{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,8]],"date-time":"2026-01-08T09:48:37Z","timestamp":1767865717889,"version":"3.49.0"},"reference-count":31,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2021,1,6]],"date-time":"2021-01-06T00:00:00Z","timestamp":1609891200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Radiosondes are important for calibrating satellite sensors and assessing sounding retrievals. Vaisala RS41 radiosondes have mostly replaced RS92 in the Global Climate Observing System (GCOS) Reference Upper Air Network (GRUAN) and the conventional network. This study assesses RS41 and RS92 upper tropospheric humidity (UTH) accuracy by comparing with Infrared Atmospheric Sounding Interferometer (IASI) upper tropospheric water vapor absorption spectrum measurements. Using single RS41 and RS92 soundings at three GRUAN and DOE Atmospheric Radiation Measurement (ARM) sites and dual RS92\/RS41 launches at three additional GRUAN sites, collocated with cloud-free IASI radiances (OBS), we compute Line-by-Line Radiative Transfer Model radiances for radiosonde profiles (CAL). We analyze OBS-CAL differences from 2015 to 2020, for daytime, nighttime, and dusk\/dawn separately if data is available, for standard (STD) RS92 and RS41 processing, and RS92 GRUAN Data Processing (GDP; RS41 GDP is in development). We find that daytime RS41 (even without GDP) has ~1% smaller UTH errors than GDP RS92. RS41 may still have a dry bias of 1\u20131.5% for both daytime and nighttime, and a similar error for nighttime RS92 GDP, while standard RS92 may have a dry bias of 3\u20134%. These sonde humidity biases are probably upper limits since \u201ccloud-free\u201d scenes could still be cloud contaminated. Radiances computed from European Centre for Medium-Range Weather Forecasts (ECMWF) analyses match better than radiosondes with IASI measurements, perhaps because ECMWF assimilates IASI measurements. Relative differences between RS41 STD and RS92 GDP, or between radiosondes and ECMWF humidity profiles obtained from the radiance analysis, are consistent with their differences obtained directly from the RH measurements.<\/jats:p>","DOI":"10.3390\/rs13020173","type":"journal-article","created":{"date-parts":[[2021,1,6]],"date-time":"2021-01-06T20:45:42Z","timestamp":1609965942000},"page":"173","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["Accuracy of Vaisala RS41 and RS92 Upper Tropospheric Humidity Compared to Satellite Hyperspectral Infrared Measurements"],"prefix":"10.3390","volume":"13","author":[{"given":"Bomin","family":"Sun","sequence":"first","affiliation":[{"name":"IMSG at NOAA NESDIS Center for Satellite Applications and Research (STAR), College Park, MD 20740, USA"}]},{"given":"Xavier","family":"Calbet","sequence":"additional","affiliation":[{"name":"AMET, C\/Leonardo Prieto Castro, 8, Ciudad Universitaria, 28071 Madrid, Spain"}]},{"given":"Anthony","family":"Reale","sequence":"additional","affiliation":[{"name":"NOAA NESDIS Center for Satellite Applications and Research (STAR), College Park, MD 20740, USA"}]},{"given":"Steven","family":"Schroeder","sequence":"additional","affiliation":[{"name":"Department of Atmospheric Sciences, Texas A&amp;M University, College Station, TX 77843, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5818-4277","authenticated-orcid":false,"given":"Manik","family":"Bali","sequence":"additional","affiliation":[{"name":"Cooperative Institute for Satellite Earth System Studies, University of Maryland, College Park, MD 20740, USA"}]},{"given":"Ryan","family":"Smith","sequence":"additional","affiliation":[{"name":"IMSG at NOAA NESDIS Center for Satellite Applications and Research (STAR), College Park, MD 20740, USA"}]},{"given":"Michael","family":"Pettey","sequence":"additional","affiliation":[{"name":"IMSG at NOAA NESDIS Center for Satellite Applications and Research (STAR), College Park, MD 20740, USA"}]}],"member":"1968","published-online":{"date-parts":[[2021,1,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1175\/BAMS-D-14-00072.1","article-title":"Reference upper-air observations for climate: From concept to reality","volume":"97","author":"Bodeker","year":"2016","journal-title":"Bull. Am. Meteorol. Soc."