Retrieval of aerosol optical properties from GOCI-II observations: Continuation of long-term geostationary aerosol monitoring over East Asia.

Since the Geostationary Ocean Color Imager (GOCI) was successfully launched in 2010, the GOCI Yonsei aerosol retrieval (YAER) algorithm has been continuously updated to retrieve hourly aerosol optical properties. GOCI-II has 4 more channels including UV, finer spatial resolution (250 m), and daily full disk coverage as compared to GOCI, and was launched in February 2020, onboard the GEO-KOMPSAT-2B (GK-2B) satellite. In this study, we extended the YAER algorithm to GOCI-II data based on its improved performance in many aspects and present the first results of aerosol optical properties retrieved from GOCI-II data. Utilizing the overlapping period between the GOCI-II and GOCI in geostationary Earth orbit, we present GOCI-II aerosol retrievals for high aerosol-loading cases over East Asia and show that these have a consistent spatial distribution with those from GOCI. Furthermore, GOCI-II provides AOD at an even higher spatial resolution, revealing finer changes in aerosol concentrations. Validation results for one year data show that the GOCI-II AOD has a correlation coefficient of 0.83 and a ratio within the expected error (EE) of 59.4 % when compared with the aerosol robotic network (AERONET) data. We compared statistical metrics for the GOCI and GOCI-II AODs to assess the consistency between the two datasets. In addition, it was found that there is a strong correlation between the two datasets from the comparison of gridded GOCI and GOCI-II AOD products. It is expected that data from GOCI-II will continue long-term aerosol records with high accuracy that can be used to address air-quality issues over East Asia.

Superior laryngeal nerve block for treatment of throat pain and cough following laryngeal herpes zoster: A case report.

BACKGROUND: Herpes zoster is caused by reactivation of latent varicella-zoster virus infection within the sensory nerve ganglion of the spinal or cranial nerves. Laryngeal herpes zoster is rare and involves superior laryngeal nerve, which leads to several complications such as throat pain, and cough. CASE SUMMARY: Patient concerns: A 52-year old woman presented with a 70 d history of throat pain and a 67 d history of non-productive cough. Three days after onset of pain, she was diagnosed with laryngeal herpes zoster. Flexible nasolaryngoscopy revealed multiple white ulcerated lesions on the left hemi epiglottis and the left supraglottic area. She was prescribed with 750 mg famciclovir a day for 7 d, and 150 mg pregabalin, 100 mg tramadol and 10 mg nortriptyline a day for 67 d. However, despite of these medications, she complained of pain and persistent cough. Therefore, superior laryngeal nerve block under ultrasound guidance was performed. Three days after the intervention, the throat pain and cough disappeared. The patient remained symptom-free at 3 mo follow-up. CONCLUSION: A superior laryngeal nerve block can be an effective option for treatment of pain and cough following laryngeal herpes zoster.

Floating Debris in the Northern Gulf of Mexico after Hurricane Katrina.

Hurricane Katrina (category 5 with maximum wind of 280 km/h when the eye is in the central Gulf of Mexico) made landfall near New Orleans on August 29, 2005, causing millions of cubic meters of disaster debris, severe flooding, and US$125 billion in damage. Yet, despite numerous reports on its environmental and economic impacts, little is known about how much debris has entered the marine environment. Here, using satellite images (MODIS, MERIS, and Landsat), airborne photographs, and imaging spectroscopy, we show the distribution, possible types, and amount of Katrina-induced debris in the northern Gulf of Mexico. Satellite images collected between August 30 and September 19 show elongated image features around the Mississippi River Delta in a region bounded by 92.5°W-87.5°W and 27.8°N-30.25°N. Image spectroscopy and color appearance of these image features indicate that they are likely dominated by driftwood (including construction lumber) and dead plants (e.g., uprooted marsh) and possibly mixed with plastics and other materials. The image sequence shows that if aggregated together to completely cover the water surface, the maximal debris area reached 21.7 km2 on August 31 to the east of the delta, which drifted to the west following the ocean currents. When measured by area in satellite images, this perhaps represents a historical record of all previously reported floating debris due to natural disasters such as hurricanes, floodings, and tsunamis.

