WACCM STATUS August 28 th, 2006

UCAR Quarterly – winter 1999

MOZART CAM3 WACCM TIME GCM + Chemistry Dynamics + Physical processes+Software engineering Mesospheric + Thermospheric Processes (Community Atmosphere Model, version 3) (Model for Ozone and Related Tracers) (Thermosphere- Ionosphere-Mesosphere Electrodynamics GCM) WACCM1 (ca. 2001): Non-interactive chemistry WACCM2 (ca. 2004): Interactive chemistry Valid to ~100 km WACCM3 (2005): Full lower thermosph. phys. Extend validity to ~150 km Heritage and Structure WACCM

WACCM STATUS WACCM3 is operational and running on several platforms WACCM3 incorporates a complete physical mechanism that includes treatment of non-LTE LW, SW radiation in the far and extreme UV wavelengths, auroral process, ion drag and molecular diffusion above 65 km. Below 65 km, WACCM is CAM, with some relevant differences regarding gravity wave processes and other tunable parameters. At all altitudes, WACCM incorporates a chemical mechanism (65 species) not present in CAM.

Additions to CAM3 Finite Volume dynamics & transport (Lin, 2004) 66 layers (0-150 km), 1.9x2.5 deg lat-lon grid Non-LTE longwave cooling in meso/thermosphere Fomichev (15 μm CO 2 ), Kockarts (5.3 μm NO) Merged with CAM3 param between km Solar heating in meso/thermosphere nm: interactive chemistry or specified from another model run Molecular diffusion (dominant above 100 km) Includes diffusive separation of constituents Gravity wave spectrum parameterization Garcia/Lindzen discrete spectrum Includes molecular dissipation Full parameterization of ion drag and auroral processes

THE MOTIVATION

WACCM Motivation Roble, Geophysical Monographs, 123, 53, 2000 Coupling between atmospheric layers: - Waves transport energy and momentum from the lower atmosphere to drive the QBO, SAO, sudden warmings, mean meridional circulation - Solar inputs, e.g., auroral production of NO in the mesosphere and downward transport to the stratosphere - Stratosphere-troposphere exchange Climate Variability and Climate Change: - What is the impact of the stratosphere on tropospheric variability, e.g., the Artic oscillation or “annular mode”? - How important is coupling among radiation, chemistry, and circulation? (e.g., in the response to O 3 depletion or CO 2 increase) Jarvis, “Bridging the Atmospheric Divide” Science, 293, 2218, 2001

WACCM Motivation Response to Solar Variability: -Recent satellite observations have shown that solar cycle variation is: 0.1% for total Solar Irradiance 5-10% at  200nm - Radiation at wavelengths near 200 nm is absorbed in the stratosphere => Impacts on global climate may be mediated by stratospheric chemistry and dynamics Satellite observations: -There are several satellite programs that can benefit from a comprehensive model to help interpret observations - e.g., UARS, TIMED, EOS Aura UARS / SOLSTICE

Topics of research for Climate impacts of stratospheric chemistry and sea-surface temperature (Sassi) The impact of the middle atmosphere on tropospheric climate sensitivity (Garcia+Sassi) Process oriented evaluation of climate chemistry models (Kinnison) Tropospheric sources of gravity waves (Richter+Sassi) Solar proton events and their role on the stratospheric composition (Marsh) Solar variability/QBO interactions in middle atmosphere climate simulations (Matthes, Garcia, Marsh) Atmospheric predictability in the whole atmosphere (Liu, Sassi, Garcia) Polar mesospheric clouds variability (Gettelman, Marsh) Tropical tropopause layer (Pan, Gettelman)

Topics of research for Climate impacts of stratospheric chemistry and sea-surface temperature (Sassi) The impact of the middle atmosphere on tropospheric climate sensitivity (Garcia+Sassi) Process oriented evaluation of climate chemistry models (Kinnison) Tropospheric sources of gravity waves (Richter+Sassi) Solar proton events and their role on the stratospheric composition (Marsh) Solar variability/QBO interactions in middle atmosphere climate simulations (Matthes, Garcia, Marsh) Atmospheric predictability in the whole atmosphere (Liu, Sassi, Garcia) Polar mesospheric clouds variability (Gettelman, Marsh) Tropical tropopause layer (Pan, Gettelman)

