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This study evaluates the impact of assimilating Global Navigation Satellite System (GNSS) radio occultation (RO) bending angles from Formosa Satellite Mission-7/Constellation Observing System for Meteorology, Ionosphere, and Climate-2 (COSMIC-2) receiver satellites on Hurricane Weather Research and Forecasting (HWRF) model tropical cyclone (TC) forecasts. Launched in June 2019, the COSMIC-2 mission provides significantly higher tropics data coverage compared to its predecessor COSMIC constellation. GNSS RO measurements yield information about atmospheric pressure, temperature, and water vapor profiles. HWRF is cycled with and without COSMIC-2 bending angle data assimilation for six 2020 Atlantic hurricane cases. COSMIC-2 assimilation has little impact on HWRF track forecasts, consistent with HWRF’s design limiting cycled data assimilation impacts on surrounding large-scale flows; however, COSMIC-2 assimilation results in a statistically significant ~ 8-12 % mean absolute forecast error reduction in minimum central sea-level pressure for t = 36, 54, 60, and 108-120 hour lead times. Forecasts initialized from analyses assimilating COSMIC-2 observations also have a 1-4 % smaller 600-700 hPa specific humidity (SPFH) root-mean-squared-deviation compared to radiosondes and dropwindsondes for most lead times. While not all HWRF intensity forecasts benefit from COSMIC-2 assimilation, a few show notable improvement. For example, assimilating two COSMIC-2 profiles within the inner core of developing Hurricane Hanna (2020) increases 800-hPa SPFH by up to 1 g kg−1 locally, helping correct a dry bias. The forecast initialized from this analysis better captures Hanna’s observed intensification rate, likely because its moister inner core facilitates development of persistent deep convection near the TC center, where diabatic heating is more efficiently converted to cyclonic wind kinetic energy.

Satellite observations are indispensable for weather forecasting, climate change monitoring, and environmental studies. Understanding and quantifying errors and uncertainties associated with satellite observations are essential for hardware calibration, data assimilation, and developing environmental and climate data records. Satellite observation errors can be classified into four categories: measurement, observation operator, representativeness, and preprocessing errors. Current methods for diagnosing observation errors still yield large uncertainties due to these complex errors. When simulating satellite errors, empirical errors are usually used, which do not always accurately represent the truth. We address these challenges by developing an error inventory simulator, the Satellite Error Representation and Realization (SatERR). SatERR can simulate a wide range of observation errors, from instrument measurement errors to model assimilation errors. Most of these errors are based on physical models, including existing and newly-developed algorithms. SatERR takes a bottom-up approach: Errors are generated from root sources and forward propagate through radiance and science products. This is different from, but complementary to, the top-down approach of current diagnostics, which inversely solves unknown errors. The impact of different errors can be quantified and partitioned, and a ground-truth testbed can be produced to test and refine diagnostic methods. SatERR is a community error inventory, open-source on GitHub, which can be expanded and refined with input from engineers, scientists, and modelers. This debut version of SatERR is centered on microwave sensors, covering traditional large satellites and small satellites operated by NOAA, NASA, and EUMETSAT.