Detecting the Great Pacific Garbage Patch floating plastic litter using WorldView-3 satellite imagery.

We present a direct and proxy-based approach to qualitatively and semi-quantitatively observe floating plastic litter in the Great Pacific Garbage Patch (GPGP) based on a survey in 2018 using very high geo-spatial resolution 8-waveband WorldView-3 imagery. A proxy for the plastics was defined as a waveband difference for anomalies in the top-of-the-atmosphere spectra. The anomalies were computed by subtracting spatially varying reflectance of the surrounding ocean water as background from the top-of-the-atmosphere reflectance. Spectral shapes and magnitude were also evaluated using a reference target of known plastics, The Ocean Cleanup System 001 Wilson. Presence of 'suspected plastics' was confirmed by the similarity in derived anomalies and spectral shapes with respect to the known plastics in the image as well as direct observations in the true color composites. The proposed proxy-based approach is a step towards future mapping techniques of suspected floating plastics with potential operational monitoring applications from the Sentinel-2 that recently started regular imaging over the GPGP that will be supported or validated by numerical solutions and net trawling survey.

Anesthetic experience: congenital methemoglobinemia due to hemoglobin M.

Methemoglobinemia is rare. It is classified into two types: congenital methemoglobinemia and acquired methemoglobinemia. Methemoglobin is incapable of binding oxygen, leading to complications such as cyanosis, dyspnea, headache, and heart failure. In the present case, a 35-year-old man with congenital methemoglobinemia underwent general anesthesia for thyroidectomy. The patient was diagnosed with hemoglobin M at 7 years of age. Ventilation was performed with FiO2 1.0. Arterial blood gas analysis showed that the pH was 7.4, PaO2 439 mmHg, PaCO2 40.5 mmHg, oxyhemoglobin level of 83.2%, and methemoglobin level of 15.5%. The patient had a stable course, although cyanosis was observed during surgery.

Geometric accuracy analysis of the Geostationary Ocean Color Imager (GOCI) Level 1B (L1B) product.

The Geostationary Ocean Color Imager (GOCI) has been used for many remote sensing applications to observe and monitor the ocean color of East Asia around the Korean Peninsula. However, to date, its geometric accuracy has not been thoroughly investigated; the only studies conducted so far have focused on verifying its radiometric quality. This study investigates the geometric accuracy of the Level 1B (L1B) product created from the GOCI geometric correction. The paper contains a brief description of the geometric correction process and an analysis of the positioning accuracy of GOCI L1B. Independent check points to assess accuracy were extracted from L1B and compared to their corresponding features in Google Maps, whose positioning accuracy has been thoroughly verified. Our analysis showed that, on average, the positioning accuracy of the GOCI L1B is ∼500-600 m, although there are differences in accuracy throughout the coverage area. It was confirmed that the GOCI L1B's overall accuracy fully meets geometrical image quality requirements (about 1 km). No specific bias pattern was identified, and there was little difference in accuracy throughout the acquisition time. The accuracy of the GOCI when landmark determination failed, e.g. due to a cloud, was further analyzed, and analysis showed that geometric quality was maintained even in the case of failure, although a slightly higher number of errors was observed. The experimental results support the hypothesis that the GOCI's geometric correction works well and provides sufficiently accurate positional information on ocean properties to be used for remote sensing applications.

Remote quantification of Cochlodinium polykrikoides blooms occurring in the East Sea using geostationary ocean color imager (GOCI).

Accurate and timely quantification of widespread harmful algal bloom (HAB) distribution is crucial to respond to the natural disaster, minimize the damage, and assess the environmental impact of the event. Although various remote sensing-based quantification approaches have been proposed for HAB since the advent of the ocean color satellite sensor, there have been no algorithms that were validated with in-situ quantitative measurements for the red tide occurring in the Korean seas. Furthermore, since the geostationary ocean color imager (GOCI) became available in June 2010, an algorithm that exploits its unprecedented observation frequency (every hour during the daytime) has been highly demanded to better track the changes in spatial distribution of red tide. This study developed a novel red tide quantification algorithm for GOCI that can estimate hourly chlorophyll-a (Chl a) concentration of Cochlodinium (Margalefidinium) polykrikoides, one of the major red tide species around Korean seas. The developed algorithm has been validated using in-situ Chl a measurements collected from a cruise campaign conducted in August 2013, when a massive C. polykrikoides bloom devastated Korean coasts. The proposed algorithm produced a high correlation (R2=0.92) with in-situ Chl a measurements with robust performance also for high Chl a concentration (300mg/m3) in East Sea areas that typically have a relatively low total suspended particle concentration (<0.5mg/m3).

