1. Coastal transport phenomena in CalNex 2010 Wayne M. Angevine Jerome Brioude CIRES, University of Colorado, and NOAA ESRL

2. Purpose • Get familiar with coastal phenomena • Land breeze • Coastal eddy • Marine cloud • Bay Area inflow to Central Valley • Introduce tools available for interpretation • (Briefly) describe model/tool evaluation

3. Tools for interpretation • WRF model output: • 4 km horizontal grid covering all of California+ • 40 vertical levels, lowest level ~20 m • Output every half hour • Physical variables: Winds, temperature, water vapor, etc. • Flexpart: • Lagrangian particle dispersion model • Driven by WRF output • Forward: “What should we see here?” • Three tracers mimic CO from So.Cal., Bay Area, and “other” • Backward: “Where did this come from?” • Surface and column residence time of air at the ship location, plain or convolved with emissions

4. A note about applicability • WRF-based tools are best used at scales of 10s-100s km • “True” resolution is ~6x grid size (20-30 km) • Measurements very near sources are best interpreted with ship wind measurements directly • Long-range [O(1000 km)] transport needs to be addressed with global model based tools • You can make your own plots of WRF physical parameters and Flexpart forward tracers at http://www.esrl.noaa.gov/csd/metproducts/wrf • and of Flexpart back trajectories at • http://www.esrl.noaa.gov/csd/metproducts/flexpart/#back • or contact Wayne.M.Angevine@noaa.gov • We encourage interaction!!! Model and measurement evaluation must be a two-way process.

5. Land breeze to Santa Monica Bay and LA bight 4-31 May All hours Note land breeze (E-SE) and sea breeze (W-SW) lobes Slight daytime northerly bias and slight high speed bias in model Measured Modeled

6. Land breeze to Santa Monica Bay and LA bight 4-31 May Night (0600-1500 UTC) Note lower speed of land breeze Slight southerly bias in model, no significant speed bias Measured Modeled

7. Coastal (“Catalina”) eddy 24 May 0-200 m AGL Southern California CO tracer Log scale Roughly similar eddies occurred most days of May

8. Transport in LA bight from Flexpart Measured CO (red) and forward Flexpart CO tracer (blue, all, arbitrarily scaled)

9. Marine cloud 16 May 1500 UTC Note inland penetration of marine cloud and/or fog, varying texture

10. Marine cloud 16 May 2100 UTC Note eddy pattern in LA bight

11. Marine cloud 21 May 1500 UTC Note eddy pattern in LA bight

12. Marine cloud 21 May 1500 UTC Nearly clear in ops area

13. Clouds in WRF:Are they in the right places? 16 May 21Z Testing several methods of prognosing or diagnosing cloud fraction Evaluation of cloud fraction, cloud base, and cloud top is ongoing Look at: Offshore N and central LA bight Monterey Bay LA near-shore land

14. Bay Area inflow to Central Valley Flexpart plots of Bay Area CO tracer (left) and all other CO (right) show approximately equal contributions at Sacramento at 1500 UTC 4 June

15. Questions? http://www.esrl.noaa.gov/csd/metproducts/wrf http://www.esrl.noaa.gov/csd/metproducts/flexpart/#back Wayne.M.Angevine@noaa.gov

20. Cloud top along ship track RH tops too low in REF, better in TEMF, but uncorrelated with measurements TEMF internal top is correlated, but systematically low (consistent with LAX wind measurements)

21. Met data along ship track TEMF qv better than REF (deeper BL?) Temperature maybe better but not clearly No clear winner in wind speed or direction