Abstract
Abstract. A method is proposed for merging different nadir-sounding climate data records using measurements from high-resolution limb sounders to provide a transfer function between the different nadir measurements. The two nadir-sounding records need not be overlapping so long as the limb-sounding record bridges between them. The method is applied to global-mean stratospheric temperatures from the NOAA Climate Data Records based on the Stratospheric Sounding Unit (SSU) and the Advanced Microwave Sounding Unit-A (AMSU), extending the SSU record forward in time to yield a continuous data set from 1979 to present, and providing a simple framework for extending the SSU record into the future using AMSU. SSU and AMSU are bridged using temperature measurements from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), which is of high enough vertical resolution to accurately represent the weighting functions of both SSU and AMSU. For this application, a purely statistical approach is not viable since the different nadir channels are not sufficiently linearly independent, statistically speaking. The near-global-mean linear temperature trends for extended SSU for 1980–2012 are −0.63 ± 0.13, −0.71 ± 0.15 and −0.80 ± 0.17 K decade−1 (95 % confidence) for channels 1, 2 and 3, respectively. The extended SSU temperature changes are in good agreement with those from the Microwave Limb Sounder (MLS) on the Aura satellite, with both exhibiting a cooling trend of ~ 0.6 ± 0.3 K decade−1 in the upper stratosphere from 2004 to 2012. The extended SSU record is found to be in agreement with high-top coupled atmosphere–ocean models over the 1980–2012 period, including the continued cooling over the first decade of the 21st century.
Highlights
Stratospheric cooling has long been regarded as a key indicator of two anthropogenic climate forcings (IPCC 2013; WMO, 2014): that from increasing abundances of CO2, and that from the ozone decline associated with the increased abundances of ozone-depleting substances (ODSs)
The CMAM30 data set, which extends from 1979 to 2011, is produced using a specified-dynamics version of the Canadian Middle Atmosphere Model (CMAM) that is driven by winds and temperatures from the interim version of the European Centre for Medium-Range Weather Forecasts Reanalysis (ERA Interim; Dee et al, 2011), where the global-mean temperatures have been adjusted in the upper stratosphere to remove temporal discontinuities in 1985 and 1998 that have arisen from the introduction of new satellite data in the assimilation process (McLandress et al, 2014)
The first part (Sect. 3.1) pertains to the merging of the Stratospheric Sounding Unit (SSU) and AMSU data sets. Since this is achieved using Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) data as a transfer function, we begin by demonstrating that MIPAS is in good agreement with SSU and AMSU
Summary
Stratospheric cooling has long been regarded as a key indicator of two anthropogenic climate forcings (IPCC 2013; WMO, 2014): that from increasing abundances of CO2, and that from the ozone decline associated with the increased abundances of ozone-depleting substances (ODSs). We propose a method for merging different nadir-sounding climate data records, and apply it to the NOAA SSU and AMSU global-mean stratospheric temperature records. We propose a physically based method using limbsounding measurements, with much higher vertical resolution, to accurately represent the weighting functions of both SSU and AMSU and thereby act as a transfer function between the two nadir-sounding data sets. For this purpose we use temperature data from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). The temperature retrieval method and validation are discussed in Schwartz et al (2008)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
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 call
