Pub Date : 2023-04-12DOI: 10.1175/jtech-d-22-0097.1
A common dilemma for oceanographers is the choice of horizontal diffusivity. There is no single answer as we could argue that diffusion depends precisely on those processes that cannot be sampled or modeled. Here we propose the radial offset by diffusion (ROD) method as a simple model-dependent approach for estimating these coefficients, and show its application for the southwestern South Atlantic. The method compares actual displacements of field drifters with numerical trajectory predictions. The observed-predicted differences in radial positions (radial offsets), which respond to diffusive motions not captured by the numerical model, are reproduced with a one-dimensional radial-diffusive solution through a proper selection of the diffusion coefficient. The method is tested at eight depths, from the sea surface down to 2000 m, using several drifter datasets and the Parcels software applied to the GLORYS12v1 (1/12° daily) velocity outputs. In all cases the radial offsets show Gaussian distributions that are well reproduced by the radial diffusive solution. Maximum diffusivities of 4630-4980 m2 s−1 happen in the upper 200 m of the water column and minimum values of 1080-1270 m2 s−1 occur between 1400 and 2000 m. The 15-m diffusivity is fairly constant in latitude (3850 to 5270 m2 s−1), but the 1000-m diffusivity decreases from 1640-1820 m2 s−1 north of the Polar Front to 530 m2 s−1 south of the Southern Boundary. A comparison with other diffusivity studies validates the good adequacy of the ROD method for numerical and field applications.
对于海洋学家来说，选择水平扩散率是一个常见的难题。没有一个单一的答案，因为我们可以争辩说，扩散恰恰取决于那些无法采样或建模的过程。本文提出了径向扩散偏移(ROD)方法作为估算这些系数的一种简单的模式依赖方法，并展示了其在南大西洋西南部的应用。该方法将野外漂船的实际位移与数值轨迹预测结果进行了比较。观测到的和预测到的径向位置(径向偏移量)的差异，响应于数值模型没有捕捉到的扩散运动，通过适当选择扩散系数，用一维径向扩散解再现。该方法在8个深度进行了测试，从海面到2000米，使用了几个漂移数据集和应用于GLORYS12v1(1/12°每日)速度输出的包裹软件。在所有情况下，径向偏移量都显示高斯分布，这是由径向扩散解很好地再现的。最大扩散系数为4630-4980 m2 s -1，发生在水柱上方200 m处，最小值为1080-1270 m2 s -1，发生在1400 - 2000 m之间。15米的扩散率在纬度上是相当恒定的(3850 ~ 5270 m2 s -1)，但1000米的扩散率从极锋以北的1640 ~ 1820 m2 s -1下降到南边界以南的530 m2 s -1。与其他扩散系数研究的比较验证了ROD方法在数值和现场应用中的良好充分性。
{"title":"A simple method for estimating horizontal diffusivity","authors":"","doi":"10.1175/jtech-d-22-0097.1","DOIUrl":"https://doi.org/10.1175/jtech-d-22-0097.1","url":null,"abstract":"\u0000A common dilemma for oceanographers is the choice of horizontal diffusivity. There is no single answer as we could argue that diffusion depends precisely on those processes that cannot be sampled or modeled. Here we propose the radial offset by diffusion (ROD) method as a simple model-dependent approach for estimating these coefficients, and show its application for the southwestern South Atlantic. The method compares actual displacements of field drifters with numerical trajectory predictions. The observed-predicted differences in radial positions (radial offsets), which respond to diffusive motions not captured by the numerical model, are reproduced with a one-dimensional radial-diffusive solution through a proper selection of the diffusion coefficient. The method is tested at eight depths, from the sea surface down to 2000 m, using several drifter datasets and the Parcels software applied to the GLORYS12v1 (1/12° daily) velocity outputs. In all cases the radial offsets show Gaussian distributions that are well reproduced by the radial diffusive solution. Maximum diffusivities of 4630-4980 m2 s−1 happen in the upper 200 m of the water column and minimum values of 1080-1270 m2 s−1 occur between 1400 and 2000 m. The 15-m diffusivity is fairly constant in latitude (3850 to 5270 m2 s−1), but the 1000-m diffusivity decreases from 1640-1820 m2 s−1 north of the Polar Front to 530 m2 s−1 south of the Southern Boundary. A comparison with other diffusivity studies validates the good adequacy of the ROD method for numerical and field applications.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":"1 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64665988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-12DOI: 10.1175/jtech-d-22-0079.1
S. Saia, Sean P. Heuser, Myleigh D. Neill, William A. LaForce, John A. McGuire, K. Dello
