Comparisons  of  in  situ  HIPPO  minor  gas  measurements  with  ground-­‐based  MIR  spectroscopically  

retrieved  VMR  profiles    Rebecca  Batchelor1,  Jim  Hannigan1,  

 Mike  Coffey1,  Akiko  Kagawa2  and  Yasko  Kasai2  

1.NCAR,  Boulder    2.NICT,  Japan  

HIPPO  Workshop  March  2011   1  

NCAR is sponsored by the National Science Foundation

2  HIPPO  Workshop  March  2011  

A  very  brief  intro  to  FTIR  spectroscopy  

Fourier transform

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7/7/10   5  

C2H6 Simulation

The  retrieval  We  determine  the  ‘best’  mixing  ratio  profile  to  fit  the  data  in  an  iterative  way  (optimal  estimation)  using:    -­‐  the  spectrum    -­‐  our  knowledge  of  the  noise  in  the  spectrum    -­‐  an  ‘a  priori’  profile  (in  this  case,  from  WACCM)    -­‐  an  estimate  of  the  uncertainty/correlation  in  the  a  priori    -­‐  knowledge  of  line  parameters,  the  instrument  line  shape,        interfering  species  and  solar  effects  There  are  multiple  factors  in  the  retrieval,  as  there  are  many  solutions  to  the  retrieval  problem.  We  continually  work  on  improving  our  retrievals  to  give  us  the  best  profiles.        

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O3 Spectral Fit 7  HIPPO  Workshop  March  2011  

Altitude Resolution Depends on:  Vertical profile  Spectroscopy  Interfering species  Spectral Resolution & SNR  Solar zenith angle

CO retrieval at Mauna Loa ~ 2 DOFS

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Typical data products are column or partial column measurements. Recently we’ve been investigating the quality of our retrieved profiles, which are to be archived in the NDACC database.

The Mauna Loa mid IR data set goes back to 1995, giving excellent climatological information about a number of species.

Comparisons  over  Hawaii  •  Coincident  measurements  at  Mauna  Loa  were  available  for  flights  3  (11/04/09),  8  (11/16/09)  and  9  (11/19/09)  

•  Multiple  spectra  were  recorded  on  each  of  these  days  

•  HIPPO  measurements  within  5°  lat/lon  (a  box  approximately  1000  km  square)  were  compared  with  those  taken  at  Mauna  Loa  

•  HIPPO_2_merge_20110219.tbl  merge  file  has  been  used  for  these  comparisons  

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O3  

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Excellent agreement

Retrievals dominated by very high strat O3

Individual peaks smoothed out

FTIR

HIPPO-2 Flight 9 over Hawaii

0 20 40 60 80 100O3 (ppb)

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O3_ppbO3_UO3

Unless otherwise labeled: Colored *’s = HIPPO data Solid colored lines = HIPPO data smoothed with FTIR a priori and averaging kernels Solid black lines = FTIR profiles Dotted black lines = FTIR a priori

HIPPO-­‐2  O3  in  context  

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Climatology  –  mean  tropospheric  VMR  

HIPPO-2

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HIPPO-2 Flight 8 over Hawaii

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HIPPO-2 Flight 9 over Hawaii

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CO_QCLSCO_RAF

CO  There is not as much information in the CO FTIR measurements as for O3, but the retrieval moves to the correct amount and identifies the enhancements.

Smoothing the aircraft data is complicated by how best to handle regions above/below the aircraft measurements.

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Climatology  –  mean  tropospheric  VMR  

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HIPPO-2

H2O  

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HIPPO-2 Flight 3 over Hawaii

0 5.0•103 1.0•104 1.5•104 2.0•104 2.5•104

H2O (ppm)

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H2O_UWVH2Oppmv_vxl

HIPPO-2 Flight 8 over Hawaii

0 5.0•103 1.0•104 1.5•104 2.0•104 2.5•104

H2O (ppm)

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H2O_UWV

HIPPO-2 Flight 9 over Hawaii

0 5.0•103 1.0•104 1.5•104 2.0•104 2.5•104

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H2O_UWVH2Oppmv_vxl

While FTIR can’t resolve the small scale features in the H2O measurements, we do a really good job of capturing the magnitude of free-tropospheric water.

H2O  in  Boulder  

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H2O at Boulder, 20100408

0 2000 4000 6000 8000H2O (ppm)

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H2O at Boulder, 20100408

10-2 100 102 104 106

H2O (ppm)

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H2O at Boulder, 20100526

0 2.0•1034.0•1036.0•1038.0•1031.0•1041.2•104

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H2O at Boulder, 20100526

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H2O at Boulder, 20101020

0 2000 4000 6000 8000 10000H2O (ppm)

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H2O at Boulder, 20101020

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Comparisons of similar H2O retrievals with our instrument in Boulder show excellent agreement with the NOAA frost point hygrometers, over a significant range of water quantities. This work is ongoing.

CH4  

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HIPPO-2 Flight 9 over Hawaii

1700 1750 1800 1850 1900CH4 (ppb)

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CH4_QCLS

CH4_UGC

CH4 retrievals are complicated by poor lab spectroscopy in the mid-IR region. HIPPO CH4 profiles have been very valuable for finding the best retrieval strategy for this important gas. A tight constraint is used to restrict oscillations, though this loses some of the small-scale variability.

CH4  at  Poker  Flat  during  HIPPO-­‐3  

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HIPPO-3 Flight 2 over Alaska

1500 1600 1700 1800 1900 2000CH4 (ppb)

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CH4_CCGCH4_QCLS

HIPPO-3 Flight 10 over Alaska

1500 1600 1700 1800 1900 2000CH4 (ppb)

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CH4_CCGCH4_QCLS

HIPPO data from HIPPO_3_merge_20110202.tbl CH4 profiles provided by Akiko Kagawa and Yasko Kasai, NICT, Japan

Doing well at moving away from the a priori and to the right amount in the troposphere; non-ideal at the surface.

Other  gases  and  FTIRs  

From our spectra, we can also retrieve: – N2O, CFC-11, CFC-12, HCFC-22, CO2, COS and

SF6 (though we didn’t get to all of those here) – Your profiles help enormously for evaluating the

quality of these more challenging retrievals – And our measurements can help provide

climatological information for you There are other FTIR’s all around the world!

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FTIR spectrometers around the world

IRWGTCCONBoth IRWG & TCCONOther or proposed

See www.ndacc.org for more information

Thank  You  

The NESL Mission is: To advance understanding of weather, climate, atmospheric composition and processes;

To provide facility support to the wider community; and, To apply the results to benefit society.

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NCAR is sponsored by the National Science Foundation

HIPPO  Workshop  March  2011