Satellite Oceanography: from Concept to Implementation and Launch Yi Chao [email protected] 818-354-8168 1 A brief history about my long science career • 1980-85, B.S. Atmospheric Physics, University of Science & Technology of China • 1985-87, M.A., Geophysical Fluid Dynamics, Princeton University • 1987-90, Ph.D., Atmospheric and Oceanic Sciences, Princeton University • 1990-93, Postdoctoral Fellow, UCLA Dept. of Atmospheric and Oceanic Sciences • 1993-present, Jet Propulsion Laboratory, California Institute of Technology China – Scientist (1993-96), Research Scientist (1997-2004), Principal1985-90 ---1980Scientist (2005-present) – Supervisor of Ocean-Atmosphere Interaction group (2005-06), 1980-85 Deputy Manager for Earth Remote Sensing Science Section (2006-07) 1990-present 2 • 2006-present, Adjunct Professor, UCLA Dept. of Atmospheric and Oceanic Sciences & Joint Institute for Regional Earth JPL is known as sending Rovers to Mars 3 JPL’s Mission to Planet Earth 10 missions/instruments in operations; ~600 active engineers/scientists Operational Development Carbon Cycle: QuikSCAT Ocean Surface Orbiting Carbon ACRIMSAT (1998) MISR Topography Sea Surface Observatory (OCO) (1999) (1999) Mission Salinity: (2008) (2008) Aquarius (2009) Columbia ASTER GRACE Supercomputer, Jason-1 (1999) (2002) (2001) 10,240 Intel Itanium®2, AIRS (2002) SGI® NUMAflex™ MLS architecture, (2004) Linux operating system, 440 TES CloudSat terabytes online, (2004) (2006) 10 petabytes4 tape ------ OUTLINE ------ • History of Satellite Oceanography • Overview of Present and Future Satellite Missions – Sea surface temperature – Sea surface topography (or sea level) • Theory/Method (how to measure?) • Application Examples (how to use the data?) • Aquarius sea surface salinity satellite – From concept to implementation and launch • Summary and concluding remarks 5 Satellite Oceanography or Satellite Remote Sensing • Remote Sensing: any technique which measures the ocean remotely without actually sampling it, or putting instruments in the water. • In addition to satellite oceanography, remote sensing includes measuring from land-based platforms, airplanes or by acoustic methods (tomography) 6 In Situ Observations: Early Sea Exploration (1873-1914) Challenger Expedition •226 feet, 3.5 years •362 stations, 68,890 nautical miles •100+ scientists, 29,500 pages report 7 Modern In Situ Observations: World Ocean Circulation Experiment (1990-2002) 8 Why Do We Measure Ocean from Space? It is impossible to measure the global ocean from in situ platforms •In situ measurements over a large area (e.g., basin to global scale) can be expensive, and impractical (satellite measurements can be simultaneously over large areas or even the global ocean) • Ship operations are limited to relatively calm conditions; however, many interesting processes occur in those places that make ship operations impractical (e.g., winter time in the Labrador Sea) 9 1st Weather (Meteorological) Satellite (1960) 10 1st Oceanographic Satellite (1978) Satellite’s view of the Gulf Stream 1770 Benjamin Franklin (postmaster) collected information about ships sailing between New England and England, counting dolphin populations (located near the fronts), discovering and mapping the Gulf Stream 11 Global Ocean Observing System from Space: Golden Age of Satellite Oceanography TRMM GPM (2010) QuikSCAT AVHRR TOPEX/Poseidon SeaWiFS TMI, AMSR Aquarius (2009) Jason 12 MODIS GOES OSTM (2008) Sea Surface Temperature Satellites 13 How to Measure Sea Surface Temperature from Space • Physics: B( λλλ, T)=2 εεεhc 2/ { λλλ5[exp(hc/kT λλλ)-1]} Blackbody radiation – Through molecular motion, all substances above absolute zero emit radiation (e.g., thermal infrared) 14 Blended Satellite and In Situ SST (Weekly for Climate Applications) 15 New Technology: Microwave SST Imager seeing through clouds 16 Ocean Surface Topography (Sea Level) Satellite 17 How to Measure Sea Level from Space? Satellite Altimetry 830 miles, 4 miles/sec 10-day repeat Accuracy < 2 inches 18 IPCC-2001 Application Examples: Tracking Global Sea Level Rise 19 Ocean Winds Satellites 20 Tracking Hurricanes with Satellites 21 Sea Surface Salinity Satellite: from concept to implementation and launch Planning : Formulation : Implementations : Launch : Needs Concept Cut-metal Operation Community Theory Build Components Data return Academy Design Test Analysis Budget Test Integration Science Schedule Iterations Test Applications Peer-reviews Education 22 I (We the oceanographers) have a dream! 