Topics of research for Climate impacts of stratospheric chemistry and sea-surface temperature (Sassi) The impact of the middle atmosphere on tropospheric climate sensitivity (Garcia+Sassi) Process oriented evaluation of climate chemistry models (Kinnison) Tropospheric sources of gravity waves (Richter+Sassi) Solar proton events and their role on the stratospheric composition (Marsh) Solar variability/QBO interactions in middle atmosphere climate simulations (Matthes, Garcia, Marsh) Atmospheric predictability in the whole atmosphere (Liu, Sassi, Garcia) Polar mesospheric clouds variability (Gettelman, Marsh) Tropical tropopause layer (Pan, Gettelman)

Topics of research for Climate impacts of stratospheric chemistry and sea-surface temperature (Sassi) The impact of the middle atmosphere on tropospheric climate sensitivity (Garcia+Sassi) Process oriented evaluation of climate chemistry models (Kinnison) Tropospheric sources of gravity waves (Richter+Sassi) Solar proton events and their role on the stratospheric composition (Marsh) Solar variability/QBO interactions in middle atmosphere climate simulations (Matthes, Garcia, Marsh) Atmospheric predictability in the whole atmosphere (Liu, Sassi, Garcia) Polar mesospheric clouds variability (Gettelman, Marsh) Tropical tropopause layer (Pan, Gettelman)

Topics of research for Climate impacts of stratospheric chemistry and sea-surface temperature (Sassi) The impact of the middle atmosphere on tropospheric climate sensitivity (Garcia+Sassi) Process oriented evaluation of climate chemistry models (Kinnison) Tropospheric sources of gravity waves (Richter+Sassi) Solar proton events and their role on the stratospheric composition (Marsh) Solar variability/QBO interactions in middle atmosphere climate simulations (Matthes, Garcia, Marsh) Atmospheric predictability in the whole atmosphere (Liu, Sassi, Garcia) Polar mesospheric clouds variability (Gettelman, Marsh) Tropical tropopause layer (Pan, Gettelman)

Topics of research for Climate impacts of stratospheric chemistry and sea-surface temperature (Sassi) The impact of the middle atmosphere on tropospheric climate sensitivity (Garcia+Sassi) Process oriented evaluation of climate chemistry models (Kinnison) Tropospheric sources of gravity waves (Richter+Sassi) Solar proton events and their role on the stratospheric composition (Marsh) Solar variability/QBO interactions in middle atmosphere climate simulations (Matthes, Garcia, Marsh) Atmospheric predictability in the whole atmosphere (Liu, Sassi, Garcia) Polar mesospheric clouds variability (Gettelman, Marsh) Tropical tropopause layer (Pan, Gettelman)

Topics of research for Climate impacts of stratospheric chemistry and sea-surface temperature (Sassi) The impact of the middle atmosphere on tropospheric climate sensitivity (Garcia+Sassi) Process oriented evaluation of climate chemistry models (Kinnison) Tropospheric sources of gravity waves (Richter+Sassi) Solar proton events and their role on the stratospheric composition (Marsh) Solar variability/QBO interactions in middle atmosphere climate simulations (Matthes, Garcia, Marsh) Atmospheric predictability in the whole atmosphere (Liu, Sassi, Garcia) Polar mesospheric clouds variability (Gettelman, Marsh) Tropical tropopause layer (Pan, Gettelman)

Topics of research for Climate impacts of stratospheric chemistry and sea-surface temperature (Sassi) The impact of the middle atmosphere on tropospheric climate sensitivity (Garcia+Sassi) Process oriented evaluation of climate chemistry models (Kinnison) Tropospheric sources of gravity waves (Richter+Sassi) Solar proton events and their role on the stratospheric composition (Marsh) Solar variability/QBO interactions in middle atmosphere climate simulations (Matthes, Garcia, Marsh) Atmospheric predictability in the whole atmosphere (Liu, Sassi, Garcia) Polar mesospheric clouds variability (Gettelman, Marsh) Tropical tropopause layer (Pan, Gettelman)

