Pub Date : 2023-10-31DOI: 10.1175/jtech-d-23-0026.1
Chong Wang, Xiaofeng Li
Abstract In this paper, a data-driven transfer learning (TL) model for locating tropical cyclone (TC) centers from satellite infrared images in the Northwest Pacific is developed. A total of 2450 satellite infrared TC images derived from 97 TC between 2015 and 2018 were used for this paper. The TC center location model (ResNet-TCL) with added residual fully-connected modules is built for the TC center location. The MAE of the ResNet-TCL model is 34.8 km. Then TL is used to improve the model performance, including obtaining a pre-trained model based on the ImageNet dataset, transferring the pre-trained model parameters to the ResNet-TCL model, and using TC satellite infrared imagery to fine-train the ResNet-TCL model. The results show that the TL-based model improves the location accuracy by 14.1% (29.3 km) over the No-TL model. The model performance increases logarithmically with the amount of training data. When the training data are large, the benefit of increasing the training samples is smaller than the benefit of using TL. The comparison of model results with the Best Track data of TCs shows that the MAEs of TCs center is 29.3 km for all samples and less than 20 km for H2-H5 TCs. In addition, the visualization of the TL-based TC center location model shows that the TL model can accurately extract the most important features related to TC center location, including TC eye, TC texture, and contour. On the other hand, the No-TL model does not accurately extract these features.
{"title":"Developing Data-driven Transfer Learning Model to Locate Tropical Cyclone Centers on Satellite Infrared Imagery","authors":"Chong Wang, Xiaofeng Li","doi":"10.1175/jtech-d-23-0026.1","DOIUrl":"https://doi.org/10.1175/jtech-d-23-0026.1","url":null,"abstract":"Abstract In this paper, a data-driven transfer learning (TL) model for locating tropical cyclone (TC) centers from satellite infrared images in the Northwest Pacific is developed. A total of 2450 satellite infrared TC images derived from 97 TC between 2015 and 2018 were used for this paper. The TC center location model (ResNet-TCL) with added residual fully-connected modules is built for the TC center location. The MAE of the ResNet-TCL model is 34.8 km. Then TL is used to improve the model performance, including obtaining a pre-trained model based on the ImageNet dataset, transferring the pre-trained model parameters to the ResNet-TCL model, and using TC satellite infrared imagery to fine-train the ResNet-TCL model. The results show that the TL-based model improves the location accuracy by 14.1% (29.3 km) over the No-TL model. The model performance increases logarithmically with the amount of training data. When the training data are large, the benefit of increasing the training samples is smaller than the benefit of using TL. The comparison of model results with the Best Track data of TCs shows that the MAEs of TCs center is 29.3 km for all samples and less than 20 km for H2-H5 TCs. In addition, the visualization of the TL-based TC center location model shows that the TL model can accurately extract the most important features related to TC center location, including TC eye, TC texture, and contour. On the other hand, the No-TL model does not accurately extract these features.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":"116 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135863395","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 : 2023-10-26DOI: 10.1175/jtech-d-22-0103.1
Alice S. Ren, Daniel L. Rudnick, Alistair Twombly
Abstract The Sea-Bird 63 dissolved oxygen optode sensors used on various oceanographic platforms are known to drift over time. Corrections for drift are necessary for accurate dissolved oxygen measurements on the timescale of months to years. Here, drift on 14 Sea-Bird 63 dissolved oxygen optode sensors deployed on Spray underwater gliders over 5 years is described. The gliders with oxygen sensors were deployed regularly for 100-day missions as part of the California Underwater Glider Network (CUGN). A laboratory two-point calibration was performed on the oxygen sensor before and after glider deployment. Sensor drift during 100-day deployments was larger than during 100-day storage periods. Sensor behavior is modeled with a gain that asymptotes to 1.090 ± 0.005 with an e-folding timescale of 3.70 ± 0.361 years. At zero oxygen concentration, the sensor consistently reads around 3 μmol kg −1 ; a negative offset term is used in addition to the gain to correct the sensor oxygen. The correction procedure removes the error due to long time drift, one of the major sources of error, with an uncertainty of 0.5% (0.9% including outliers) or 0.5 μmol kg −1 depending on concentration, which improves the accuracy of the Sea-Bird 63 although uncertainty from other sources of error including the initial factory calibration and the sensor response time remain. Suggested procedures for implementing a two-point calibration procedure in the laboratory are discussed. Calibrations must be considered starting 6 months after initial factory calibration to keep error from sensor time drift under 1%.