Regional weather networks–also referred to as mesonets–are imperative for filling in the spatial and temporal data gaps between nationally supported weather stations. The North Carolina Environment and Climate Observing Network (ECONet) fills this regional role; it is a mesoscale network of 44 (as of 2023) automated stations collecting 12 environmental variables every minute across North Carolina. Measured variables include air temperature, precipitation, relative humidity, barometric pressure, wind speed, wind direction, total solar radiation, photosynthetically active radiation, soil temperature, soil moisture, leaf wetness index, and black globe temperature. All data undergo quality control procedures and are made freely available to the public via data portals hosted by the State Climate Office of North Carolina at North Carolina State University. This paper provides a technical overview of ECONet, including a description of the siting criteria, station maintenance procedures, data quality control procedures, and data availability. We also summarize unique aspects of ECONet data collection as well as innovative research and applications that rely on ECONet data. ECONet data are used by many sectors including, but not limited to, emergency management, natural resources management, public health, agriculture, forestry, science education, outdoor recreation, and research. ECONet data and data-powered applications offer valuable insights to local, regional, and federal partners yet opportunities to expand ECONet research and applications remain.
{"title":"A Technical Overview of the North Carolina ECONet","authors":"S. Saia, Sean P. Heuser, Myleigh D. Neill, William A. LaForce, John A. McGuire, K. Dello","doi":"10.1175/jtech-d-22-0079.1","DOIUrl":"https://doi.org/10.1175/jtech-d-22-0079.1","url":null,"abstract":"\u0000Regional weather networks–also referred to as mesonets–are imperative for filling in the spatial and temporal data gaps between nationally supported weather stations. The North Carolina Environment and Climate Observing Network (ECONet) fills this regional role; it is a mesoscale network of 44 (as of 2023) automated stations collecting 12 environmental variables every minute across North Carolina. Measured variables include air temperature, precipitation, relative humidity, barometric pressure, wind speed, wind direction, total solar radiation, photosynthetically active radiation, soil temperature, soil moisture, leaf wetness index, and black globe temperature. All data undergo quality control procedures and are made freely available to the public via data portals hosted by the State Climate Office of North Carolina at North Carolina State University. This paper provides a technical overview of ECONet, including a description of the siting criteria, station maintenance procedures, data quality control procedures, and data availability. We also summarize unique aspects of ECONet data collection as well as innovative research and applications that rely on ECONet data. ECONet data are used by many sectors including, but not limited to, emergency management, natural resources management, public health, agriculture, forestry, science education, outdoor recreation, and research. ECONet data and data-powered applications offer valuable insights to local, regional, and federal partners yet opportunities to expand ECONet research and applications remain.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48547713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-10DOI: 10.1175/jtech-d-22-0064.1
Dylan Dumas, Charles-Antoine Guérin
Original techniques are proposed for the improvement of surface current mapping with phased-array oceanographic High-Frequency Radars. The first idea, which works only in bistatic configuration, is to take advantage of a remote transmitter to perform an automatic correction of the receiving antennas based on the signal received in the direct path, an adjustment that is designated as “self-calibration”. The second idea, which applies to both mono- and bistatic systems, consists in applying a Direction Finding (DF) technique (instead of traditional Beam Forming) not only to the full antenna array but also to subarrays made of a smaller number of sequential antennas, a method which is referred to as “antenna grouping”. In doing this, the number of sources can also be varied, leading to an increased number of DF maps that can be averaged, an operation which is designated as “source stacking”. The combination of self-calibration, antenna grouping, and source stacking makes it possible to obtain high-resolution maps with increased coverage and is found robust to damaged antennas. The third improvement concerns the mitigation of noise in the antenna signal. These methods are illustrated with the multistatic High-Frequency Radar network in Toulon and their performances are assessed with drifters. The improved DF technique is found to significantly increase the accuracy of radar-based surface current when compared to the conventional Beam Forming technique.
