers with over 100 instruments from NCAR’s Integrated Surface Flux System from November 2022 to June 2023 in the East River watershed, Colorado, in conjunction with the U.S. Department of Energy’s Surface Atmosphere Integrated Field Laboratory (SAIL) and the National Oceanic and Atmospheric Administration (NOAA)’s Study of Precipitation, the Lower Atmosphere and Surface for Hydrometeorology (SPLASH) campaigns. Mass balance observations, snow pits, particle flux sensors, and terrestrial lidar scans of the evolving snowfield demonstrated how blowing snow influences sublimation rates, which we quantified with latent heat fluxes measured by eddy-covariance systems at heights 1–20 m above the snow surface. Detailed temperature profiles at finer resolutions highlighted the role of the stable boundary layer. Four-stream radiometers indicated the important role of changing albedo in the energy balance and its relationship to water vapor losses. Collectively, these observations span scales from seconds to seasons, from boundary layer turbulence to valley circulation to mesoscale meteorology. We describe the field campaign, highlights in the observations, and outreach and education products we are creating to facilitate cross-disciplinary dialogue and convey relevant findings to those seeking to better understand Colorado River snow and streamflow.Significance StatementSnow provides over 80% of water for the overallocated Colorado River, and in recent years, less runoff has occurred per unit snowfall. Sublimation, the conversion of ice to water vapor, results in less water for runoff, but due to a historic lack of observations, this process is hard to constrain. Variations in how sublimation is represented in models have led to a large divergence of projected water resource availability for the Colorado River basin over both current and future climates. The field campaign described here provides the first comprehensive examination of how snow accumulates, blows around, evolves, and sublimates over 8 months in the Colorado Rocky Mountains, providing a critical benchmark for process understanding and model development.
The Thermal Equator on Earth and MarsMcKay, Christopher P.; Cintron, Mateo N.
doi: 10.1175/bams-d-23-0214.1pmid: N/A
AbstractThe thermal equator (also known as the heat equator) is the circumplanetary set of points that represent the highest mean annual temperature at each longitude. Recent high precision global datasets for Earth and Mars provide a basis for a detailed calculation of the thermal equator on these worlds. On Earth, the temperature values that comprise the thermal equator range from 25.85° to 34.75°C, with a mean of 27.75° ± 1.3°C, and extends in latitude as high as 20°N in Mexico and 29.3°N in the Indian subcontinent. The maximum southern extent is 20°S in Australia. On Mars, lacking oceans, the thermal equator takes a simpler track and is roughly parallel to the equator, and displaced 5°–10°S. However, there is a region of longitude on Mars where the thermal equator becomes bimodal with a northern branch centered at 10°N and a southern branch centered at 20°S.Significance StatementTemperature is one of the factors that affects tropical ecosystems. However, the proximity of an ecosystem to geographical equator is not necessarily an indication of the temperature. The hottest annual average surface temperature at each longitude defines the thermal equator. Using new and detailed global temperature data, we have determined the precise path of the thermal equator on Earth and on Mars. We find that on both planets, the thermal equator moves well above and well below the geographical equator. On Mars, this may affect the distribution of ground ice. On Earth, this matters for understanding ecosystems in the tropics. Future studies might find aspects of tropical ecosystems that correlate with the distance from the thermal equator.
Providing Better Support for Entrepreneurial Activities in the Weather, Water, and Climate CommunitySeitter, Keith L.; Tipton, Emma; Higgins, Paul A. T.
