PLAN

1. An Update on A Few Issues Relevant to OceanSalinityRetrieval for SMOSJoe TenerelliSMOS QualityWorking Group 11July 4-5 2013ESA ESRIN

2. PLAN Part 1: Review of celestialskymaperrors and the potential impact upon the oceanbiases. Part 2: Review of the impact of Level 1 Version 601 on oceanbiases. Part 3: Review of impact of the All-LICEF approach on oceanbiases.

3. Part 1:On the Errors in the CelestialSkyBrightnessMaps for SMOS and AQUARIUS

4. CELESTIAL SKY BRIGHTNESS AT L-BAND Radiation from distant sources incident atearth’s surface… From: http://en.wikipedia.org/wiki/Celestial_sphere

5. CELESTIAL SKY BRIGHTNESS AT L-BAND Need a coordinate system to describethis radiation: Use equatorialcoordinates (spherical) Images takenfrom: http://hyperphysics.phy-astr.gsu.edu/hbase/eclip.html

6. CELESTIAL SKY BRIGHTNESS AT L-BAND The celestialsky radiation is the sum of unpolarizedcosmicmicrowave background radiation (2.7), hydrogen line emission (up to around 3 K) and continuum emission (dominant along the galacticequator): CMB+continuum Hydrogen line emission total + =

7. SUMMARY OF PROBLEM Below are the twoskymaps, one from ESA and the otherfrom NASA, that are currentlyused for analyzing SMOS data. They have been produced by combining the cosmicmicrowave background, continuum, and hydrogen line emission contributions. The ESA mapisdocumented to be in B1950 equatorialcoordinates (EC) while the NASA mapisdocumented to be in J2000 equatorialcoordinates. There is a shift of about .64o in right ascension betweenthesetwocoordinatesystems. Herewe have remapped the NASA mapinto B1950 EC. ORIGINAL ESA MAP IN B1950 EC ORIGINAL NASA MAP IN B1950 EC

8. SUMMARY OF PROBLEM Unfortunately, itappearsthat, up to this point, theseESA and NASA skymaps for the 19 MHz MIRAS bandwidth have containedsignificantsystematicerrorsthatreachseveral kelvin in the first Stokes parameterdivided by two. Compared to the ‘correct’ skymap for MIRAS, the errormaps (first Stokes parameterdivided by two) are shownbelowin B1950 equatorialcoordinates. ESA MAP ERROR NASA MAP ERROR

9. The error in the ESA skymapismostlyrelated to an inversion of the hydrogen line contribution in galactic latitude and longitude, before transformation intoequatorialcoordinates: Transformation of hydrogen line contribution fromgalactic to equatorialcoordinatesrequiredbeforeadding to the continuum map. From: http://en.wikipedia.org/wiki/Celestial_coordinate_system

10. Original version of Floury HI line map in B1950 equatorialcoordinates:

11. NASA SMOS 19 MHz HI line map in B1950 equatorialcoordinates. This version isinverted in bothgalactic latitude and longitude relative to the Floury HI line map. This map shows the correct orientation:

12. Second version of Floury HI line map in B1950 equatorialcoordinates. This one isstillerroneouslyinverted in galactic latitude:

13. Most recent (and best) version of Floury HI line map in B1950 equatorialcoordinates:

14. Original version of Floury HI line map – NASA SMOS HI line map (Th+Tv)/2 in B1950 equatorialcoordinates:

15. Second version of Floury HI line map – NASA SMOS HI line map in B1950 equatorialcoordinates:

16. Third (latest) version of Floury HI line map – NASA SMOS HI line map in B1950 equatorialcoordinates. Much better but thereisstill a smallsystematicdifference the maps.

17. This systematicdifferenceis more clear if wereduce the range of the colorscale:

18. LatestFloury HI line map– NASA SMOS HI line map in B1950 equatorialcoordinates.This mapdiffersfromthat of the previousslide in thathere I have transformed the HI line contribution fromgalactic to B1950 equatorialcoordinatesmyselfusing a transformation thatagreesexactlywithindependent sources available on the internet. The residualsystematicdifferencesseem to bereducedfurther.