{"title":"New signal processing techniques for phased-array oceanographic radars: self-calibration, antenna grouping, and denoising","authors":"Dylan Dumas, Charles-Antoine Guérin","doi":"10.1175/jtech-d-22-0064.1","DOIUrl":"https://doi.org/10.1175/jtech-d-22-0064.1","url":null,"abstract":"\u0000Original techniques are proposed for the improvement of surface current mapping with phased-array oceanographic High-Frequency Radars. The first idea, which works only in bistatic configuration, is to take advantage of a remote transmitter to perform an automatic correction of the receiving antennas based on the signal received in the direct path, an adjustment that is designated as “self-calibration”. The second idea, which applies to both mono- and bistatic systems, consists in applying a Direction Finding (DF) technique (instead of traditional Beam Forming) not only to the full antenna array but also to subarrays made of a smaller number of sequential antennas, a method which is referred to as “antenna grouping”. In doing this, the number of sources can also be varied, leading to an increased number of DF maps that can be averaged, an operation which is designated as “source stacking”. The combination of self-calibration, antenna grouping, and source stacking makes it possible to obtain high-resolution maps with increased coverage and is found robust to damaged antennas. The third improvement concerns the mitigation of noise in the antenna signal. These methods are illustrated with the multistatic High-Frequency Radar network in Toulon and their performances are assessed with drifters. The improved DF technique is found to significantly increase the accuracy of radar-based surface current when compared to the conventional Beam Forming technique.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47790862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-07DOI: 10.1175/jtech-d-22-0063.1
S. Brown, A. Tanner, S. Reising, W. Berg
Passive microwave sounders are critical for accurate forecasts from numerical weather prediction models. These sensors are calibrated using a traditional two-point approach, with one source typically a free-space blackbody target and the second a clear view to the cosmic microwave background, commonly referred to as “cold space.” Occasionally, one or both of these calibration sources can become corrupted, either by solar/lunar intrusion in the cold space view or by thermal instability of the blackbody calibration source. A Temporal Experiment for Storms and Tropical Systems (TEMPEST) microwave sounder instrument is currently deployed on the International Space Station (ISS) for a 3-year mission. TEMPEST is also calibrated using a blackbody target and cold space view; however, the cold space view will be routinely obstructed by objects present on the ISS. Here we test an alternative single point calibration methodology that uses only the blackbody calibration target. We find the brightness temperature difference between this new approach and the traditional two-point calibration approach to be < 0.1 K when applied to 3 years of the TEMPEST CubeSat Demonstration (TEMPEST-D) mission data from 2018-2020. This approach is applicable to other microwave radiometers that experience occasional degradation of calibration sources, such as thermal effects, intrusions or instability of noise diodes.
