{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T03:50:41Z","timestamp":1760241041001,"version":"build-2065373602"},"reference-count":26,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2019,11,26]],"date-time":"2019-11-26T00:00:00Z","timestamp":1574726400000},"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>Absolute calibration of radiometers is usually implemented onboard using one hot and one cold external calibration targets. However, two-point calibration methods are unable to differentiate calibration drifts and associated errors from fluctuations in receiver gain and offset. Furthermore, they are inadequate to characterize temporal calibration stability of radiometers. In this paper, a preliminary study with linear radiometer systems has been presented to show that onboard external three-point calibration offers the means to quantify calibration drifts in the radiometer systems, and characterize associated errors as well as temporal stability in Earth and space measurements. Radiometers with three external calibration reference targets operating two data processing paths: i.e., (1) measurement path and (2) calibration validation path have been introduced. In the calibration validation data processing path, measurements of one known calibration target is calibrated using the other two calibration references, and temporal calibration stability and possible calibration temperature drifts are analyzed. In the measurement data processing path, the impact of the calibration drifts on Earth and space measurements is quantified and bounded by an upper limit. This two-path analysis is performed through calibration error analysis (CEA) diagrams introduced in this paper.<\/jats:p>","DOI":"10.3390\/rs11232790","type":"journal-article","created":{"date-parts":[[2019,11,26]],"date-time":"2019-11-26T10:57:27Z","timestamp":1574765847000},"page":"2790","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["A Preliminary Study of Three-Point Onboard External Calibration for Tracking Radiometric Stability and Accuracy"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5452-1862","authenticated-orcid":false,"given":"Mustafa","family":"Aksoy","sequence":"first","affiliation":[{"name":"Department of Electrical and Computer Engineering, University at Albany\u2013State University of New York, Albany, NY 12222, USA"}]},{"given":"Paul E.","family":"Racette","sequence":"additional","affiliation":[{"name":"NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA"}]}],"member":"1968","published-online":{"date-parts":[[2019,11,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1303","DOI":"10.1175\/BAMS-86-9-1303","article-title":"Satellite Instrument Calibration for Measuring Global Climate Change. Report of a Workshop","volume":"86","author":"Ohring","year":"2005","journal-title":"Bull. Am. Meteorol. Soc."},{"key":"ref_2","first-page":"125","article-title":"Workshop on strategies for calibration and validation of global change measurements","volume":"1397","author":"Guenther","year":"1997","journal-title":"NASA Ref. Publ."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1109\/36.823900","article-title":"Detection of calibration drifts in spaceborne microwave radiometers using a vicarious cold reference","volume":"38","author":"Ruf","year":"2000","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"3452","DOI":"10.1109\/JSTARS.2015.2403303","article-title":"The global precipitation measurement (GPM) microwave imager (GMI): Instrument overview and early on-orbit performance","volume":"8","author":"Draper","year":"2015","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"100","DOI":"10.1109\/JOE.1980.1145458","article-title":"The Seasat scanning microwave radiometer (SMMR): Instrument description and performance","volume":"5","author":"Njoku","year":"1980","journal-title":"IEEE J. Oceanic Eng."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"781","DOI":"10.1109\/36.58964","article-title":"SSM\/I instrument evaluation","volume":"28","author":"Hollinger","year":"1990","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"125","DOI":"10.1109\/36.368215","article-title":"TOPEX\/POSEIDON microwave radiometer (TMR)\u2014I: Instrument description and antenna temperature calibration","volume":"33","author":"Ruf","year":"1995","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_8","unstructured":"Wilson, W.J., Tanner, A.B., Pellerano, F.A., and Horgan, K.A. (2005). Ultra Stable Microwave Radiometers for Future Sea Surface Salinity Missions."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1029\/2004RS003132","article-title":"Radiometer design analysis based upon measurement uncertainty","volume":"40","author":"Racette","year":"2005","journal-title":"Radio Sci."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"4239","DOI":"10.1109\/JSTARS.2015.2406661","article-title":"Assessing calibration stability using the Global Precipitation Measurement (GPM) Microwave Imager (GMI) noise diodes","volume":"8","author":"Draper","year":"2015","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_11","unstructured":"Weissbrodt, E. (2017). Active Electronic loads for Radiometric Calibration. [Ph.D. Thesis, University of Stuttgart]."