摘要海鸟63型溶解氧光电传感器用于各种海洋学平台，已知会随时间漂移。为了在月到年的时间尺度上精确地测量溶解氧，对漂移进行校正是必要的。本文描述了5年来部署在Spray水下滑翔机上的14个海鸟63溶解氧光电传感器的漂移情况。这些装有氧气传感器的滑翔机作为加州水下滑翔机网络(CUGN)的一部分，定期执行为期100天的任务。在滑翔机展开前后对氧传感器进行了实验室两点标定。在100天的部署期间，传感器漂移大于100天的存储期间。传感器行为模型的增益渐近线为1.090±0.005，电子折叠时间标度为3.70±0.361年。在零氧浓度下，传感器读数稳定在3 μmol kg−1左右;除增益外，还使用负偏移项来校正传感器氧。校正过程消除了由于长时间漂移引起的误差，这是误差的主要来源之一，根据浓度的不同，不确定性为0.5%(包括异常值为0.9%)或0.5 μmol kg - 1，这提高了海鸟63的精度，尽管其他误差来源(包括初始工厂校准和传感器响应时间)的不确定性仍然存在。讨论了在实验室实施两点校准程序的建议程序。必须考虑在初始工厂校准后6个月开始校准，以使传感器时间漂移的误差低于1%。
{"title":"Drift characteristics of Sea-Bird dissolved oxygen optode sensors","authors":"Alice S. Ren, Daniel L. Rudnick, Alistair Twombly","doi":"10.1175/jtech-d-22-0103.1","DOIUrl":"https://doi.org/10.1175/jtech-d-22-0103.1","url":null,"abstract":"Abstract The Sea-Bird 63 dissolved oxygen optode sensors used on various oceanographic platforms are known to drift over time. Corrections for drift are necessary for accurate dissolved oxygen measurements on the timescale of months to years. Here, drift on 14 Sea-Bird 63 dissolved oxygen optode sensors deployed on Spray underwater gliders over 5 years is described. The gliders with oxygen sensors were deployed regularly for 100-day missions as part of the California Underwater Glider Network (CUGN). A laboratory two-point calibration was performed on the oxygen sensor before and after glider deployment. Sensor drift during 100-day deployments was larger than during 100-day storage periods. Sensor behavior is modeled with a gain that asymptotes to 1.090 ± 0.005 with an e-folding timescale of 3.70 ± 0.361 years. At zero oxygen concentration, the sensor consistently reads around 3 μmol kg −1 ; a negative offset term is used in addition to the gain to correct the sensor oxygen. The correction procedure removes the error due to long time drift, one of the major sources of error, with an uncertainty of 0.5% (0.9% including outliers) or 0.5 μmol kg −1 depending on concentration, which improves the accuracy of the Sea-Bird 63 although uncertainty from other sources of error including the initial factory calibration and the sensor response time remain. Suggested procedures for implementing a two-point calibration procedure in the laboratory are discussed. Calibrations must be considered starting 6 months after initial factory calibration to keep error from sensor time drift under 1%.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136382077","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 : 2023-10-13DOI: 10.1175/jtech-d-23-0027.1
Kristin Zeiden, Jim Thomson, James Girton
Abstract High resolution profiles of vertical velocity obtained from two different surface-following autonomous platforms, Surface Wave Instrument Floats with Tracking (SWIFTs) and a Liquid Robotics SV3 Wave Glider, are used to compute dissipation rate profiles ϵ ( ɀ ) between 0.5 and 5 m depth via the structure function method. The main contribution of this work is to update previous SWIFT methods (Thomson 2012) to account for bias due to surface gravity waves, which are ubiquitous in the near-surface region. We present a technique where the data are pre-filtered by removing profiles of wave orbital velocities obtained via empirical orthogonal function (EOF) analysis of the data prior to computing the structure function. Our analysis builds on previous work to remove wave bias in which analytic modifications are made to the structure function model (Scannell et al. 2017). However, we find the analytic approach less able to resolve the strong vertical gradients in ϵ ( ɀ ) near the surface. The strength of the EOF filtering technique is that it does not require any assumptions about the structure of non-turbulent shear, and does not add any additional degrees of freedom in the least-squares fit to the model of the structure function. In comparison to the analytic method, ϵ ( ɀ ) estimates obtained via empirical filtering have substantially reduced noise and clearer dependence on near-surface wind speed.