{"title":"Single-Point Calibration for Microwave Sounders: Application to TEMPEST-D","authors":"S. Brown, A. Tanner, S. Reising, W. Berg","doi":"10.1175/jtech-d-22-0063.1","DOIUrl":"https://doi.org/10.1175/jtech-d-22-0063.1","url":null,"abstract":"\u0000Passive microwave sounders are critical for accurate forecasts from numerical weather prediction models. These sensors are calibrated using a traditional two-point approach, with one source typically a free-space blackbody target and the second a clear view to the cosmic microwave background, commonly referred to as “cold space.” Occasionally, one or both of these calibration sources can become corrupted, either by solar/lunar intrusion in the cold space view or by thermal instability of the blackbody calibration source. A Temporal Experiment for Storms and Tropical Systems (TEMPEST) microwave sounder instrument is currently deployed on the International Space Station (ISS) for a 3-year mission. TEMPEST is also calibrated using a blackbody target and cold space view; however, the cold space view will be routinely obstructed by objects present on the ISS. Here we test an alternative single point calibration methodology that uses only the blackbody calibration target. We find the brightness temperature difference between this new approach and the traditional two-point calibration approach to be < 0.1 K when applied to 3 years of the TEMPEST CubeSat Demonstration (TEMPEST-D) mission data from 2018-2020. This approach is applicable to other microwave radiometers that experience occasional degradation of calibration sources, such as thermal effects, intrusions or instability of noise diodes.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46026652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-03DOI: 10.1175/jtech-d-22-0107.1
Curtis J. Seaman, W. Line, R. Ziel, Jennifer L. Jenkins, C. Dierking, Greg Hanson
Two multispectral satellite imagery products are presented that were developed for use within the fire management community. These products, which take the form of false color red-green-blue composites, were designed to aid fire detection and characterization, and for assessment of the environment surrounding a fire. The first, named the Fire Temperature RGB, uses spectral channels near 1.6 μm, 2.2 μm and 3.9 μm for fire detection and rapid assessment of the range of fire intensity through intuitive coloration. The second, named the Day Fire RGB, uses spectral channels near 0.64 μm, 0.86 μm and 3.9 μm for rapid scene assessment. The 0.64 μm channel provides information on smoke, the 0.86 μm channel provides information on vegetation health and burn scars, and the 3.9 μm channel provides active fire detections. Examples of these red-green-blue composite images developed from observations collected by three operational satellite imagers (VIIRS on the polar-orbiting platform and the Advanced Baseline Imager and Advanced Himawari Imager on the geostationary platform) demonstrate that both red-green-blue composites are useful for fire detection and contain valuable information that is not present within operational fire detection algorithms. In particular, it is shown that Fire Temperature RGB and Day Fire RGB images from VIIRS have similar utility for fire detection as the operational VIIRS Active Fire products, with the added benefit that the imagery provides context for more than just the fires themselves.
介绍了为在消防管理界使用而开发的两种多光谱卫星图像产品。这些产品采用假彩色红-绿-蓝复合材料的形式，旨在帮助火灾探测和表征，并评估火灾周围的环境。第一种被命名为“火灾温度RGB”，使用1.6μm、2.2μm和3.9μm附近的光谱通道进行火灾探测，并通过直观的着色快速评估火灾强度范围。第二种被命名为Day Fire RGB，使用0.64μm、0.86μm和3.9μm附近的光谱通道进行快速场景评估。0.64微米通道提供烟雾信息，0.86微米通道提供植被健康和烧伤疤痕信息，3.9微米通道提供主动火灾探测。从三个运行卫星成像仪（极轨平台上的VIIRS和地球静止平台上的高级基线成像仪和高级Himawari成像仪）收集的观测结果中获得的这些红-绿-蓝复合图像的例子表明，这两种红-绿/蓝复合图像都可用于火灾探测，并包含内部不存在的宝贵信息可操作的火灾探测算法。特别是，研究表明，VIIRS的Fire Temperature RGB和Day Fire RGB图像在火灾检测方面与运行中的VIIRS Active Fire产品具有相似的实用性，其额外的好处是，图像提供的不仅仅是火灾本身的背景。
{"title":"Multispectral Satellite Imagery Products for Fire Weather Applications","authors":"Curtis J. Seaman, W. Line, R. Ziel, Jennifer L. Jenkins, C. Dierking, Greg Hanson","doi":"10.1175/jtech-d-22-0107.1","DOIUrl":"https://doi.org/10.1175/jtech-d-22-0107.1","url":null,"abstract":"\u0000Two multispectral satellite imagery products are presented that were developed for use within the fire management community. These products, which take the form of false color red-green-blue composites, were designed to aid fire detection and characterization, and for assessment of the environment surrounding a fire. The first, named the Fire Temperature RGB, uses spectral channels near 1.6 μm, 2.2 μm and 3.9 μm for fire detection and rapid assessment of the range of fire intensity through intuitive coloration. The second, named the Day Fire RGB, uses spectral channels near 0.64 μm, 0.86 μm and 3.9 μm for rapid scene assessment. The 0.64 μm channel provides information on smoke, the 0.86 μm channel provides information on vegetation health and burn scars, and the 3.9 μm channel provides active fire detections. Examples of these red-green-blue composite images developed from observations collected by three operational satellite imagers (VIIRS on the polar-orbiting platform and the Advanced Baseline Imager and Advanced Himawari Imager on the geostationary platform) demonstrate that both red-green-blue composites are useful for fire detection and contain valuable information that is not present within operational fire detection algorithms. In particular, it is shown that Fire Temperature RGB and Day Fire RGB images from VIIRS have similar utility for fire detection as the operational VIIRS Active Fire products, with the added benefit that the imagery provides context for more than just the fires themselves.