scholarly journals Intercalibration of GOES-11 and GOES-12 Water Vapor Channels with MetOp IASI Hyperspectral Measurements

2009 ◽  
Vol 26 (9) ◽  
pp. 1843-1855 ◽  
Author(s):  
Likun Wang ◽  
Changyong Cao ◽  
Mitch Goldberg
Keyword(s):  
Water Vapor ◽  
Weather Forecasting ◽  
Spectral Response ◽  
Sensor Performance ◽  
Calibration Accuracy ◽  
Polar Orbiting Satellite ◽  
One Year ◽  
Climate Studies ◽  
Better Than

Abstract The calibrated radiances from geostationary water vapor channels play an important role for weather forecasting, data assimilation, and climate studies. Therefore, better understanding the data quality for radiance measurements and independently assessing their onboard calibrations become increasingly more important. In this study, the Infrared Atmospheric Sounding Interferometer (IASI) hyperspectral measurements on the polar-orbiting Meteorological Operation-A (MetOp-A) satellite are used to assess the calibration accuracy of water vapor channels on the Geostationary Operational Environmental Satellite-11 (GOES-11) and GOES-12 imagers with one year of data. The near-simultaneous nadir observations with homogeneous scenes from IASI and GOES imagers are spatially collocated. The IASI spectra are convolved with the GOES imager spectral response functions (SRFs) to compare with GOES imager observations. Assuming that IASI is well calibrated and can be used as an on-orbit radiometric reference standard, then the GOES imager water vapor channels have an overall relative calibration bias to IASI of better than 0.3 K (with a standard deviation of ∼0.2 K) at the brightness temperature (BT) range of 240–260 K, which meets the design specification (1.0-K calibration accuracy for infrared channels). This study further demonstrates the technique of using hyperspectral radiance measurements in a polar-orbiting satellite to accurately assess broadband radiometer calibration of the GOES imager, which also provides an effective way for monitoring sensor performance over time. In addition, the potential of using the intercalibration results to integrate and merge data from different observing systems involving both IASI and different GOES imagers to create consistent, seamless global products is explored. The method presented here can potentially be applied to other instruments on both polar-orbiting and geostationary satellites for generating long-term time series.

scholarly journals Recent divergences in stratospheric water vapor measurements by frost point hygrometers and the Aura Microwave Limb Sounder

2016 ◽  
Author(s):  
Dale F. Hurst ◽  
William G. Read ◽  
Holger Vömel ◽  
Henry B. Selkirk ◽  
Karen H. Rosenlof ◽  
...  
Keyword(s):  
Water Vapor ◽  
Linear Regression Analysis ◽  
San Jose ◽  
Average Growth ◽  
Upper Troposphere ◽  
Stratospheric Water Vapor ◽  
Frost Point ◽  
Comparison Period ◽  
Better Than

Abstract. Balloon-borne frost point hygrometers (FPs) and the Aura Microwave Limb Sounder (MLS) provide high-quality vertical profile measurements of water vapor in the upper troposphere and lower stratosphere (UTLS). A previous comparison of stratospheric water vapor measurements by FPs and MLS over three FP sites, Boulder, Colorado (40.0° N), Hilo, Hawaii (19.7° N) and Lauder, New Zealand (45.0° S), from August 2004 through December 2012, demonstrated agreement better than 1 % between 68 and 26 hPa, but also exposed statistically significant biases of 2 to 10 % at 83 and 100 hPa (Hurst et al., 2014). A simple linear regression analysis of the FPH-MLS differences revealed no significant long-term drifts between the two instruments. Here we extend the drift comparison to mid-2015 and add two FP sites, Lindenberg, Germany (52.2° N) and San José, Costa Rica (10.0° N) that employ FPs of different manufacture and calibration for their water vapor soundings. The extended comparison period reveals that stratospheric FP and MLS measurements over 4 of the 5 sites have diverged at rates of 0.03 to 0.07 ppmv yr−1 (0.6 to 1.5 % yr−1) from ~2010 to mid-2015. These rates are similar in magnitude to the 30-year (1980–2010) average growth rate of stratospheric water vapor (~1 % yr−1) measured by FPs over Boulder (Hurst et al., 2011). By mid-2015, the FP-MLS differences at some sites were large enough to exceed the combined accuracy estimates of the FP and MLS measurements.