Atmospheric water vapor plays an essential role in the global energy balance, hydrological cycle, and climate system. High-quality and consistent water vapor data from different sources are critical for numerical weather prediction and climate studies. This study evaluates the consistencies between Formosa Satellite Mission 3–Constellation Observing System for Meteorology, Ionosphere and Climate (FORMOSAT-3/COSMIC) radio occultation (RO) and European Centre for Medium-Range Weather Forecasts (ECMWF) ReAnalysis Model 5 (ERA5) water vapor datasets. The COSMIC and ERA5 water vapor data at lower (850 hPa), mid- (500 hPa), and upper troposphere (300 hPa) from 2007 to 2018 are compared. These two water vapor datasets generally show good agreements in space and time. At 500 and 850 hPa, COSMIC water vapor retrieval is lower than water vapor from ERA5 globally, with asymmetric latitudinal variability between the southern and northern hemispheres. The water vapor increases around 2015–2016 due to the El Niño event are identifiable in both COSMIC and ERA5 water vapor time-series data. COSMIC global water vapor increasing trends are 3.47±0.24, 3.25±1.06, 2.03±2.93 %/Decade at 300, 500, and 850 hPa, respectively. COSMIC's increasing water vapor trends at 500 and 850 hPa are ~0.8 %/Decade lower than ERA5. Large regional water vapor trend variabilities with strong increasing and decreasing slopes are observed in the tropics and sub-tropics regions. At 500 and 850 hPa, strong water vapor increasing trends in the equatorial Pacific Ocean and the Laccadive Sea and decreasing trends in the Indo-Pacific Ocean region and the Arabian Sea are recognizable. This study also found that the increasing water vapor trends at 850 hPa estimated from COSMIC are significantly higher than ERA5 data for two low-height stratocumulus cloud-rich ocean regions to the west of Africa and the west of South America. Over land, significant water vapor increasing trends at 850 hPa are around the southern United States, and decreasing trends are observed at sites in the south of Africa and Australia. The differences between the water vapor trends of COSMIC and ERA5 are primarily negative in the tropical regions at 850 hPa. At 500 hPa, the negative differences between COSMIC and ERA5 trends are mainly distributed in the Indo-Pacific Ocean region. In contrast, the positive differences are in the northern Indian Ocean and its northern coast. These regions with notable water vapor trending differences between COSMIC and ERA are located in the Intertropical Convergence Zone (ITCZ) area with frequent occurrences of convection, such as deep clouds. The difference in characterizing water vapor distribution between RO and ERA5 in the presence of a deep cloud may cause such trending differences. Quantitative evaluation of the spatiotemporal variabilities of atmospheric water vapor data helps assure the qualities of RO-derived and reanalysis water vapor for climate studies.

Turbulent mixing in the planetary boundary layer (PBL) governs the vertical exchange of heat, moisture, momentum, trace gases, and aerosols in the surface–atmosphere interface. The PBL height (PBLH) represents the maximum height of the free atmosphere that is directly influenced by Earth’s surface. This study uses a multidata synthesis approach from an ensemble of multiple global datasets of radiosonde observations, reanalysis products, and climate model simulations to examine the spatial patterns of long-term PBLH trends over land between 60°S and 60°N for the period 1979–2019. By considering both the sign and statistical significance of trends, we identify large-scale regions where the change signal is robust and consistent to increase our confidence in the obtained results. Despite differences in the magnitude and sign of PBLH trends over many areas, all datasets reveal a consensus on increasing PBLH over the enormous and very dry Sahara Desert and Arabian Peninsula (SDAP) and declining PBLH in India. At the global scale, the changes in PBLH are significantly correlated positively with the changes in surface heating and negatively with the changes in surface moisture, consistent with theory and previous findings in the literature. The rising PBLH is in good agreement with increasing sensible heat and surface temperature and decreasing relative humidity over the SDAP associated with desert amplification, while the declining PBLH resonates well with increasing relative humidity and latent heat and decreasing sensible heat and surface warming in India. The PBLH changes agree with radiosonde soundings over the SDAP but cannot be validated over India due to lack of good-quality radiosonde observations.