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"344","DOI":"10.1109\/TGRS.2014.2322336","article-title":"Design and characterization of a Peltier-cold calibration target for a 110-GHz radiometer","volume":"53","author":"Fernandez","year":"2015","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_13","unstructured":"Jewell, P. (2003). Millimeter Wave Calibration, Single Dish Summer School, National Radio Astronomy Observatory."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1547","DOI":"10.1109\/TAP.2013.2242828","article-title":"Low mass calibration target for MM-wave remote sensing instruments","volume":"61","author":"Murk","year":"2013","journal-title":"IEEE Trans. Antennas Propag."},{"key":"ref_15","unstructured":"Houtz, D.A. (2017). NIST Microwave Blackbody: The Design, Testing, and Verification of a Conical Brightness Temperature Source. [Ph.D. Thesis, University of Colorado]."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Draper, N.R., and Smith, H. (1998). Applied Regression Analysis, John Wiley. [3rd ed.].","DOI":"10.1002\/9781118625590"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Aksoy, M., and Racette, P.E. (2018, January 27\u201330). Tracking Radiometer Calibration Stability Using Three-Point Onboard Calibration. Proceedings of the 2018 IEEE 15th Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment (MicroRad), Cambridge, MA, USA.","DOI":"10.1109\/MICRORAD.2018.8430710"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Aksoy, M., and Racette, P.E. (2017, January 23\u201328). Tracking calibration stability in climate monitoring microwave radiometers using onboard 3-point calibration. Proceedings of the 2017 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Fort Worth, TX, USA.","DOI":"10.1109\/IGARSS.2017.8127402"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Racette, P.E. (2010, January 25\u201330). Application of Ensemble Detection and Analysis to modeling uncertainty in non stationary processes. Proceedings of the 2010 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Honolulu, HI, USA.","DOI":"10.1109\/IGARSS.2010.5650690"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"610","DOI":"10.1175\/1520-0426(1996)013<0610:AAMWIR>2.0.CO;2","article-title":"An airborne millimeter-wave imaging radiometer for cloud, precipitation, and atmospheric water vapor studies","volume":"13","author":"Racette","year":"1996","journal-title":"J. Atmos. Oceanic Technol."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Racette, P.E. (2005). Radiometer Design Analysis Based on Measurement Uncertainty. [Ph.D. Thesis, George Washington University].","DOI":"10.1029\/2004RS003132"},{"key":"ref_22","unstructured":"Racette, P.E., Wang, J., Evans, P., Saunders, R., Gasiewski, A., and Jackson, D. (1995, January 10\u201314). A calibration experiment using the millimeter-wave imaging radiometer at the UK Meteorological Office calibration facility. Proceedings of the 1995 International Geoscience and Remote Sensing Symposium (IGARSS): Quantitative Remote Sensing for Science and Applications, Firenze, Italy."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"760","DOI":"10.1109\/22.375222","article-title":"The radiometric characterization of AMSU-B","volume":"43","author":"Saunders","year":"1995","journal-title":"IEEE Trans. Microw. Theory Tech."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1908","DOI":"10.1109\/TGRS.2006.888098","article-title":"On the Long-Term Stability of Microwave Radiometers Using Noise Diodes for Calibration","volume":"45","author":"Brown","year":"2007","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Draper, D.W., and Newell, D.A. (2010, January 1\u20134). Global Precipitation Measurement (GPM) Microwave Imager (GMI) calibration features and predicted performance. Proceedings of the 2010 IEEE 11th Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environement, Washington, DC, USA.","DOI":"10.1109\/MICRORAD.2010.5559555"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"2444","DOI":"10.1109\/36.964981","article-title":"NPOESS Aircraft Sounder Testbed-Microwave (NAST-M): Instrument description and initial flight result","volume":"39","author":"Blackwell","year":"2001","journal-title":"IEEE Trans. Geosci. Remote Sens."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/23\/2790\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T13:37:35Z","timestamp":1760189855000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/23\/2790"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,11,26]]},"references-count":26,"journal-issue":{"issue":"23","published-online":{"date-parts":[[2019,12]]}},"alternative-id":["rs11232790"],"URL":"https:\/\/doi.org\/10.3390\/rs11232790","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2019,11,26]]}}}