Intercalibration of Broadband Geostationary Imagers Using AIRS

2009 ◽  
Vol 26 (4) ◽  
pp. 746-758 ◽  
Author(s):  
Mathew M. Gunshor ◽  
Timothy J. Schmit ◽  
W. Paul Menzel ◽  
David C. Tobin
Keyword(s):  
Spectral Resolution ◽  
Spectral Response ◽  
High Spectral Resolution ◽  
Spectral Gaps ◽  
Atmospheric Infrared Sounder ◽  
Earth Observing System ◽  
First Approximation ◽  
Atmospheric Sounding ◽  
Calibration Accuracy ◽  
Polar Orbiting Satellite

Abstract Geostationary simultaneous nadir observations (GSNOs) are collected for Earth Observing System (EOS) Atmospheric Infrared Sounder (AIRS) on board Aqua and a global array of geostationary imagers. The imagers compared in this study are on (Geostationary Operational Environmental Satellites) GOES-10, GOES-11, GOES-12, (Meteorological Satellites) Meteosat-8, Meteosat-9, Multifunctional Transport Satellite-IR (MTSAT-IR), and Fenguyun-2C (FY-2C). It has been shown that a single polar-orbiting satellite can be used to intercalibrate any number of geostationary imagers. Using a high-spectral-resolution infrared sensor, in this case AIRS, brings this method closer to an absolute reckoning of imager calibration accuracy based on laboratory measurements of the instrument’s spectral response. An intercalibration method is presented here, including a method of compensating for AIRS’ spectral gaps, along with results for approximately 22 months of comparisons. The method appears to work very well for most bands, but there are still unresolved issues with bands that are not spectrally covered well by AIRS (such as the water vapor bands and the 8.7-μm band on Meteosat). To the first approximation, most of the bands on the world’s geostationary imagers are reasonably well calibrated—that is, they compare to within 1 K of a standard reference (AIRS). The next step in the evolution of geostationary intercalibration is to use Infrared Atmospheric Sounding Interferometer (IASI) data. IASI is a high-spectral-resolution instrument similar to AIRS but without significant spectral gaps.

scholarly journals The Stratospheric Water and Ozone Satellite Homogenized (SWOOSH) database: A long-term database for climate studies

2016 ◽  
Author(s):  
Sean M. Davis ◽  
Karen H. Rosenlof ◽  
Birgit Hassler ◽  
Dale F. Hurst ◽  
William G. Read ◽  
...  
Keyword(s):  
Water Vapor ◽  
Data Set ◽  
Future Studies ◽  
Source Data ◽  
Reference Satellite ◽  
Data Record ◽  
Reference Measurements ◽  
Climate Studies ◽  
Term Data

Abstract. In this paper, we describe the construction of the Stratospheric Water and Ozone Satellite Homogenized (SWOOSH) database, which includes vertically resolved ozone and water vapor data from limb profiling satellite instruments operating since the 1980’s. SWOOSH includes both individual satellite source data as well as a merged data product. A key aspect of the merged product is that the source records are homogenized to account for inter-satellite biases and to minimize artificial jumps in the record. We describe the SWOOSH homogenization process, which involves adjusting the satellite data records to a “reference” satellite using coincident observations during time periods of instrument overlap. The reference satellite is chosen based on the best agreement with independent balloon-based sounding measurements, with the goal of producing a long-term data record that is both homogeneous and accurate. This paper details the choice of reference measurements, homogenization, and gridding process involved in the construction of the combined SWOOSH product, and also presents the ancillary information stored in SWOOSH that can be used in future studies of water vapor and ozone variability. Furthermore, a discussion of uncertainties in the combined SWOOSH record is presented, and examples of the SWOOSH record are provided to illustrate its use for studies of ozone and water vapor variability on interannual to decadal time scales. The version 2.5 SWOOSH data are publicly available at https://data.noaa.gov/dataset/stratospheric-water-and-ozone-satellite-homogenized-swoosh-data-set.

scholarly journals An update on the uncertainties of water vapor measurements using Cryogenic Frostpoint Hygrometers

2016 ◽  
Author(s):  
Holger Vömel ◽  
Tatjana. Naebert ◽  
Ruud Dirksen ◽  
Michael Sommer
Keyword(s):  
Water Vapor ◽  
Data Series ◽  
Climate Variables ◽  
Stratospheric Water Vapor ◽  
Tropospheric Measurements ◽  
Long Time ◽  
Climate Series ◽  
Term Data ◽  
Better Than