Global Navigation Satellite System (GNSS) radio occultation (RO) is a remote sensing technique that uses International System of Units (SI) traceable GNSS signals for atmospheric limb soundings. The retrieved atmospheric temperature profile is believed to be more accurate and stable than those from other remote sensing techniques, although rigorous comparison between independent measurements is difficult because of time and space differences between individual RO events. Typical RO comparisons are based on global statistics with relaxed matchup criteria (within 3 h and 250 km) that are less than optimal given the dynamic nature and spatial nonuniformity of the atmosphere. This study presents a novel method that allows for direct comparison of bending angles when simultaneous RO measurements occur near the simultaneous nadir overpasses (SNO) of two low-Earth-orbit satellites receiving the same GNSS signal passing through approximately the same atmosphere, within minutes in time and less than 125 km in distance. Using this method, we found very good agreement between Formosa Satellite 7 (FORMOSAT-7)/second Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC-2) satellite measurements and those from MetOp-A/B/C, COSMIC-1, Korea Multi-Purpose Satellite 5 (KOMPSAT-5), and Paz, although systematic biases are also found in some of the intercomparisons. Instrument and processing algorithm performances at different altitudes are also characterized. It is expected that this method can be used for the validation of GNSS RO measurements for most missions and would be a new addition to the tools for intersatellite calibration. This is especially important given the large number of RO measurements made available both publicly and commercially, and the expansion of receiver capabilities to all GNSS systems.

The Constellation Observing System for Meteorology, Ionosphere and Climate-2/Formosa Satellite Mission 7 (COSMIC-2) Global Navigation Satellite System (GNSS) Radio Occultation (RO) constellation is the follow-on to the highly successful COSMIC-1 program. The GNSS RO atmospheric soundings have historically been used to generate Community Radiative Transfer Model simulated background (B) microwave (MW) brightness temperature data needed to monitor NOAA operational MW sounding instrument observed (O) antenna temperature (Ta) product quality. This study is motivated by the need to determine the impact of COSMIC-2 RO soundings on this critical long-term monitoring capability. This study is based on individual MW sensor O-B Ta bias (∆Ta) statistics and "double-difference" inter-sensor Ta bias (δTa) statistics for two time periods. Time Period 1 (TP1—May 1, 2017, to September 30, 2019) exclusively uses COSMIC-1 and Korea Multi-Purpose Satellite-5 soundings, while Time Period 2 (TP2—October 1, 2019, to December 31, 2020) expands the analysis with COSMIC-2 soundings. The TP1 and TP2 ∆Ta statistics comparisons indicate COSMIC-2 data population augmentation and latitudinal distribution impact the MW sounder performance monitoring tool transition from TP1 to TP2. COSMIC-2 competently supports long-term MW individual sensor and inter-sensor product monitoring for MW radiometer channels with weighting functions that peak between 8 and 30 km. Individual sensor ∆Ta monitoring for other microwave channels that depend on COSMIC-2 data below 8 km and from 30 km to 60 has limitations, but these limitations are shown not to inhibit critical δTa monitoring.

Launched in 2006, the Formosa Satellite Mission 3–Constellation Observing System for Meteorology, Ionosphere and Climate (FORMOSAT-3/COSMIC) was the first constellation of microsatellites carrying global positioning system (GPS) radio occultation (RO) receivers. Radio occultation is an active remote sensing technique that provides valuable information on the vertical variations of electron density in the ionosphere, and temperature, pressure, and water vapor in the stratosphere and troposphere. COSMIC has demonstrated the great value of RO data in ionosphere, climate, and meteorological research and operational weather forecasting. However, there are still challenges using RO data, particularly in the moist lower troposphere and upper stratosphere. A COSMIC follow-on constellation, COSMIC-2, was launched into equatorial orbit in 2019. With increased signal-to-noise ratio (SNR) from improved receivers and digital beam steering antennas, COSMIC-2 will produce at least 5,000 high-quality RO profiles daily in the tropics and subtropics. In this paper, we summarize 1) recent (since 2011 when the last review was published) contributions of COSMIC and other RO observations to weather, climate, and space weather science; 2) the remaining challenges in RO applications; and 3) potential contributions to research and operations of COSMIC-2.

