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  • 1
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    Online Resource
    Data_Sheet_1.docx
    Frontiers Media SA ; 2021
    In:  Frontiers in Marine Science Vol. 8 ( 2021-5-3)
    Details
    In: Frontiers in Marine Science, Frontiers Media SA, Vol. 8 ( 2021-5-3)
    Abstract: More high-quality, in situ observations of essential marine variables are needed over the seasonal ice zone to better understand Arctic (or Antarctic) weather, climate, and ecosystems. To better assess the potential for arrays of uncrewed surface vehicles (USVs) to provide such observations, five wind-driven and solar-powered saildrones were sailed into the Chukchi and Beaufort Seas following the 2019 seasonal retreat of sea ice. They were equipped to observe the surface oceanic and atmospheric variables required to estimate air-sea fluxes of heat, momentum and carbon dioxide. Some of these variables were made available to weather forecast centers in real time. Our objective here is to analyze the effectiveness of existing remote ice navigation products and highlight the challenges and opportunities for improving remote ice navigation strategies with USVs. We examine the sources of navigational sea-ice distribution information based on post-mission tabulation of the sea-ice conditions encountered by the vehicles. The satellite-based ice-concentration analyses consulted during the mission exhibited large disagreements when the sea ice was retreating fastest (e.g., the 10% concentration contours differed between analyses by up to ∼175 km). Attempts to use saildrone observations to detect the ice edge revealed that in situ temperature and salinity measurements varied sufficiently in ice bands and open water that it is difficult to use these variables alone as a reliable ice-edge indicator. Devising robust strategies for remote ice zone navigation may depend on developing the capability to recognize sea ice and initiate navigational maneuvers with cameras and processing capability onboard the vehicles.
    Type of Medium: Online Resource
    ISSN: 2296-7745
    URL: Article
    URL: Article
    DOI: 10.3389/fmars.2021.640697
    DOI: 10.3389/fmars.2021.640697.s001
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2021
    detail.hit.zdb_id: 2757748-X
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  • 2
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    DataSheet_1.docx
    Frontiers Media SA ; 2024
    In:  Frontiers in Marine Science Vol. 10 ( 2024-1-8)
    Details
    In: Frontiers in Marine Science, Frontiers Media SA, Vol. 10 ( 2024-1-8)
    Abstract: On September 30, 2021, a saildrone uncrewed surface vehicle intercepted Hurricane Sam in the northwestern tropical Atlantic and provided continuous observations near the eyewall. Measured surface ocean temperature unexpectedly increased during the first half of the storm. Saildrone current shear and upper-ocean structure from the nearest Argo profiles show an initial trapping of wind momentum by a strong halocline in the upper 30 m, followed by deeper mixing and entrainment of warmer subsurface water into the mixed layer. The ocean initial conditions provided to operational forecast models failed to capture the observed upper-ocean structure. The forecast models failed to simulate the warming and developed a surface cold bias of ~0.5°C by the time peak winds were observed, resulting in a 12-17% underestimation of surface enthalpy flux near the eyewall. Results imply that enhanced upper-ocean observations and, critically, improved assimilation into the hurricane forecast systems, could directly benefit hurricane intensity forecasts.
    Type of Medium: Online Resource
    ISSN: 2296-7745
    URL: Article
    URL: Article
    DOI: 10.3389/fmars.2023.1297974
    DOI: 10.3389/fmars.2023.1297974.s001
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2024
    detail.hit.zdb_id: 2757748-X
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  • 3
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    Sensitivity of prescribed burn weather windows to atmospheric dispersion parameters over southeastern USA
    CSIRO Publishing ; 2019
    In:  International Journal of Wildland Fire Vol. 28, No. 8 ( 2019), p. 589-
    Details
    In: International Journal of Wildland Fire, CSIRO Publishing, Vol. 28, No. 8 ( 2019), p. 589-
    Abstract: Prescribed burning is an essential tool for forest and rangeland management that requires specific weather conditions to enable the efficient and safe application of fire. Prescribed burning is often limited by the ability to find suitable burn-days that fit within the identified weather parameters that balance good smoke dispersion and erratic fire behaviour. We analysed the sensitivity of the occurrence of widely used weather windows in the southeastern USA to modest changes in how they are defined. This analysis identified the most limiting prescription components and assessed where small changes in the prescription window can yield the greatest gains in additional burn-days. In the growing season (April–September), adjustments to mixing height offered the greatest such opportunity: a 12.5% increase in the upper-limit yields ~25% more burn-days during this period. During the dormant season (November–January), a 12.5% change in the upper-limit of transport wind yields ~20% more burn-days. Performing this analysis on the ventilation index revealed that comparable increases in burn-days were available by changing its upper limits. These results help inform ongoing discussions on potential changes to regional prescribed burn weather parameters that might help meet smoke management and treatment objectives in the southeastern USA and more broadly.
