Role of parameterized convection scheme in Regional Climate Model to simulate Indian summer monsoon rainfall Soumik
1 Ghosh *,
R.
1 Bhatla ,
P.K.
2 Srivastava
and RK
2 Mall
1. Department of Geophysics, Institute of Science, Banaras Hindu University, Varanasi, India 2. Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, India *Presenting Author: Soumik Ghosh:
[email protected]
Objective:
Introduction: The climate model faces considerable difficulties in simulating the rainfall characteristics of the South-West summer monsoon. In this study, the dynamical downscaling of European Centre for Medium Range Weather Forecasts (ECMWF) Era interim is performed for simulation of Indian summer monsoon (ISM) using the Regional Climate Model version 4.3 (RegCM-4.3) over the South-Asia Co-ordinated Regional Climate Downscaling Experiment (CORDEX) domain.
Study is aimed to improve the simulation of the dynamical mechanism of ISM using ECMWF downscaled RegCM-4.3 output with time depended lateral boundary condition along with various SST specified over ocean. It also has been tried to understand the role of parameterized convection scheme in RegCM-4.3 with EIN15 ICBC to simulate Indian summer monsoon rainfall over a particular region during its different phases.
Table 1: Model Hydrostatics
Methods and Materials RegCM-4.3 of ICTP’s (International Center for Theoretical Physics’, Italy) with a horizontal resolution of 50 Km for 30 years (19812010) is used throughout this study. For the sensitivity analysis of Mix99 PCS is continued with two types SST (ERSST & OI_WK) as lower boundary condition. Model simulated daily Rainfall, Outgoing Long-wave Radiation (OLR), Mean Sea Level Pressure (MSLP) and wind at 925hPa and 850hPa are considered over the South-Asia CORDEX region (22oS-50oN and 10oE-130oE) are compared with the Obs/reanalysis data of IMD, NOAA, NCEP and ERA15 respectively. For statistical verification and validation sustained using Quantile–Quantile (Q-Q) distribution, Empirical Cumulative Distribution Function (ECDF), Standard Deviation (SD) and the absolute bias (Bias) is considered.
Result & Discussions Table 2: Onset dates along with their deviation.
Fig.1: Spatial pattern of in situ and CMO simulated rainfall and olr distribution during 1981-2010 by following the new IMD criteria for onset declaring monsoon Onset.
Fig.2: Distribution of in situ and CMO simulation of olr over the region Lat 5oN -10oN and Lon 70oE -75oE and zonal wind at 925hPa over the region Lat 5oN-10oN and Lon 70oE -80oE for the respective onset date.
Year 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Actual 30 M 28 M 13 J 30 M 28 M 04 J 02 J 26 M 03 J 19 M 02 J 05 J 28 M 28 M 05 J 03 J 09 J 02 J 25 M 01 J 23 M 29 M 08 J 18 M 05 J 26 M 28 M 31 M 23 M 31 M
Onset Dates OI_WK 04 J (+ 7) 21 J (+ 8) 31M (+ 1) 29M (+ 1) 25 M (-10) 08 J (+ 6) 23 M (- 3) 25 M (- 9) 19 M ( 0) 07 J (+ 5) 06 J (+ 1) 30 M (+ 2) 06 J (+ 9) 11 J (+ 6) 24 M (-10) 30 M (- 3) 02 J (+ 8) 25 M (- 7) 26 M (+ 3) 17 M (-12) 06 J (- 2) 21 M (+ 3) 07 J (+ 2) 25 M (- 1) 31 M ( 0) 19 M (-12)
Table 3: Active/Break periods and days (NCC Research Report 2013)
ERSST 24 M (- 6) 02 J (+ 5) 21 J (+ 8) 31M (+ 1) 06 J (+ 9) 24 M (-11) 07 J (+ 5) 27 M (+ 1) 29 M (- 5) 18 M (- 1) 02 J ( 0) 25 M (-11) 31 M (+ 3) 04 J (+ 7) 11 J (+ 6) 03 J ( 0) 29 M (-11) 30 M (- 3) 21 M (- 4) 22 M (- 1) 17 M (-12) 12 M (- 6) 09 J (+ 4) 28 M (+ 2) 01 J (+ 4) 26 M (- 5) 21 M (-10)
Year 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Total
active/break spells act=1, brk=1 act=2, brk=1 act=1, brk=1 act=3, brk=1 act=3, brk=1 act=2, brk=1 act=1,brk=3 act=1,brk=1 act=0,brk=2 act=3,brk=0 act=3,brk=1 act=2,brk=1 act=2,brk=3 act=6,brk=0 act=2,brk=2 act=2,brk=1 act=2,brk=2 act=2,brk=2 act=1,brk=3 act=2,brk=1 act=1,brk=2 act=1,brk=2 act=2,brk=0 act=2,brk=3 act=3,brk=2 act=4,brk=0 act=2,brk=2 act=1,brk=3 act=2,brk=2 act=0,brk=0 act=59, brk=44
active/break days act=5, brk=4 act=6, brk=8 act=3, brk=3 act=10, brk=3 act=10, brk=3 act=7,brk=9 act=6,brk=14 act=3,brk=4 act=0,brk=8 act=10,brk=0 act=10,brk=3 act=9,brk=7 act=8,brk=17 act=24,brk=0 act=7,brk=12 act=8,brk=3 act=8,brk=14 act=8,brk=12 act=3,brk=15 act=7,brk=11 act=4,brk=6 act=3,brk=23 act=9,brk=0 act=9,brk=14 act=13,brk=16 act=23,brk=0 act=13,brk=9 act=3,brk=13 act=8,brk=15 act=0,brk=0 act=237, brk=246
Dynamics Model domain
Hydrostatics South Asia CORDEX domain (15o S- 45o N; 10oE-130o E) ROTMER – Rotated Mercator 50 km horizontal 18 sigma vertical levels ERA15 1. OI_WK – OISST Weekly Optimal Interpolation dataset 2. ERSST – ERA Interim 6 hourly 1.5ox1.5o SST Modified CCM3 Modified Holtslag
Domain cartographic projection Resolution Vertical level Initial and boundary conditions SST
Land surface parameterization Radiation Parameterization PBL Convective parameterization
Mix99 (Emanuel over ocean and Grell over land)
Grell Closure Scheme
Arakawa & Schubert (1974)
Fig.9: Q-Q distribution of different synoptic parameter during Onset, Active and Break phase in respect to in situ dataset.