doi: 10.1175/bams-d-23-0301.1pmid: N/A
AbstractThere has been an increase in entrepreneurial activity within the weather, water, and climate (WWC) community over the past decade, with the potential for much more as artificial intelligence/machine learning techniques continue to develop and as new opportunities arise across the weather, climate, and ocean service enterprises. Despite indications of recent growth, this study reports on key challenges that are limiting the community’s ability to achieve the full potential of commercialization of new WWC products and services. Most of these challenges are related to the preparation of those in the WWC community for jobs in the private sector in general and entrepreneurial activities in particular. These results extend and build upon the work of others who have reported on shortcomings in the preparation of students for positions in the private sector, with this study showing that deficits in preparation and awareness of available resources affect potential entrepreneurs well into their career—most researchers are unaware of the resources available to them. Based on a synthesis of input from successful WWC entrepreneurs, many of the challenges could be greatly reduced by relatively minor adjustments to curriculums at universities and through new programs that could be offered by scientific and professional societies to help potential entrepreneurs better take advantage of existing resources as they spin up a new business.Significance StatementThis study examined the challenges faced by those seeking to engage in entrepreneurial activity to take innovative ideas toward commercialization as new products or services related to weather, climate, or oceans. We found that many researchers in the geosciences lack adequate preparation to make the transition to entrepreneur. Moreover, preparation at the university level has great influence over student readiness for careers in the private sector, in general, and entrepreneurial careers in particular. We suggest relatively minor adjustments that could be made to university curriculums, as well as modest programs that could be implemented by scientific and professional societies that could greatly reduce the challenges currently experienced by potential entrepreneurs working in the disciplines covering weather, water, and climate.
Making Social Science Actionable for the NWS: The Brief Vulnerability Overview Tool (BVOT)Friedman, Jack R.; LaDue, Daphne S.; Hurst, Elizabeth H.; Saunders, Michelle E.; Marmo, Alex N.
doi: 10.1175/bams-d-23-0042.1pmid: N/A
AbstractThis paper provides an introduction to a new tool that is designed to provide operationally useful vulnerability information to National Weather Service (NWS) Weather Forecasting Offices (WFOs). The Brief Vulnerability Overview Tool (BVOT) is a shapefile containing local known, spatially specific, and weather-hazard-related vulnerabilities in a format that is easily integrated into the existing forecasting, warning, and decision support responsibilities and tasks of NWS WFO meteorologists. The methods for gathering vulnerability data and then building a BVOT for a WFO leverage and strengthen the relationships that NWS WFOs already have with their local emergency managers (EMs) and core partners to work together to identify operationally useful, local vulnerability knowledge. The BVOT is populated with discrete, known vulnerabilities to provide NWS meteorologists spatial situational awareness of those people, places, and things of greatest concern to their core partners. Crucially, the BVOT is a subsample of all potential vulnerabilities; its primary purpose is to make meteorologists aware of those weather-hazard-specific vulnerabilities that, as we posed to them, “keep them awake at night.” Here, we describe the development of the BVOT as a social science–informed operational tool; how the BVOT methods have evolved and how it can be integrated into the culture of the NWS as a tool for building and maintaining relationships with partners; and how the BVOT is designed to be used and its impact on operational decision-making as observed in NOAA’s Hazardous Weather Testbed.Significance StatementOperational meteorologists in the National Weather Service often rely on everyday knowledge of vulnerabilities to shape their messaging to communities threatened by hazardous weather. This study seeks to test methods that will permit meteorologists to work with local communities and emergency managers to collect knowledge about local vulnerabilities so that they can be formally shared and integrated into everyday operations. The results of this research provide an illustrative pathway demonstrating how social science–informed research can be used to improve meteorological operations. Future work should investigate how other findings from social science can be translated into real, operational impacts.
Multiagency Ensemble Forecast of Wildfire Air Quality in the United States: Toward Community Consensus of Early WarningLi, Yunyao; Tong, Daniel; Makkaroon, Peewara; DelSole, Timothy; Tang, Youhua; Campbell, Patrick; Baker, Barry; Cohen, Mark; Darmenov, Anton; Ahmadov, Ravan; James, Eric; Hyer, Edward; Xian, Peng
doi: 10.1175/bams-d-23-0208.1pmid: N/A
AbstractWildfires pose increasing risks to human health and properties in North America. Due to large uncertainties in fire emission, transport, and chemical transformation, it remains challenging to accurately predict air quality during wildfire events, hindering our collective capability to issue effective early warnings to protect public health and welfare. Here, we present a new real-time Hazardous Air Quality Ensemble System (HAQES) by leveraging various wildfire smoke forecasts from three U.S. federal agencies (NOAA, NASA, and Navy). Compared to individual models, the HAQES ensemble forecast significantly enhances forecast accuracy. To further enhance forecasting performance, a weighted ensemble forecast approach was introduced and tested. Compared to the unweighted ensemble mean, the multilinear regression weighted ensemble reduced fractional bias by 34% in the major fire regions, false alarm rate by 72%, and increased hit rate by 17%. Finally, we improved the weighted ensemble using quantile regression and weighted regression methods to enhance the forecast of extreme air quality events. The advanced weighted ensemble increased the PM2.5 exceedance hit rate by 55% compared to the ensemble mean. Our findings provide insights into the development of advanced ensemble forecast methods for wildfire air quality, offering a practical way to enhance decision-making support to protect public health.Significance StatementWildfires are a growing threat to health and safety in North America. Accurately predicting air quality during these events is crucial but challenging. In response, we have developed the real-time Hazardous Air Quality Ensemble System (HAQES), by combining forecasts from three U.S. federal agencies (NOAA, NASA, and Navy). HAQES significantly improves accuracy compared to individual models. Moreover, we further improve the wildfire air quality forecast by introducing the weighted ensemble method. The weighted ensemble reduced bias by 34% and false alarms by 72%, while increasing hit rates by 55%. HAQES advances our ability to protect public health during wildfire events.