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44850193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-01DOI: 10.1175/jtech-d-22-0061.1
I. Cazzaniga, G. Zibordi
The Ocean Color Component of the Aerosol Robotic Network (AERONET-OC) aims at supporting the assessment of satellite ocean color radiometric products with in situ reference data derived from automated above-water measurements. This study, applying metrology principles and taking advantage of recent technology and science advances, revisits the uncertainty estimates formerly provided for AERONET-OC normalized water-leaving radiances LWN. The new uncertainty values are quantified for a number of AERONET-OC sites located in marine regions representative of chlorophyll-a-dominated waters (i.e., Case 1) and a variety of optically complex waters. Results show uncertainties typically increasing with the optical complexity of water and wind speed. Relative and absolute uncertainty values are provided for the various sites together with contributions from each source of uncertainty affecting measurements. In view of supporting AERONET-OC data users, the study also suggests practical solutions to quantify uncertainties for LWN from its spectral values. Additionally, results from an evaluation of the temporal variability characterizing LWN at various AERONET-OC sites are presented to address the impact of temporal mismatches between in situ and satellite data in matchup analysis.
{"title":"AERONET-OC LWN Uncertainties: Revisited","authors":"I. Cazzaniga, G. Zibordi","doi":"10.1175/jtech-d-22-0061.1","DOIUrl":"https://doi.org/10.1175/jtech-d-22-0061.1","url":null,"abstract":"\u0000The Ocean Color Component of the Aerosol Robotic Network (AERONET-OC) aims at supporting the assessment of satellite ocean color radiometric products with in situ reference data derived from automated above-water measurements. This study, applying metrology principles and taking advantage of recent technology and science advances, revisits the uncertainty estimates formerly provided for AERONET-OC normalized water-leaving radiances LWN. The new uncertainty values are quantified for a number of AERONET-OC sites located in marine regions representative of chlorophyll-a-dominated waters (i.e., Case 1) and a variety of optically complex waters. Results show uncertainties typically increasing with the optical complexity of water and wind speed. Relative and absolute uncertainty values are provided for the various sites together with contributions from each source of uncertainty affecting measurements. In view of supporting AERONET-OC data users, the study also suggests practical solutions to quantify uncertainties for LWN from its spectral values. Additionally, results from an evaluation of the temporal variability characterizing LWN at various AERONET-OC sites are presented to address the impact of temporal mismatches between in situ and satellite data in matchup analysis.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46981948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The Chebyshev polynomial fitting (CPF) method has been proved to be effective to construct reliable cotidal charts for the eight major tidal constituents (M 2 , S 2 , K 1 , O 1 , N 2 , K 2 , P 1 , and Q 1 ) and six minor tidal constituents (2N 2 , J 1 , L 2 , Mu 2 , Nu 2 , and T 2 ) near Hawaii in Part I and Part II, respectively. In this paper, this method is extended to estimate the harmonic constants of four long-period tidal constituents (M f , M m , S a , and S sa ). The harmonic constants obtained by this method were compared with those from the TPXO9, Finite Element Solutions 2014 (FES2014), and Empirical Ocean Tide 20 (EOT20) models, using benchmark data from satellite altimeters and eight tide gauges. The accuracies of the M f and M m constituents derived from the CPF method are comparable to those from the models, but the accuracies of the S a and S sa constituents are significantly higher than those from the FES2014 and EOT20 models. The results indicate that the CPF method is also effective for estimating harmonic constants of long-period tidal constituents. Furthermore, since the CPF method relies only on satellite altimeter data, it is an easier-to-use method than these ocean tide models.