{"title":"Estimating profiles of dissipation rate in the upper ocean using acoustic Doppler measurements made from surface following platforms","authors":"Kristin Zeiden, Jim Thomson, James Girton","doi":"10.1175/jtech-d-23-0027.1","DOIUrl":"https://doi.org/10.1175/jtech-d-23-0027.1","url":null,"abstract":"Abstract High resolution profiles of vertical velocity obtained from two different surface-following autonomous platforms, Surface Wave Instrument Floats with Tracking (SWIFTs) and a Liquid Robotics SV3 Wave Glider, are used to compute dissipation rate profiles ϵ ( ɀ ) between 0.5 and 5 m depth via the structure function method. The main contribution of this work is to update previous SWIFT methods (Thomson 2012) to account for bias due to surface gravity waves, which are ubiquitous in the near-surface region. We present a technique where the data are pre-filtered by removing profiles of wave orbital velocities obtained via empirical orthogonal function (EOF) analysis of the data prior to computing the structure function. Our analysis builds on previous work to remove wave bias in which analytic modifications are made to the structure function model (Scannell et al. 2017). However, we find the analytic approach less able to resolve the strong vertical gradients in ϵ ( ɀ ) near the surface. The strength of the EOF filtering technique is that it does not require any assumptions about the structure of non-turbulent shear, and does not add any additional degrees of freedom in the least-squares fit to the model of the structure function. In comparison to the analytic method, ϵ ( ɀ ) estimates obtained via empirical filtering have substantially reduced noise and clearer dependence on near-surface wind speed.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":"16 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135855636","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 : 2023-10-13DOI: 10.1175/jtech-d-23-0013.1
David Halpern, Megan K. Le, Timothy A. Smith, Patrick Heimbach
Abstract The Pacific Equatorial Undercurrent (EUC) flows eastward across the Pacific at the equator in the thermocline. Its variability is related to El Niño. Moored acoustic Doppler current profiler (ADCP) measurements recorded at 4 widely-separated sites along the equator in the EUC were compared to currents generated by version 4 release 4 of the Estimating the Circulation and Climate of the Ocean (ECCOv4r4) global model-data synthesis product. We are interested to learn how well ECCOv4r4 currents could complement sparse in situ current measurements. ADCP measurements were not assimilated in ECCOv4r4. Comparisons occurred at 5-m depth intervals at 165°E, 170°W, 140°W, and 110°W over time intervals of 10-14 years from 1995-2010. Hourly values of ECCOv4r4 and ADCP EUC core speeds were strongly correlated; similar for the EUC transport per unit width (TPUW). Correlations were substantially weaker at 110°W. Although we expected means and standard deviations of ECCOv4r4 currents to be smaller than ADCP values because of ECCOv4r4’s grid representation error, the large differences were unforeseen. The appearance of ECCOv4r4 diurnal-period current oscillations was surprising. As the EUC moved eastward from 170°W to 140°W, the ECCOv4r4 TPUW exhibited a much smaller increase compared to the ADCP TPUW. A consequence of smaller ECCOv4r4 EUC core speeds was significantly fewer instances of gradient Richardson number (Ri) less than ¼ above and below the depth of the core speed compared to Ri computed with ADCP observations. We present linear regression analyses to use monthly-mean ECCOv4r4 EUC core speeds and TPUWs as proxies for ADCP measurements.
