Attributing Excessive Upper-Tropospheric Warm Biases in CMIP6 Models over Tropical Oceans to Missing Physical Processes: Evidence from Satellite Observations

A. Reference temperature Datasets: ta_mon_Aura-MLS-v04-2_BE_gn_200408-201012.nc The Microwave Limb Sounder (MLS) is an instrument aboard NASA’s Aura satellite, launched in 2004 as part of the Earth Observing System (EOS) program. MLS measures atmospheric temperature, pressure, and various trace gases, primarily in the upper troposphere, stratosphere, and mesosphere, using microwave limb sounding techniques (Waters et al., 2006). Operating in the microwave spectrum, MLS observes thermal emission from the atmospheric limb to derive temperature profiles with coarse vertical resolution but global coverage. We use the Version 3.3 Level 2 data (MLS 2004 v03.3) spanning 2005–2010 at 300 hPa. These data are particularly useful for evaluating upper-tropospheric temperature structure in models. Quality control and data documentation are available at http://mls.jpl.nasa.gov/data/v3-3_data_quality_document.pdf. ta_mon_GNSS-RO-1-3_BE_gn_200201-201412.nc GNSS Radio Occultation (RO) is a satellite-based remote sensing technique that uses signals from Global Navigation Satellite System (GNSS) satellites to derive high-vertical-resolution profiles of atmospheric refractivity, from which temperature, pressure, and humidity can be inferred. RO offers excellent vertical resolution (~100 m in the upper troposphere and lower stratosphere) and is less affected by calibration drift or satellite-to-satellite biases, making it ideal for long-term climate monitoring. ta_mon_AIRS-2-1_BE_gn_200209-201609-mb.nc AIRS Obs4MIPs Version 2.1 dataset (Tian & Hearty, 2020), which provides monthly mean tropospheric air temperature profiles from September 2002 to September 2016. This version includes corrections for sampling biases, improving consistency with reanalysis products. B. NCAR-DOE CESM2-CAM6 sensitivity experiments The National Center for Atmospheric Research – Department of Energy (NCAR-DOE) Community Earth System Model version 2 (CESM2) is a fully coupled climate model developed to simulate the Earth's climate system. CESM2, which incorporates the CAM6 atmospheric component, participated in CMIP6 and features an updated two-moment stratiform cloud microphysics scheme (MG2; Gettelman & Morrison, 2015). Sensitivity simulations were performed with falling ice radiative effects turned off (CESM2-NOS) and on (CESM2-SON). Both experiments were initialized from the CMIP6 preindustrial control (PiControl) run and followed the "historical" protocol from 1850 to 2014, using consistent model components, initial conditions, and prescribed external forcings (e.g., greenhouse gases, ozone, aerosols, and solar variability). The analysis in this study focuses on the 1980–2014 period. f09.CAM6.B-hist.NOS.T.plev.1980-2014-CDO_1x1.n With falling ice radiative effects turned off (CESM2-NOS) f09.CAM6.B-hist.SON.T.plev.1980-2014-CDO_1x1.nc With falling ice radiative effects turned off (CESM2-NOS)