摘要切比雪夫多项式拟合(CPF)方法已经被证明是有效的构建可靠的八大潮汐成分同潮时图表(M 2 S 2 K 1 O, N, K, P,和问1)和六个小潮汐成分(2 N 2, J 1 L 2μ2,ν2,和T 2)夏威夷附近海域在第一部分和第二部分,分别。本文将该方法推广到四种长周期潮汐成分(M f, M M, sa, sa)的谐波常数估计。利用卫星高度计和8个潮汐计的基准数据，将该方法得到的调和常数与TPXO9、Finite Element Solutions 2014 (FES2014)和Empirical Ocean Tide 20 (EOT20)模型的调和常数进行了比较。CPF方法得到的M - f和M - M成分的精度与模型相当，但S - a和S - sa成分的精度显著高于FES2014和EOT20模型。结果表明，CPF方法对长周期潮汐成分的谐波常数估计也是有效的。此外，由于CPF方法仅依赖于卫星高度计数据，因此它比这些海潮模型更容易使用。
{"title":"Ocean Tides near Hawaii from Satellite Altimeter Data. Part III","authors":"Yibo Zhang, Shengyi Jiao, Yuzhe Wang, Yonggang Wang, Xianqing Lv","doi":"10.1175/jtech-d-22-0052.1","DOIUrl":"https://doi.org/10.1175/jtech-d-22-0052.1","url":null,"abstract":"Abstract The Chebyshev polynomial fitting (CPF) method has been proved to be effective to construct reliable cotidal charts for the eight major tidal constituents (M 2 , S 2 , K 1 , O 1 , N 2 , K 2 , P 1 , and Q 1 ) and six minor tidal constituents (2N 2 , J 1 , L 2 , Mu 2 , Nu 2 , and T 2 ) near Hawaii in Part I and Part II, respectively. In this paper, this method is extended to estimate the harmonic constants of four long-period tidal constituents (M f , M m , S a , and S sa ). The harmonic constants obtained by this method were compared with those from the TPXO9, Finite Element Solutions 2014 (FES2014), and Empirical Ocean Tide 20 (EOT20) models, using benchmark data from satellite altimeters and eight tide gauges. The accuracies of the M f and M m constituents derived from the CPF method are comparable to those from the models, but the accuracies of the S a and S sa constituents are significantly higher than those from the FES2014 and EOT20 models. The results indicate that the CPF method is also effective for estimating harmonic constants of long-period tidal constituents. Furthermore, since the CPF method relies only on satellite altimeter data, it is an easier-to-use method than these ocean tide models.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136121334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-29DOI: 10.1175/jtech-d-22-0067.1
J. Moum, D. Rudnick, E. Shroyer, K. Hughes, B. Reineman, Kyle R. Grindley, J. Sherman, Pavan Vutukur, Craig Van Appledorn, Kerry Latham, Aurélie J. Moulin, T. M. Johnston
A new autonomous turbulence profiling float has been designed, built and tested in field trials off Oregon. Flippin’ χSOLO (FχS) employs a SOLO-II buoyancy engine that not only changes but also shifts ballast to move the center of mass to positions on either side of the center of buoyancy thus causing FχS to flip. FχS is outfitted with a full suite of turbulence sensors—two shear probes, two fast thermistors and pitot tube as well as a pressure sensor and 3-axis linear accelerometers. FχS descends and ascends with turbulence sensors leading, thereby permitting measurement through the sea surface. The turbulence sensors are housed antipodal from communication antennae so as to eliminate flow disturbance. By flipping at the sea surface, antennae are exposed for communications. The mission of FχS is to provide intensive profiling measurements of the upper ocean from 240m and through the sea surface, particularly during periods of extreme surface forcing. While surfaced, accelerometers provide estimates of wave height spectra and significant wave height. From day field trials, here we evaluate (i) the statistics from two FχS units and our established shipboard profiler, Chameleon, and (ii) FχS-based wave statistics by comparison to a nearby NOAA wave buoy.