{"title":"Comparison of ADCP and ECCOv4r4 Currents in the Pacific Equatorial Undercurrent","authors":"David Halpern, Megan K. Le, Timothy A. Smith, Patrick Heimbach","doi":"10.1175/jtech-d-23-0013.1","DOIUrl":"https://doi.org/10.1175/jtech-d-23-0013.1","url":null,"abstract":"Abstract The Pacific Equatorial Undercurrent (EUC) flows eastward across the Pacific at the equator in the thermocline. Its variability is related to El Niño. Moored acoustic Doppler current profiler (ADCP) measurements recorded at 4 widely-separated sites along the equator in the EUC were compared to currents generated by version 4 release 4 of the Estimating the Circulation and Climate of the Ocean (ECCOv4r4) global model-data synthesis product. We are interested to learn how well ECCOv4r4 currents could complement sparse in situ current measurements. ADCP measurements were not assimilated in ECCOv4r4. Comparisons occurred at 5-m depth intervals at 165°E, 170°W, 140°W, and 110°W over time intervals of 10-14 years from 1995-2010. Hourly values of ECCOv4r4 and ADCP EUC core speeds were strongly correlated; similar for the EUC transport per unit width (TPUW). Correlations were substantially weaker at 110°W. Although we expected means and standard deviations of ECCOv4r4 currents to be smaller than ADCP values because of ECCOv4r4’s grid representation error, the large differences were unforeseen. The appearance of ECCOv4r4 diurnal-period current oscillations was surprising. As the EUC moved eastward from 170°W to 140°W, the ECCOv4r4 TPUW exhibited a much smaller increase compared to the ADCP TPUW. A consequence of smaller ECCOv4r4 EUC core speeds was significantly fewer instances of gradient Richardson number (Ri) less than ¼ above and below the depth of the core speed compared to Ri computed with ADCP observations. We present linear regression analyses to use monthly-mean ECCOv4r4 EUC core speeds and TPUWs as proxies for ADCP measurements.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135857354","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 : 2023-10-02DOI: 10.1175/jtech-d-23-0056.1
Adam Majewski, Jeffrey R. French, Samuel Haimov
Abstract High resolution airborne cloud Doppler radars such as the W-Band Wyoming Cloud Radar (WCR) have, since the 1990s, investigated cloud microphysical, kinematic, and precipitation structures down to 30-m resolution. These measurements revolutionized our understanding of fine-scale cloud structure and the scales at which cloud processes occur. Airborne cloud Doppler radars may also resolve cloud turbulent eddy structure directly at 10-meter scales. To date, cloud turbulence has been examined as variances (Schwartz et al. 2019) and dissipation rates (Strauss et al. 2015) at coarser resolution than individual pulse volumes. The present work advances the potential of near-vertical pulse pair Doppler spectrum width as a metric for turbulent air motion. Doppler spectrum width has long been used to investigate turbulent motions from ground-based remote sensors. However, complexities of airborne Doppler radar and spectral broadening resulting from platform and hydrometeor motions have limited airborne radar spectrum width measurements to qualitative interpretation only. Here we present the first quantitative validation of spectrum width from an airborne cloud radar. Echoes with signal-to-noise ratio greater than 10 dB yield spectrum width values that strongly correlate with retrieved mean Doppler variance for a range of non-convective cloud conditions. Further, Doppler spectrum width within turbulent regions of cloud also shows good agreement with in-situ eddy dissipation rate (EDR) and gust probe variance. However, the use of pulse pair estimated spectrum width as a metric for turbulent air motion intensity is only suitable for turbulent air motions more energetic than the magnitude of spectral broadening, estimated to be < 0.4 m s −1 for the WCR in these cases.