The Global Navigation Satellite System (GNSS) radio occultation (RO) is a remote sensing technique that uses International System of Units (SI) traceable GNSS signals for atmospheric limb soundings. The RO bending angle/sounding profiles are needed for assimilation in Numerical Weather Prediction (NWP) models, weather, climate, and space weather applications. Evaluating these RO data to ensure the high data quality for these applications is becoming more and more critical. This study presents a method for predicting radio occultation events, from which simultaneous radio occultation (SRO) for a pair of low-Earth-orbit (LEO) satellites on the limb to the same GNSS satellite can be obtained. The SRO method complements the Simultaneous Nadir Overpass (SNO) method (for nadir viewing satellite instruments), which has been widely used to inter-calibrate LEO to LEO and LEO to geosynchronous-equatorial-orbit (GEO) satellites. Unlike the SNO method, the SRO method involves three satellites: a GNSS and two LEO satellites with RO receivers. The SRO method allows for the direct comparison of bending angles when the simultaneous RO measurements for two LEO satellites receiving the same GNSS signal pass through approximately the same atmosphere within minutes in time and within less than 200 km of distance from each other. The prediction method can also be applied to radiosonde overpass prediction, and coordinate radiosonde launches for inter-comparisons between RO and radiosonde profiles. The main advantage of the SRO comparisons of bending angles is the significantly reduced uncertainties due to the much shorter time and smaller atmospheric path differences than traditional RO comparisons. To demonstrate the usefulness of this method, we present a comparison of the Constellation Observing System for Meteorology, Ionosphere, and Climate-2 (COSMIC-2) and GeoOpitcs RO profiles using SRO data for two time periods: Commercial Weather Data (CWD) data delivery order-1 (DO-1): 15 December 2020–15 January 2021 and CWD DO-2: 17 March 2021–31 August 2021. The results show good agreement in the bending angles between the COSMIC-2 RO measurements and those from GeoOptics, although systematic biases are also found in the inter-comparisons. Instrument and processing algorithm performances for the signal-to-noise ratio (SNR), penetration height, and bending angle retrieval uncertainty are also characterized. Given the efficiency of this method and the many RO measurements that are publicly and commercially available as well as the expansion of receiver capabilities to all GNSS systems, it is expected that this method can be used to validate/inter-calibrate GNSS RO measurements from different missions.

Graphical abstract, Highlights • Emergence of carbapenem-resistant S. algae is a severe problem. • Re-sensitization of S. algae to carbapenem by CRISPR/Cas9 genome editing. • The blaOXA-55-like gene is essential for carbapenem resistance in S. algae. • One-plasmid genome editing system for CRISPR/Cas9 genome editing in S. algae. • CRISPR/Cas9 genome editing is a promising approach to validate the gene function., Antibiotic resistance in pathogens is a growing threat to human health. Of particular concern is resistance to carbapenem, which is an antimicrobial agent listed as critically important by the World Health Organization. With the global spread of carbapenem-resistant organisms, there is an urgent need for new treatment options. Shewanella algae is an emerging pathogen found in marine environments throughout the world that has increasing resistance to carbapenem. The organism is also a possible antibiotic resistance reservoir in humans and in its natural habitat. The development of CRISPR/Cas9-based methods has enabled precise genetic manipulation. A number of attempts have been made to knock out resistance genes in various organisms. The study used a single plasmid containing CRISPR/Cas9 and recE/recT recombinase to reverse an antibiotic-resistant phenotype in S. algae and showed blaOXA-55-like gene is essential for the carbapenem resistance. This result demonstrates a potential validation strategy for functional genome annotation in S. algae.

