Abstract
AbstractOpportunistic constant target matching is a new method for satellite intercalibration. It solves a long‐standing issue with the traditional simultaneous nadir overpass (SNO) method, namely, that it typically provides only data points with cold brightness temperatures for humidity sounding instruments on sun‐synchronous satellites. In the new method, a geostationary infrared sensor (SEVIRI) is used to select constant target matches for two different microwave sensors (MHS on NOAA 18 and Metop A). We discuss the main assumptions and limitations of the method and explore its statistical properties with a simple Monte Carlo simulation. The method was tested in a simple case study with real observations for this combination of satellites for MHS Channel 3 at 183 ± 1 GHz, the upper tropospheric humidity channel. For the studied 3‐month test period, real observations are found to behave consistently with the simulations, increasing our confidence that the method can be a valuable tool for intercalibration efforts. For the selected case study, the new method confirms that the bias between NOAA 18 and Metop A MHS Channel 3 is very small, with absolute value below 0.05 K.
Highlights
Intercalibrating sensors on different satellites is one of the greatest challenges in observational climate science, since global and continuous data sets spanning decades can only be constructed from multiple satellites (e.g., Hans et al, 2019; Mears & Wentz, 2005; Ohring et al, 2005; Shi & Bates, 2011; Scott et al, 1999; Tabata et al, 2019; Zou & Wang, 2011, among many others)
Opportunistic constant target matching is a new method for satellite intercalibration
For the studied 3-month test period, real observations are found to behave consistently with the simulations, increasing our confidence that the method can be a valuable tool for intercalibration efforts
Summary
Intercalibrating sensors on different satellites is one of the greatest challenges in observational climate science, since global and continuous data sets spanning decades can only be constructed from multiple satellites (e.g., Hans et al, 2019; Mears & Wentz, 2005; Ohring et al, 2005; Shi & Bates, 2011; Scott et al, 1999; Tabata et al, 2019; Zou & Wang, 2011, among many others). The most established method, simultaneous nadir overpasses (SNOs), has several shortcomings, most importantly that it yields only cold (in terms of brightness temperature) calibration points for many important observation frequencies, whereas an optimal intercalibration requires warm calibration points, so that the full dynamical range of the involved sensors is covered. The new method does not require the two sensors to observe the same target at the same time. We opportunistically identify cases where the atmosphere has been stable between matches that can be several hours to days apart in time. Geostationary satellite imagery is used for identifying these cases. The new method has the potential to allow for the first time a precise intercalibration of any simultaneously operational sounding satellites, a problem for which hitherto no method without severe shortcomings existed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