Fig.10: Empirical Cumulative Distribution Function (ECDF) of different parameter during Onset, Active and Break phase of Indian summer monsoon.
Fig.7: Vertical level-days of different phases (a-b) and Longitude-days of different phases at 850hPa (c-d) of EIN15 zonal wind distribution (Knots/s; shaded) during active and break phase over the core region (71oE-83oE and 21oN28oN).
IMD onset simulating criteria (Pai and Rajeevan, 2007) 1. 60% of stations among 14 around Kerala receiving minimum rainfall of 2.5mm/day for minimum two consecutive days after 10th May are considered as Onset of monsoon. 2. Depth of westerly has to be maintained 600hPa over 0oN -10oN and 55oE -80oE region. 3. Zonal wind will blow with 15-20 knots at 925hPa over the Lat 5oN-10oN and Lon 70oE -80oE 4. INSAT olr will be less than 200Wm-2 over Lat 5oN 10oN and Lon 70oE -75oE.
Fig.8: Distribution of EIN15 zonal wind during Active and Break phases of Intraseasonal summer monsoon period. Fig.3: Composite spatial pattern of in situ and CMO simulated rainfall, olr and mslp distribution during active phase for the duration 19812010. EIN15 and CMO derived wind circulation is superimposed at 850hPa for the respective cases.
The wind passes through the Central India with a speed of ~28 knots/s during the active and with a speed of less than ~15 knots/s during break phase at 850hPa (Varikoden H, 2006), which is not depicted in EIN15 zonal wind.
Table 3: Statistical score during phases of monsoon Onset Phase OLR
Fig.4: distribution of rainfall and olr during active spells of 1981-2010.
Large deviation from the obs/reanalyze
Active Phase
Break Phase
BIAS
Reanalyze
SD 29.24
U Wind SD BIAS 4.46
Rainfall SD BIAS 5.06
OLR SD BIAS 20.02
Rainfall SD BIAS 1.65
OLR SD BIAS 21.50
ERSST
12.26
-2.77
1.32
-1.54
2.84
-9.8
8.56
55.68
2.25
-1.60
13.16 -22.28
OI_WK
11.68
-3.2
1.87
-1.08
2.71
-9.5
9.22
55.82
2.76
-2.04
13.18 -21.8
Conclusions: 1. Among all factors, the analysis indicates that in small scale the zonal wind of EIN15 is lacking the enough speed over the Indian subcontinent during Onset and active phase. 2. Activity of boundary conditions of zonal wind circulation speed causes an increase in the uncertainty of the model output over the region under investigation. 3. Lacks of zonal wind speed induce the model simulated OLR distribution with the warm biases which regulates the rainfall distribution over the rainbelt area and RegCM-4.3 simulated rainfall is affected with lack of rainfall. Fig.6: Distribution of rainfall and olr during break spells of 1981-2010. Acknowledgement: The authors wish to thank to The India Meteorology Department (IMD), NOAA/OAR/ESRL (Boulder, Colorado, USA; http://www.esrl.noaa.gov/psd/) and European Centre for Medium-Range Weather Forecasts (ECMWF) for providing gridded datasets. Special thanks to International Center for Theoretical Physics (ICTP), Italy, for providing the RegCM-4.3 model.
Fig.5: Composite spatial pattern of in situ and CMO simulated rainfall, olr and mslp distribution during break phase for the duration 19812010. EIN15 and CMO derived wind circulation is superimposed at 850hPa for the respective cases.
References: 1. Bhatla R, S Ghosh, B Mandal, RK Mall, Kuldeep Sharma (2016). Simulation of Indian summer Monsoon Onset with different Parameterization Convection Schemes of RegCM-4.3. Atmopheric Research. 176–177: 10–18. doi: 10.1016/j.atmosres.2016.02.010 2. Raju PVS, Bhatla R, Mohanty UC (2009). The evolution of mean conditions of surface meteorological fields during active/break phases of the Indian summer monsoon. Theor. Appl. Climatol. 95: 135–149 3. NCC Research Report. (2013). Development and Analysis of A New High Spatial Resolution (0.25o x 0.25o) Long Period (1901-2010) Daily Gridded Rainfall Data Set Over India. [Ed/Author: DS Pai, Latha Sridhar, M Rajeevan, OP Sreejith, NS Satbhai and B Mukhopadhyay]. NCC Research Report No. 1/2013. 63 4. Varikoden H. (2006). Dynamic Characteristics of Atmospheric Boundary Layer during different Phases of Monsoon. Doctoral Thesis. Department of Atmospheric Sciences Cochin University of Science and Technology, Lakeside Campus, Cochin, India. 5. Pai DS. Rajeevan M. (2007). Indian summer monsoon onset: variability and prediction. National Climate Centre, India Meteorological Department.
