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Learn about hardware upgrades and model adjustments for improved forecasts. Testing new systems and transitioning to updated versions.
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Hardware Failures! • Only a few disk failures…but those taken care of by the RAID system. • Enhanced back scripts as well. • Other hardware issue: hoping to get a ten-times increase in bandwidth into dept server by running optical all the way into computer room (6-12 months out).
Ready for Some Major Changes • Fixing the upper boundary of the model to reduce reflections from the top, producing more robust and less noisy forecasts—particularly in the upper troposphere and lower stratosphere. • Do this by: • raising the model top from 100 hPa to 50 hPa. • Adding Rayleigh damping to the upper seven layers. • Much smoother transitions in model resolution.
Testing • Have evaluated over extended period in winter and summer: little impact in lower troposphere on key fields. • Does lessen excessive waves in upper troposphere and even cleans up mid-troposphere somewhat.
Land Surface Model Testing • We are NOT using the NOAH Land Surface Model because it produced an unacceptable cold bias during winter. • A new version of the NOAH LSM has been released: NOAH-MP (Multi-physics)
Noah-MP (Niu et al., 2011) (multi-physics) • Uses multiple options for key land-atmosphere interaction processes. • Noah-MP contains a separate vegetation canopy defined by a canopy top and bottom with leaf physical and radiometric properties used in a two-stream canopy radiation transfer scheme that includes shading effects. • Noah-MP contains a multi-layer snow pack with liquid water storage and melt/refreeze capability and a snow-interception model describing loading/unloading, melt/refreeze, and sublimation of the canopy-intercepted snow. • Multiple options are available for surface water infiltration and runoff, and groundwater transfer and storage including water table depth to an unconfined aquifer. • Horizontal and vertical vegetation density can be prescribed or predicted using prognostic photosynthesis and dynamic vegetation models that allocate carbon to vegetation (leaf, stem, wood and root) and soil carbon pools (fast and slow).
The Issue • We found it doesn’t work in latest version of WRF! (“Water budget problem in NOAHMP LSM”) • WRFhelp and others confirmed our findings. • Hopefully, they will correct the issues this fall, so we can test it and have the option of going with it before winter snows. • If this doesn’t work, we will experiment with other LSMs (e.g., RUC LSM).
Transition to WRF 3.4.1 • We have been using a relatively old version of WRF for a long time (WRF 3.1.1)—and wisely so! (released July 2009). • Our verification showed degradation of results for 3.2, 3.3, and 3.4. • Air Force Weather Agency Testing by the DTC (Developmental Testbed Center) showed the same thing. • FINALLY, they found a key problem: an error in the YSU PBL scheme that entered with 3.2
Early Summer Testing • Before 3.4.1 was available, we tested a new version of our drag parameterization (using 3.1.1) that pulled back the drag during well mixed conditions. Looked good. • But then 3.4.1 came out and we did comprehensive tests on it.
51 different experiments:http://www.atmos.washington.edu/~ovens/windbias/
Transition to 3.4.1 • We have completed extensive testing with 3.4.1 (which includes a number of bug fixes and minor improvements as well). • A change from 3.1.1 to 3.4.1 would produce a minor, but perceptible improvement and we recommend that the Consortium approve the change. • But there is an interesting wrinkle in all of this…a surprise.
In Winter 3.4.1 is clear winner, more mixed results in summer
Conclusions • After looking at hundreds and hundreds of comparisons, Dave and I believe that the “vanilla, out of the box” 3.4.1 is superior to 3.1.1 and brings us absolutely up to date. • But should we continue to use our current drag parameteriztion?….there is a complication here.
Big Question: Do we need to recalibrate our drag mods? Might we be slowing down the winds too much?
