Planetary boundary layer schemes in RegCM: evaluation and impact on the climate change signal over Europe and Mediterranean region

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1 Seventh ICTP Workshop on the Theory and Use of Regional Climate Models Planetary boundary layer schemes in RegCM: evaluation and impact on the climate change signal over Europe and Mediterranean region Ivan Güttler Thanks to Čedo Branković, Lidija Srnec, Mirta Patarčić (DHMZ), Filippo Giorgi, Csaba Torma, Erika Coppola (ICTP), Travis O Brien (Lawrence Berkeley National Lab), Branko Grisogono (GFZ, University of Zagreb) ICTP, Trieste,

2 1/25 Introduction The main objectives of this talk are: (1) to present two PBL schemes implemented in the RegCM model (2) to investigate possibilities of the reduction of systematic errors for the lower atmosphere in the RegCM model results using the UW PBL scheme (3) to explore the impact of the two PBL schemes on the simulated climate change signal Based on: (1) Güttler I, Č Branković, TA O'Brien, E Coppola, B Grisogono, F Giorgi, 2013: Sensitivity of the regional climate model RegCM4.2 to planetary boundary layer parameterisation. Clim. Dyn., doi: /s (2)

3 PBL parameterisations in RegCM: Holtslag and UW schemes 2/25 Holtslag et al. (1990), Troen and Mahrt (1986) Grenier and Bretherton (2001), Mellor and Yamada (1982) Holtslag and Boville (1993) Bretherton and Park (2008)

4 PBL parameterisations in RegCM Blackadar (1962) 3/25 Nicholls and Turton (1986) Nieuwstadt (1984) Bretherton and Park (2008) O Brien et al. (2012)

5 Model domain and experiments RegCM(HL,EI) and RegCM(UW,EI) 4/25 ERA- Interim (1) ERA-Interim reanalysis boundary conditions (2) 50-km resolution, 126 x 126 x 23 (3) (4) Additional exp: (5) BATS LSM, CCM3 radiation, MIT Emanuel convection RegCM(HL,HA) and RegCM(UW,HA) HadGEM2- ES (1) HadGEM2-ES ESM boundary conditions (2) 50-km resolution, 141 x 79 x 23 (3) (Nov): historical (4) 2005 (Dec) 2098: scenario RCP8.5 (5) 2005 (Dec) 2098: scenario RCP4.5 (6) Differences: (a) hybrid Emanuel+Grell convection; (b) seasonal desert albedo; (c ) crop land-type modification (Torma and Giorgi, 2014)

6 Systematic errors in surface and near-surface variables: seasonal T2m errors 5/25 DJF RegCM(HL,EI)- CRU RegCM(UW,EI)- CRU JJA RegCM(HL,EI)- CRU RegCM(UW,EI)- CRU

7 Systematic errors in surface and near-surface variables: monthly T2m errors 6/25 RegCM(HL,EI) > RegCM(UW,EI)

8 Systematic errors in surface and near-surface variables: monthly R errors 7/25 RegCM(HL,EI) < RegCM(UW,EI)

9 Systematic errors in surface and near-surface variables: net surface SW radiation 8/25 SWR RegCM(HL,EI) > RegCM(UW,EI) Kothe et al. (2011)

10 Systematic errors in surface and near-surface variables: CLD annual cycle 9/25 RegCM(HL,EI) < RegCM(UW,EI)

11 Systematic errors in surface and near-surface variables: net surface LW radiation 10/25 LWR RegCM(HL,EI) > RegCM(UW,EI)

12 Systematic errors in surface and near-surface variables: SHF PDF&PSS 11/25 Figure S2.1: RegCM domain and the locations of the C-SRNWP flux measurements. Güttler et al. (2013) However, hcps://climatedataguide.ucar.edu/climate- data/fluxnet- mte- muln- tree- ensemble!!!

