ECS event #15

Our 15th symposium was Feb. 22, 2022

• Brett McKim (University of Exeter), “Radiator fins and the longwave clear-sky feedback”

• Osamu Miyawaki (University of Chicago), “Quantifying energy balance regimes in the modern climate, their link to lapse rate regimes, and their response to warming

• Florian Römer (University of Hamburg), “Spectrally resolved climate feedback parameter from infrared satellite observations”

• Han Huang (McGill University), “Nonlinear coupling between longwave radiative climate feedbacks”

• Yuan-Jen Lin (National Taiwan University), “The dominant contribution of southern ocean heat uptake to time-evolving radiative feedback in CESM”

09:18:21 From Ceppi, Paulo A : What’s the physical interpretation of R1 being outside the 0-1 range?

09:18:41 From Dessler, Andrew E : How do you actually calculate R1 from reanalysis?

09:19:46 From Ceppi, Paulo A : Makes perfect sense – thanks!

09:20:44 From Timothy Merlis, Dr. : Do the different latitude boundaries where RAE dominates in today’s climate succeed in accounting for CMIP LR feedback transitions to destablizing?

09:21:08 From Dessler, Andrew E : Would be interesting to see if a calculation of every term closes the budget

09:24:12 From Spencer Hill : R1 seems to me analogous to gross moist stability (GMS). Roughly, GMS = MSE import / mass flux or mass convergence and is useful non dimensional number (like R1, derived from energetic Eq.) for characterizing different things about convection. So I’m wondering if there’s a formal or empirical relationship between them.

09:24:30 From Spencer Hill : Caveat that there are many many flavors of GMS, beware… 🙂

09:26:04 From Spencer Hill : Sorry one last thing: gentle suggestion to find more descriptive name than “R1”, which I think will help w/ uptake in the community. Great work and excited to read the paper.

09:27:22 From Osamu Miyawaki : @Tim I haven't computed the lapse rate feedback in my analyses (I used the rcp85 simulation) but Fig. 13 might provide some insight into your question

09:28:00 From Osamu Miyawaki : The latitudinal extent where surface warming exceeds warming at sigma=0.3 is well captured by the extent of RAE in the SH high latitudes but has some issues in the NH

09:28:20 From Osamu Miyawaki : This might be due to zonal asymmetries in the NH

09:28:45 From Shiv Priyam Raghuraman : Do these nonlinear feedbacks cancel spatially and temporally, yielding kernels as a reasonable technique for global averages?

09:32:33 From Osamu Miyawaki : @Spencer Thanks for the suggestion! In many ways I believe GMS is a more skillful/useful metric for understanding convection/precipitation in the tropics. I didn't go into detail here but R1 has the issue that the subtropics are diagnosed as "RCE" even though that isn't a region of active convection

09:33:52 From Osamu Miyawaki : I think the strength of R1 is that it can be used to identify the RCE/RAE regimes in a unified framework

09:36:11 From Dessler, Andrew E : Very nice, Florian. Would be interesting to compare these results to model results

09:36:30 From Chris Holloway : How confident are we in those ERA5 changes in RH with warming, and do we think they will apply for long-term climate change?

09:42:22 From sergio : Hi, I work with looking at almost 20 years of AIRS infrared data. Right now it’s little hard to see how observational RH is changing wihth time. Looking at ERA5 trends, their RH seems constant in time

09:42:41 From han huang : @Shiv, Yes, they do cancel out each other (spatially and temporally, and also between different nonlinear components). For the global mean value, it might be fine (Table 3 in the paper) but will lead to larger biases locally.

09:43:25 From Shiv Priyam Raghuraman : @Han, thanks!

09:46:15 From Florian Roemer : @Sergio: The profile I showed referred to the monthly deviations from the mean annual cycle. If the trends in ERA5 are constant, this might give some indications that this is a point of difference between short-term variations and long-term trends

09:48:13 From Gavin Schmidt : Changes in SO heat uptake might have similar impacts as anomalous freshwater forcing…?

09:48:58 From Gavin Schmidt : Yes!

09:50:25 From Gavin Schmidt : thanks

09:51:53 From Cristian Proistosescu : @Yuan-jen: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GL074372

09:52:06 From Andrew Williams : @florian, in my mind it would be interesting to compare the observation-based all sky spectral feedback to something from models (even just looking at the spectral RRTMG outputs), but do you think this would be a fair comparison? You mention IASI's sampling issues, do you think that would make this comparison difficult?

09:52:17 From Andrew Williams : also very nice work!

09:52:18 From Yue Dong : Hi Yuan-Jen: Following up on Cristi’s question, if the Southern Ocean OHU changes radiative feedbacks mostly through surface temperature changes, what are the mechanisms do you think for which the Southern Ocean OHU changes the tropical EP SSTs?

09:54:05 From Cristian Proistosescu : In that paper Alex looks at the impact of OHU on feedbacks in a slab ocean model with Q fluxes. Than takes the SST patterns from that simulation and prescribes them in an atmosphere-only simulation, and gets the ~same feedbacks. So as long as the SST pattern is the same it seems the cause of the SST patterns might not matter as much (?)

09:55:41 From Yuan-Jen Lin : In our work, we calculated indices from Dong et al (2019), which implies the importance of SST pattern.

09:55:45 From Timothy Merlis, Dr. : @ Cristi, if there’s a unique relationship between energy fluxes (e.g., OHU) and SST, that should be the case. The mapping may be non-trivial

09:55:49 From Yue Dong : Thanks!