Air – Sea Measurements from Ships: Fluxes, Time Series, Remote Sensing Dr. Jeff Hare CIRES – University of Colorado and NOAA Earth Systems Research Lab CSU ATS 650 Measurements Systems and Theory

Fasullo and Trenberth, J.Clim SI = Solar Insulation ASR = Absorbed Solar OLR = Outgoing Longwave F S = Net Surface Flux R T = Net Radiation F A = Energy transport (atm)

NOAA Ship Ronald H. Brown

Turbulent fluxes (direct covariance) Latent heatρL v [W/m 2 ] Sensible heatρC p [W/m 2 ] Momentumρ [N/m 2 ] Gas (etc) Instruments: Sonic anemometer (wind, temperature) Infrared gas analyzer (humidity, CO2, etc) Motion (roll, pitch, yaw, heave, surge, sway) GPS/Compass/Doppler speed

t 1 = L / (c + v) ; t 2 = L / (c - v); v = 0.5 L (1/t 1 – 1/t 2 ); c = 0.5 L (1/t 1 + 1/t 2 ); T s = c 2 / 403; T = T s / ( e / p) L = path length t = time of flight c = speed of sound v = wind velocity T = temperature T s = “virtual” temp p = pressure e = water vapor pressure

Absorptance of a particular gas α = 1 – A / A o A = power received at absorbing wavelength A o = power received at non-absorbing wavelength ρ = P e f(α / P e ) [mol m -3 ] number density ρ = P e f([1 – z A / A o ] S / P e ); P e is equivalent pressure S is ‘span’ Channels available for water vapor and CO 2 Infrared Gas Analyzer (IRGA)

Ƭ = ρ + ρ + ρ streamwise transverse wave stress U = + u’ + u ~ V = + v’ + v ~ W = + w’ + w ~ Wind stress (momentum flux) drives currents and waves, thus driving heat transport in the ocean. Wind Stress

H s = ρ C p Sensible heat flux H L = ρ L v Latent heat flux T = + θ’ Q = + q’ Heat transfer between the sea surface and atmosphere is another primary driver of ocean circulation Heat Fluxes

Using advanced techniques for direct measurement of air-sea fluxes, we have obtained data from oceans around the world. This data has been used to develop parameterizations to estimate air-sea fluxes from mean state variables (wind speed, air temperature, sea temperature, humidity, etc). Air-sea fluxes of heat (latent/sensible) are also fundamental to cloud development (hence, surface energy budget, precipitation, etc).

Ron Brown Mast

NOAA/ESRL Turbulent Flux System

Example of power spectra for wind velocity components

Flow distortion study

Energy Budget Q NET = Q S ↑ + Q S ↓ + Q L ↑ + Q L ↓ + H S + H L + Storage Net at the surface Shortwave up/down (albedo) Longwave up/down Sensible turbulent heat flux Latent turbulent heat flux Q L ↑ = ε(σT 4 -Q L ↓)

Surface energy budget study from Stratus 2003

Radiative fluxes / Clouds / Water vapor / Boundary layer profiles Downwelling solar Downwelling IR Cloud base height, cloud fraction T / RH / wind profiles Instruments Pyrgeometer (PSP) Pyranometer (PIR) Ceilometer 60 GHz scanning microwave radiometer C-band radar Wind profiling radar (915 MHz) Cloud radars (35 GHz [K a ], 94 GHz [W])

Eppley PIR (longwave) Eppley PSP (shortwave) Issues with roll, pitch of ship are resolved with stabilized platform

TAO/PACS Heat Fluxes 95 & 110˚W Model TAO buoy WHOI ( ) [Yu and Weller 2007] CORE ( ) [Large and Yeager 2004] NOAA ship observations ( ) [Fairall et al. 2008] GFDL CM2.1 latent sensible longwave solar net IROAM north latitude

NOAA Ship Ronald H. Brown

Ron Brown C-band Radar reflectivity 08:00 UTC 08/01/2004

Ron Brown C-band Precip Radar

Radiometers and raingauge Radiosonde launch can be difficult

ceilometer Radiometers 23 – 32 GHz Passive “Mailbox” -> integrated water vapor, liquid, brightness temperature

Radiometrics Model GHz Continuous water vapor profiles up to 10km, integrated liquid water. NOAA ESRL also has a Model WVR-1100 (mailbox)

TeraScan visible image with Stratus Buoy (NOAA-18, 20:43 UTC 10/19/2006) GOES, NOAA, DMSP, SeaWiFS, Aqua, etc

Ron Brown 915-MHz Wind Profiler

Water-side measurements Currents Temperature and salinity profiles Wave measurement systems Instruments Conductivity temperature depth (CTD) Acoustic Doppler current profiler (ADCP) WAMOS Laser altimeter

CTD Strain gauge pressure sensor Thermistor to measure temperature Conductivity = Current / Voltage (1/R) Uses a bridge circuit to detect small changes in resistance

CTD and water sampling bottle array ADCP

WAMOS (Wave and Surface Current Monitoring System)

Significant wave height (height of the highest 1/3 of waves) H s = 4 1/2 ζ is the standard deviation of surface displacement. ω = 2 π f ω is wave frequency (f is in Hz) ω = 2 π / TT is wave period k = 2 π / LL is wave length ω 2 = g kDeep water c = (g/k) 1/2 Phase velocity

PACS Synthesis Examples

Liquid and vapor water column diurnal sampling

diurnal sampling degrees longitude height (km) surface LCL cloud base cloud top Cloud height

cloud base 10% higher than LCL Cloud base above 900 m decoupled from surface layer Effect of stratification and mixing on cloud base

“Sea Snake” Surface temperature measurement