Showing papers in "Journal of Atmospheric and Oceanic Technology in 2018"
TL;DR: The Integrated Global Radiosonde Archive (IGRA) as mentioned in this paper is a collection of historical and near-real-time radiosonde and pilot balloon observations from around the globe, consisting of a foundationa...
Abstract: The Integrated Global Radiosonde Archive (IGRA) is a collection of historical and near-real-time radiosonde and pilot balloon observations from around the globe. Consisting of a foundationa...
70 citations
TL;DR: The Lagrangian Submesoscale Experiment (LASER) as discussed by the authors involved the deployment of ~1000 biodegradable GPS-tracked Consortium for Advanced Research on Transport of Hydrocarbon in the Environment (CA...
Abstract: The Lagrangian Submesoscale Experiment (LASER) involved the deployment of ~1000 biodegradable GPS-tracked Consortium for Advanced Research on Transport of Hydrocarbon in the Environment (CA...
46 citations
TL;DR: The potential value of small unmanned aircraft systems (UAS) for monitoring the preconvective environment and providing useful information in real time to weather forecasters for evaluation is discussed in this article.
Abstract: The potential value of small unmanned aircraft systems (UAS) for monitoring the preconvective environment and providing useful information in real time to weather forecasters for evaluation...
43 citations
TL;DR: In this article, a simple algorithm that flags the pixels that contain intense ice precipitation above the height of C is implemented in version 5 of the DPR products, which can provide precipitation echoes at two different frequencies, which may enable differentiating solid precipitation echoes from liquid precipitation echoes.
Abstract: Detection of ice precipitation is one of the objectives in the Global Precipitation Measurement (GPM) mission. The dual-frequency precipitation radar (DPR) can provide precipitation echoes at two different frequencies, which may enable differentiating solid precipitation echoes from liquid precipitation echoes. A simple algorithm that flags the pixels that contain intense ice precipitation above the height of C is implemented in version 5 of the DPR products. In the inner swath of DPR measurements in which both Ku- and Ka-band radar echoes are available, the measured dual-frequency ratio () together with the measured radar reflectivity factor is used to judge the existence of intense ice precipitation. Comparisons of the flagged pixels with surface measurements show that the algorithm correctly identifies relatively intense ice precipitation regions. The global distribution of the flagged pixels indicates an interesting difference between land and ocean, in particular in the distribution of ice pr...
41 citations
TL;DR: In this article, the feasibility of wind vector profile measurement using small UAVs was investigated and the results showed that it is possible to estimate wind vector profiles using a single UAV.
Abstract: Small unmanned aerial vehicles (UAVs), also known as drones, have recently become promising tools in various fields. We investigated the feasibility of wind vector profile measurement using...
40 citations
TL;DR: In this article, the variational approach appears to be a promising way to opt out of the traditional QPE with polarimetric radar measurements, which suffers from different sources of uncertainty.
Abstract: Quantitative precipitation estimation (QPE) with polarimetric radar measurements suffers from different sources of uncertainty. The variational approach appears to be a promising way to opt...
34 citations
TL;DR: In this article, the depth-average velocity is calculated using data from underwater gliders using dead reckoning, where the difference between the glider's velocity over ground and its velocity over water is calculated.
Abstract: The depth-average velocity is routinely calculated using data from underwater gliders. The calculation is a dead reckoning, where the difference between the glider’s velocity over ground an...
33 citations
TL;DR: The Lagrangian Submesoscale Experiment (LASER) as mentioned in this paper was designed to study surface flows during winter conditions in the northern Gulf of Mexico More than 1000 mostly biodegradable drifters were
Abstract: The Lagrangian Submesoscale Experiment (LASER) was designed to study surface flows during winter conditions in the northern Gulf of Mexico More than 1000 mostly biodegradable drifters were
32 citations
TL;DR: A lot of tidal phenomena, including river tides, tides in ice-covered bays, and internal tides in fjords, are nonstationary as discussed by the authors, and these tidal processes present a severe challenge for the convent.
Abstract: A lot of tidal phenomena, including river tides, tides in ice-covered bays, and internal tides in fjords, are nonstationary. These tidal processes present a severe challenge for the convent...
31 citations
TL;DR: In this paper, classical tidal current harmonic analysis has been widely used to obtain harmonic parameters of internal tidal currents, and it has been shown that it is an effective tool to distinguish different tidal components.
Abstract: As an effective tool to distinguish different tidal components, classical tidal current harmonic analysis has been widely used to obtain harmonic parameters of internal tidal currents. Howe...
29 citations
TL;DR: The prediction of sea surface temperature (SST) on the basis of artificial neural networks (ANNs) can be viewed as complementary to numerical SST predictions, and it has fairly sustained in this paper.
Abstract: The prediction of sea surface temperature (SST) on the basis of artificial neural networks (ANNs) can be viewed as complementary to numerical SST predictions, and it has fairly sustained in...
TL;DR: Visible satellite images contain high-resolution information about clouds that would be well suited for convective-scale data assimilation, and this application requires a forward operator to gesticulate towards these clouds.