Objective: This study retrospectively evaluated the incidences of small supernumerary marker chromosomes (sSMCs) in prenatal diagnoses and detected with gain of pathogenic copy number variation through array comparative genomic hybridization (CGH) in a laboratory in Taiwan. Materials and methods: We retrospectively searched and reviewed the sSMC cases detected during prenatal diagnoses in the Youthgene medical laboratory, between 2004 and 2015 and used array CGH to successfully analyze 45 of 47,XN,+mar or 47,XN + mar/46,XN. Results: A total of 68,087 cases of amniocentesis were analyzed, of which 59 were identified as sSMCs. The overall frequency of sSMCs was 0.087%, and 7 of 45 sSMCs were identified with gain of pathogenic copy number variation (CNV). Conclusion: Array CGH offers useful tools that can be used to detect small fragments of chromosomal abnormalities and sSMC origins in prenatal diagnosis. In this study, we successfully used array CGH to detect 7 out of 45 sSMCs, which were identified with gain in pathogenic CNV. Keywords: Small supernumerary marker chromosome (sSMC), Array comparative genomic hybridization, Prenatal diagnosis, Cat eye syndrome, Pallister–Killian syndrome

This study was aimed to develop a simple, fast, and reliable technique to detect fluoroquinolones (FQs)-conjugated bovine serum albumin (BSA). Four tested FQs, enrofloxacin, ofloxacin, danofloxacin, and orbifloxacin, were conjugated with BSA by following the N-hydroxysuccinimide ester method. The technique was designed according to the different absorption characteristics of the FQs and BSA; FQs can be detected by both UV and fluorescence detectors, but BSA can only be detected by UV. The results demonstrated that the developed method was efficient in detecting FQs-BSA conjugates. In addition, the method not only trace the FQs and BSA conjugation responses but also can be used to estimate the level of FQs-BSA conjugation. Therefore, this technique is a valuable tool for the detection drug-carrier-conjugated antigens, especially for FQs-BSA-conjugates during the production of anti-FQs monoclonal antibodies.

We analyzed the residual of oxolinic acid in the serum and muscle of the Chinese mitten crab by high-performance liquid chromatography (HPLC) coupled with a fluorescence detector. A standard solution of oxolinic acid was prepared by dilution with 0.05 M phosphate buffered saline (PBS) (pH 7.4). Serum and muscle samples were completely homogenized prior to addition of oxolinic acid. Samples were then transferred into an ultrasonic water bath and centrifuged. The supernatants of serum and water layer of hexane defatted muscle were passed through C-18 solid phase extraction columns. Finally, oxolinic acid in the column was eluted with methanol/NH4OH (75:25 v/v), and then was evaporated to dry by nitrogen gas. Extracted oxolinic acid was determined by HPLC with a fluorescence detector (excitation/emission=335 nm/378 nm) and a Cosmosil 5C18-MS reverse phase column (5 μm, 4.6×150 mm i.d.). A mixture of acetonitrile and 0.02 M PBS pH 3.0 (25:75) was used as the mobile phase at a flow rate of 1.0 mL/min. A peak with retention time around 8 min was observed. With the addition of 100 μg L^(-1) oxolinic acid treatments, the mean recoveries from serum and muscle were 92% and 82%, respectively. The detection limit was 1 ppb and standard curves spiked at different levels showed a good linear correlation coefficient (R(superscript 2)＞0.999 for oxolinic acid). Because residual oxolinic acid could not be detected in all tested crabs initially, five crabs were fed with oxolinic acid for 7 days by oral administration on purpose and the residual oxolinic acid in both sera and muscle were measured, respectively. The results showed that the residual oxoilinic acid in both sera and muscle could be quantified by this method. Therefore, our developed technique may be employed as a practical method for detection of residual oxolinic acid residue in Chinese mitten crabs or other aquaculture products.

Shewanella haliotisis an emerging human pathogen. Many infectious cases were linked to shellfish ingestion or aquatic exposure. Therefore, it is important to study the phylogeny and distribution ofS. haliotisin shellfish aquaculture. We investigated the distribution ofS. haliotisin cultivated shellfish farming in Taiwan in whichS. haliotiswas found in the shellfish from all sampling sites.S. haliotiswas identified in cultivated shellfish by 16S rRNA gene sequencing, such as abalone (Haliotis diversicolor), clam (Meretrix lusoria), and oyster (Crassostrea gigas). This study highlighted the contamination ofS. haliotisin cultivated shellfish and importance of further study regarding the biodiversity and pathogenesis ofS. haliotis.