Topics of research for Climate impacts of stratospheric chemistry and sea-surface temperature (Sassi) The impact of the middle atmosphere on tropospheric climate sensitivity (Garcia+Sassi) Process oriented evaluation of climate chemistry models (Kinnison) Tropospheric sources of gravity waves (Richter+Sassi) Solar proton events and their role on the stratospheric composition (Marsh) Solar variability/QBO interactions in middle atmosphere climate simulations (Matthes, Garcia, Marsh) Atmospheric predictability in the whole atmosphere (Liu, Sassi, Garcia) Polar mesospheric clouds variability (Gettelman, Marsh) Tropical tropopause layer (Pan, Gettelman)

What do we have to show for our efforts?

R. Garcia is also a coauthor on WMO (2006)

THE FUTURE DIRECTION

OUTSTANDING QUESTIONS 1.WACCM in relation to NCAR 2.Byron’s heritage 3.The strategic plan

WACCM IN RELATION TO NCAR Past success is not an excuse for inaction. Things are changing around us and we need to position ourselves to take full advantage of future opportunities. What is the role of WACCM in the re-organization of ESSL? What role is WACCM going to play in the new world of peta-scale computing? WACCM is currently homeless. Do we need a home? Do we need a label to identify us? Or is physical collocation more desirable?

BYRON’S HERITAGE What CGD does with Byron’s position will almost certainly impact us. Do we want to ask for specific help? In what form? A senior level person, a mid-level scientist, or just a software engineer/associate scientist? We need to realize that Byron was one of the principal instigators for this project, let alone the only person with a broad knowledge of atmospheric processes, climatology and software engineering. Are we at the risk of being directionless?

THE STRATEGIC PLAN After a long time of model development, have we peaked? Is the development of WACCM finished? There are possibilities but they require personnel commitment and funding. What are our scientific objectives for the next 4-5 years? What are the major scientific questions that we would like to address? It will help us to identify them and write a document (strategic plan) that needs to be circulated with the higher levels. How do we establish and maintain group cohesiveness within this strategic plan?

SCIENTIFIC OBJECTIVES - I (my personal view) Schemes improvements and correction of outstanding biases: –Tropospheric sources of gravity waves –Mountain drag schemes –Tropical oscillations  convection –Effects of model resolution on the quality of the simulation –??? Extension of WACCM to 500 km: –Space weather –Support/validation of satellite observations in the MLT region –??? Climate interactions: –WACCM coupled to an interactive ocean (full depth) –Impact of stratospheric variability on the troposphere –???

SCIENTIFIC OBJECTIVES - I (my personal view) Schemes improvements and correction of outstanding biases: –Tropospheric sources of gravity waves –Mountain drag schemes –Tropical oscillations  convection –Effects of model resolution on the quality of the simulation –??? Extension of WACCM to 500 km: –Space weather –Support/validation of satellite observations in the MLT region –??? Climate interactions: –WACCM coupled to an interactive ocean (full depth) –Impact of stratospheric variability on the troposphere –???

SCIENTIFIC OBJECTIVES - I (my personal view) Schemes improvements and correction of outstanding biases: –Tropospheric sources of gravity waves –Mountain drag schemes –Tropical oscillations  convection –Effects of model resolution on the quality of the simulation –??? Extension of WACCM to 500 km: –Space weather –Support/validation of satellite observations in the MLT region –??? Climate interactions: –WACCM coupled to an interactive ocean (full depth) –Impact of stratospheric variability on the troposphere –???

SCIENTIFIC OBJECTIVES - II Simulation of the near past –PMC variability –Maunder minimum Simulations of the remote past –Major asteroid impact (dinosaur extinction)

Open discussion