Aqua Mission Review Atmospheric Infrared Sounder

1. Aqua Mission ReviewAtmospheric Infrared Sounder Moustafa Chahine, AIRS Science Team Leader Hartmut G. Aumann, AIRS Project Scientist Bjorn Lambrigtsen, AMSU Instrument Scientist Steven Friedman, AIRS Project Manager (Acting) August 23, 2005 Jet Propulsion Laboratory California Institute of Technology Pasadena, CA

2. http://airs.jpl.nasa.gov • The AIRS/AMSU/HSB data will be used to address several climate questions • Improving weather prediction: AIRS Already Achieved 6 hours in 6 days improvement in NH with NCEP Operational Model (JCSDA) • Climate Studies: Determine the distribution and variations of water vapor - Earth’s primary greenhouse gas • Tropospheric Minor Constituents: O3, CO2, CO, CH4, SO2. • Will provide the first satellite global map of the distribution of the tropospheric concentration of CO2

3. AIRS – Providing High Quality Sounding Data • AIRS provides extensive data for weather and climate analysis: • Daily coverage exceeds 90% of Earth’s surface and atmosphere • Nearly continuous coverage from August 31, 2002 forward • In 3+ years since launch in May 2002, AIRS continues to provide hyperspectral sounding data that is: • Uniquely stable • frequencies stable to <5 ppm • radiometry stable to <8mK/Y • Effective for studying diurnal, seasonal, annual climate trends • AIRS data products available to the public: • Calibrated Level 1B radiances available since November 2002 • Validated Level 2 products available since September 2003 • Validated Level 3 products available since April 2005

4. Above 500mb Total Version 4 Core Science Products Jan. 03 Clouds Jan.03 Tropospheric H2O Jan. 03 Air-Surface Temp

5. OPERATIONAL ACHIEVEMENTS • AIRS has been a key weather forecasting data source for more than 2 years • Using JPL developed software, NOAA processes and distributes AIRS data to global numerical weather prediction centers: • AIRS data assimilated by: • NOAA/NCEP • ECMWF • UKMetOffice • Use of AIRS data has increased the accuracy of weather forecasting. • 6-hour improvement in six-day weather forecasts • “Normally takes several years to achieve at operational weather centers…” • “This magnitude of improvement is quite significant when compared with the rate of general forecast improvement over the last decade.” – John Le Marshall (JCSDA) • Improves accuracy of positioning and intensity of Tropical Cyclone (TC) forecasts • “We can say with reasonable confidence that AIRS has an important impact on TC forecasts.” – James Cameron (UKMetOffice)

6. AIRS PUBLICATIONS • Publications by AIRS Team (JPL and external) • 39 publications in 2004 • 17 publications during 2005, to date • Special sessions on AIRS conducted at: • American Geophysical Union San Francisco Fall Annual Meeting, December 2004 • American Meteorological Society Annual Meeting, January 2005 • American Meteorological Society Annual Meeting, January 2006 (scheduled) • Submitted for publication: • 1 article: Bulletin of the American Meteorological Society (BAMS) • 1 article: Geophysical Research Letters (GRL) • Scheduled for publication: • 15 papers: special issue in Journal of Geophysical Research (JGR) on AIRS Validation (Publication date: early 2006)

7. RECENT SCIENCE ACHIEVEMENTS • AIRS Channel Slicing Used to Depict Upper Tropospheric Moisture • Intense convective activity associated with a hurricane pushes water into the upper troposphere, measured by AIRS • The upper tropospheric water above 300 mb was measured by AIRS on Aqua • 1:30 pm overpass on Saturday July 9, 2005 • Hurricane Dennis was at its peak intensity. Note the band of elevated upper tropospheric moisture along the path of the hurricane.  AIRS Infrared Window Channel AMSU Channel AIRS Near IR

8. RECENT SCIENCE ACHIEVEMENTS CH4 Aerosols Barnet, NOAA Strow, UMBC TotalOzone SO2 Irion, JPL CO Lee, JPL AIRS MODIS Anatahan April 6, 2005 McMillan, UMBC

9. SCIENCE ACHIEVEMENTS • AIRS is well suited to study a number of processes poorly represented in numerical weather models: • Tracking upper tropospheric water vapor variations(Chahine / Hearty, JPL) • Madden-Julian Oscillation (Tian, JPL/Caltech) • Cirrus Clouds (Kahn, JPL) • Recent studies with trace gases and aerosols show promising results, many of which are only available with AIRS globally: • CO2(Chahine, JPL) • CO (McMillan, UMBC) • Silicate signatures (Strow, UMBC)

10. AMSU-A1 POWER BUS CURRENT SPIKES • Current spikes detected on the AMSU-A1-2 noisy bus that powers the AMSU-A1-2 antenna • Spikes, first identified during May 2005, have tapered off since July 1 • At peak, maximum current was ~50mA, 7% over normal • Peak current remained well below red limit of 125 mA • Current spikes have NOT affected instrument operations • This specific problem: • Has been logged in an ISA • Is being closely monitored • Has been studied in detail • There is no imminent danger to the AMSU-A1 instrument at this time • NO indication of instrument failure • Recommendation: maintain routineoperations, continue monitoring • Note: AMSU instruments onboard Aqua have exceeded their three-year design lifespans andcontinue to perform well. AMSU instruments onboard other (NOAA) satellites continue to operate well beyond their projected lifespans.

11. AMSU-A1 POWER BUS CURRENT SPIKES • Potential Science Impact: • Generation of AIRS Level 2 Products currently uses AMSU for cloud clearing • Continued cloud clearing can be generated solely from AIRS data • It is the consensus of the AIRS Science Team that AMSU remains the preferred approach for AIRS cloud-clearing • Potential Forecast Impact to Numerical Weather Centers: Minimal • Minimal: Radiances are assimilated only, not AIRS retrievals

12. AMSU-A1 POWER BUS CURRENT SPIKES • Current Status • As a contingency measure, the AIRS Project is developing a modification to the Level 2 retrieval program that will successfully operate, even with the absence of AMSU data. • GOAL: Complete and have upgrade available, should AMSU-A1-2 fail • JPL expects to complete this upgrade early this fall • Planned inclusion in Version 5 release • As long as AMSU-A1-2 continues in NORMAL operations, utilize AIRS and AMSU data in retrieval processing • The GSFC DAAC, NOAA and JPL continue to utilize AMSU data in all Level 1, Level 2 and Level 3 processes

13. Aqua Mission ReviewAtmospheric Infrared Sounder Backup Slides - AMSU Anomaly

14. Case study: July 18, 2005 ~1800 UT

15. Case study: Granules 171-189

16. AMSU-A1-2 anomaly analysis

17. Evidence, Hypotheses & Conclusions • The evidence • Increased mechanical resistance  increased motor current • Cooling caused by very cold Antarctic plateau (motor temp vs. OLR) • Anomalous heating @ closest approach to SP (10 minute lag) • Current anomalies started ~ May 1; peaked ~ July 1; now rapidly declining • The hypothesis • Anomaly is triggered by strong radiative cooling over the Antarctic plateau during winter and brief solar heating during transition from descending to ascending (sun illuminates nadir deck) • Solar heating does not vary by season but radiative cooling is strongest in southern winter • Cooling/heating differentials may cause thermal stress on scan system • Thermal stress may cause increased loading on motor bearings • Bearings may have deteriorated and now more susceptible to thermal stress/strain • There may have been deterioration/loss of thermal protection systems (MLI) • Anomaly is expected to reappear next southern winter • The conclusions • No cause for concern at this time • Instrument science performance is not affected • So far no indications of a deteriorating situation