CESM2 (WACCM6): Stratospheric Evaluation

Transcription

1 CESM2 (WACCM6): Stratospheric Evaluation D. Kinnison, M. Mills, R. Garcia, D. Marsh, A. Gettelman, F. Vitt, S. Glanville, C. Bardeen, S. Tilmes, A. Smith, J-F. Lamarque, L. Emmons, A. Conley, J. Richter, J. Bacmeister, Fei Wu, and William Randel (NCAR) Whole Atmosphere Working Group, Boulder, 13 February 2018

2 Evaluation of CESM2 (first cut) Chemistry Climate Model Initiative (CCMI): Status Examine Total Column Ozone (TCO) 2011: vs OMI, SBUV Examine T, HCl, ClO, HNO 3, and O 3 : vs Aura MLS Examine SH Temperature and NH SSWs: vs MERRA Compare AOA: CESM1 vs CESM2 Examine H 2 O Tape Recorder: vs Aura MLS Examine Temperature Trends: vs SSU and MSU Model Versions: CESM1 (WACCM-CCMI), tag34 version (released to community) CESM2 (WACCM), F-case and SD, #262a

3 CESM1-WACCM4 CCMI Simulations (~45 publications; 10 in review) Scenario Period Ocean RCP Members REF-C Data - 5 REFC1-fODS Data - 5 REF-C1-PI Data - 1 REF-C1SD / MERRA Data - 1 REF-C Interactive RCP6.0 3 SEN-C Interactive RCP4.5 1 SEN-C Interactive RCP8.5 3 SEN-C2-fGHG Interactive RCP6.0 3 SEN-C2-fODS Interactive RCP6.0 3 SEN-C2-fODS Interactive RCP6.0 3 SEN-C2-nVSL Interactive RCP6.0 1 SEN-C2-fEmis Interactive RCP6.0 1 SEN-C2-fCO Interactive RCP6.0 1 SEN-C2-fN2O Interactive RCP6.0 1 SEN-C2-fCH Interactive RCP6.0 1 SEN-C2-CH4RCP Interactive Mixed 1

4 Column Physics Chemistry CCMI vs CESM2 Chemistry (Major Changes!) CESM1 (WACCM4) CCMI CESM2 (WACCM6) Horizontal Resolution 1.9 x x1.25 Vertical Layers 26/66/88 32/70/88 Boundary Layer HB CLUBB Shallow Convection Hack CLUBB Deep Convection ZM ZM Macrophysics R&K CLUBB Microphysics R&K MG 2.0 Radiation CAMRT RRTMG Aerosols Bulk MAM4 QBO Nudged to Observations Interactive (70L) Chemical Mechanism 180 species 228 Species, with SOAs Chemical rates JPL-11 JPL-15 Sulfate SAD Prescribed (CCMI) Interactive (MAM) ICE SAD Bulk Scheme MG 2.0 Solar Variability Lean ETF (SPEs) CMIP6 ETF (SPEs, MEEs) GHG abundances Meinshausen, 2011 (RCPs) Meinshausen, 2016 (SSP) Halogens WMO, 2010 Meinshausen, 2016; Future?

5 First we will Examine the representation of: Total Column Ozone (TCO); Polar de-nitrification (de-no Y ); Polar dehydration (de-h 2 O); Heterogeneous chlorine activation (ClOx); Local Polar ozone depletion. Polar decent (using N 2 O); The model results will be from the SD CESM2 (WACCM) / MERRA #262 simulation.

6 Latitude, degree Latitude, degree CCMI (2011) - 2deg CESM2 (2011) - 1deg Aura OMI (2011) DU Total Column Ozone (TCO), SD configuration Comments: Overall, both model versions compare well to TOZ observations for year Studied this year in the Solomon et al., JGR, 2015 paper (CCMI version). Latitude, degree Day-of-Year CESM2 simulation completed by M. Mills, NCAR.

7 Latitude, degree Latitude, degree CCMI (2011) - 2deg CESM2 (2011) - 1deg Aura OMI (2011) DU Total Column Ozone (TCO), SD configuration Comments: Overall, both model versions compare well to TOZ observations for year Tropics: CESM2 is more consistent with OMI. There is larger regions of low (260DU) TOZ. (Black circles) Polar NH (60N) Spring maximum: CESM2 is more consistent with OMI. (Green Box) Polar SH (60S) Spring maximum: CESM2 is more consistent with OMI. (Blue circle) Latitude, degree Day-of-Year Polar SH (>70S) Winter: CESM2 has less TCO (~10DU) than CCMI? A region where OMI doesn t observe. (red arrows)

8 Pressure, hpa Pressure, hpa Aura MLS Aura MLS Day-of-Year Aura MLS binned up by Chuck Bardeen, NCAR Temperature (K) H 2 O (ppmv) CESM2 (WACCM) CESM2 (WACCM) Day-of-Year 81S, 2011 SD Configuration Model over dehydrates by ~0.4ppmv