{"title":"Flippin’ χSOLO, an Upper Ocean Autonomous Turbulence Profiling Float","authors":"J. Moum, D. Rudnick, E. Shroyer, K. Hughes, B. Reineman, Kyle R. Grindley, J. Sherman, Pavan Vutukur, Craig Van Appledorn, Kerry Latham, Aurélie J. Moulin, T. M. Johnston","doi":"10.1175/jtech-d-22-0067.1","DOIUrl":"https://doi.org/10.1175/jtech-d-22-0067.1","url":null,"abstract":"\u0000A new autonomous turbulence profiling float has been designed, built and tested in field trials off Oregon. Flippin’ χSOLO (FχS) employs a SOLO-II buoyancy engine that not only changes but also shifts ballast to move the center of mass to positions on either side of the center of buoyancy thus causing FχS to flip. FχS is outfitted with a full suite of turbulence sensors—two shear probes, two fast thermistors and pitot tube as well as a pressure sensor and 3-axis linear accelerometers. FχS descends and ascends with turbulence sensors leading, thereby permitting measurement through the sea surface. The turbulence sensors are housed antipodal from communication antennae so as to eliminate flow disturbance. By flipping at the sea surface, antennae are exposed for communications. The mission of FχS is to provide intensive profiling measurements of the upper ocean from 240m and through the sea surface, particularly during periods of extreme surface forcing. While surfaced, accelerometers provide estimates of wave height spectra and significant wave height. From day field trials, here we evaluate (i) the statistics from two FχS units and our established shipboard profiler, Chameleon, and (ii) FχS-based wave statistics by comparison to a nearby NOAA wave buoy.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45614924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-24DOI: 10.1175/jtech-d-22-0121.1
P. Ernst, B. Subrahmanyam, Y. Morel, C. Trott, A. Chaigneau
Coherent ocean vortices, or eddies, are usually tracked on the surface of the ocean. However, tracking subsurface eddies is important for a complete understanding of deep ocean circulation. In this study, we develop an algorithm designed for the detection of subsurface eddies in the Arabian Sea using Nucleus for European Modelling of the Ocean (NEMO) model simulations. We optimize each parameter of our algorithm to achieve favorable results when compared with an algorithm using sea surface height (SSH). When compared to similar methods, we find that using the rescaled isopycnal potential vorticity (PV) is best for subsurface eddy detection. We proceed to demonstrate that our new algorithm can detect eddies successfully between specific isopycnals, such as those that define the Red Sea Water (RSW). In doing so, we showcase how our method can be used to describe the properties of eddies within the RSW and even identify specific long-lived subsurface eddies. We conduct one such case study by discerning the structure of a completely subsurface RSW eddy near the Chagos Archipelago using Lagrangian particle tracking and PV diagnostics. We conclude that our rescaled PV method is an efficient tool for investigating eddy dynamics within the ocean’s interior, and publicly provide our optimization methodology as a way for other researchers to develop their own subsurface detection algorithms with optimized parameters for any spatiotemporal model domain.