19. THE CONTINUUM MYSTERY The skymaps for the Aquarius and SMOS missions are provided in equatorialcoordinates, withsphericalcoordinatesnamed ‘right ascension’ and ‘declination’. Belowis the total skybrightnessmap in ‘B1950’ equatorialcoordinates:

20. THE CONTINUUM MYSTERY The ‘B1950’ refers the thereference direction used to define the equatorialcoordinate system. The reference direction isdefined to correspond to the vernal (or northernhemispherespring) intersection of the earth orbital and equatorial planes, as shownbelow. Owing to precession (and to a muchsmallerextent nutation, or ‘wobbling’), thisreference direction shifts slowly relative to the stars, and soitisnecessary to specify a date atwhich the intersection istaken.Twocommonreferences are B1950 (reference direction takenat the beginning of the Besselianyear 1950) and J2000 (reference direction takenat the beginningof the Julian year 2000). Additionally, the coordinate system reference direction may or may not takeintoaccount nutation. If itdoes, then the coordinate system isreferred to as ‘true of date’, otherwiseitisreferred to as ‘mean of date’. Images takenfrom: http://hyperphysics.phy-astr.gsu.edu/hbase/eclip.html

21. THE CONTINUUM MYSTERY The transformation from B1950 to J2000 equatorialcoordinatesismainly a shift of lessthan 1o in right ascension:

22. THE CONTINUUM MYSTERY Now the discrepanciesshown in the precedingslidesinvolveonly the hydrogen line emission. It turns out that the continuum mapsagreeperfectlyawayfromCassiopeiawhen the maps are comparedwith no coordinate transformations applied. This issurprisingbecause the NASA mapisdocumented to be in J2000 EC while the ESA mapisdocumented to be in B1950 EC. NASA CONTINUUM TRANSFORMED TO B1950 EC (ESA B1950 EC)-(NASA B1950 EC) Cassiopeia STRANGE: THE DIFFERENCE MAP ON THE RIGHT SHOULD BE ZERO AWAY FROM CASSIOPEIA!

23. THE CONTINUUM MYSTERY Differences in the precedingslidesinvolveonly the hydrogen line emission. It turns out that the continuum mapsagreeperfectlyawayfromCassiopeiawhen the maps are comparedwith no coordinate transformations applied. This issurprisingbecause the NASA mapisdocumented to be in J2000 EC while the ESA mapisdocumented to be in B1950 EC. NASA CONTINUUM IN DOCUMENTED J2000 EC (ESA B1950 EC)-(NASA J2000 EC) Cassiopeia INSTEAD, THE NASA MAP IN DOCUMENTED J2000 EC MATCHES THE ESA MAP IN B1950 EC!

24. ESA – STOCKERT CONTINUUM To determine the coordinate system of the ESA and NASA continuum maps, the original Stockert continuum maps for the northernsky in both B1950 and J2000 EC weredownloaded and compared to both the ESA and NASA continuum maps in their original coordinatesystems (B1950 EC for the ESA map and J2000 EC for the NASA map). Belowwe show the comparison for the ESA continuum map. Obviously the ESA continuum agreeswith the B1950 EC Stockertmapawayfromtwo areas where the Stockert data have been deliberatelymodified. (ESA)– (STOCKERT IN J2000 EC) (ESA)– (STOCKERT IN B1950 EC) Cassiopeia Northern and southernskymapoverlap

25. NASA– STOCKERT CONTINUUM Surprisingly, the NASA continuum mapalsoagreeswith the B1950 EC StockertmapawayfromCassiopeia and the declination range where the southernsurvey information wasapparentlyintroduced. This issurprisingbecause the NASA mapisdocumented to be in J2000 EC, not B9105 EC. But the continuum portion isobviously in B1950 EC. In factitisidentical to the ESA continuum awayfromCassiopeia. Unfortunately; because the HI component isis J2000EC, the total NASA skymapis the sum of the B1950 EC continuum and the J2000 HI maps, whichis not a consistent sum. Therefore the total skymapiserroneous. (NASA)– (STOCKERT IN J2000 EC) (NASA)– (STOCKERT IN B1950 EC) Cassiopeia Northern and southernskymapoverlap

26. The following four slides show the original ESA skymap, followed by the two best ESA maps and, finally, the NASA map for the MIRAS bandwidth of 19 MHz. The current ‘best’ mapis the thirdslide and youcan flip between the slides to compare. All mapsshow the first Stokes parameterdivided by two for the total skybrightness (CMB, continuum, and 19 Mhz hydrogen line emission).