Abstract. Long time series of observations of essential climate variables in the troposphere and stratosphere are often impacted by inconsistencies in instrumentation and ambiguities in the interpretation of the data. To reduce these problems of long term data series all measurements should include an estimate of their uncertainty and a description of their sources. Here we present an update of the uncertainties for tropospheric and stratospheric water vapor observations using the Cryogenic Frostpoint Hygrometer (CFH). The largest source of measurement uncertainty is the controller stability, which is discussed here in detail. We describe a method to quantify this uncertainty for each profile based on the measurements. We also show the importance of a manufacturer independent ground check, which is an essential tool to continuously monitor the uncertainty introduced by instrument variability. A small bias, which has previously been indicated in lower tropospheric measurements, is described here in detail and has been rectified. Under good conditions the total from all sources of uncertainty of frostpoint or dewpoint measurements using the CFH can be better than 0.2 K. Systematic errors, which are most likely to impact long term climate series are verified to be less than 0.1 K.

scholarly journals Pharmacotherapy of Peptic Ulcer Disease

1991 ◽  
Vol 5 (1) ◽  
pp. 21-33
Author(s):  
F Molina ◽  
MM Vohra ◽  
CN Williams
Keyword(s):  
Peptic Ulcer ◽  
Relapse Rate ◽  
Elderly Women ◽  
Medication Cost ◽  
Ulcer Disease ◽  
Ulcer Relapse ◽  
Patient Groups ◽  
One Year ◽  
Better Than

The etiology of peptic ulcer is multifactorial; except for omeprazole, all drugs used for the treatment of peptic ulcer result in healing with no statistical difference at four weeks. The healing rare increases with time for active medication and placebo, and is lower among smokers than nonsmokers for all drugs but misoprostol. Mucosal protectives (or ‘cytoprotectives’) as a group seem to have a lower relapse rate than the H2receptor antagonists at one year. Combination therapy has not yet proved to be better than single drug therapy; however, the number of studies is still small, and more clinical trials are necessary. Resistant ulcers have demonstrated that acid is one of several etiological factors and that more research is needed to elucidate the reason(s) for refractoriness. The choice of therapeutic agent is generally made according to patient compliance, medication cost, side effects, effectiveness, relapse rate and physician experience with the drug. Long term maintenance therapy is effective in the prevention of ulcer relapse and is especially recommended for selected patient groups, including patients with recurrent or bleeding ulcer, patients with concomitant nonsteroidal anti-inflammatory drug use, and elderly women. Omeprazole is the treatment of choice for moderate to severe esophagitis and should be reserved for large and resistant ulcers.

scholarly journals Climate Data Records from Meteosat First Generation Part III: Recalibration and Uncertainty Tracing of the Visible Channel on Meteosat-2–7 Using Reconstructed, Spectrally Changing Response Functions

2019 ◽  
Vol 11 (10) ◽  
pp. 1165 ◽  
Author(s):  
Frank Rüthrich ◽  
Viju O. John ◽  
Rob A. Roebeling ◽  
Ralf Quast ◽  
Yves Govaerts ◽  
...  
Keyword(s):  
First Generation ◽  
Near Infrared ◽  
Weather Forecasting ◽  
Spectral Response ◽  
Temporal Correlation ◽  
Climate Data ◽  
Metrological Analysis ◽  
Horizon 2020 ◽  
Data Record ◽  
Climate Studies

This paper presents a new Fundamental Climate Data Record (FCDR) for the visible (VIS) channel of the Meteosat Visible and Infrared Imager (MVIRI), with pixel-level metrologically traceable uncertainties and error covariance estimates. MVIRI has flown onboard Meteosat First Generation (MFG) satellites between 1982 and 2017. It has served the weather forecasting community with measurements of “visible”, “infra-red” and “water vapour” radiance in near real-time. The precision of the pre-launch sensor spectral response function (SRF) characterisation, particularly of the visible band of this sensor type, improved considerably with time, resulting in higher quality radiances towards the end of the MFG program. Despite these improvements, the correction of the degradation of this sensor has remained a challenging task and previous studies have found the SRF degradation to be faster in the blue than in the near-infrared part of the spectrum. With these limitations, the dataset cannot be immediately applied in climate science. In order to provide a data record that is suited for climate studies, the Horizon 2020 project “FIDelity and Uncertainty in Climate-data records from Earth Observation” (FIDUCEO) conducted (1) a thorough metrological uncertainty analysis for each instrument, and (2) a recalibration using enhanced input data such as reconstructed SRFs. In this paper, we present the metrological analysis, the recalibration results and the resulting consolidated FCDR. In the course of this study we were able to trace-back the remaining uncertainties in the calibrated MVIRI reflectances to underlying effects that have distinct physical root-causes and spatial/temporal correlation patterns. SEVIRI and SCIAMACHY reflectances have been used for a validation of the harmonised dataset. The resulting new FCDR is publicly available for climate studies and for the production of climate data records (CDRs) spanning about 35 years.

