Earth System Modeling at UCLA
Applications and Further Developments
Carlos Roberto Mechoso
Department of Atmospheric Sciences,
University of California Los Angeles, USA
Goal: Develop and apply to problems of climate change a model
that describes the coupled global atmosphere - global ocean
system, including chemical tracers. Each model component
designed for high-performance parallel internal execution and
as a Common Architecture Component (CCA), and integrated in
NASA’s ESM Framework.
www.atmos.ucla.edu/~mechoso/esm
Atmospheric General
Circulation Model
(AGCM)
Atmospheric
Chemical Tracer
Model (ACTM)
Data
Broker
Oceanic
General Circulation
Model (OGCM)
Oceanic
Chemical Tracer
Model (OCTM)
UCLA Earth System Model
Stage 3
Model elements:
• UCLA AGCM with upgraded PBL parameterization
• LANL version of Parallel Ocean Program (POP) upgraded to
hybrid vertical coordinates (HYPOP)
• UCLA ACTM (which can include up to 64 species)
• JPL Ocean Chemical Transport Model
• MIT and MOM OGCMs as options
Stratocumulus
clouds play key
roles in the climate
system.
Global climate
models have serious
difficulties in
simulating these
clouds.
ENSO simulations
and predictions can
be greatly improved
by improving model
performance with
tropical
stratocumulus decks.
UCLA AGCM v7.5
R. Terra, 2002
Diurnal Cycle in Amazonia
4:00pm
In Amazonia during
the monsoon season,
rainfall peaks at
around 2 pm and
convection peaks a
few hours later.
2:00pm
The model captures the early afternoon peak of
precipitation over the continental areas with
monsoon circulations
A particular event
Events in 20 years
Simulated Year
Sea surface temperature at equator
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
140
160
180
200
220
240
260
280
Below average Longitude Above average
-1.50 -1.25 -1.00 -0.75 -0.50 -0.25 0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00
The highly realistic ENSO produced by the
coupled AGCM/OGCM was obtained
through extensive model development and
numerical experimentation allowed by the
efficient model codes developed under this
project. (Contour interval: 0.50C left, 0.250C
right )
A Multi-layer PBL parameterization
(Konor and Arakawa, 2001)
E
Characteristics/assumptions:
Multiple layers near the surface are assigned for the
PBL
Resolves low-level vertical wind shear associated with low-level baroclinicity
Includes effects of cumulus cloud roots
The PBL-depth is predicted (Suarez et al., 1983)
Easier to maintain PBL top discontinuity
Within the PBL, a -coordinate is used (Suarez et. al., 1983)
PBL-top and Earth surface are coordinate surfaces
Properties of PBL quantities are nearly uniform along coordinate surfaces
The processes near the PBL top are easier to formulate
A bulk formulation for convective eddy effects (Randall et al. unpublished)
A local K-closure formulation for diffusive eddy effects
Vertical profiles of PBL quantities can deviate from purely mixed profiles
National Aeronautics and Space
Administration
Earth Science Enterprise
The First Comprehensive Picture of
Chlorofluorocarbons in the Atmosphere
Thirty-five year long simulations with the UCLA ESM
yielded a comprehensive 3-D
picture of the evolution in the
atmosphere of 20 million tons of
chlorofluorocarbons
(CFCs)
released since 1965, and
subsequent chemical reactions.
By simulating the full stratosphere rather than just the
lower stratosphere where most
CFC break-up occurs, the
results
significantly
narrow
uncertain-ties in CFC lifetimes.
Percent CFC-11 emissions rate
for 1965–1996. The highest
emissions cluster over major
industrial areas in the eastern
United States and western
Europe. (M. Gupta, R. P. Turco,
C. R. Mechoso, and J. A. Spahr,
2001, JGR - Atmospheres.)
CFC-12 Evolutions in Selected Locations
Validation for the simulations
came from a network of eight
surface observation stations,
including the five Advanced
Global Atmospheric Gases
Experiment (AGAGE) stations.
The results typically differed
by just a few percentage
points from each station’s
readings.
After 1997, all
simulations show decreases in
CFC-12, while the data show
continued increases.
Methodology for concurrent execution
of ESM components
Atmospheric surface fluxes that drive the ocean are produced by the model component
known as AGCM/Physics; sea surface temperatures (SSTs) that drive the atmosphere
are produced by the ocean model component known as OGCM/Baroclinic.
Coupling between ESM
components
• Data transfers between ESM components are
handled by Data Brokers.
• One type is a Centralized Data Broker
(CDB), which assembles the entire data field
from a producer on a single processor before
sending it to consumers.
• CDBs can introduce performance bottlenecks
and have processor memory limitations.
• In view of these considerations, we have
developed the UCB/UCLA Distributed Data
Broker.
Distributed Data Broker
Function
To handle distributed data exchanges
between the ESM component.
Major Tasks
•Gather information from each model
component (may have been decomposed into
many subdomains running at different
processors).
•Convert data resolutions, units…, etc. and
redistribute them to the needed model
components.
•Keep track of coupling sequence, such as
how often AGCM needs sea surface
temperature, and which processors have
those information.
Distributed Data Broker (DDB)
Components
• Communications Library
General communication routines to manage the data
exchanges based on standard communication toolkits
(PVM(current), MPI (proposed), etc).
• Model Communications Library
Callable routines for registering and exchanging
information between model components.
• Data Translation Library
Routines for data regridding.
Reported Performance: 40 GFLOPS (2001)
UCLA ESM Component Structure
UCLA ESM Application Component
Coupler Component
UCLA
Atmospheric
Model
Component
CCSM
Coupler
LANL
Ocean
Model
Component
UCLA
Chemistry
and
Aerosol
Model
LANL
Sea-Ice
Model
Component
Check-Point
•
Code optimization and parallelization completed to a
level acceptable with (1) research objectives, (2)
available computer resources.
•
Case studies completed that demonstrate good model
performance.
•
Perceived need to “modularize” major model components
in order to facilitate implementation of model upgrades
designed both in house and at other development groups.
Earth System Modeling
Application
ESMF_AppComp
Coupled atmosphere / ocean simulation driver
ESMF_CplComp
Coupler Component performs data transformations and
transfers between atmosphere and ocean Components
ESMF_GridComp
ESMF_GridComp
NCAR/LANL CCSM
NCEP Forecast
UCLA AGCM atmosphere
NCEP Forecast
MIT OGCM ocean
CCA ESM Prototype
Palette
Arena
Run Atmos
Driver
Ocean
Produce
Consume
GO
Atmos
Run Ocean
Run Atmos
Atmos
Driver
Produce
DDB
Consume
DDB
Process Set A
Run Ocean
Produce
Consume
GO
Ocean
Run Atmos
Run Ocean
Driver
Produce
Consume
DDB
Process Set B
Summary
• An ESM (ocean-atmosphere dynamics and
chemistry) has been developed for high performance
computers.
• The ESM includes a novel Distributed Data Broker, a
flexible, high-level syntax for coupling components of
multidisciplinary applications.
• The ESM is been applied to ENSO predictability and
the evolution of chemical tracers (CFCs, Rn) in the
atmosphere.
• The ESM code is been integrated in NASA’s ESM
Framework. Model components are been designed
as Common Architecture Components (CCA).