    Type of Medium: Online Resource
    ISSN: 1049-8001
    URL: Article
    DOI: 10.1071/WF18209
    Language: English
    Publisher: CSIRO Publishing
    Publication Date: 2019
    SSG: 12
    SSG: 23
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  • 4
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    El Niño Impacts on Seasonal U.S. Atmospheric Circulation, Temperature, and Precipitation Anomalies: The OLR-Event Perspective*
    American Meteorological Society ; 2013
    In:  Journal of Climate Vol. 26, No. 3 ( 2013-02-01), p. 822-837
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 26, No. 3 ( 2013-02-01), p. 822-837
    Abstract: This study shows that, since 1979 when outgoing longwave radiation (OLR) observations became reliably available, most of the useful U.S. seasonal weather impact of El Niño events is associated with the few events identified by the behavior of outgoing longwave radiation (OLR) over the eastern equatorial Pacific (“OLR–El Niño events”). These events produce composite seasonal regional weather anomalies that are 95% statistically significant and robust (associated with almost all events). Results also show that there are very few statistically significant seasonal weather anomalies, even at the 80% level, associated with the non-OLR–El Niño events. A major enhancement of statistical seasonal forecasting skill over the contiguous United States appears possible by incorporating these results. It is essential to respect that not all events commonly labeled as El Niño events lead to statistically useful U.S. seasonal forecast skill.
    Type of Medium: Online Resource
    ISSN: 0894-8755 , 1520-0442
    URL: Article
    DOI: 10.1175/JCLI-D-12-00097.1
    RVK:
    UA 4548
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2013
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 5
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    Equatorial Pacific Easterly Wind Surges and the Onset of La Niña Events*
    American Meteorological Society ; 2015
    In:  Journal of Climate Vol. 28, No. 2 ( 2015-01-15), p. 776-792
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 28, No. 2 ( 2015-01-15), p. 776-792
    Abstract: The processes responsible for the onset of La Niña events have not received the same attention as those responsible for the onset of El Niño events, for which westerly wind events (WWEs) in the tropical Pacific have been identified as important contributors. Results here show that synoptic-scale surface easterly wind surges (EWSs) play an important role in the onset of La Niña events, akin to the role of WWEs in the onset of El Niño events. It is found that EWSs are a substantial component of zonal wind stress variance along the equatorial Pacific. Using reanalysis wind stress fields, validated against buoy measurements, 340 EWS events are identified between 1986 and 2012. Their distributions in space, time, and El Niño–Southern Oscillation (ENSO) state are described. About 150 EWSs occur during ENSO-neutral conditions, during the months associated with La Niña initiation and growth (April–December). Composites of changes in sea surface temperature anomaly (SSTA) following these ~150 events show statistically significant cooling (0.1°–0.4°C) along the oceanic waveguide that persists for 2–3 months following the EWSs. Experiments with EWS forcing of an ocean general circulation model show SSTA patterns like those in the observations. It is suggested that EWSs play an important role in the onset of La Niña waveguide surface cooling and deserve additional study.
    Type of Medium: Online Resource
    ISSN: 0894-8755 , 1520-0442
    URL: Article
    DOI: 10.1175/JCLI-D-14-00227.1
    RVK:
    UA 4548
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2015
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 6
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    Hurricane Alley SST Variability in 2005 and 2006*
    American Meteorological Society ; 2008
    In:  Journal of Climate Vol. 21, No. 18 ( 2008-09-15), p. 4710-4722
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 21, No. 18 ( 2008-09-15), p. 4710-4722
    Abstract: The North Atlantic hurricane seasons of 2005 and 2006 were dramatically different for the Gulf Coast and eastern seaboard of the United States. The 2005 hurricane season was one of the most destructive seasons in history, whereas there was limited impact in 2006. Hurricane activity had been forecast to be above normal in 2006, but it was not. One of the conspicuous differences in environmental conditions between these two years was sea surface temperature anomaly (SSTA) over a region of the western Atlantic and Caribbean (15°–30°N, 70°–40°W), which is important for hurricane formation and intensification. SSTA was more than 1.5 standard deviations warmer during the 2005 hurricane season, but it was much less in 2006 through most of its hurricane season. The intent of this study is to determine the mechanisms responsible for this SSTA difference. It is shown that the difference can be reproduced using a simple one-dimensional (1D) ocean mixed layer model forced with surface fluxes from the NCEP–NCAR reanalysis project. It is found that there are two causes of SSTA difference over this region during July through September: the first is latent heat flux variability caused by wind speed effects, and the second is nonlinear ocean warming caused by submonthly atmospheric variability. The observed SSTA difference is reproduced by our model even though solar forcing damps the observed difference, contrary to previous hypotheses.