9 Pressure, hpa Pressure, hpa Aura MLS Aura MLS Day-of-Year Temperature (K) HNO 3 (g) (ppbv) CESM2 (WACCM) CESM2 (WACCM) Day-of-Year 81S, 2011 SD Configuration The de-noy is underestimated by ~0.5ppbv. This comparison can be improved by changing the #part. cm -3 from 0.01 to

10 Pressure, hpa Pressure, hpa Aura MLS Aura MLS Day-of-Year Temperature (K) HCl (g) (ppbv) CESM2 (WACCM) CESM2 (WACCM) Day-of-Year 81S, 2011 SD Configuration All CCMs tend to underestimate HCl depletion in winter. However by spring, HCl => ClOx and good ozone depletion is derived

11 Pressure, hpa Pressure, hpa Aura MLS Aura MLS Day-of-Year Temperature (K) ClO (ppbv) CESM2 (WACCM) CESM2 (WACCM) Day-of-Year 81S, 2011 SD Configuration The model does an excellent job of het. activation of LS ClO in Spring. The US gas-phase chemistry is also well represented

12 Pressure, hpa Pressure, hpa Aura MLS Aura MLS Day-of-Year Temperature (K) O 3 (ppmv) CESM2 (WACCM) CESM2 (WACCM) Day-of-Year 81S, 2011 SD Configuration In Winter, the model underestimates O 3 consistent with the low TCO. In Spring, O 3 is well represented, within 0.3ppmv of obs

13 Pressure, hpa Pressure, hpa Aura MLS Aura MLS Day-of-Year Temperature (K) N 2 O (ppmv) CESM2 (WACCM) CESM2 (WACCM) Day-of-Year 81S, 2011 SD Configuration The decent rate of N 2 O in SH Polar Winter / Spring is well represented by the nudging of CESM2 to MERRA

14 Next we will Examine the representation of: SH Polar temperature biases and NH SSWs; Representation of the TCO; Tropical H 2 O tape recorder; Stratosphere mean AOA; Global temperature trends. The model results will be from the Fcase #262a simulation ( ) and the previously discussed SD CESM2 (WACCM) / MERRA #262 simulation.

15 CESM2: Temperature Bias Reduced in the SH Polar Region (90S-60S) 262a FR Configuration, CESM2, #262 MERRA WACCM results within ± 1 degrees in Sept. and October. 262a-MERRA 262a-MERRA Figures Courtesy of R. Garcia, NCAR CESM2 includes a new Ridge scheme that excites Orographic GW (Julio Bacmeister, NCAR).

16 Northern Hemisphere Sudden Stratospheric Warming (SSWs) FR Configuration, CESM2, #262 SSW definition: zonal wind reversal at 10hPa, 60 N. Promising agreement between MERRA and CESM2 Fcase. Possibly too few events in February; however, more realizations are needed to properly characterize this diagnostic. Figure Courtesy of R. Garcia, NCAR

17 CESM1 (WACCM-CCMI) *** Southern Hemisphere 400 TCO [63S-90S] - October Observations CESM1 (WA-Fcase), CCMI (5) 350 Total Column Ozone (DU) Dashed line is ~1980 TOZ Blue line is ensemble mean Symbols are individual realizations Year Similar variability between CESM1 (WACCM) and the observations post 1990.

18 CESM2-SD *** Southern Hemisphere TCO [63S-90S] - October Observations CESM1 (WA-Fcase), CCMI (5) CESM2 (WA-SD), #262 Total Column Ozone (DU) Dashed line is ~1980 TOZ Blue line is ensemble mean Symbols are individual realizations Year For the period, CESM2 (WACCM-SD) compares well with observations.

19 CESM2 vs CCMI *** Southern Hemisphere TCO [63S-90S] - October Observations CESM1 (WA-Fcase), CCMI (5) CESM2 (WA-SD), #262 CESM2 (WA-Fcase), #262a Total Column Ozone (DU) Dashed line is ~1980 TOZ Blue line is ensemble mean Symbols are individual realizations Year We do need to examine the pre-1975 period to make sure we are not biased during low Chlorine period.

20 CESM2 vs CCMI *** Northern Hemisphere Observations CESM1 (WA-Fcase), CCMI (5) CESM2 (WA-SD), #262 TCO [63N-90N] - March Total Column Ozone (DU) Dashed line is ~1980 TOZ Blue line is ensemble mean Symbols are individual realizations Year Extreme depletion events in the observations for several years during the 1990s and year 2011.

21 CESM2 vs CCMI *** Northern Hemisphere TCO [63N-90N] - March Observations CESM2 (WA-Fcase), #262a CESM1 (WA-Fcase), CCMI (5) CESM2 (WA-SD), #262 Total Column Ozone (DU) Dashed line is ~1980 TOZ Blue line is ensemble mean Symbols are individual realizations Year The pre-1980 period is in good agreement. The higher chlorine loading period has a few extreme depletion years.