Association of lower tropospheric variations with the cold point tropopause (CPT) is examined on inter-seasonal basis over the tropical region (30°N-30°S) during 2007–2010 using COSMIC/FORMOST-3 Radio Occultation (RO) data. Temperature analyses for this association are shown over different regions of the globe having contrast topography namely over Western Pacific sector, Indian sector, and African sector. Correlation coefficient (r), taken as a measurement of association, show specific longitudinal differences between the lower troposphere (from 1 km to 5 km height) and the CPT. The northern and southern hemispheres show contrast coupling of temperature variation between lower tropospheric region and the CPT. Land and ocean effects are found to contribute in a different way to the correlation coefficient. Analyses show symmetrical structure of ‘r’ on both sides of the equator over the African region, as data include mostly land region on both side of equator. Data represent positive correlation (r ~ 0.5) over 15°–20° latitudes on either side of the equator over the African region, suggesting strong hold of the inter-seasonal variation of solar diabatic heating influence over the tropic of Cancer and tropic of Capricorn. On the other hand, there is a contrast behaviour over the Indian region, ‘r’ is nearly negative (~− 1.0) each year in the southern hemisphere (SH) and positive (~ 0.4) in the northern hemisphere (NH) with a maxima near tropic of Cancer. Western Pacific region is found to display a linear increase in ‘r’ from negative (~− 1.0) in SH to positive (~ 0.8) in NH. In general, ‘r’ (positive) maximizes over the land region around 15°–20° latitudes, suggesting a control of in phase inter-seasonal solar heating on the coupling of boundary layer/lower troposphere and CPT region, whereas it turns negative over water body. Analyses suggest that variabilities in CPT over different regions of globe show significant inter-seasonal association with the lower troposphere. Thus CPT variabilities are not only governed by QBO, ENSO, gravity waves and Kelvin wave system as reported in earlier studies but also considerably affected by inter-seasonal changes taking place in the lower troposphere.

Radio occultation (RO) sensor measurements have critical roles in numerical weather prediction (NWP) by complementing microwave and infrared sounder measurements with information of the atmospheric profiles at high accuracy, precision, and vertical resolution. This study evaluates Constellation Observing System for Meteorology, Ionosphere, and Climate 2 (COSMIC-2) wet temperature and humidity data products’ consistency and stability through inter-comparison with SNPP advanced technology microwave sounder (ATMS) measurements. Through the community radiative transfer model (CRTM), brightness temperature (BT) at SNPP ATMS channels are simulated with COSMIC-2 retrieved atmospheric profiles from two versions of the University Corporation for Atmospheric Research (UCAR) wet profiles (WETprf and WETpf2) as inputs to the CRTM simulation. The analysis was focused on ATMS sounding channels CH07–14 and CH19–22 with sounding weighting function peak heights from 3.2 to 35 km. The COSMIC-2 vs. ATMS inter-comparison indicates that their BT biases are consistent, and the latitudinal difference is

Radiosonde observations (RAOBs) have provided the only long-term global in situ temperature measurements in the troposphere and lower stratosphere since 1958. In this study, we use consistently reprocessed Global Positioning System (GPS) radio occultation (RO) temperature data derived from the COSMIC and Metop-A/GRAS missions from 2006 to 2014 to characterize the inter-seasonal and interannual variability of temperature biases in the upper troposphere and lower stratosphere for different radiosonde sensor types. The results show that the temperature biases for different sensor types are mainly due to (i) uncorrected solar-zenith-angle-dependent errors and (ii) change of radiation correction. The mean radiosonde–RO global daytime temperature difference in the layer from 200 to 20 hPa for Vaisala RS92 is equal to 0.20 K. The corresponding difference is equal to −0.06 K for Sippican, 0.71 K for VIZ-B2, 0.66 K for Russian AVK-MRZ, and 0.18 K for Shanghai. The global daytime trend of differences for Vaisala RS92 and RO temperature at 50 hPa is equal to 0.07 K/5 yr. Although there still exist uncertainties for Vaisala RS92 temperature measurement over different geographical locations, the global trend of temperature differences between Vaisala RS92 and RO from June 2006 to April 2014 is within ±0.09 K/5 yr. Compared with Vaisala RS80, Vaisala RS90, and sondes from other manufacturers, the Vaisala RS92 seems to provide the most accurate RAOB temperature measurements, and these can potentially be used to construct long-term temperature climate data records (CDRs). Results from this study also demonstrate the feasibility of using RO data to correct RAOB temperature biases for different sensor types.