scholarly journals Recent divergences in stratospheric water vapor measurements by frost point hygrometers and the Aura Microwave Limb Sounder

2016 ◽  
Vol 9 (9) ◽  
pp. 4447-4457 ◽  
Author(s):  
Dale F. Hurst ◽  
William G. Read ◽  
Holger Vömel ◽  
Henry B. Selkirk ◽  
Karen H. Rosenlof ◽  
...  
Keyword(s):  
Water Vapor ◽  
Linear Regression Analysis ◽  
San Jose ◽  
Average Growth ◽  
Upper Troposphere ◽  
Stratospheric Water Vapor ◽  
Frost Point ◽  
Comparison Period ◽  
Better Than

Abstract. Balloon-borne frost point hygrometers (FPs) and the Aura Microwave Limb Sounder (MLS) provide high-quality vertical profile measurements of water vapor in the upper troposphere and lower stratosphere (UTLS). A previous comparison of stratospheric water vapor measurements by FPs and MLS over three sites – Boulder, Colorado (40.0° N); Hilo, Hawaii (19.7° N); and Lauder, New Zealand (45.0° S) – from August 2004 through December 2012 not only demonstrated agreement better than 1 % between 68 and 26 hPa but also exposed statistically significant biases of 2 to 10 % at 83 and 100 hPa (Hurst et al., 2014). A simple linear regression analysis of the FP–MLS differences revealed no significant long-term drifts between the two instruments. Here we extend the drift comparison to mid-2015 and add two FP sites – Lindenberg, Germany (52.2° N), and San José, Costa Rica (10.0° N) – that employ FPs of different manufacture and calibration for their water vapor soundings. The extended comparison period reveals that stratospheric FP and MLS measurements over four of the five sites have diverged at rates of 0.03 to 0.07 ppmv year−1 (0.6 to 1.5 % year−1) from  ∼  2010 to mid-2015. These rates are similar in magnitude to the 30-year (1980–2010) average growth rate of stratospheric water vapor ( ∼  1 % year−1) measured by FPs over Boulder (Hurst et al., 2011). By mid-2015, the FP–MLS differences at some sites were large enough to exceed the combined accuracy estimates of the FP and MLS measurements.

scholarly journals Constructing a precipitable water vapor map from regional GNSS network observations without collocated meteorological data for weather forecasting

2018 ◽  
Vol 11 (9) ◽  
pp. 5153-5166 ◽  
Author(s):  
Biyan Chen ◽  
Wujiao Dai ◽  
Zhizhao Liu ◽  
Lixin Wu ◽  
Cuilin Kuang ◽  
...  
Keyword(s):  
Water Vapor ◽  
Weather Forecasting ◽  
Meteorological Data ◽  
Precipitable Water ◽  
Precipitable Water Vapor ◽  
Total Delay ◽  
Weighted Mean Temperature ◽  
Synoptic Observations ◽  
Gnss Network ◽  
Better Than

Abstract. Surface pressure (Ps) and weighted mean temperature (Tm) are two necessary variables for the accurate retrieval of precipitable water vapor (PWV) from Global Navigation Satellite System (GNSS) zenith total delay (ZTD) estimates. The lack of Ps or Tm information is a concern for those GNSS sites that are not collocated with meteorological sensors. This paper investigates an alternative method of inferring accurate Ps and Tm at the GNSS station using nearby synoptic observations. Ps and Tm obtained at the nearby synoptic sites are interpolated onto the location of the GNSS station by performing both vertical and horizontal adjustments, in which the parameters involved in Ps and Tm calculation are estimated from ERA-Interim reanalysis profiles. In addition, we present a method of constructing high-quality PWV maps through vertical reduction and horizontal interpolation of the retrieved GNSS PWVs. To evaluate the performances of the Ps and Tm retrieval, and the PWV map construction, GNSS data collected from 58 stations of the Hunan GNSS network and synoptic observations from 20 nearby sites in 2015 were processed to extract the PWV so as to subsequently generate the PWV maps. The retrieved Ps and Tm and constructed PWV maps were assessed by the results derived from radiosonde and the ERA-Interim reanalysis. The results show that (1) accuracies of Ps and Tm derived by synoptic interpolation are within the range of 1.7–3.0 hPa and 2.5–3.0 K, respectively, which are much better than the GPT2w model; (2) the constructed PWV maps have good agreements with radiosonde and ERA-Interim reanalysis data with the overall accuracy being better than 3 mm; and (3) PWV maps can well reveal the moisture advection, transportation and convergence during heavy rainfall.