自20世纪90年代以来，高分辨率机载云多普勒雷达，如w波段怀俄明云雷达(WCR)，已经研究了低至30米分辨率的云微物理、运动学和降水结构。这些测量彻底改变了我们对精细尺度云结构和云过程发生的尺度的理解。机载云多普勒雷达也可以直接在10米尺度上分辨云湍流涡结构。迄今为止，云湍流已经以比单个脉冲体积更粗的分辨率作为方差(Schwartz等人，2019)和耗散率(Strauss等人，2015)进行了研究。本工作提出了近垂直脉冲对多普勒频谱宽度作为湍流空气运动度量的潜力。多普勒频谱宽度长期以来一直用于研究地面遥感器的湍流运动。然而，机载多普勒雷达的复杂性以及平台和水流星运动导致的频谱加宽限制了机载雷达频谱宽度测量只能定性解释。在这里，我们提出了从机载云雷达光谱宽度的第一个定量验证。信噪比大于10 dB的回波产生的频谱宽度值与非对流云条件下检索到的平均多普勒方差密切相关。云湍流区的多普勒谱宽与原位涡耗散率(EDR)和阵风探测方差吻合较好。然而，使用脉冲对估计谱宽作为湍流空气运动强度的度量只适用于比谱宽幅度更有能量的湍流空气运动，估计为<在这些情况下，WCR为0.4 m s−1。
{"title":"Airborne Radar Doppler Spectrum Width as a Scale-Dependent Turbulence Metric","authors":"Adam Majewski, Jeffrey R. French, Samuel Haimov","doi":"10.1175/jtech-d-23-0056.1","DOIUrl":"https://doi.org/10.1175/jtech-d-23-0056.1","url":null,"abstract":"Abstract High resolution airborne cloud Doppler radars such as the W-Band Wyoming Cloud Radar (WCR) have, since the 1990s, investigated cloud microphysical, kinematic, and precipitation structures down to 30-m resolution. These measurements revolutionized our understanding of fine-scale cloud structure and the scales at which cloud processes occur. Airborne cloud Doppler radars may also resolve cloud turbulent eddy structure directly at 10-meter scales. To date, cloud turbulence has been examined as variances (Schwartz et al. 2019) and dissipation rates (Strauss et al. 2015) at coarser resolution than individual pulse volumes. The present work advances the potential of near-vertical pulse pair Doppler spectrum width as a metric for turbulent air motion. Doppler spectrum width has long been used to investigate turbulent motions from ground-based remote sensors. However, complexities of airborne Doppler radar and spectral broadening resulting from platform and hydrometeor motions have limited airborne radar spectrum width measurements to qualitative interpretation only. Here we present the first quantitative validation of spectrum width from an airborne cloud radar. Echoes with signal-to-noise ratio greater than 10 dB yield spectrum width values that strongly correlate with retrieved mean Doppler variance for a range of non-convective cloud conditions. Further, Doppler spectrum width within turbulent regions of cloud also shows good agreement with in-situ eddy dissipation rate (EDR) and gust probe variance. However, the use of pulse pair estimated spectrum width as a metric for turbulent air motion intensity is only suitable for turbulent air motions more energetic than the magnitude of spectral broadening, estimated to be < 0.4 m s −1 for the WCR in these cases.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135830064","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 : 2023-10-01DOI: 10.1175/jtech-d-22-0083.1
Alexei Sentchev, Max Yaremchuk, Denis Bourras, Ivane Pairaud, Philippe Fraunié
Abstract A method of assessing the mean eddy viscosity profile (EVP) in the sea surface boundary layer (SBL) under variable wind conditions is proposed. Performance of the method is tested using observations by an ADCP-equipped platform in the coastal environment of the northwestern Mediterranean Sea under variable (3–12 m s −1 ) wind conditions. EVP retrievals are made by a variational method strongly constrained by the Ekman dynamics, with the wind and velocity observations assumed to be uncertain within the prescribed error bars. Results demonstrate a reasonable agreement of the EVPs with KPP shape functions for stronger (8–12 m s −1 ) wind conditions and appear to be consistent with the classical Pacanowski–Philander parameterization of the viscosity profile based on the Richardson number. For weaker (3–5 m s −1 ) winds, the EVP retrievals turn out to be less accurate, which is primarily attributed to the decay of the wind-driven turbulence energy in the SBL. Feasibility and prospects of the retrieval technique are discussed in the context of uncertainties in the structure of the background flow and limitations of the microstructure and ADCP profiling.