27. The original mapfromFlourywith HI line mapflipped in bothgalactic latitude and longitude:

28. The mostrecentmapfromFlourywith HI line mapcorrectlyoriented but with a verysmalldistortion relative to the NASA HI line map:

29. The mostrecentmapfromFlourywith HI line mapcorrectlyoriented and adjusted to remove the remainingdistortion relative to the NASA HI line map:

30. The NASA skymapwith the J2000 EC HI line maperroneouslyadded to the B1950 EC continuum map:

31. The followingtwoslides show the errors in the original ESA skymap and the current NASA map for the MIRAS bandwidth of 19 MHz, relative to the current ‘best map’. The mapsshow the error in the first Stokes parameterdivided by two.

32. The error in the original ESA skymapinvolveserror all along the galacticequatorwithtoolittlebrightnessnear the brightest portion of the galaxy:

33. The error in the current NASA mapismostly a shift of the map to smaller right ascension. Rough surface scatteringwill tend to smooththis out and reduce the error:

34. Potential Impact of SkyMapErrorson BiasCalculations • Caveats: • Impact assessed by comparingresultsusing NASA and ESA skymaps. • Donebeforeweknew the NASA mapiswrongtoo. • Ned to reevaluateusing the correct skymap.

35. OLD GALACTIC (DPGS MAP)

36. NEW GALACTIC (NASA SKY MAP)

38. OLD GALACTIC (DPGS MAP)

39. NEW GALACTIC (NASA SKY MAP)

41. IMPACT HARDLY VISIBLE AFTER INTEGRATION FROM 40oS to 5oN:

42. CONCLUSIONS FOR PART 1 Both the ESA and NASA skymaps have containederrors of up to several kelvin in the first Stokes parameterdivided by two up to this point. There errors in the twomaps have differentorigins and the spatial patterns of the errorsdiffer. Impact on bias analyses appears to be minimal baseduponcomparingbiasesderivedfrom the ESA and NASA skymaps. Must reevaluatethis conclusion with the correct skymap.

43. Part 2:Comparing the Operational and Level 1 V601 Solutions in Terms of Bias over the Ocean

44. COMPARING OPERATIONAL AND V601 LEVEL 1 BIASES OVER THE OCEAN Many changes in V601 relative to currentoperationalLevel 1 Processor, but two key changes are: L1 isfixed (at 0.15 dB) ratherthancomputedusing the 1-slope model; Only NIR CA isused for the zerobaselineratherthanbothNIRs BC and CA. Wewill examine the impact of these changes on 76 eastern Pacific half-orbits (38 ascending and 38 descending) fromJune 2010 to January 2013.

45. COMPARING OPERATIONAL AND V601 LEVEL 1 BIASES OVER THE OCEAN In terms of ascending and descending passes separately, withbiasesaveragedbetween 40oS and 5oN:

46. COMPARING OPERATIONAL AND V601 LEVEL 1 BIASES OVER THE OCEAN Descending-ascending passes, withbiasesaveragedbetween 40oS and 5oN. V601 descendingpass drop late in yearis about halfthat for the operational L1:

47. COMPARING OPERATIONAL AND V601 LEVEL 1 BIASES OVER THE OCEAN Comparing NIR TA and corresponding AF-FoVbiases, averagedbetween 25oS and 5oN. Good correspondence for ascendingpasses.

48. COMPARING OPERATIONAL AND V601 LEVEL 1 BIASES OVER THE OCEAN Correspondence for descending passes is not as good late in the year, withdescrepanciesbetween NIR TA and AF-FoVbiasesreaching up to 0.4 K. For V601 the seasonal cycle in NIR CA issmallerthan in NIR CA, but the interannual drift islarger for NIR BC.

49. COMPARING OPERATIONAL AND V601 LEVEL 1 BIASES OVER THE OCEAN Descending-ascendingpass AF-FoVbiasesaveragedbetween 25oS and 5oN. Magenta curve shows impact of V601 relative to operationalL1:

50. COMPARING OPERATIONAL AND V601 LEVEL 1 BIASES OVER THE OCEAN If we overlay in cyan the differencebetween V601 NIR TA and operational TA the curve matches veryclosely the AF-FoVcurve: