simulations of the present and future precipitation climate of the central andes

Simulations of the Present and Future Precipitation Climate of the Central

Andes

COAWST Modelling System Training

27 August 2014

Stephen D. Nicholls and Karen I. Mohr

NASA-Goddard Space Flight Center

Precipitation climate: Diurnal cycle, total rainfall, distribution

Motivation: GCMs and CORDEX lack temporal and spatial resolution. Central Andes very sensitive to climate change.

Objectives:Determine stability and feasibility of

COAWST as a regional climate modelRun year-long COAWST simulation to

gain precipitation climate “snapshots”

Definition and objectives

Model Configuration (1)COAWST rev 727 (May

2012)WRF

2 domains (27, 9 km)61 vertical levelsModel top: 50 hPa

ROMS1 domain (~10 km)16 vertical levelsOpen boundaries

No SWANCurrent and future

wave climate?Coupling: WRF 1 <>

ROMS

WRF

ROMS

Model Configuration (2)Lateral boundaries:

Atm, Ocn: MIROC5 (0.7°)Tides: OSU

Time steps:WRF: 60 sec, 20 secROMS: 10 sec

Coupling: 30 minsFree-running simulationModified landuse

USGS = 1991, MODIS = 2003Forest and glacier loss

WRF

ROMS

SimulationsAll simulations for entire year (Oct-Oct)“Current” climate (2003-04)

WRF uncoupled, WRF-ROMS coupledFuture climate (2031-32, 2059-60, 2087-

88)Two parts

RCP comparisons (RCP 4.5, 6.0, 8.5)Year comparisons (RCP 6.0)

Current Climate: Convection

Cumulus parameterization (Kain-Fritsch) off domain 2Over-generation of rain when active

Model and parameterization at 9 km??

Precipitation + SSTImpacts on atmospherePrecipitation impacts in Andes

Current Climate

Current Climate: Precipitation + SST

TRMM = Tropical Rainfall Measuring Mission Daily 3B42ECM03 = ECMWF interim analysis

WMH03 = WRF with MIROC5 input, no ROMSCMH03 = WRF with MIROC5 input, coupled to ROMS

Plots:Top

(Oct)Bottom

(June)

Ocean upwelling

Decreased instability

Atmospheric impacts: θe and Sfc Winds

Andes Precipitation

No change to distribution, but changes in average precip

∆Precip daysCuzco -9Sajama +6Sucre +21Tuni -11

Andes Diurnal Cycle

PrecipitationPrecipitation impacts in Andes

Future Climate

Future Climate: Precipitation

CMH03 = WRF-ROMS simulation from 2003, with historical MIROC5 input

CMR6031 = WRF-ROMS simulation from 2031, with MIROC5 RCP 6.0 input



Future Andes Precipitation

Diurnal cycle fairly robust

Temp precip “bump” Cuzco,

SajamaUpper air

∆Precip days (2087-2003)Cuzco -12Sajama -9Sucre -16Tuni -20

Future Andes Diurnal Cycle

WRF-ROMS runs lean toward a La Niña patternMIROC issue or ROMS bias or WRF radiation issue

or forcing issueConvective parameterization: No parameterization

works well short term, but less effective long termPotential issues with model configuration?

Eg. WRF model top, etc.Problem with two-way interaction when both WRF

grids not coupled to ROMS.Model buffer zonesFuture work

Remaining questions

Thanks for you attention and time!!!

Questions, comments???

Landcover/landuse changeModified raw MODIS

landcover (WPS_geog)Landcover change rates

Amazon (AZ) = ↓7000.0 km2/yr (Davidson et al. 2012) > 2003

Atlantic Forest (AF): ↓0.343%/yr (Ribiero et al. 2009)

Chaco (CH): ↓2.2%/yr (Zak et al. 2004)

Tropical Glaciers (TG): 0.6785% (Slayback and Yegar 2006)

Forest (#1-5 vary) to cropland (#12)

Ice (#25) to tundra (#20)

• Microphysics – Goddard• Longwave Rad. – New Goddard• Shortwave Rad. – New Goddard• Surface layer – Eta similarity• Land Surface – NOAH• Boundary Layer – Mellor-Yamada-Janjic• Cumulus – Kain Fritsch (Turned off domain 2)

WRF Parameterizations

#define ROMS_MODEL# define WRF_MODEL# define MCT_INTERP_OC2AT#define UV_ADV#define UV_COR#define UV_VIS2#define MIX_S_UV#define TS_U3HADVECTION#define TS_C4VADVECTION#undef TS_MPDATA# define UV_LOGDRAG#define DJ_GRADPS#define TS_DIF2#define MIX_GEO_TS#define SALINITY#define SOLVE3D#define SPLINES#undef AVERAGES#define NONLIN_EOS#define MASKING

ROMS Parameterizations#define MCT_LIB# undef BULK_FLUXES# define ATM2OCN_FLUXES# define ANA_SSFLUX# undef LONGWAVE_OUT#undef MY25_MIXING# define KANTHA_CLAYSON# define N2S2_HORAVG#define RADIATION_2D /* ok */#define RAMP_TIDES /* ok */#defineSSH_TIDES /* ok */#define ADD_FSOBC /* ok */#define ANA_FSOBC /* ok */#defineUV_TIDES /* ok */#define ADD_M2OBC /* ok */#define ANA_M2OBC /* ok */#define EAST_FSCHAPMAN #define EAST_M2FLATHER #define EAST_M3RADIATION #define EAST_TRADIATION /*

Energy normScale-adjusted

perturbations (model-obs) of U, V, W, P, T, and Q)

Despite SST errors and free running, model simulation remains stable

Model Error

simulations of the present and future precipitation climate of the central andes

Documents

wrfroms simulation

wrfroms coupledfuture

roms current climate

miroc5 rcp

input future climate

future precipitation

climate change

romscurrent climate