Abstract: Visible satellite images contain high-resolution information about clouds that would be well suited for convective-scale data assimilation. This application requires a forward operator to g...
TL;DR: A positive impact of adding directional information to observations from the Cyclone Global Navigation Satellite System (CYNGSS) constellation of microsatellites is observed in simulation as mentioned in this paper.
Abstract: A positive impact of adding directional information to observations from the Cyclone Global Navigation Satellite System (CYNGSS) constellation of microsatellites is observed in simulation u...
TL;DR: Using a machine learning approach, complex relationships between pressure bias and ancillary sensor data were used to predict and correct future pressure biases over a 4-week period from 10 November to 5 December 2016, producing an 82% reduction in the average smartphone pressure bias.
Abstract: Over half a billion smartphones worldwide are now capable of measuring atmospheric pressure, providing a pressure network of unprecedented density and coverage. This paper describes novel approaches for the collection, quality control, and bias correction of such smartphone pressures. An Android app was developed and distributed to several thousand users, serving as a test bed for onboard pressure collection and quality-control strategies. New methods of pressure collection were evaluated, with a focus on reducing and quantifying sources of observation error and uncertainty. Using a machine learning approach, complex relationships between pressure bias and ancillary sensor data were used to predict and correct future pressure biases over a 4-week period from 10 November to 5 December 2016. This approach, in combination with simple quality-control checks, produced an 82% reduction in the average smartphone pressure bias, substantially improving the quality of smartphone pressures and facilitating t...
TL;DR: Deep convolutional neural networks are shown to be an effective model for fusing heterogeneous geospatial data to create radar-like analyses of precipitation intensity to create seamless radar mosaics that extend to offshore sectors and beyond.
Abstract: In this work deep convolutional neural networks (CNNs) are shown to be an effective model for fusing heterogeneous geospatial data to create radar-like analyses of precipitation intensity (...
TL;DR: In this article, the effect of assimilating Himawari-8 (HIMA-8) atmospheric motion vectors (AMVs) on forecast errors in East Asia is evaluated using observation system experiments based on th...
Abstract: In this study, the effect of assimilating Himawari-8 (HIMA-8) atmospheric motion vectors (AMVs) on forecast errors in East Asia is evaluated using observation system experiments based on th...
TL;DR: An estimate of depolarization ratio (DR) based on differential reflectivity (ZDR) and copolar correlation coefficient (ρHV) measurements to separate both types of echoes was evaluated and achieved 96% separation between weather and biological echoes.
Abstract: To satisfy the needs of the meteorological and aeroecological communities wanting a simple but effective way of flagging each other’s unwanted echo for a variety of different operational ra...
TL;DR: In this paper, the authors present the motivation, instrument concept, hardware descriptions, and initial validation testing for a Doppler wind lidar (DWL) system that uses optical autocovariance (OA) in a field-wound environment.
Abstract: We present the motivation, instrument concept, hardware descriptions, and initial validation testing for a Doppler wind lidar (DWL) system that uses optical autocovariance (OA) in a field-w...
TL;DR: In this article, the wakes of 2836 ships in 32 optical images with different resolutions were observed, and the results showed that ship wakes are more distinct than the hulls and can be visually observed in optical images.
Abstract: Ship wakes are more distinct than the hulls and can be visually observed in optical images. In this paper the wakes of 2836 ships in 32 optical images with different resolutions are observe...
TL;DR: The Nebraska Mesonet was established in 1981 as one of the nation's first automated state weather networks as discussed by the authors, which is defined by the nature of the observations being made and recorded, i.e.
Abstract: The Nebraska Mesonet was established in 1981 as one of the nation’s first automated state weather networks. “Automated” is defined by the nature of the observations being made and recorded ...
TL;DR: In this paper, the fluctuation of radio occultation (RO) signals in the presence of refractivity irregularities in the moist lower troposphere results in uncertainties of retrieved bending angle and refra...
Abstract: The fluctuation of radio occultation (RO) signals in the presence of refractivity irregularities in the moist lower troposphere results in uncertainties of retrieved bending angle and refra...
TL;DR: Biases have been identified in historical expendable bathythermograph (XBT) datasets, which are one of the major sources of uncertainty in the ocean subsurface database.
Abstract: Biases have been identified in historical expendable bathythermograph (XBT) datasets, which are one of the major sources of uncertainty in the ocean subsurface database. More than 10 correc...
TL;DR: The filter that attenuates both the small-scale and the high-frequency components of SLA removes aliased baroclinic tidal variability and improves the accuracy of tidal analysis in the open ocean while also performing acceptably in the coastal ocean.
