Journal of Atmospheric and Oceanic Technology最新文献_第8页

Subsurface Eddy Detection Optimized with Potential Vorticity from Models in the Arabian Sea 利用阿拉伯海模型中的潜在涡度优化地下涡流探测

IF 2.2 4区地球科学

Journal of Atmospheric and Oceanic Technology Pub Date : 2023-03-24 DOI: 10.1175/jtech-d-22-0121.1

P. Ernst, B. Subrahmanyam, Y. Morel, C. Trott, A. Chaigneau

{"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}

引用次数: 1

Cross Coupling Mitigation in Polarimetric PAR via Antenna Tilt 通过天线倾斜抑制极化标准杆数中的交叉耦合

IF 2.2 4区地球科学

Journal of Atmospheric and Oceanic Technology Pub Date : 2023-03-17 DOI: 10.1175/jtech-d-22-0059.1

I. Ivić

{"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}

引用次数: 0

Simulated Clear-Sky Water Vapor and Temperature Retrievals from PREFIRE Measurements PREFIRE测量的模拟晴空水汽和温度反演

IF 2.2 4区地球科学

Journal of Atmospheric and Oceanic Technology Pub Date : 2023-03-16 DOI: 10.1175/jtech-d-22-0128.1

N. B. Miller, A. Merrelli, T. L’Ecuyer, B. Drouin

{"title":"Simulated Clear-Sky Water Vapor and Temperature Retrievals from PREFIRE Measurements","authors":"N. B. Miller, A. Merrelli, T. L’Ecuyer, B. Drouin","doi":"10.1175/jtech-d-22-0128.1","DOIUrl":"https://doi.org/10.1175/jtech-d-22-0128.1","url":null,"abstract":"\u0000The Polar Radiant Energy in the Far InfraRed Experiment (PREFIRE) mission will measure the Earth’s emission at wavelengths ranging from 3-54 µm. The pre-launch clear-sky retrieval algorithm, evaluated with simulated test data, indicates that PREFIRE measurements will be valuable for retrieving atmospheric water vapor and temperature profiles. Far infrared measurements provide unique retrieval information, indicated by the high ranking of select FIR channels as primary contributors to the total degrees of freedom for signal (DFS). In utilizing all the PREFIRE channels, the average total DFS of 4 test regions ranges from 1.90 - 4.71. The information content increases with higher column water vapor and in the presence of near surface temperature inversions. Using the DFS profiles for guidance, the retrieval concentrates information into 7 distinct layers to reduce the retrieval uncertainty per layer. Sensitivity tests indicate forward model error due to surface emissivity uncertainty results in about a 9% increase in column water vapor uncertainty. The clear-sky retrieval is sensitive to the presence of undetected ice clouds, especially those with optical depths larger than 0.2. Hence, in addition to a separate PREFIRE cloud mask, optimal estimation retrieval metrics are explored as possible indicators of cloudy scenes.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45911554","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}

引用次数: 0

Comparative performance of Radar, Laser, and Waverider Buoy measurements of ocean waves – Part 1: Frequency domain analysis 海浪的雷达、激光和乘波浮标测量的比较性能——第1部分：频域分析

IF 2.2 4区地球科学

Journal of Atmospheric and Oceanic Technology Pub Date : 2023-03-09 DOI: 10.1175/jtech-d-22-0108.1

P. Jangir, K. Ewans, I. Young

{"title":"Comparative performance of Radar, Laser, and Waverider Buoy measurements of ocean waves – Part 1: Frequency domain analysis","authors":"P. Jangir, K. Ewans, I. Young","doi":"10.1175/jtech-d-22-0108.1","DOIUrl":"https://doi.org/10.1175/jtech-d-22-0108.1","url":null,"abstract":"\u0000Accurate ocean wave measurements are needed for the safe design and operation of offshore facilities, but despite many ocean wave measurements, the accuracy of wave measurement systems remains an ongoing issue. Of paramount importance are measurements during extreme sea states. This paper examines wave measurements made with an Optech Laser, a Rosemount WaveRadar, and a Datawell Waverider buoy at North Rankin A platform (NRA), Australia; Ekofisk, North Sea; and several South China Sea locations. We evaluate the relative performance of these instruments based upon various frequency domain comparisons, including comparisons of their 1-D frequency spectra using spectrograms, spectral moments, high-frequency tail slopes, and significant wave heights derived from their wave spectra. A spectral relationship (transfer function) in terms of mean spectral ratio of the instruments is developed, which can be used for spectral calibration. On average, Laser and Waverider spectral estimates agree well at all sea states. However, at low wind speeds, the higher frequency spectral levels of the Laser are relatively high and noisy compared with the other two instruments. Radar higher frequency spectral estimates are relatively low compared to the other two instruments, particularly at lower sea states. In additionally, the higher frequency tail slopes of all three instruments vary between f‒4 and f‒5. However, at higher sea states, the Waverider tail slopes become steeper than f‒5. The Radar produces the lowest significant wave heights (Hm0) compared to the Laser and Waverider, but its second moment period (Tm02) estimates are longer than the Laser and Waverider.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47569051","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}