摘要提出了一种计算变风条件下海面边界层平均涡动粘度廓线(EVP)的方法。在地中海西北部沿海环境中，在可变(3-12 m s - 1)风条件下，通过配备adcp的平台对该方法的性能进行了测试。EVP的反演是由一种受Ekman动力学强烈约束的变分方法进行的，风速和速度观测假设在规定的误差条内是不确定的。结果表明，在强风(8-12 m s−1)条件下，evp与KPP形状函数具有合理的一致性，并且与基于Richardson数的经典Pacanowski-Philander参数化黏度剖面一致。对于较弱的风(3-5 m s−1)，EVP反演结果不太准确，这主要是由于SBL中风驱动湍流能量的衰减。在背景流结构的不确定性、微观结构和ADCP剖面的局限性的背景下，讨论了反演技术的可行性和前景。
{"title":"Estimation of the Eddy Viscosity Profile in the Sea Surface Boundary Layer from Underway ADCP Observations","authors":"Alexei Sentchev, Max Yaremchuk, Denis Bourras, Ivane Pairaud, Philippe Fraunié","doi":"10.1175/jtech-d-22-0083.1","DOIUrl":"https://doi.org/10.1175/jtech-d-22-0083.1","url":null,"abstract":"Abstract A method of assessing the mean eddy viscosity profile (EVP) in the sea surface boundary layer (SBL) under variable wind conditions is proposed. Performance of the method is tested using observations by an ADCP-equipped platform in the coastal environment of the northwestern Mediterranean Sea under variable (3–12 m s −1 ) wind conditions. EVP retrievals are made by a variational method strongly constrained by the Ekman dynamics, with the wind and velocity observations assumed to be uncertain within the prescribed error bars. Results demonstrate a reasonable agreement of the EVPs with KPP shape functions for stronger (8–12 m s −1 ) wind conditions and appear to be consistent with the classical Pacanowski–Philander parameterization of the viscosity profile based on the Richardson number. For weaker (3–5 m s −1 ) winds, the EVP retrievals turn out to be less accurate, which is primarily attributed to the decay of the wind-driven turbulence energy in the SBL. Feasibility and prospects of the retrieval technique are discussed in the context of uncertainties in the structure of the background flow and limitations of the microstructure and ADCP profiling.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135810338","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 : 2023-10-01DOI: 10.1175/jtech-d-23-0015.1
Zhen Wang, Yini Chen, Liangyu Liu, Hao Yuan, Li Zou
Abstract Currents have a significant impact on wave parameters around islands. In this study, high-resolution unsteady current simulations based on island geography and wind fields from Weather Research and Forecasting (WRF) Model are used as input sources. The wave action balance model uses an unstructured grid to assess the wave conditions in the Atoll during Typhoon Noul. The characteristic wave parameters, with and without the effect of currents, are compared with the field observation data, including significant wave height, wave period, and the spatial distribution of significant wave height. The results show that simulated significant wave heights and wave periods are close to observed data, considering the effect of currents. The energy and shape of the spectrum are also verified during Typhoon Noul, and the observed agreement is improved when considering the currents. The effects of current within the Atoll are relatively weaker compared to the surroundings, while stronger current effects are observed in the deeper water outside the Atoll. Refraction caused by current expands the area of moderate sea state behind the island. Significance Statement Several innovations of this article are as follows: 1) the influence of currents on wave conditions at the Atoll; 2) exploring the impact of currents using key parameters, such as significant wave height, wave period, and wave spectrum, especially during the passage of Typhoon Noul; 3) swell emerges as the dominant factor influencing wave conditions as the center of Typhoon Noul gradually moves away; and 4) refraction caused by current expands the area of moderate sea state behind the island.
{"title":"Current Effect on Wave Condition around Island in the South China Sea","authors":"Zhen Wang, Yini Chen, Liangyu Liu, Hao Yuan, Li Zou","doi":"10.1175/jtech-d-23-0015.1","DOIUrl":"https://doi.org/10.1175/jtech-d-23-0015.1","url":null,"abstract":"Abstract Currents have a significant impact on wave parameters around islands. In this study, high-resolution unsteady current simulations based on island geography and wind fields from Weather Research and Forecasting (WRF) Model are used as input sources. The wave action balance model uses an unstructured grid to assess the wave conditions in the Atoll during Typhoon Noul. The characteristic wave parameters, with and without the effect of currents, are compared with the field observation data, including significant wave height, wave period, and the spatial distribution of significant wave height. The results show that simulated significant wave heights and wave periods are close to observed data, considering the effect of currents. The energy and shape of the spectrum are also verified during Typhoon Noul, and the observed agreement is improved when considering the currents. The effects of current within the Atoll are relatively weaker compared to the surroundings, while stronger current effects are observed in the deeper water outside the Atoll. Refraction caused by current expands the area of moderate sea state behind the island. Significance Statement Several innovations of this article are as follows: 1) the influence of currents on wave conditions at the Atoll; 2) exploring the impact of currents using key parameters, such as significant wave height, wave period, and wave spectrum, especially during the passage of Typhoon Noul; 3) swell emerges as the dominant factor influencing wave conditions as the center of Typhoon Noul gradually moves away; and 4) refraction caused by current expands the area of moderate sea state behind the island.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":"129 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135965843","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 : 2023-09-29DOI: 10.1175/jtech-d-23-0043.1