13 12/25 Perkins et al. (2007) (1) RegCM vs C-SRNWP (2) RegCM vs ERA-Interim (3) RegCM vs ERA-Interim Figure S2.4 Perkins skill scores for PDFs of sensible heat flux at the locations of C-SRNWP observations. Period: The coloured bars 1 to 6 in each season indicate comparisons for: 1) RegCM Holt vs. observations, 2) RegCM UW vs. observations, 3) ERA-Interim vs. observations, 4) RegCM UW vs. RegCM Holt, 5) RegCM Holt vs. ERA-Interim and 6) RegCM UW vs. ERA-Interim. The numbers bellow DJF, MAM, JJA and SON are the differences between the two RegCM comparisons against observations (between comparisons 1 and 2). Güttler et al. (2013)

14 The impact of PBL parameterisations on systematic errors: T profiles 13/25 RegCM(HL,EI) DJF JJA RegCM(UW,EI)-RegCM(HL,EI) T reduced in the lower atmosphere Güttler et al. (2013)

15 The impact of PBL parameterisations on systematic errors: RegCM vs ERA-Interim profiles RegCM(HL,EI), ERA-Interim RegCM(UW,EI) - RegCM(HL,EI) RegCM(HL,EI) - ERA-Interim 14/25

16 The impact of PBL parameterisations on systematic errors: K H profiles 15/25 RegCM(HL,EI) DJF JJA RegCM(UW,EI)-RegCM(HL,EI) Reduced turbulent diffusivity

17 The impact of PBL parameterisations on systematic errors: T PBL tendency profiles 16/25 RegCM(HL,EI) DJF JJA Only in RegCM(HL,EI) RegCM(UW,EI)-RegCM(HL,EI) Cooling dominates In the lower atmosphere Güttler et al. (2013)

18 The impact of PBL schemes on the projected climate change: T2m CRU DJF JJA CRU 17/25 P0: P3:

19 The impact of PBL schemes on the projected climate change: R CRU DJF JJA P0: P3: CRU 18/25

20 The impact of PBL schemes on the projected climate change: T2m 19/25 RegCM(UW,HA) < RegCM(HL,HA) P(i=1,2,3) > P0 P0: P1: P2: P3:

21 The impact of PBL schemes on the projected climate change: soil moisture SMW 20/25 RegCM(UW,HA) <, RegCM(HL,HA) P(i=1,2,3) < P0

22 The impact of PBL parameterisations on the projected climate change: R 21/25 RegCM(UW,HA) < (JJA), > (DJF) RegCM(HL,HA) P(i) > P0 (DJF) P(i) < P0 (JJA, SON)

23 The impact of PBL parameterisations on the projected climate change: SWR 22/25 RegCM(UW,HA) < RegCM(HL,HA) P(i=1,2,3) > P0

24 The impact of PBL parameterisations on the projected climate change: CLD 23/25 RegCM(UW,HA) > RegCM(HL,HA) P(i=1,2,3) < P0

25 The impact of PBL parameterisations on the projected climate change: LHF 24/25 RegCM(UW,HA) >(DJF, SON), <(MAM->JJA) RegCM(HL,HA) P(i) > P0 in DJF,MAM,SON

26 Conclusions 25/25 (1) The use of the UW PBL scheme reduces near-surface temperature errors over eastern Europe and Russia. [Other approaches? See the bonus slide] (2) The impact of the UW scheme is a function of season, location and variable. (3) Differences in the prognostic tendency due to the PBL scheme are generally consistent with the simulated changes in the near-surface and surface variables. [idiag=1 could be used to extend this methodology] (4) Although for the historical period the two RegCM simulations yield different climatology over the Mediterranean region, the climate change projections for the 21 st century are not strongly sensitive to the choice of the PBL scheme. Thank you for attention!

27 Bonus slide RegCM4.2 (50km) - > RegCM4.4 (12.5km) ERA- Interim ICBC Physics opnons the same: BATS, MIT, JJA errors reduced (but not the case with the DJF errors)