    Type of Medium: Online Resource
    ISSN: 1520-0442 , 0894-8755
    URL: Article
    DOI: 10.1175/2008JCLI2084.1
    RVK:
    UA 4548
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2008
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 7
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    Diagnosing and Predicting ENSO SSTA Development from Moored-Buoy and Scatterometer Winds
    American Meteorological Society ; 2019
    In:  Journal of Climate Vol. 32, No. 24 ( 2019-12-15), p. 8755-8770
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 32, No. 24 ( 2019-12-15), p. 8755-8770
    Abstract: Accurate real-time knowledge of equatorial Pacific wind stress is critical for monitoring the state of the tropical Pacific Ocean and understanding sea surface temperature anomaly (SSTA) development associated with El Niño–Southern Oscillation (ENSO) events. The tropical Pacific moored-buoy array has been shown to adequately provide this knowledge when operating as designed. Ocean model simulation of equatorial Pacific SSTA by moored-buoy winds reveals that recent western Pacific buoy losses exceed the array’s minimal redundancy. Additional wind measurements are needed to adequately simulate ENSO-related SSTA development when large portions of the moored-buoy array have been lost or decommissioned. Prospects for obtaining this supplemental wind information in real time are evaluated from simulations of central equatorial Pacific SSTA development during 2017 and end-of-year Niño-3.4 conditions during the previous 25 years. Results show that filling multiple-buoy-dropout gaps with winds from a pair of scatterometers (2000–17) achieves simulation accuracy improving upon that available from the moored-buoy array in the case in which large portions of the array are out. Forcing with the reanalysis-product winds most commonly used in recent ENSO studies or the scatterometer measurements (without the buoy winds) degrades simulation accuracy. The utility of having accurate basinwide wind stress information is demonstrated in an examination of the role that easterly weather-scale wind events played in driving the unexpected development of La Niña in 2017 and by showing that wintertime Niño-3.4 conditions can be statistically forecast, with skill comparable to state-of-the-art coupled models, on the basis of accurate knowledge of equatorial Pacific wind variability over spring or summer.
    Type of Medium: Online Resource
    ISSN: 0894-8755 , 1520-0442
    URL: Article
    URL: Article
    DOI: 10.1175/JCLI-D-19-0183.1
    DOI: 10.1175/jcli-d-19-0183.s1
    RVK:
    UA 4548
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2019
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 8
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    Comments on “Characterizing ENSO Coupled Variability and Its Impact on North American Seasonal Precipitation and Temperature”
    American Meteorological Society ; 2017
    In:  Journal of Climate Vol. 30, No. 1 ( 2017-01), p. 427-436
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 30, No. 1 ( 2017-01), p. 427-436
    Abstract: El Niño and La Niña seasonal weather anomaly associations provide a useful basis for winter forecasting over the North American regions where they are sufficiently strong in amplitude and consistent in character from one event to another. When the associations during La Niña are different than El Niño, however, the obvious quasi-linear-statistical approach to modeling them has serious shortcomings. The linear approach of L’Heureux et al. is critiqued here based on observed land surface temperature and tropospheric circulation associations over North America. The La Niña associations are quite different in pattern from their El Niño counterparts. The El Niño associations dominate the statistics. This causes the linear approach to produce results that are inconsistent with the observed La Niña–averaged associations. Further, nearly all the useful North American associations have been contributed by the subset of El Niño and La Niña years that are identifiable by an outgoing longwave radiation (OLR) El Niño index and a distinct OLR La Niña index. The remaining “non-OLR events” exhibit winter weather anomalies with large event-to-event variability and contribute very little statistical utility to the composites. The result is that the linear analysis framework is sufficiently unable to fit the observations as to question its utility for studying La Niña and El Niño seasonal temperature and atmospheric circulation relationships. An OLR-event based approach that treats La Niña and El Niño separately is significantly more consistent with, and offers an improved statistical model for, the observed relationships.