Looking Back: An Account of How Ice Nucleation by Bacteria Was Discovered (1963 to about Mid-1980s). Part II: Broadening the ScopeSchnell, Russell C.; Vali, Gabor
doi: 10.1175/bams-d-23-0115.1pmid: N/A
AbstractIn Part I, we described the discoveries we and our associates made in the 1960s and 1970s about biological ice nucleating particles (bio-INPs). The bio-INPs are far more effective than mineral INPs at temperatures above −10°C. The bio-INPs were found in decayed vegetation and in ocean water, and then, bacteria were identified as being the most active source for this remarkable activity. In this Part II, we recount how, within a few years, the worldwide distribution of bio-INP sources was shown to correlate with climate zones, as was the abundance of INPs in precipitation. Oceanic sources were further studied, and the presence of bio-INPs in fog diagnosed. The potential for release of bio-INPs from the ground to the atmosphere was demonstrated. Bacterial INPs were found to play a crucial role in a plant’s frost resistance. These and other early developments of biological INPs are described. A bibliography of related recent literature is presented in the online supplemental material (https://doi.org/10.1175/BAMS-D-23-0114.s1).Significance StatementIn the decade following the discovery of biological ice nucleating particles (bio-INPs) in the 1960s, evidence was found for the abundance of bio-INPs in plant litters and in rain that correlated with the climate the vegetation grew in, and for the factors governing their presence in the oceans where they were being produced by marine bacteria. These findings laid the groundwork for the current recognition of the atmospheric role of bio-INPs.
Observing System Simulation Experiments (OSSEs) in Support of Next-Generation NOAA Satellite ConstellationCucurull, Lidia; Anthes, Richard A.; Casey, Sean P. F.; Mueller, Michael J.; Vidal, Andres
doi: 10.1175/bams-d-23-0060.1pmid: N/A
AbstractBetween 2014 and 2018, the National Oceanic and Atmospheric Administration conducted the NOAA Satellite Observing System Architecture (NSOSA) study to plan for the next generation of operational environmental satellites. The study generated some important questions that could be addressed by observing system simulation experiments (OSSEs). This paper describes a series of OSSEs in which benefits to numerical weather prediction from existing observing systems are combined with enhancements from potential future capabilities. Assessments include the relative value of the quantity of different types of thermodynamic soundings for global numerical weather applications. We compare the relative impact of several sounding configuration scenarios for infrared (IR), microwave (MW), and radio occultation (RO) observing capabilities. The main results are 1) increasing the revisit rate for satellite radiance soundings produces the largest benefits but at a significant cost by requiring an increase in the number of polar-orbiting satellites from 2 to 12; 2) a large positive impact is found when the number of RO soundings per day is increased well beyond current values and other observations are held at current levels of performance; 3) RO can be used as a mitigation strategy for lower MW/IR sounding revisit rates, particularly in the tropics; and 4) smaller benefits result from increasing the horizontal resolution along the track of the satellites of MW/IR satellite radiances. Furthermore, disaggregating IR and MW instruments into six evenly distributed sun-synchronous orbits is slightly more beneficial than when the same instruments are combined and collocated on three separate orbits.Significance StatementThe results of this paper are significant because they inform decision-makers about the future configuration of the NOAA’s environmental satellite constellation, which serves millions of diverse users.