23 Salinity affects water density that drives ocean circulation It is gravity! (hot air rises; heavy water sinks) 24 Salinity is a missing piece of the climate puzzle: Melting ice changes ocean salinity At high latitudes, salinity determines the density and controls the sinking of water Speedup/slowdown of the “conveyor belt” will impact weather & climate 25 Earth Water Cycle is Constantly Changing: Ocean’s Response to Hurricane Rain Hurricane Isabel (2003) accumulation of rainfall as measured by TRMM satellite. Over 400 trillion tons of freshwater were dumped on the North Atlantic Ocean during this26 event. How to Measure Salinity from Space? Find an engineer to find out how Tb = e T e = Emissivity T = Physical Temperature e = function ( freq, S, T ) = 1 - R2 = 1 - [(1-√ε)/(1+ √ε)] 2 (normal incidence) ε = Relative Dielectric Constant = ε(freq, S, T) 27 How do you know theory works? First test in the controlled environment JPL Salt Water Pond Measurements L-Band Vertical (20-40 psu at 26 C) Oct 28 K&S Model Input file: D:\PALSTest\Oct1\10282029r.smr 1 40 1 35 1 30 Tant (K) 1 25 1 20 20 25 30 35 40 45 SSS (psu) L-Band Horizontal Oct 28 K&S Model Input f ile: D:\PALSTest\Oct1\10282029r.smr 8 2 8 0 7 8 7 6 7 4 Tant(K) 7 2 7 0 6 8 20 25 30 35 40 45 SSS (ps u) Pond Size: 3.7 x 4.3 x 0.1 m 28 Aircraft Test the Concept: Looking for the big signal Gulf Stream field experiment, 1999 29 Test what you fly: The same configuration to be used in space Instrument being mounted on top of the back door of the C-130 aircraft, which flies at 10,000 feet with the back door open. 2000 & 2003 Monterey Experiments 30 How do we know the accuracy of remotely- sensed salinity? Ground truth from ship Fishing Boat being rented for a 2-day cruise @ 5K/day Taking water samples from a pipe/pump and run through a conductivity sensor 3 7 3 6 Project 3 5 Scientist at sea: SSS Retrieval 3 4 exciting Salinity (PSS) 3 3 Sh ip SSS moment at a 3 2 fishing break 37 37.1 37.2 37.3 37.4 Latitude (deg) 31 Proposal, Funding, & Implementation Aquarius instrument accuracy will be 0.2 psu/ppt. How much salt should be added to 1 gallon of water to change its salinity by 0.2 psu? • 1 tablespoon • 1 teaspoon • 1/2 teaspoon 32 • 1/6 teaspoon Implementation (fast forward): Money JPL Director & Solar Mars Astronomy Earth Work Breakdown Structure (WBS) Management System Exploration & Physics Science & Explorati Technology on Systems & Software Science Communication s, Tracking, Radar People Autonomous Systems Mechanical Systems Enterprise Engineering Instruments & Science Data Milestones and Reviews Systems Cost Estimation 33 Satellite Launch: July 2009 34 Aquarius Salinity Satellite Operations Ground Track Equator Aquarius Sun Line Ground Track Stowed in fairing Sun Lit Side Shadow Side Deployed configuration Science Data Center Delta 7320-10 8 days from VAFB Mission Operations Center Global salinity map (To be launched in 2009) 35 SUMMARY (take-home messages) • In-water measurements are difficult and expensive; Satellite is the only method for global coverage within days • Ocean satellites are routine: sea surface temperature, sea level, wind, ocean color • A missing piece of the puzzle: sea surface salinity satellite to be launched in 2009 • Satellite, from concept to implementation and launch, takes 5-10 years 36 Limitations of Satellite Oceanography • Satellite oceanography is – technologically challenging: 1 st satellite dedicated for oceanography in late 1970s – at high cost: a single satellite costs >$100M to build, and ~$50M to launch; – at high risk: a satellite has a design lifetime of 3 years; it is not uncommon that a satellite failed within 3 years; single point of failures • Satellite data have much larger errors simply because it is 100s miles away from the ocean surface • Satellite can only measure the ocean surface (except the upcoming laser technology) 37 Satellite Oceanography: An importance piece of the ocean puzzle Observations Theoretical & Education (satellite, in situ) Numerical Public Outreach Models Data Synthesis Input Products Forecasting Feedback 38.