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1175\/1520-0426(2001)018<0135:CACORH>2.0.CO;2","article-title":"Characterization and correction of relative humidity measurements from Vaisala RS80-A radiosondes at cold temperatures","volume":"18","author":"Miloshevich","year":"2001","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1305","DOI":"10.1175\/1520-0426(2004)021<1305:DAVOAT>2.0.CO;2","article-title":"Development and validation of a time-lag correction for Vaisala radiosonde humidity measurements","volume":"21","author":"Miloshevich","year":"2004","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_4","first-page":"D09D10","article-title":"Absolute accuracy of water vapor measurements from six operational radiosonde types launched during AWEX-G and implications for AIRS validation","volume":"111","author":"Miloshevich","year":"2006","journal-title":"J. Geophys. Res."},{"key":"ref_5","first-page":"D11305","article-title":"Accuracy assessment and correction of Vaisala RS92 radiosonde water vapor measurements","volume":"114","author":"Miloshevich","year":"2009","journal-title":"J. Geophys. Res."},{"key":"ref_6","unstructured":"Nash, J., Oakley, T., V\u00f6mel, H., and Wei, L. (2021, January 04). WMO Intercomparison of High-Quality Radiosonde Systems, Yangjiang, China, 12 July\u20133 August 2010. Available online: https:\/\/www.wmo.int\/pages\/prog\/www\/IMOP\/publications\/IOM-107_Yangjiang.pdf."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"953","DOI":"10.1175\/JTECH2019.1","article-title":"Radiation dry bias of the Vaisala RS92 humidity sensor","volume":"24","author":"Selkirk","year":"2007","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1235","DOI":"10.1175\/1520-0442(1996)009<1235:AAOSAR>2.0.CO;2","article-title":"An assessment of satellite and radiosonde climatologies of upper-tropospheric water vapor","volume":"9","author":"Soden","year":"1996","journal-title":"J. Clim."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"248","DOI":"10.1175\/JTECH-D-11-00080.1","article-title":"On the importance of Vaisala RS92 radiosonde humidity corrections for a better agreement between measured and modeled satellite radiances","volume":"29","author":"Kottayil","year":"2012","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1177","DOI":"10.5194\/amt-4-1177-2011","article-title":"Matching radiative transfer models and radiosonde data from the EPS\/Metop Sodankyl\u00e4 campaign to IASI measurements","volume":"4","author":"Calbet","year":"2011","journal-title":"Atmos. Meas. Tech."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"3615","DOI":"10.1109\/TGRS.2012.2220551","article-title":"Evaluating instrumental inhomogeneities in global radiosonde upper tropospheric humidity data using microwave satellite data","volume":"51","author":"Moradi","year":"2013","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"8040","DOI":"10.1002\/jgrd.50589","article-title":"Assessing the quality of humidity measurements from global operational radiosonde sensors","volume":"118","author":"Moradi","year":"2013","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2323","DOI":"10.5194\/amt-10-2323-2017","article-title":"Consistency between GRUAN sondes, LBLRTM and IASI","volume":"10","author":"Calbet","year":"2017","journal-title":"Atmos. Meas. Tech."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1016\/j.jqsrt.2017.10.022","article-title":"PCA determination of the radiometric noise of high spectral resolution infrared observations from spectral residuals: Application to IASI","volume":"206","author":"Serio","year":"2018","journal-title":"J. Quant. Spectrosc. Radiat. Transf."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"233","DOI":"10.1016\/j.jqsrt.2004.05.058","article-title":"Atmospheric radiative transfer modeling: A summary of the AER codes","volume":"91","author":"Clough","year":"2005","journal-title":"J. Quant. Spectrosc. Radiat. Transf."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"4463","DOI":"10.5194\/amt-7-4463-2014","article-title":"Reference quality upper-air measurements, GRUAN data processing for the Vaisala RS92 radiosonde","volume":"7","author":"Dirksen","year":"2014","journal-title":"Atmos. Meas. Tech."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"629","DOI":"10.1175\/JTECH-D-11-00072.1","article-title":"The NOAA Products Validation System (NPROVS)","volume":"29","author":"Reale","year":"2012","journal-title":"J. Atmos. Ocean. Tech."