引用次数: 1

A Periodically Updated Adaptive Sampling Framework for Marine Mobile Observation Platforms 海洋移动观测平台周期性更新自适应采样框架

IF 2.2 4区地球科学

Journal of Atmospheric and Oceanic Technology Pub Date : 2023-03-03 DOI: 10.1175/jtech-d-22-0090.1

Yuxin Zhao, Hengde Zhao, Xiong Deng

{"title":"A Periodically Updated Adaptive Sampling Framework for Marine Mobile Observation Platforms","authors":"Yuxin Zhao, Hengde Zhao, Xiong Deng","doi":"10.1175/jtech-d-22-0090.1","DOIUrl":"https://doi.org/10.1175/jtech-d-22-0090.1","url":null,"abstract":"\u0000While numerical models have been developed for several years, some of these have been applied to ocean state sampling. Adaptive sampling deploys limited assets using prior information; then, observation assets are concentrated in areas of greater sampling value, which is very suitable for an extensive and dynamic marine environment. The improved resolution allows numerical models to be used on mobile platforms. However, the existing adaptive sampling framework for mobile platforms lacks regular interaction with the numerical model. And the observation scheme is easy to deviate from the optimal. This study sets up a closed-loop adaptive sampling framework for mobile platforms that realizes the optimization of model → sampling → model. Linking coupled model with the sampling points of the mobile platforms, the adaptive method configures key sampling locations to determine when and where the sampling schemes are adjusted. With the aid of a coupled model, we selected an optimization algorithm for the framework and simulated the process under the twin experimental framework. This research provides theoretical technical support for the combination of model and mobile sampling platforms.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43275024","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}

引用次数: 1

Saildrone direct covariance wind stress in various wind and current regimes of the tropical Pacific 热带太平洋不同风况和海流条件下的Saildone直接协方差风应力

IF 2.2 4区地球科学

Journal of Atmospheric and Oceanic Technology Pub Date : 2023-02-27 DOI: 10.1175/jtech-d-22-0077.1

J. R. Reeves Eyre, M. Cronin, Dongxiao Zhang, E. Thompson, C. Fairall, J. Edson

引用次数: 1

Global High-Resolution Random Forest Regression Maps of Ocean Heat Content Anomalies Using in Situ and Satellite Data 基于原位和卫星数据的全球高分辨率海洋热含量异常随机森林回归图

IF 2.2 4区地球科学

Journal of Atmospheric and Oceanic Technology Pub Date : 2023-02-24 DOI: 10.1175/jtech-d-22-0058.1

J. Lyman, G. Johnson

{"title":"Global High-Resolution Random Forest Regression Maps of Ocean Heat Content Anomalies Using in Situ and Satellite Data","authors":"J. Lyman, G. Johnson","doi":"10.1175/jtech-d-22-0058.1","DOIUrl":"https://doi.org/10.1175/jtech-d-22-0058.1","url":null,"abstract":"\u0000The ocean, with its low albedo and vast thermal inertia, plays key roles in the climate system, including absorbing massive amounts of heat as atmospheric greenhouse gas concentrations rise. While the Argo array of profiling floats has vastly improved sampling of ocean temperature in the upper half of the global ocean volume since the mid-2000s, they are not sufficient in number to resolve eddy scales in the oceans. However, satellite sea-surface temperature (SST) and sea-surface height (SSH) measurements do resolve these scales. Here we use Random Forest regressions to map ocean heat content anomalies (OHCA) using in situ training data from Argo and other sources on a 7-day × ¼° grid with latitude, longitude, time, SSH, and SST as predictors. The maps display substantial patterns on eddy scales, resolving variations of ocean currents and fronts. During the well sampled Argo period, global integrals of these maps reduce noise relative to estimates based on objective mapping of in situ data alone by roughly a factor of three when compared to time series of CERES (satellite data) top-of-the-atmosphere energy flux measurements and improve correlations of anomalies with CERES on annual time scales. Prior to and early on in the Argo period, when in situ data were sparser, global integrals of these maps retain low variance, and do not relax back to a climatological mean, avoiding potential deficiencies of various methods for infilling data-sparse regions with objective maps by exploiting temporal and spatial patterns of OHCA and its correlations with SST and SSH.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48539328","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}

引用次数: 1

Assessment of OTT-Parsivel2 Raindrop Fall Speed Measurements ot - parsivel2雨滴下落速度测量的评估

IF 2.2 4区地球科学

Journal of Atmospheric and Oceanic Technology Pub Date : 2023-02-10 DOI: 10.1175/jtech-d-22-0091.1

