Relevant timescales: convective events diurnal intraseasonal. 3 ocean-atmosphere communication methods: freshwater flux flux momentum flux

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Radar Perspective on Air-Sea Interactions during DYNAMO

Dolan, Jim Moum, Aurelie Moulin, Chris Fairall, Bob Rilling,

communication methods: net heat flux buoyancy freshwater flux

1 Radar Perspective on Air-Sea Interactions during DYNAMO Elizabeth Thompson; July Update Steve Rutledge, Brenda Dolan, Jim Moum, Aurelie Moulin, Chris Fairall, Bob Rilling, Mike Dixon, Scott Ellis, Scott Powell 1 3 ocean-atmosphere communication methods: net heat flux buoyancy freshwater flux flux momentum flux Relevant timescales: convective events diurnal intraseasonal

Rainfall Estimation MOTIVATION: Single- and dual-polarimetric radar rainfall disagree S-Pol Hybrid Algorithm has not been modified or tested in tropical oceanic conditions Are rainfall microphysics

2DVD DSD EM scattering model radar variables conv/strat partitioning " ##Bringi et al. 2009: D 0 vs.

2 Rainfall Estimation MOTIVATION: Single- and dual-polarimetric radar rainfall disagree S-Pol Hybrid Algorithm has not been modified or tested in tropical oceanic conditions Are rainfall microphysics different in DYNAMO and TOGA COARE regions? If so, why and what rainfall relationships are needed? METHODS Gan & Manus Is. 2DVD DSD EM scattering model radar variables conv/strat partitioning " ##Bringi et al. 2009: D 0 vs. log 10 (N W ) linear regression R(z) & R(K dp ): conv/strat R(K dp, ζ dr ) R(z, ζ dr ) What are the contributions of stratiform and convective rainfall to total rain? Rainfall errors are limiting factor in parameterization motivations/ implementation REMAINING RESEARCH Assess rain PDFS for old vs. new relationships (CSU, NCAR, MISMO, TOGA-COARE, GATE) Assess error 2

3 Microphysics of tropical, oceanic rainfall smaller, quasispherical, high LWC drops more oscillations w/o ice core? 3

Reflectivity Conv/Strat partitioning (c/o

100 km High resolution rainfall maps More

4 Reflectivity Conv/Strat partitioning (c/o Scott Powell UW) Nov Revelle radar Outcomes of rainfall estimation research: RAIN from MISMO z-r eq. RAIN from CSU z-r eq. 100 km High resolution rainfall maps More trustworthy rainfall rates = more meaningful rainfall metrics 4

Freshwater puddle hunts with Aurelie Moulin (OSU) MOTIVATION (convective) rainfall is the dominant contributor of spatiotemporal inhomogeneities in the air-sea buoyancy flux Freshwater puddles affect

mixing, overnight overturning, evaporation, additional precipitation Puddle days are also probably DWL days most puddles are advected to the ship RESEARCH OPPORTUNITIES Can the variability of radar

5 Freshwater puddle hunts with Aurelie Moulin (OSU) MOTIVATION (convective) rainfall is the dominant contributor of spatiotemporal inhomogeneities in the air-sea buoyancy flux Freshwater puddles affect upper ocean stability, available energy to atmosphere, and SST gradients The nature of freshwater puddles is still unknown differential heating from above, cooling from below, turbulence, wind mixing, overnight overturning, evaporation, additional precipitation Puddle days are also probably DWL days most puddles are advected to the ship RESEARCH OPPORTUNITIES Can the variability of radar observed rainfall explain (some) variability of observed puddles at the Revelle? convective/stratiform Can we isolate physical processes that lead to longlived puddles? METHODS find parents of orphaned puddles future (LES, CRM) modeling opportunities: investigate puddle formations/ lifecycles during suppressed phase test air-sea feedback mechanisms 5

6 not all puddles are created equally Nov hourly radar rainfall accumulation [mm] 0900 UTC 1700 UTC 150 km 6

non-negligible momentum flux from precipitating systems QUESTIONS How does the nature of radarobserved cold pools/gust fronts/ outflow boundaries vary with the MJO and diurnal cycle?

