Stratospheric Temperature Climate Data Records from Satellite Observations

Due to sparseness of conventional measurements of temperature profiles over the middle and upper stratospheres, satellite observations play a key role in providing datasets critical for understanding the long-term climate changes over the regions of interest. In this regard, satellite temperature measurements from Microwave Sounding Unit (MSU), Stratospheric Sounding Unit (SSU), and Advanced Microwave Sounding Unit (AMSU) on board NOAA polar orbiting satellites comprise an indispensable climate data record (CDR) for stratospheric climate change investigations from 1978 to present. However, reprocessing and recalibration for consistencies between satellites must be conducted for the observations to be able to reliably detect long-term climate changes. Over the last few years, NOAA/Center for Satellite Applications and Research (STAR) has been reprocessing these instrument observations to develop well inter-calibrated and merged stratospheric layer temperature CDRs. The datasets being developed included merged MSU/AMSU lower-stratospheric temperature from 1978 to present, SSU layer temperature CDR from middle to upper stratospheres covering period from 1978 to 2006, and high resolution AMSU-only layer temperature CDRs from lower to upper stratospheres from 1998 to present. The datasets have global coverage with 2.5°×2.5° grid resolution that can be directly used for climate change studies. This talk will review the characteristics of these CDRs. We will discuss the challenges in reprocessing and our approaches to overcome the challenges in removing inter-satellite biases for consistent time series development. Trend differences often occur between different processing groups. We will compare the STAR SSU dataset with versions developed by other groups and discuss the underlying reasons for the trend differences. We will discuss the uncertainty and reliability of the datasets to establish confidence on the reprocessing and thus the long-term stratospheric temperature trends. Finally, newly reprocessed SSU observations are compared with chemistry-climate model simulations and consistencies/discrepancies between them are discussed.