scholarly journals Long-term efficacy of gliflozins versus gliptins for Type 2 Diabetes after metformin failure: a systematic review and network meta-analysis

2020 ◽  
Vol 66 (4) ◽  
pp. 458-465
Author(s):  
Renato Wilberto Zilli ◽  
Chennyfer Dobbins Abi Rached ◽  
Fabiano Pinheiro da Silva ◽  
Renato Corrêa Baena
Keyword(s):  
Systematic Review ◽  
Type 2 Diabetes ◽  
Missing Data ◽  
Meta Analysis ◽  
Cochrane Library ◽  
Term Efficacy ◽  
One Year ◽  
Better Than

SUMMARY After metformin failure in treatment for diabetes type 2, there is no trivial option for adjuvant medication. The last two oral class medications, gliflozins and gliptins, have different mechanisms of action but have never been compared in long run studies. The aim of the present meta-analysis is to assess the overall long-term efficacy of these drugs after metformin failure. A systematic review and meta-analysis were performed, including all trials with a duration of over 2 years, comparing gliflozins or gliptins after metformin failure in type 2 diabetes. Data Sources: Pubmed (Medline), Embase, Lilacs, and the Cochrane Library from inception through July 2016 without language restrictions. The longest study period found in the literature was 4 years. We selected 1 article on empagliflozin, 1 on dapagliflozin, and 1 on saxagliptin with missing data. After one year of treatment, over 50% of the patients presented HbA1c > 7%. Efficacy rate after 4 years of empagliflozin (23%) was better than dapagliflozin (5%) and saxagliptin (7%); however, it presented statistically non-significant values for HbA1c (7.4 and 7.3% between gliflozins), and missing data for saxaglifozin. Nonetheless, empagliflozin performed better than glimepiride in the 4-year period (standardized mean difference SMD 0.4, confidence interval CI 95% 0.23 to 0.56). The failure of the secondary treatment using gliflozins occurs in less than one year of treatment (less than 50% of the patients presenting HbA1c > 7 %). Empagliflozin offered better glycemic control compared to sulfonylureas but was similar to dapagliflozin.

scholarly journals The Stratospheric Water and Ozone Satellite Homogenized (SWOOSH) database: a long-term database for climate studies

2016 ◽  
Vol 8 (2) ◽  
pp. 461-490 ◽  
Author(s):  
Sean M. Davis ◽  
Karen H. Rosenlof ◽  
Birgit Hassler ◽  
Dale F. Hurst ◽  
William G. Read ◽  
...  
Keyword(s):  
Water Vapor ◽  
Future Studies ◽  
Source Data ◽  
Reference Satellite ◽  
Data Record ◽  
Reference Measurements ◽  
Climate Studies ◽  
Mean Time ◽  
Term Data

Abstract. In this paper, we describe the construction of the Stratospheric Water and Ozone Satellite Homogenized (SWOOSH) database, which includes vertically resolved ozone and water vapor data from a subset of the limb profiling satellite instruments operating since the 1980s. The primary SWOOSH products are zonal-mean monthly-mean time series of water vapor and ozone mixing ratio on pressure levels (12 levels per decade from 316 to 1 hPa). The SWOOSH pressure level products are provided on several independent zonal-mean grids (2.5, 5, and 10°), and additional products include two coarse 3-D griddings (30° long  ×  10° lat, 20°  ×  5°) as well as a zonal-mean isentropic product. SWOOSH includes both individual satellite source data as well as a merged data product. A key aspect of the merged product is that the source records are homogenized to account for inter-satellite biases and to minimize artificial jumps in the record. We describe the SWOOSH homogenization process, which involves adjusting the satellite data records to a “reference” satellite using coincident observations during time periods of instrument overlap. The reference satellite is chosen based on the best agreement with independent balloon-based sounding measurements, with the goal of producing a long-term data record that is both homogeneous (i.e., with minimal artificial jumps in time) and accurate (i.e., unbiased). This paper details the choice of reference measurements, homogenization, and gridding process involved in the construction of the combined SWOOSH product and also presents the ancillary information stored in SWOOSH that can be used in future studies of water vapor and ozone variability. Furthermore, a discussion of uncertainties in the combined SWOOSH record is presented, and examples of the SWOOSH record are provided to illustrate its use for studies of ozone and water vapor variability on interannual to decadal timescales. The version 2.5 SWOOSH data are publicly available at doi:10.7289/V5TD9VBX.

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