Update README.md

README.md

@@ -37,12 +37,13 @@ The strengths of ACE2S are:
 - stochastic (generative) emulator of 100km coarsened X-SHiELD 
 - improved small scale variability compared to deterministic ACE2 (especially surface precipitation)
 - exact conservation of global dry air mass and moisture
-- low time-mean biases for most variables 
+- low time-mean biases for most variables relative to the 10-year training data available
 - compatible with HiRO model with no observed degradation
 
 Some known weaknesses of ACE2S are:
 - trained only on 9 years of X-SHiELD (2014-2022)
-- not expected to generalize outside of the limited forcing conditions used during training (e.g., SSTs and CO2)
+- not expected to generalize outside of the limited forcing conditions used during training (e.g., past/future SSTs and CO2)
+- may not produce statistically independent and representative samples of the base X-SHiELD model when run for significantly longer than 9 years
 - not suitable for weather forecasting (e.g., not trained on reanalysis data only climate model output)
 - model was not tested as rigorously as ACE2-ERA5 (e.g., cannot comment on stratospheric variability, etc) 
 - overestimation of tropical cyclone generation compared to X-SHiELD