BACKGROUND Proton pump inhibitors (PPIs) are widely applied for acid related disorders, and possess pleiotropic biological functions. The effect of PPIs on the gastric mucosa, neutrophil and Helicobacter pylori (H. pylori) infiltration and glandular atrophy has not been well investigated, particularly the duration of the effects of PPIs. OBJECTIVES To investigate the effects of PPIs on neutrophil infiltration, H. pylori infiltration and the gastric mucosa. MATERIAL AND METHODS A total of 76 adult patients with gastrointestinal symptoms who had undergone upper gastrointestinal endoscopy were enrolled in the study. Each patient's history was recorded, including smoking, alcohol consumption and the duration of PPI use prior to gastric biopsy. Endoscopic biopsies of gastric antral mucosa were performed and evaluated by histology. Neutrophil and H. pylori infiltration were graded by H & E staining in accordance with the updated Sydney system. RESULTS Among the 76 patients, 44 patients had H. pylori infection and 19 patients had taken PPIs for varying durations prior to gastric biopsy. Neutrophil infiltration was significantly inhibited by PPIs (p = 0.005). The duration of PPI use was correlated with inhibition of neutrophil and H. pylori infiltration. A logistical regression analysis demonstrated that PPIs significantly inhibited neutrophil infiltration in the gastric mucosa and were associated with atrophy of the mucosa. CONCLUSIONS PPIs attenuated neutrophil infiltration of gastric mucosa, and may be related to atrophy of the mucosa.

To date, a large variety of water vapour data records from satellite and reanalysis are available. It is key to understand the quality and uncertainty of these data records in order to fully exploit these records and to avoid data being employed incorrectly or misinterpreted. Therefore, it is important to inform users on accuracy and limitations of these data records based on consistent inter-comparisons carried out in the framework of international assessments. Addressing this challenge is the major objective of the Global Water and Energy Exchanges (GEWEX) water vapor assessment (G-VAP) which was initiated by the GEWEX Data and Assessments Panel (GDAP). Here, an overview of G-VAP objectives and an introduction to the results from G-VAP’s first phase are given. After this overview, a summary of available data records on water vapour and closely related variables and a short introduction to the utilized methods are presented. The results from inter-comparisons, homogeneity testing and inter-comparison of trend estimates, achieved within G-VAP’s first phase are summarized. The conclusions on future research directions for the wider community and for G-VAP’s next phase are outlined and recommendations have been formulated. For instance, a key recommendation is the need for recalibration and improved inter-calibration of radiance data records and subsequent reprocessing in order to increase stability and to provide uncertainty estimates. This need became evident from a general disagreement in trend estimates (e.g., trends in TCWV ranging from −1.51 ± 0.17 kg/m2/decade to 1.22 ± 0.16 kg/m2/decade) and the presence of break points on global and regional scale. It will be a future activity of G-VAP to reassess the stability of updated or new data records and to assess consistency, i.e., the closeness of data records given their uncertainty estimates. Informus GmbH was funded under ESA’s Long-Term Data Preservation program under contract 4000109537/13/I-AM.