Katia Lamer, Pavlos Kollias, Edward P. Luke, Bernat P. Treserras, Mariko Oue, Brenda Dolan
Abstract Multisensor Agile Adaptive Sampling (MAAS), a smart sensing framework, was adapted to increase the likelihood of observing the vertical structure (with little to no gaps), spatial variability (at sub-km scale), and temporal evolution (at ~2-min resolution) of convective cells. This adaptation of MAAS guided two mechanically scanning C-band radars (the CSAPR2 and CHIVO) by automatically analyzing the latest NEXRAD data to identify, characterize, track, and nowcast the location of all convective cells forming in the Houston domain. MAAS used either a list of predetermined rules or real-time user input to select a convective cell to be tracked and sampled by the C-band radars. The CSAPR2 tracking radar was first tasked to collect 3 sector Plan Position Indicator (PPI) scans towards the selected cell. Edge computer processing of the PPI scans was used to identify additional targets within the selected cell. In less than 2 min, both the CSAPR2 and CHIVO radars were able to collect bundles of 3-6 Range Height Indicator (RHI) scans toward different targets of interest within the selected cell. Bundles were successively collected along the path of cell advection for as long as the cell met a pre-determined set of criteria. Between 01 June and 30 September 2022 over 315,000 vertical cross-section observations were collected by the C-band radars through ~1,300 unique isolated convective cells, most of which were observed for over 15-min of their lifecycle. To the best of our knowledge, this dataset, collected primarily through automatic means, constitutes the largest dataset of its kind.
{"title":"Multisensor Agile Adaptive Sampling (MAAS): a methodology to collect radar observations of convective cell lifecycle","authors":"Katia Lamer, Pavlos Kollias, Edward P. Luke, Bernat P. Treserras, Mariko Oue, Brenda Dolan","doi":"10.1175/jtech-d-23-0043.1","DOIUrl":"https://doi.org/10.1175/jtech-d-23-0043.1","url":null,"abstract":"Abstract Multisensor Agile Adaptive Sampling (MAAS), a smart sensing framework, was adapted to increase the likelihood of observing the vertical structure (with little to no gaps), spatial variability (at sub-km scale), and temporal evolution (at ~2-min resolution) of convective cells. This adaptation of MAAS guided two mechanically scanning C-band radars (the CSAPR2 and CHIVO) by automatically analyzing the latest NEXRAD data to identify, characterize, track, and nowcast the location of all convective cells forming in the Houston domain. MAAS used either a list of predetermined rules or real-time user input to select a convective cell to be tracked and sampled by the C-band radars. The CSAPR2 tracking radar was first tasked to collect 3 sector Plan Position Indicator (PPI) scans towards the selected cell. Edge computer processing of the PPI scans was used to identify additional targets within the selected cell. In less than 2 min, both the CSAPR2 and CHIVO radars were able to collect bundles of 3-6 Range Height Indicator (RHI) scans toward different targets of interest within the selected cell. Bundles were successively collected along the path of cell advection for as long as the cell met a pre-determined set of criteria. Between 01 June and 30 September 2022 over 315,000 vertical cross-section observations were collected by the C-band radars through ~1,300 unique isolated convective cells, most of which were observed for over 15-min of their lifecycle. To the best of our knowledge, this dataset, collected primarily through automatic means, constitutes the largest dataset of its kind.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135245748","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 : 2023-09-21DOI: 10.1175/jtech-d-23-0036.1
Briana M. Wyatt, Nathan Leber, Mark Olden
Abstract Accurate, timely, and accessible meteorological and soil moisture measurements are essential for a number of applications including weather forecasting, agricultural decision making, and flood and drought prediction. Such data are becoming increasingly available globally, but the large number of networks and various data reporting formats often make utilization of such data difficult. The TexMesonet is a “network of networks” developed within the state of Texas to collect, process, and make public data collected from more than 1,700 monitoring stations throughout the state. This paper describes the TexMesonet, with special attention paid to monitoring sites installed and managed by the Texas Water Development Board. It also provides a case study exemplifying how these data may be used and gives recommendations for future data applications.