Abstract: Sea level anomaly (SLA) maps are routinely produced by objective analysis of data from the constellation of satellite altimeter missions in operation since 1992. Beginning in 2014, changes in the Data Unification and Altimeter Combination System (DUACS) used to create the SLA maps resulted in improved spatial resolution of mesoscale variability, but it also increased the levels of aliased tidal variability compared to the methodology employed prior to 2014. The present work investigates the magnitude and spatial distribution of these tidal signals, which are typically smaller than 1 cm in the open ocean but can reach tens of centimeters in the coastal ocean. In the open ocean, the signals are caused by a combination of phase-locked and phase-variable baroclinic tides. In the coastal ocean, the signals are a combination of aliased high-frequency nontidal variability and aliased variability caused by erroneous tidal corrections applied to the along-track altimetry prior to objective analysis. Several low-pass and bandpass filters are implemented to reduce the tidal signals in the mapped SLA, and independent tide gauge data are used to provide an objective assessment of the performance of the filters. The filter that attenuates both the small-scale (less than 200 km) and the high-frequency (period shorter than 108 days) components of SLA removes aliased baroclinic tidal variability and improves the accuracy of tidal analysis in the open ocean while also performing acceptably in the coastal ocean.
TL;DR: In this paper, the effect of thermal mass on the salinity estimate from conductivity-temperature-depth (CTD) tags mounted on marine mammals is documented, and a correction scheme is proposed to mitigated the effect.
Abstract: The effect of thermal mass on the salinity estimate from conductivity–temperature–depth (CTD) tags sensor mounted on marine mammals is documented, and a correction scheme is proposed to mit...
TL;DR: In this paper, the authors assess the volume of Western Boundary Currents (WBCs) by using high-resolution temporal and spatial data, and find that the required high resolution temporal information is not sufficient.
Abstract: Western boundary currents (WBCs) are highly variable narrow meandering jets, making assessment of their volume transports a complex task. The required high-resolution temporal and spatial m...
TL;DR: A systematic evaluation of the performance of the World Wide Lightning Location Network (WWLLN) over the Tibetan Plateau is conducted using data from the Cloud-to-Ground Lightning Location....
Abstract: A systematic evaluation of the performance of the World Wide Lightning Location Network (WWLLN) over the Tibetan Plateau is conducted using data from the Cloud-to-Ground Lightning Location ...
TL;DR: In this article, the impact of sensor response and aircraft airspeed on the accuracy of in situ observations collected by small unmanned aircraft systems is assessed, and the authors propose a method to assess the impact on the performance of the system.
Abstract: The objective of the research presented is to assess the impact of sensor response and aircraft airspeed on the accuracy of in situ observations collected by small unmanned aircraft systems...
TL;DR: A major component of the TRMM version 8 reprocessing is the improvement of geolocation as mentioned in this paper, which is a major part of the final phase of the mission closeout.
Abstract: The National Aeronautics and Space Administration (NASA) has always included data reprocessing as a major component of every science mission. A final reprocessing is typically a part of mission closeout (known as phase F). The Tropical Rainfall Measuring Mission (TRMM) is currently in phase F, and NASA is preparing for the last reprocessing of all the TRMM precipitation data as part of the closeout. This reprocessing includes improvements in calibration of both the TRMM Microwave Imager (TMI) and the TRMM Precipitation Radar (PR). An initial step in the version 8 reprocessing is the improvement of geolocation. The PR calibration is being updated by the Japan Aerospace Exploration Agency (JAXA) using data collected as part of the calibration of the Dual-Frequency Precipitation Radar (DPR) on the Global Precipitation Measurement (GPM) Core Observatory. JAXA undertook a major effort to ensure TRMM PR and GPM Ku-band calibration is consistent.A major component of the TRMM version 8 reprocessing is to ...
TL;DR: In this article, a two-regime linear model is proposed for wind-generated underwater noise to measure wind speed, a method known as Weather Observations Through Ambient Noise (WOTAN).
Abstract: Wind speed measurements are needed to understand ocean–atmosphere coupling processes and their effects on climate. Satellite observations provide sufficient spatial and temporal coverage but are lacking adequate calibration, while ship- and mooring-based observations are spatially limited and have technical shortcomings. However, wind-generated underwater noise can be used to measure wind speed, a method known as Weather Observations Through Ambient Noise (WOTAN). Here, we adapt the WOTAN technique for application to ocean gliders, enabling calibrated wind speed measurements to be combined with contemporaneous oceanographic profiles over extended spatial and temporal scales. We demonstrate the methodology in three glider surveys in the Mediterranean Sea during winter 2012/13. Wind speeds ranged from 2 to 21.5 m s−1, and the relationship to underwater ambient noise measured from the glider was quantified. A two-regime linear model is proposed, which validates a previous linear model for light winds (below 12 m s−1) and identifies a regime change in the noise generation mechanism at higher wind speeds. This proposed model improves on previous work by extending the validated model range to strong winds of up to 21.5 m s−1. The acquisition, data processing, and calibration steps are described. Future applications for glider-based wind speed observations and the development of a global wind speed estimation model are discussed.
TL;DR: In this paper, a remote sensing method to retrieve the mean temperature of cloud liquid using ground-based microwave radiometer measurements is evaluated and tested by comparison with direct cloud temperatures using direct cloud temperatures.
Abstract: A remote sensing method to retrieve the mean temperature of cloud liquid using ground-based microwave radiometer measurements is evaluated and tested by comparisons with direct cloud temper...