Impact of Sea Surface Temperature Errors on Evaporative Duct Height LCDR Marc C. Eckardt

Evaporation Duct Height Model Motivation Evaporation Duct Height Model

SPY-1 Tactical Environmental Processor IT21 Radar Data via Passive Data Tap Radar Products TEDS/NITES (CVBG, ARG) Moriah Shipboard MET Conditions Ducts from Surface & Rocketsonde Obs Complements TEP Radar Measurements TEP AN/SPY-1 Radar “Through the Sensor” Measurements Real-Time METOC to 200 nmi - Day and Night Air Defense Support NOWCAST Support 200 nmi Surface Weather Refractivity and Duct Height Cloud Base/Tops † Volumetric Wind Mapping † Real-Time Volumetric Ducting (RFC) Radar Doctrine TDA (SEAWASP) Chaff Evolution Clutter Map, N-Time Around Clutter Automated Radar Optimization † † Low/Slow Flyers † † CIC Displays - VDDS Feed (CO/TAO) and RSC † = TEP Phase II † † = TEP Phase III Data Distribution to CVBG or ARG via SIPRNET and TEDS

SPY-1/TEP Aboard USS O’KANE Refractivity From Clutter (SPAWAR) Hazardous Conditions Florida Georgia Offshore Wallops Island, August 28, 1999 Chaff Mapping Hurricane Dennis August 30, 1999 Developing Chaff Cloud Nighttime Squall off JAX Sept 10, 1999 Wind Mapping Cloud Base/Tops Air Dropped Chaff, Hawaii OPAREA Dec 12, 1999 Winds off JAX Sept 10, 1999 Cloud Tops/Bases Mar 18, 1997

SMOOS Measurements SMOOS Upgrade Slide 5 SMOOS Upgrade Hope for the Best, Prepare for the Worst Air Temperature; Relative Humidity (Dew Point, Wet Bulb) Atmospheric Pressure (Station Pressure, Sea-Level Pressure, Altimeter Setting, Density Altitude, Pressure Altitude) Relative Wind (2 sec); True Wind (1, 2 & 10 min); Shift and Gust Vertical PTH Profile from Rocketsonde Upper Air PTH and Winds from UMQ-12 IR Sea Temperature (automatic); Sea Water Intake Temperature Cloud Height and Thickness (12 kft); Visibility/Precipitation Evaporation Duct Height; Modified Refractivity Profile (near real time) Future – IR Extinction; Rain Rate; Sea State Note: Derived measurements are in Italics

REF: 0001028_UK.PPT

SST Data “Main Unit” – data output every 52 seconds Injection temp Boom temp Air temp Relative Humidity “Bow Unit” – data sampled every 5s, output every 2 min IR sea temp Wind speed Manual logs - data recorded hourly IR sea temp Handheld IR sea temp Handheld IR sky temp Corrected the sea temp using   Tsea = [(Tmeas4 – (1- )Tsky4)/  ] ¼

SST Data Conclusions IR correction can make up to a 5% difference Accuracy of measurement ± .5° (within 1°) Calibration and cleaning (IR) is important

Evaporative Duct Evaporative Duct “Height” – actually axis height Bulk method uses Sea surface temp Air temp Relative humidity Wind Speed Profile dependent on stability of air-sea interface Calculated using Paul Frederickson’s model Limited to 100 meters

Different Types of Ducts 300 200 100 Height (m) Elevated Duct Surface-based Duct Evaporation Duct M

Evaporation Duct 15 10 5 Z0 Z (m) M 80 90 100 RH (%)

Duct Height Determination: Profile Approach zduct at M(z) = minimum Typical Unstable Conditions (T < 0) Typical Stable Conditions (T > 0) zduct= 72 m zduct= 7 m

Evaporative Duct Calculated duct height using ship injection temperature with a 0.5° STD Compared against wind speed and relative humidity Compared against air-sea T

Evaporative Duct 2nd run calculated duct height using uncorrected ship IR temperature with observed 0.644° STD Compared against wind speed and relative humidity Compared against air-sea T Results not as dramatic due to higher values (+1.7 ° mean)

Unstable Stable