Novel ray tracing method for stray light suppression from ocean remote sensing measurements.

We developed a new integrated ray tracing (IRT) technique to analyze the stray light effect in remotely sensed images. Images acquired with the Geostationary Ocean Color Imager show a radiance level discrepancy at the slot boundary, which is suspected to be a stray light effect. To determine its cause, we developed and adjusted a novel in-orbit stray light analysis method, which consists of three simulated phases (source, target, and instrument). Each phase simulation was performed in a way that used ray information generated from the Sun and reaching the instrument detector plane efficiently. This simulation scheme enabled the construction of the real environment from the remote sensing data, with a focus on realistic phenomena. In the results, even in a cloud-free environment, a background stray light pattern was identified at the bottom of each slot. Variations in the stray light effect and its pattern according to bright target movement were simulated, with a maximum stray light ratio of 8.5841% in band 2 images. To verify the proposed method and simulation results, we compared the results with the real acquired remotely sensed image. In addition, after correcting for abnormal phenomena in specific cases, we confirmed that the stray light ratio decreased from 2.38% to 1.02% in a band 6 case, and from 1.09% to 0.35% in a band 8 case. IRT-based stray light analysis enabled clear determination of the stray light path and candidates in in-orbit circumstances, and the correction process aided recovery of the radiometric discrepancy.

Simple aerosol correction technique based on the spectral relationships of the aerosol multiple-scattering reflectances for atmospheric correction over the oceans.

An estimation of the aerosol multiple-scattering reflectance is an important part of the atmospheric correction procedure in satellite ocean color data processing. Most commonly, the utilization of two near-infrared (NIR) bands to estimate the aerosol optical properties has been adopted for the estimation of the effects of aerosols. Previously, the operational Geostationary Color Ocean Imager (GOCI) atmospheric correction scheme relies on a single-scattering reflectance ratio (SSE), which was developed for the processing of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) data to determine the appropriate aerosol models and their aerosol optical thicknesses. The scheme computes reflectance contributions (weighting factor) of candidate aerosol models in a single scattering domain then spectrally extrapolates the single-scattering aerosol reflectance from NIR to visible (VIS) bands using the SSE. However, it directly applies the weight value to all wavelengths in a multiple-scattering domain although the multiple-scattering aerosol reflectance has a non-linear relationship with the single-scattering reflectance and inter-band relationship of multiple scattering aerosol reflectances is non-linear. To avoid these issues, we propose an alternative scheme for estimating the aerosol reflectance that uses the spectral relationships in the aerosol multiple-scattering reflectance between different wavelengths (called SRAMS). The process directly calculates the multiple-scattering reflectance contributions in NIR with no residual errors for selected aerosol models. Then it spectrally extrapolates the reflectance contribution from NIR to visible bands for each selected model using the SRAMS. To assess the performance of the algorithm regarding the errors in the water reflectance at the surface or remote-sensing reflectance retrieval, we compared the SRAMS atmospheric correction results with the SSE atmospheric correction using both simulations and in situ match-ups with the GOCI data. From simulations, the mean errors for bands from 412 to 555 nm were 5.2% for the SRAMS scheme and 11.5% for SSE scheme in case-I waters. From in situ match-ups, 16.5% for the SRAMS scheme and 17.6% scheme for the SSE scheme in both case-I and case-II waters. Although we applied the SRAMS algorithm to the GOCI, it can be applied to other ocean color sensors which have two NIR wavelengths.

Vicarious calibration of the Geostationary Ocean Color Imager.