METHODS gust front/cold pool/outflow boundary detection algorithm with cell feature tracking compare Langrangian analysis with Eulerian observations at Revelle can we extrapolate local

7 non-negligible momentum flux from precipitating systems QUESTIONS How does the nature of radarobserved cold pools/gust fronts/ outflow boundaries vary with the MJO and diurnal cycle? spectrum of precip wind shear w/r/t MJO How do the radar derived characteristics of these features compare to those cataloged at the ship? METHODS gust front/cold pool/outflow boundary detection algorithm with cell feature tracking compare Langrangian analysis with Eulerian observations at Revelle can we extrapolate local responses throughout radar domain? Do these phenomena contribute significantly to diurnal ocean mixing cycle, ML/thermocline depth, and surface flux anomalies? (gustiness) 7 What is the role of cold pools on boundary layer recovery?

surface salinity change due to E-P heat flux from T rain -T ML MEANING As the surface loses

8 air-sea interface buoyancy flux DESCRIBES...flux into ocean ML through the air-sea interface due to: LW, SW, sensible, latent heat fluxes surface salinity change due to E-P heat flux from T rain -T ML MEANING As the surface loses buoyancy, the surface can become denser than below, causing convective overturning and mixing As the surface gains buoyancy, upper ocean becomes more stabilized 8

9 air-sea interface buoyancy flux Data Availability Flux balances at ships and buoys global satellite products have lower resolution precipitation radar data spans ~ 4-9 flux points Revelle radar: 150 km, 1.3 radius 1.0 grid 9

10 air-sea interface buoyancy flux Data Availability Flux balances at ships and buoys global satellite products have lower resolution precipitation radar data spans ~ 4-9 flux points Revelle radar: 150 km, 1.3 radius 0.5 grid 10

air-sea interface buoyancy flux NULL HYPOTHESIS: extent, frequency, organization, intensity of precipitation cannot explain variability in airsea

11 air-sea interface buoyancy flux NULL HYPOTHESIS: extent, frequency, organization, intensity of precipitation cannot explain variability in airsea fluxes on various time scales * develop horizontal mixing parameterization as a function of precip? 0.5 grid Revelle radar: 150 km, 1.3 radius 11

Summary for coupled atmosphere-ocean, wind and buoyancy forcing can lead to a sequence of events that make cause and effect difficult to determine Cronin and

12 Summary for coupled atmosphere-ocean, wind and buoyancy forcing can lead to a sequence of events that make cause and effect difficult to determine Cronin and Sprintall 2001 GOAL: Use observational air, sea, and interfacial datasets to document their (shared) variability and contributions to air-sea interactions during DYNAMO 12

13 Other ideas Mirai : SCTR interesting, but collaboration more likely DWLs vs. afternoon convection diurnal jet velocity no velocity data in upper-upper ocean barrier layer formation/erosion advection important, plus we left station order matters, what is the accumulated rainfall effect? What rainfall products would be useful to YOU? 13

14 Gan vs. Manus Island 2DVD Gan Island = subset of Manus Island, so rainfall should be same for DYNAMO and TOGA COARE... So why are Z-R relationships different? Are they really different?

< all 2DVD data log 10 (N W ) = -0.3*D 0 + 9.5 Bringi, V. N.

15 < all 2DVD data log 10 (N W ) = -0.3*D Bringi, V. N., C. R. Williams, M. Thurai, P. T. May, 2009: JTECH 6/11/13

Large-Eddy Simulations of Tropical Convective Systems, the Boundary Layer, and Upper Ocean Coupling

DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Large-Eddy Simulations of Tropical Convective Systems, the Boundary Layer, and Upper Ocean Coupling Eric D. Skyllingstad