# Presentation: 686614

## Coupling MM5 with ISOLSM: Development, Testing, and Application

- W.J. Riley, H.S. Cooley, Y. He*, M.S. Torn
- Lawrence Berkeley National Laboratory

- Yun (Helen) He

- June 2003

## Outline

- Introduction
- Model Integration
- Model Configuration
- Model Testing
- Simulation and Impacts of Winter Wheat Harvest
- Conclusions
- Observations and Future Work

- Yun (Helen) He

- June 2003

## Introduction

- CO2 fluxes and other trace-gas exchanges are tightly coupled to the surface water and energy fluxes.
- Land-use change has strong impact on surface energy fluxes.
- We coupled MM5 with ISOLSM (Riley et. al 2003), which is based on LSM1 (Bonan, 1995).
- LSM1, thus ISOLSM, simulates: vegetation response to water vapor, CO2, and radiation; soil moisture and temperature.
- ISOLSM also simulates gases and aqueous fluxes within the soil column and 18O composition of water and CO2 exchanges between atmosphere and vegetation.

- Yun (Helen) He

- June 2003

## Model Integration

- New interface between MM5 and ISOLSM based on the current OSULSM interface with MM5 and includes:
- partitioning shortwave radiation between diffuse and direct components
- spatially and temporally-dependent vegetation dynamics               (i.e., leaf area index).
- Compiler options changed to accommodate two different source code styles.
- Automatic script to retrieve and process pregrid data from NCEP NNRP data.

- Yun (Helen) He

- June 2003

## Model Integration (cont’d)

- Import MM5 to NERSC IBM SP machine.
- 380 compute nodes, 16 way each  6,656 processors
- 16 to 64 GB memory per node
- 375 MHz per CPU  10 Tflop/sec peak speed
- 44 TB disk space in GPFS
- Revise MPP library and MPP object files for ISOLSM.
- Investigate optimization levels to achieve bit-for-bit MPP results with sequential runs.
- Run scripts with automatic I/O from NERSC HPSS.
- Speedup with 64 CPUs is about 36.
- Simulation time: 15 min for domain 1
- 			         50 min for domain 2

- Yun (Helen) He

- June 2003

## Model Configuration

- Model Initialization:
- First-guess and boundary condition interpolated from NCEP NNRP.
- Model Grids:
- Outer Domain 1: Continental USA                                                          		           grid size: 54 x 68, resolution: 100 km x 100 km
- One-way nestdown
- Inner Domain 2: FIFE or ARM-CART region
-       	           grid size: 41 x 41, resolution: 10 km x 10 km
- Vertical: 18 -layers  between 100 mb and surface
- Physics package used:
- Grell convective scheme
- Simple ice microphysics
- MRF PBL scheme
- CCM2 radiation package

- Yun (Helen) He

- June 2003

## Model Testing

- Comparisons between:
- MM5 coupled with ISOLSM
- MM5 coupled with OSULSM (Chen and Dudhia, 2001)
- FIFE dataset: 3-year measured data (Betts and Ball 1998)
- surface fluxes, soil moisture, soil temperature, etc.
- spatially averaged over 225 km2 area of Kansas.
- June, July, August of 1987-1989.
- ISOLSM performed comparably or better than OSULSM.

- Yun (Helen) He

- June 2003

## Slide 8

- Yun (Helen) He

- June 2003

## Slide 9

- Yun (Helen) He

- June 2003

## Winter Wheat Harvest Simulation

- MM5-ISOLSM model applied to ARM-CART region from June to July 1987.
- Two scenarios:
- Early harvest: June 4, 1987 (Julian day 155)
- Late harvest:  July 5, 1987  (Julian day 186)
- Set harvest area with bare soil.
- Four distinct time periods are evident in the simulations:
- JD 155-158: large evaporation at harvest area
- JD 158-170: reduced evaporation at harvest area
- JD 170-186: increased precipitation
- JD 186-210: two scenarios converge

- Yun (Helen) He

- June 2003

##      ARM-CART Region 

-      ARM-CART Region
-  early harvest – late harvest

- Yun (Helen) He

- June 2003

##      ARM-CART Region 

-      ARM-CART Region
-  early harvest - late harvest

- Yun (Helen) He

- June 2003

## early harvest – late harvest

- Yun (Helen) He

- June 2003

## Conclusions

- Successfully coupled MM5 and ISOLSM.
- Built and ran the coupled model in parallel.
- Validated the coupled model against current MM5 model and FIFE dataset.
- Utilized the coupled model to study the impact of winter wheat harvest.
- Winter wheat harvest simulation indicates that harvest impacts both regional and local surface fluxes, 2 m air temperature, and soil temperature and moisture.

- Yun (Helen) He

- June 2003

## Observations and Future Work

- The coupled model allows us to estimate surface fluxes  that are consistent with ecosystem CO2 exchange.
- The soil advection and diffusion sub-models allow us to simulate the impacts of regional meteorology on other distributed trace-gases.
- Study the impact of human-induced land-use change on regional climate and predict regionally-distributed estimates of CO2 exchanges.
- Investigate the practicality of estimating distributed trace-gas fluxes from atmospheric measurements.

- Yun (Helen) He

- June 2003