Measurements of ocean color from Geostationary Ocean Color Imager (GOCI) with a moderate spatial resolution and a high temporal frequency demonstrate high value for a number of oceanographic applications. This study aims to propose and evaluate the calibration of GOCI as needed to achieve the level of radiometric accuracy desired for ocean color studies. Previous studies reported that the GOCI retrievals of normalized water-leaving radiances (nLw) are biased high for all visible bands due to the lack of vicarious calibration. The vicarious calibration approach described here relies on the assumed constant aerosol characteristics over the open-ocean sites to accurately estimate atmospheric radiances for the two near-infrared (NIR) bands. The vicarious calibration of visible bands is performed using in situ nLw measurements and the satellite-estimated atmospheric radiance using two NIR bands over the case-1 waters. Prior to this analysis, the in situ nLw spectra in the NIR are corrected by the spectrum optimization technique based on the NIR similarity spectrum assumption. The vicarious calibration gain factors derived for all GOCI bands (except 865nm) significantly improve agreement in retrieved remote-sensing reflectance (Rrs) relative to in situ measurements. These gain factors are independent of angular geometry and possible temporal variability. To further increase the confidence in the calibration gain factors, a large data set from shipboard measurements and AERONET-OC is used in the validation process. It is shown that the absolute percentage difference of the atmospheric correction results from the vicariously calibrated GOCI system is reduced by ~6.8%.

Ocean color products from the Korean Geostationary Ocean Color Imager (GOCI).

The first geostationary ocean color satellite sensor, Geostationary Ocean Color Imager (GOCI), which is onboard South Korean Communication, Ocean, and Meteorological Satellite (COMS), was successfully launched in June of 2010. GOCI has a local area coverage of the western Pacific region centered at around 36°N and 130°E and covers ~2500 × 2500 km(2). GOCI has eight spectral bands from 412 to 865 nm with an hourly measurement during daytime from 9:00 to 16:00 local time, i.e., eight images per day. In a collaboration between NOAA Center for Satellite Applications and Research (STAR) and Korea Institute of Ocean Science and Technology (KIOST), we have been working on deriving and improving GOCI ocean color products, e.g., normalized water-leaving radiance spectra (nLw(λ)), chlorophyll-a concentration, diffuse attenuation coefficient at the wavelength of 490 nm (Kd(490)), etc. The GOCI-covered ocean region includes one of the world's most turbid and optically complex waters. To improve the GOCI-derived nLw(λ) spectra, a new atmospheric correction algorithm was developed and implemented in the GOCI ocean color data processing. The new algorithm was developed specifically for GOCI-like ocean color data processing for this highly turbid western Pacific region. In this paper, we show GOCI ocean color results from our collaboration effort. From in situ validation analyses, ocean color products derived from the new GOCI ocean color data processing have been significantly improved. Generally, the new GOCI ocean color products have a comparable data quality as those from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the satellite Aqua. We show that GOCI-derived ocean color data can provide an effective tool to monitor ocean phenomenon in the region such as tide-induced re-suspension of sediments, diurnal variation of ocean optical and biogeochemical properties, and horizontal advection of river discharge. In particular, we show some examples of ocean diurnal variations in the region, which can be provided effectively from satellite geostationary measurements.

Model of remote-sensing reflectance including bidirectional effects for case 1 and case 2 waters.

A remote-sensing reflectance model based on a lookup table is proposed for use in analyzing satellite ocean color data in both case 1 and case 2 waters. The model coefficients are tabulated for grid values of three angles--solar zenith, sensor zenith, and relative azimuth--to take account of directional variation. This model also requires, as input, a phase function parameter defined by the contribution of suspended particles to the backscattering coefficient. The model is generated from radiative transfer simulations for a wide range of inherent optical properties that cover both case 1 and 2 waters. The model uncertainty that is due to phase function variability is significantly reduced from that in conventional models. Bidirectional variation of reflectance is described and explained for a variety of cases. The effects of wind speed and cloud cover on bidirectional variation are also considered, including those for the fully overcast case in which angular variation can still be considerable (approximately 10%). The implications for seaborne validation of satellite-derived water-leaving reflectance are discussed.