{"title":"Subsurface Eddy Detection Optimized with Potential Vorticity from Models in the Arabian Sea","authors":"P. Ernst, B. Subrahmanyam, Y. Morel, C. Trott, A. Chaigneau","doi":"10.1175/jtech-d-22-0121.1","DOIUrl":"https://doi.org/10.1175/jtech-d-22-0121.1","url":null,"abstract":"\u0000Coherent ocean vortices, or eddies, are usually tracked on the surface of the ocean. However, tracking subsurface eddies is important for a complete understanding of deep ocean circulation. In this study, we develop an algorithm designed for the detection of subsurface eddies in the Arabian Sea using Nucleus for European Modelling of the Ocean (NEMO) model simulations. We optimize each parameter of our algorithm to achieve favorable results when compared with an algorithm using sea surface height (SSH). When compared to similar methods, we find that using the rescaled isopycnal potential vorticity (PV) is best for subsurface eddy detection. We proceed to demonstrate that our new algorithm can detect eddies successfully between specific isopycnals, such as those that define the Red Sea Water (RSW). In doing so, we showcase how our method can be used to describe the properties of eddies within the RSW and even identify specific long-lived subsurface eddies. We conduct one such case study by discerning the structure of a completely subsurface RSW eddy near the Chagos Archipelago using Lagrangian particle tracking and PV diagnostics. We conclude that our rescaled PV method is an efficient tool for investigating eddy dynamics within the ocean’s interior, and publicly provide our optimization methodology as a way for other researchers to develop their own subsurface detection algorithms with optimized parameters for any spatiotemporal model domain.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42053316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-17DOI: 10.1175/jtech-d-22-0059.1
I. Ivić
The existence of significant cross-polar antenna patterns, as well as the scan-dependent measurement biases, inherent to the polarimetric phased array radar (PPAR), are among the most important risk factors for using this technology in weather observations. The cross-polar patterns on receive induce cross coupling between returns from the two orthogonal fields causing biases in polarimetric variable estimates. Furthermore, the electromagnetic coupling in hardware may exacerbate the cross-coupling effects. To address this problem, a pulse-to-pulse phase coding in either the horizontal or vertical ports of the transmission elements has been proposed. However, it does not affect the scan-dependent system biases in PPAR estimates which require corrections via calibration mechanisms. Further, the cross-coupling signals are proportional to the cross-polar pattern power levels, rendering mitigation effective only at steering angles where these levels are sufficiently low (e.g., approximately less than ~-25 dB). In that regard, any approach that augments the number of such steering angles benefits the cross-coupling mitigation effectiveness. Herein, a simple approach that has a potential to achieve this via antenna tilt is presented.
{"title":"Cross Coupling Mitigation in Polarimetric PAR via Antenna Tilt","authors":"I. Ivić","doi":"10.1175/jtech-d-22-0059.1","DOIUrl":"https://doi.org/10.1175/jtech-d-22-0059.1","url":null,"abstract":"\u0000The existence of significant cross-polar antenna patterns, as well as the scan-dependent measurement biases, inherent to the polarimetric phased array radar (PPAR), are among the most important risk factors for using this technology in weather observations. The cross-polar patterns on receive induce cross coupling between returns from the two orthogonal fields causing biases in polarimetric variable estimates. Furthermore, the electromagnetic coupling in hardware may exacerbate the cross-coupling effects. To address this problem, a pulse-to-pulse phase coding in either the horizontal or vertical ports of the transmission elements has been proposed. However, it does not affect the scan-dependent system biases in PPAR estimates which require corrections via calibration mechanisms. Further, the cross-coupling signals are proportional to the cross-polar pattern power levels, rendering mitigation effective only at steering angles where these levels are sufficiently low (e.g., approximately less than ~-25 dB). In that regard, any approach that augments the number of such steering angles benefits the cross-coupling mitigation effectiveness. Herein, a simple approach that has a potential to achieve this via antenna tilt is presented.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45813300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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