200 likes | 331 Views
Surface and Boundary-Layer Fluxes during the DYNAMO Field Program C. Fairall, S. DeSzoeke, J. Edson, +. Surface cloud radiative forcing (CF) Diurnal cycles Surface flux product Radar turbulence and microphysics retrievals Convective mass flux parameterization. Cloud Forcing.
E N D
Surface and Boundary-Layer Fluxes during the DYNAMO Field ProgramC. Fairall, S. DeSzoeke, J. Edson, + • Surface cloud radiative forcing (CF) • Diurnal cycles • Surface flux product • Radar turbulence and microphysics retrievals • Convective mass flux parameterization
Cloud Forcing • Cloud forcing is the difference in the observed mean radiative flux versus what the flux would be in the absence of clouds
Mean Tropical Surface Energy Budget Terms TOGA COARE – a 3 month study of MJO and surface fluxes in the equatorial W. Pacific. JASMINE – a 40-day study of pre-monsoon and monsoon convection In the Bay of Bengal. EPIC – A multi-year set of 1-month cruises in the equatorial E. Pacific and the ITCZ. DYNAMO – a 3-4 month study Of MJO and surface fluxes in the equatorial Indian Ocean
Diurnal • Jim Edson produced updated code for coare warm layer • Also interested in diurnal variations in cloud properties.
Diurnal SST Averages in Wind Speed/Forcing Ranges:Snake and TSG: Measured and Modeled Wind speed bins: upper – strong; middle – med; bottom - light Forcing: upper – suppressed; middle – disturbed; Lower - MJO
Correcting the TSG to the Surface Mean diurnal cycle of TSG, Snake, and model estimate of Snake based on TSD Individual diurnal time series of Snake – Tx. Upper – Tx=TSG, observed; lower Tx=Tsnake model using TSG
Surface Flux Product • Spatial grid in IO region. Daily and/or 6 hr • Turbulent, radiative, precip: Blended from various products • Use in situ to evaluated accuracy. High-resolution (0.1250) radiative fluxes for one day as generated from METEOSAT-5.
Microphysic vs Turbulence • W=Wfall+Wturb • Frisch et al - 3 radar moments to 3 moments of gaussian drop distribution. Means • Pinsky – separate Vg and Wturb time series assuming variations uncorrelated • Keys on <W(dBZ)> • Wturb=a0/sig(Z)*(W-<W(dBZ)>) • Shupe et al – Relate true air motion to left side of Doppler spectrum
Application to BL Turbulence Parameterization • Local vs Non-local Turbulence closures Local gradient Non local convective mass flux Sigma is updraft area fraction Updraft fraction related to velocity skewness Mass flux related to vertical velocity moments Eddy diffusion coefficient related thru dissipation time scale Hybrid
Concept: Use Wband for incloud and Lidar for subcloud and between cloud