{"title":"Technical overview of the TexMesonet- a network of networks for improved water management and prediction in Texas","authors":"Briana M. Wyatt, Nathan Leber, Mark Olden","doi":"10.1175/jtech-d-23-0036.1","DOIUrl":"https://doi.org/10.1175/jtech-d-23-0036.1","url":null,"abstract":"Abstract Accurate, timely, and accessible meteorological and soil moisture measurements are essential for a number of applications including weather forecasting, agricultural decision making, and flood and drought prediction. Such data are becoming increasingly available globally, but the large number of networks and various data reporting formats often make utilization of such data difficult. The TexMesonet is a “network of networks” developed within the state of Texas to collect, process, and make public data collected from more than 1,700 monitoring stations throughout the state. This paper describes the TexMesonet, with special attention paid to monitoring sites installed and managed by the Texas Water Development Board. It also provides a case study exemplifying how these data may be used and gives recommendations for future data applications.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136136705","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 : 2023-09-21DOI: 10.1175/jtech-d-23-0007.1
Christopher J. Roach, Nathaniel L. Bindoff
Abstract We present a new global oxygen atlas. This atlas uses all of the available full water column profiles of oxygen, salinity and temperature available as part of the World Ocean Atlas released in 2018. Instead of optimal interpolation we use the Data Interpolating Variational Analysis (DIVA) approach to map the available profiles onto 108 depth levels between the surface and 6800 m, covering more than 99% of ocean volume. This 1/2° × 1/2° degree atlas covers the period 1955 to 2018 in 1 year intervals. The DIVA method has significant benefits over traditional optimal interpolation. It allows the explicit inclusion of advection and boundary constraints thus offering improvements in the representations of oxygen, salinity and temperature in regions of strong flow and near coastal boundaries. We demonstrate these benefits of this mapping approach with some examples from this atlas. We can explore the regional and temporal variations of oxygen in the global oceans. Preliminary analyses confirm earlier analyses that the oxygen minimum zone in the eastern Pacific Ocean has expanded and intensified. Oxygen inventory changes between 1970 and 2010 are assessed and compared against prior studies. We find that the full ocean oxygen inventory decreased by 0.84%±0.42%. For this period temperature driven solubility changes explain about 21% of the oxygen decline over the full water column, in the upper 100 m solubility changes can explain all of the oxygen decrease, for the 100-600 m depth range it can explain only 29%, 19% between 600 m and 1000 m, and just 11% in the deep ocean.
{"title":"Developing a New Oxygen Atlas of the World’s Oceans Using Data Interpolating Variational Analysis","authors":"Christopher J. Roach, Nathaniel L. Bindoff","doi":"10.1175/jtech-d-23-0007.1","DOIUrl":"https://doi.org/10.1175/jtech-d-23-0007.1","url":null,"abstract":"Abstract We present a new global oxygen atlas. This atlas uses all of the available full water column profiles of oxygen, salinity and temperature available as part of the World Ocean Atlas released in 2018. Instead of optimal interpolation we use the Data Interpolating Variational Analysis (DIVA) approach to map the available profiles onto 108 depth levels between the surface and 6800 m, covering more than 99% of ocean volume. This 1/2° × 1/2° degree atlas covers the period 1955 to 2018 in 1 year intervals. The DIVA method has significant benefits over traditional optimal interpolation. It allows the explicit inclusion of advection and boundary constraints thus offering improvements in the representations of oxygen, salinity and temperature in regions of strong flow and near coastal boundaries. We demonstrate these benefits of this mapping approach with some examples from this atlas. We can explore the regional and temporal variations of oxygen in the global oceans. Preliminary analyses confirm earlier analyses that the oxygen minimum zone in the eastern Pacific Ocean has expanded and intensified. Oxygen inventory changes between 1970 and 2010 are assessed and compared against prior studies. We find that the full ocean oxygen inventory decreased by 0.84%±0.42%. For this period temperature driven solubility changes explain about 21% of the oxygen decline over the full water column, in the upper 100 m solubility changes can explain all of the oxygen decrease, for the 100-600 m depth range it can explain only 29%, 19% between 600 m and 1000 m, and just 11% in the deep ocean.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136236465","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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