The radio occultation technique provides stable atmospheric measurements that can work as a benchmark for calibrating and validating satellite-sounding data. Launched on 25 June 2019, the Constellation Observing System for Meteorology, Ionosphere, and Climate 2 and Formosa Satellite Mission 7 (COSMIC-2/FORMOSAT-7) are expected to produce about 5000 high-quality RO observations daily over the tropics and subtropics. COSMIC-2 constellation consists of 6 Low Earth Orbit (LEO) satellites in 24° inclination orbits at 720 km altitude and distributed mainly between 45°N to 45°S. The COSMIC-2 observations have uniform temporal coverage between 30°N to 30°S. This paper presents an independent inversion algorithm to invert COSMIC-2 geometry and phase data to bending angle and refractivity. We also investigate the quality of Global Navigation Satellite System (GNSS) and LEO position vectors derived from the UCAR COSMIC Data Analysis and Archive Center (CDAAC). The GNSS and LEO position vectors are stable with LEO position variations < 1.4 mm/s. The signal-to-noise ratio (SNR) on the L1 band ranges from 300–2600 v/v with a mean of 1600 v/v. The inversion algorithm developed at NOAA Center for Satellite Applications and Research (STAR) uses the Full Spectrum Inversion (FSI) method to invert COSMIC-2 geometry and phase data to bending angle and refractivity profiles. The STAR COSMIC-2 bending angle and refractivity profiles are compared with in situ radiosonde, the current COSMIC-2 products derived from CDAAC, and the collocated European Center for Medium-Range Weather Forecasts (ECMWF) climate reanalysis data ERA5. The mean bias at 8–40 km altitude among the UCAR, ERA5, and STAR is

Atmospheric temperature soundings derived from satellite-based advanced infrared (IR) sounder radiance measurements tend to have higher uncertainty in the upper troposphere. In contrast, radio occultation (RO) measurements have high accuracy and high vertical-resolution for atmospheric sounding in the upper troposphere and lower stratosphere (UTLS). It is anticipated that the best estimation of atmospheric thermodynamic state can be obtained by the synergistic use of RO and IR radiance measurements. A physical-based algorithm accounting for the significant geometric difference between the two observing systems has been developed to combine RO refractivity and Atmospheric InfraRed Sounder (AIRS) radiances for atmospheric temperature and humidity vertical profiles. Comparisons between RO/AIRS and AIRS-alone derived profiles showed that the impact of RO observations to be most apparent in the upper troposphere between 100 and 300 hPa, where the root-mean-square difference (RMSD) of estimated temperature is reduced by 24% (0.36 K) to 35% (0.66 K). In addition to having improved temperature profile retrievals in the upper troposphere, the humidity retrievals are also improved; the RMSD below 100 hPa was reduced by 22.4% (0.298 g/kg) when compared with radiosondes observations. Results indicated that the humidity profiles retrieved using this method were overall better than the IR-only retrievals in all of the comparisons, and the temperature profiles improved upon the IR-only retrievals, most notably in the upper troposphere. These improvements are more significant using a three-dimensional (3-D) slant-path collocation procedure.

A significant change in temperature in the tropopause and stratosphere, from pole to the tropics, was observed during a major Sudden Stratospheric Warming (SSW) occurring in January 2009. The SSW event strongly modified the pattern of polar and tropical stratospheric circulation. After termination of SSW, a new pattern emerged that prevailed for ~ 2–3 months. After SSW, a clear descending cold phase completely replaced the warm phase in the polar regions. During the warm phase, temperature increased to ~ 40 °C in stratosphere (> 30 km altitude) in the polar region (80°N–90°N), then it dropped down to − 80 °C during the cold phase. Interestingly, new warm anomalies appeared over the tropical region during the cold phase at polar regions. Possible implications of these unusually warm and cold phases are demonstrated in this study. These phases altered significantly the cold point tropopause temperature and its height. SSW also affected the tropical atmospheric stability. Cross equatorial response (from northern to southern hemisphere) up to 40°S was observed in the form of persisting anomalies as a consequence of the SSW event.