Rupayan Saha, F. Testik

{"title":"Assessment of OTT-Parsivel2 Raindrop Fall Speed Measurements","authors":"Rupayan Saha, F. Testik","doi":"10.1175/jtech-d-22-0091.1","DOIUrl":"https://doi.org/10.1175/jtech-d-22-0091.1","url":null,"abstract":"\u0000This study was to assess the raindrop fall speed measurement capabilities of OTT-Parsivel2 disdrometer through comparisons with measurements of a collocated High-speed Optical Disdrometer (HOD). Raindrop fall speed is often assumed to be terminal in relevant hydrological and meteorological applications, and generally predicted using terminal speed - raindrop size relationships obtained from laboratory observations. Nevertheless, recent field studies have revealed that other factors (e.g. wind, turbulence, raindrop oscillations, and collisions) significantly influence raindrop fall speed, necessitating accurate fall speed measurements for many applications instead of reliance on laboratory-based terminal speed predictions. Field observations in this study covered rainfall events with a variety of environmental conditions, including light, moderate, and heavy rainfall events. This study also involved rigorous laboratory experiments to faithfully identify the internal filtering and calculation algorithm of OTT Parsivel2. Our assessments revealed that, for the smaller diameter bins, Parsivel2 filters out many of the observed raindrops that fall faster than predicted terminal speeds, bringing down the mean fall speed for those size bins without observational evidence. Furthermore, Parsivel2 fall speed measurements exhibited a notable artificial bell-shaped deviations from the predicted terminal speeds towards sub-terminal fall starting at around 1 mm diameter raindrops with peak deviations around 1.625 mm diameter bin. Such bell-shaped fall speed deviation patterns were not present in collocated HOD measurements. Assessment results along with the faithfully identified Parsivel2 algorithm are presented with discussions on implications on reported raindrop size distributions (DSD) and rainfall kinetic energy.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44304167","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}

引用次数: 0

Impact of Thunderstorm Location Data Assimilation on Numerical Weather Forecasting 雷暴位置数据同化对数值天气预报的影响

IF 2.2 4区地球科学

Journal of Atmospheric and Oceanic Technology Pub Date : 2023-02-01 DOI: 10.1175/jtech-d-21-0125.1

K. G. Rubinshtein, I. Gubenko

引用次数: 0

Understanding Differences in Sea Surface Temperature Intercomparisons 了解海面温度相互比较的差异

IF 2.2 4区地球科学

Journal of Atmospheric and Oceanic Technology Pub Date : 2023-02-01 DOI: 10.1175/jtech-d-22-0081.1

Boyin Huang, Xungang Yin, J. Carton, Ligang Chen, Garrett Graham, Chunying Liu, T. Smith, Huai-min Zhang

{"title":"Understanding Differences in Sea Surface Temperature Intercomparisons","authors":"Boyin Huang, Xungang Yin, J. Carton, Ligang Chen, Garrett Graham, Chunying Liu, T. Smith, Huai-min Zhang","doi":"10.1175/jtech-d-22-0081.1","DOIUrl":"https://doi.org/10.1175/jtech-d-22-0081.1","url":null,"abstract":"\u0000Our study shows that the intercomparison among sea surface temperature (SST) products is influenced by the choice of SST reference, and the interpolation of SST products. The influence of reference SST depends on whether the reference SST are averaged to a grid or in pointwise in situ locations, including buoy or Argo observations, and filtered by first-guess or climatology quality control (QC) algorithms. The influence of the interpolation depends on whether SST products are in their original grids or pre-processed into common coarse grids.\u0000The impacts of these factors are demonstrated in our assessments of eight widely used SST products (DOISST, MUR25, MGDSST, GAMSSA, OSTIA, GPB, CCI, CMC) relative to buoy observations: (a) when the reference SSTs are averaged onto 0.25°×0.25° grid boxes, the magnitude of biases is lower in DOISST and MGDSST (<0.03°C), and magnitude of root-mean-square-differences (RMSDs) is lower in DOISST (0.38°C) and OSTIA (0.43°C); (b) when the same reference SSTs are evaluated at pointwise in situ locations, the standard deviations (SDs) are smaller in DOISST (0.38°C) and OSTIA (0.39°C) on 0.25°×0.25° grids; but the SDs become smaller in OSTIA (0.34°C) and CMC (0.37°C) on products original grids, showing the advantage of those high-resolution analyses for resolving finer scale SSTs; (c) when a loose QC algorithm is applied to the reference buoy observations, SDs increase; and vice versa; however, the relative performance of products remains the same; and (d) when the drifting-buoy or Argo observations are used as the reference, the magnitude of RMSDs and SDs become smaller, potentially due to changes in observing intervals. These results suggest that high-resolution SST analyses may take advantage in intercomparisons.","PeriodicalId":15074,"journal":{"name":"Journal of Atmospheric and Oceanic Technology","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48179061","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}

引用次数: 0