    Type of Medium: Online Resource
    ISSN: 0894-8755 , 1520-0442
    URL: Article
    DOI: 10.1175/JCLI-D-15-0678.1
    RVK:
    UA 4548
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2017
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 9
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    Summertime Rainfall Events in Eastern Washington and Oregon
    American Meteorological Society ; 2016
    In:  Weather and Forecasting Vol. 31, No. 5 ( 2016-10-01), p. 1465-1480
    Details
    In: Weather and Forecasting, American Meteorological Society, Vol. 31, No. 5 ( 2016-10-01), p. 1465-1480
    Abstract: The temporal and spatial characteristics of summertime rainfall events in the Pacific Northwest are examined in relation to the prevailing regional 500-hPa geopotential height conditions, with focus on the forested slopes of eastern Washington and northeastern Oregon, where the absence/occurrence of events largely determines the start and end of the wildland fire season. The Daily U.S. Unified Precipitation dataset is used for specifying rainfall events (period 1949–2008). Events are defined as one or more consecutive days of rainfall exceeding 0.25 in. (0.65 mm), and occur on average two to three times per summer (July–September) in the focus region, east of the Cascade Mountain crest, with a minimum in frequency in late July. A relatively high percentage of the events in the northern portion of the domain of interest, and over the higher terrain, is associated with anomalous midtropospheric southwesterly flow; a high percentage of the events in the southern and lower elevation portions of the domain is associated with southeasterly flow anomalies. Southeasterly flow events are much more likely to be accompanied by lightning and a more localized rainfall distribution than southwesterly events. Southwesterly events mainly account for the late-July frequency minimum and produce more widespread/heavier precipitation on average. The forests of eastern Washington and Oregon receive a mix of southeasterly and southwesterly events. Results suggest that identifying flow types by (skillful) extended-range 500-hPa forecasts may provide a useful basis for predicting the associated aspects of the rainfall event distribution.
    Type of Medium: Online Resource
    ISSN: 0882-8156 , 1520-0434
    URL: Article
    URL: Article
    DOI: 10.1175/WAF-D-16-0024.1
    DOI: 10.1175/WAF-D-16-0024.s1
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2016
    detail.hit.zdb_id: 2025194-4
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  • 10
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    Simulating ENSO SSTAs from TAO/TRITON Winds: The Impacts of 20 Years of Buoy Observations in the Pacific Waveguide and Comparison with Reanalysis Products
    American Meteorological Society ; 2017
    In:  Journal of Climate Vol. 30, No. 3 ( 2017-02-01), p. 1041-1059
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 30, No. 3 ( 2017-02-01), p. 1041-1059
    Abstract: The fundamental importance of near-equatorial zonal wind stress in the evolution of the tropical Pacific Ocean’s seasonal cycle and El Niño–Southern Oscillation (ENSO) events is well known. It has been two decades since the TAO/TRITON buoy array was deployed, in part to provide accurate surface wind observations across the Pacific waveguide. It is timely to revisit the impact of TAO/TRITON winds on our ability to simulate and thereby understand the evolution of sea surface temperature (SST) in this region. This work shows that forced ocean model simulations of SST anomalies (SSTAs) during the periods with a reasonably high buoy data return rate can reproduce the major elements of SSTA variability during ENSO events using a wind stress field computed from TAO/TRITON observations only. This demonstrates that the buoy array usefully fulfills its waveguide-wind-measurement purpose. Comparison of several reanalysis wind fields commonly used in recent ENSO studies with the TAO/TRITON observations reveals substantial biases in the reanalyses that cause substantial errors in the variability and trends of the reanalysis-forced SST simulations. In particular, the negative trend in ERA-Interim is much larger and the NCEP–NCAR Reanalysis-1 and NCEP–DOE Reanalysis-2 variability much less than seen in the TAO/TRITON wind observations. There are also mean biases. Thus, even with the TAO/TRITON observations available for assimilation into these wind products, there remain oceanically important differences. The reanalyses would be much more useful for ENSO and tropical Pacific climate change study if they would more effectively assimilate the TAO/TRITON observations.
    Type of Medium: Online Resource
    ISSN: 0894-8755 , 1520-0442
    URL: Article
    DOI: 10.1175/JCLI-D-15-0865.1
    RVK:
    UA 4548
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2017
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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