22 CESM2 at Halley (75.35ºS, 26.39ºW) Total Column Ozone (DU) Halley Obs September October CESM1 Fcase (3) CESM2 SD CESM2 Fcase November Total Column Ozone (DU) Halley Obs December Year January Year February Year The CESM2 (WACCM) better represents both December and January TCO compared to CESM1 (WACCM-CCMI).

23 Polar Temperature (K), 78ºS, zm Aura MLS, V4 Conclusions: CESM2 (WACCM) overall is in good agreement in both magnitude and seasonality with observations. CESM2 (WACCM) - Fcase There does seem to be an enhanced warm peak in the model near hpa that is not seen in the observations?

24 Polar H 2 O (ppmv), 78ºS, zm Aura MLS, V4 Conclusions: CESM2 (WACCM) vertical Structure is consistent with observations. CESM2 (WACCM) - Fcase The model is biased ~0.4 ppmv low in the upper stratosphere. The model minimum H 2 O in the lower stratosphere vortex is consistent with observations.

25 Polar ClO (ppbv), 78ºS, zm Aura MLS, V4 Conclusions: CESM2 (WACCM) vertical Structure is consistent with observations. CESM2 (WACCM) - Fcase Model is biased ~0.05 pptv low in the Upper Stratosphere. Model LS vortex ClO is in good agreement with observations. Aura MLS does show minimum values of 0.05 pptv that is not derived by the model.

26 Polar O 3 (ppmv), 78ºS, zm Aura MLS, V4 Conclusions: Overall, CESM2 (WACCM) shows good seasonality compared to observations. CESM2 (WACCM) - Fcase The model underestimates the minimum ozone in the LS, Spring, by ~0.3 ppmv (similar to SD). The peak ozone between 5-10 hpa is underestimated by the model by ~0.5ppmv?

27 H 2 O Tape Recorder *** 10ºS-10ºN *** Very good representation of the cold phase of the TR. White lines are Aura-MLS, v4 observations WACCM-SD (MERRA) has ~0.5ppmv more entry level H 2 O. SD and FR have ~0.5ppmv more H 2 O during the wet phase of the TR Figure Courtesy of Sasha Glanville, NCAR.

28 Mean AOA 5.0 Annual Mean AOA *** 1hPa *** 23S-23N CESM1 (WACCM-CCMI) Fcase (3) CESM2 (WACCM), Fcase, #262a 4.5 Mean Age (years) Blue line is ensemble mean Years Comment: The mean AOA is ~ 0.5 years older in CESM2 (WACCM) vs CESM1 (WACCM-CCMI). The trend in AOA between the two model versions is similar over the hindcast period.

29 0.001 Annual Mean AOA *** 23S-23N Mean AOA Climatologies Pressure, hpa CESM1 (WACCM-CCMI) Fcase CESM2 (WACCM), Fcase, #262a Comment: Both the tropical average and global average mean AOA profiles are similar. Pressure, hpa year Climatology (years: ) Mean Age (years) Annual Mean AOA *** 90S-90N CESM1 (WACCM-CCMI) Fcase CESM2 (WACCM), Fcase, #262a The mean AOA is profile is similar between the two model version up to ~20hPa. More work is needed to understand why the mean AOA has increased in CESM2 (WACCM). Rolando Garcia will be doing a detailed TEM analysis of both model versions ASAP year Climatology (years: ) Mean Age (years)

30 Temperature Trend *** CESM1 (WACCM-CCMI) The CESM1 (WACCM-CCMI) Fcase compares well to observations. Here 5- realizations are show. This simulation used CCMI aerosol loading and mean radius data. See Randel et al., JGR, 2017 for details.

31 Temperature Trend *** CESM2 (WACCM) The CESM2 (WACCM) Fcase also compares well to observations. This simulation use aerosol loading and mean radius information from the interactive MAM approach (Mills et al., JGR, 2016). Here only one realization is shown. Figure Courtesy of Fei Wu and Bill Randel, NCAR.

32 General Conclusions for CESM2 (WACCM) Free-Running (Fcase): CESM2 Total Column Ozone (TOZ) is within the range of previous CCMI results and observations. The tropical H 2 O tape recorder is well represented (best I ve seen from a model simulation). Mean AOA is older in FR by ~0.5 years (relative to CCMI) a detailed TEM analysis will be conducted by R. Garcia in the next few weeks. Global temperature trends are well represented compared to SSU and MSU observations. Volcanic periods also match obs (i.e., using the new interactive MAM approach)! Specified-Dynamics (year 2011) CESM2 TCO is consistent with Aura OMI observations for year CESM2 has less TCO (relative to CCMI) from May to August at high SH latitudes. The cause of this difference is unknown. The low CESM2 TCO results are consistent with the high latitude evolution of O 3 relative to Aura MLS O 3. This ozone bias is most likely a dynamical issue since chemistry is not very active during polar winter. Comparison to Aura MLS for HNO 3 (g), HCl(g), H 2 O(g), ClO, O 3, and N 2 O are overall very well represented by CESM2 (WACCM).