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1109\/JSTARS.2017.2764751","article-title":"Assessment of NUCAPS S-NPP CrIS\/ATMS sounding products using reference and conventional radiosonde observations","volume":"10","author":"Sun","year":"2017","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"180","DOI":"10.1109\/TGRS.2017.2744558","article-title":"Validation of atmospheric profile retrievals from the SNPP NOAA-Unique Combined Atmospheric Processing System. Part I: Temperature and moisture","volume":"56","author":"Nalli","year":"2018","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"13628","DOI":"10.1002\/2013JD020436","article-title":"Validation of satellite sounder environmental data records: Application to the Cross-track Infrared Microwave Sounder Suite","volume":"118","author":"Nalli","year":"2013","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1340","DOI":"10.1016\/j.jqsrt.2012.02.028","article-title":"IASI on Metop-A: Operational level 2 retrievals after five years in orbit","volume":"113","author":"August","year":"2012","journal-title":"J. Quant. Spectrosc. Radiat. Transf."},{"key":"ref_22","unstructured":"Sun, B., Reale, A., Pettey, M., Smith, R., Nalli, N.R., and Zhou, L. (2017, January 2\u20136). Leveraging the strength of dedicated, GRUAN and conventional radiosondes for EUMETSAT IASI atmospheric sounding assessment. Proceedings of the 2017 EUMETSAT Meteorological Satellite Conference, Rome, Italy."},{"key":"ref_23","unstructured":"ECMWF (2018, December 21). IFS Documentation CY45r1, Available online: https:\/\/www.ecmwf.int\/en\/publications\/ifs-documentation."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Eresmaa, R., and McNally, A.P. (2018, December 21). Diverse Profile Datasets from the ECMWF 137-Level Short-Range Forecasts. Available online: https:\/\/nwpsaf.eu\/oldsite\/reports\/nwpsaf-ec-tr-017.pdf.","DOI":"10.1016\/j.jasrep.2018.06.023"},{"key":"ref_25","first-page":"500","article-title":"Formulations for the thermodynamic properties of the saturated phases of H2O from 173.15 K to 473.15 K","volume":"89","author":"Hyland","year":"1983","journal-title":"ASHRAE Trans."},{"key":"ref_26","first-page":"D09S14","article-title":"Atmospheric radiation measurement site atmospheric state best estimates for atmospheric infrared sounder temperature and water vapor retrieval validation","volume":"111","author":"Tobin","year":"2006","journal-title":"J. Geophys. Res."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1217","DOI":"10.5194\/amt-3-1217-2010","article-title":"Reference Quality Upper Air Measurements: Guidance for developing GRUAN data products","volume":"3","author":"Immler","year":"2010","journal-title":"Atmos. Meas. Tech."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"635","DOI":"10.1175\/JTECH-D-18-0081.1","article-title":"On the accuracy of Vaisala RS41 versus RS92 upper-air temperature observations","volume":"36","author":"Sun","year":"2019","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_29","first-page":"D07102","article-title":"Global radiosonde balloon drift statistics","volume":"116","author":"Seidel","year":"2011","journal-title":"J. Geophys. Res."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Sun, B., Reale, A., Seidel, D.J., and Hunt, D.C. (2010). Comparing radiosonde and COSMIC atmospheric profile data to quantify differences among radiosonde types and the effects of imperfect collocations on comparison statistics. J. Geophys. Res., 115.","DOI":"10.1029\/2010JD014457"},{"key":"ref_31","unstructured":"(2015, March 09). EUMETSAT 2014: IASI Level 2: Product Format Specification. Available online: https:\/\/www.eumetsat.int."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/13\/2\/173\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T05:07:47Z","timestamp":1760159267000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/13\/2\/173"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,1,6]]},"references-count":31,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2021,1]]}},"alternative-id":["rs13020173"],"URL":"https:\/\/doi.org\/10.3390\/rs13020173","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,1,6]]}}}