# Presentation: 207153

## Aura Validation Working Group Report 

- (Lucien Froidevaux)

## AGENDA: Aura Validation Working Group Meeting

**   **(L. Froidevaux, A. Douglass)
-    ***MONDAY, OCTOBER 1, 2007, 1:30 – 5:30 p.m.***
- ● **Validation Status, Issues, Plans                                                              100 mins.**
-   - HIRDLS                                                           J. Gille/B. Nardi                   [25 mins.]
-                   - MLS                                                                   L. Froidevaux                            [25 mins.]
-   - OMI                                                                  M. Kroon                             [25 mins.]
-       - TES                                                                     G. Osterman                      [25 mins.]*** ***** **
- ● **Recent/New campaigns                                                                               90 mins.**
-   - Large Balloons: Kiruna, Ft. Sumner 2007         J. Margitan                         [10 mins.]
-      and Table Mountain NO2 Intercomparison
-   - WAVES                                                           D. Whiteman                        [10 mins.]
-   - MOHAVE                                                           T. Leblanc                          [10 mins.]
-   - UT/LS H2O validation issues                   K. Rosenlof / D. Fahey                [10 mins.]
-   - TC4                                                                    M. Schoeberl                      [10 mins.]
-   - SAUNA                                                              R. McPeters                       [10 mins.]
-   - CESAR                                                                 P. Levelt                            [10 mins.]
-   - ARCTAS                                                              D. Jacob                           [15 mins.]
- ● **AVDC Status **                                   C. Retscher / B. Bojkov     **                        10 mins.  **
-    **Discussion (data access, longer-term plans,...)                                           5 mins.**
- ● **Future goals / suggestions for the working group **    Discussion               **10 mins.**

## HIRDLS: Summary of quality of validation products

- Temperature:
- 	P-Range:	1-300 hPa
- 	Precision: 0.5K at 10-100 hPa;  1K @ 1 hPa (v2.02.07)
- 	Accuracy: ±2K at 1-100 hPa
- Ozone:
- 	Range: 	1-100+ hPa (mid-high Lat), 1-50 hPa (tropics)
- 	Precision: 5-10%
- 	Accuracy: 2-10% at 1-10 hPa; biased generally low
- 		5% high bias ~10-30 hPa
- 		0-20% low bias, ~30-100+ hPa (mid & high latitudes)
- Nitric Acid:
- 	Range: 	10-100 hPa, 10-50 hPa (tropics)
- 	Precision: 10-35% at 100-10hPa
- 	Accuracy: ~10% (at 10hPa) to 30% (at 100hPa); biased low [ACE-FTS]
- Clouds/Aerosol:
- 	Range: 	400 hPa- 10 hPa
- 	Correlation with other instruments:
- 		SAGE & HALOE (cloud-top pressure): 0.85 - .93
- 		CALIPSO horizontal cloud scale: 0.99
- 	Extinction retrieval successful at rate 70%: needs improvement
- Vertical Resolution: 1-2 km

## Status of HIRDLS data products

- 1. Temperature, Ozone, HNO3, clouds – Released [v2.04.09]
- 2. H2O, CFC-11, CFC-12 – Not ready to release; 			      now most promising for future releases
- 3. CH4, NO2, N2O, ClONO2, N2O5 – Not ready to release.

##                     Current MLS Validation Issues / Needs 

|     Product | Validation                                  Issue / Investigation | Data Source                          Needs / Reason |
| --- | --- | --- |
| Temperature                  and GPH | Some retrieval biases,            2-3K vertical structure issue. |  |
| H2O (and            relative humidity) | “Kink” in MLS profiles near                 30 hPa.  Low bias near 200 hPa vs CFH and Vaisala; high bias for VMR > 500 ppmv. | Resolve aircraft in situ vs CFH profile diffs.  improve validation robustness. |
| N2O | Possibly extension of  vertical range (to 150 hPa). |  |
| O3 | Extension of vertical range (UT); more MOZAIC and UT studies. | More sonde matches under enhanced O3 conditions      in UT, for better statistics. |
| CO | Resolve UT biases              (P ≥ 215 hPa); extend data to higher P. | More UT CO data; mainly via MOZAIC (+ sat cross-val.) 
+ ARCTAS? |
| HCl
 | Better understand diffs. in 2007 Kiruna campaign; also, some small notches in MLS profiles. | Depends on Kiruna data investigation (Kiruna 2?). |

-                     **Current MLS Validation Issues / Needs**** **

##                        Current MLS Validation Issues / Needs 

|     Product | Validation                               Issue / Investigation | Data Source                            Needs / Reason |
| --- | --- | --- |
| HNO3 | MLS low bias                                           (~1 ppbv or 10 – 30%) |  |
| ClO
 | Improve retrievals for negative biases at                     P >  ~ 30 hPa.  | Possibly more validation in polar vortex |
| BrO | Extend vertical range; reduce biases and latitudinal oscillations  |  |
| OH, HO2 | Better understand residual diffs. in comparisons  | Balloon flight in Ft. Sumner, Fall 2008 (for reason at left) |
| HOCl | Continuing validation; extension of vertical range (into LS)  | More balloon flight data to resolve differences between model & data (balloon, MLS) |
| Cloud ice
 | Broader multi-sensor comparisons (IWC, IWP, cloud fraction) + enhanced MLS retrievals   | Improved “climatology” of cloud particle characteristics  |

-                        **Current MLS Validation Issues / Needs**** **

##      Current OMI Retrieval / Validation Needs 

|      Product | Retrieval Needs | Validation Needs |
| --- | --- | --- |
| Nitrogen dioxide
(total and trop. NO2 column) | Surface in-situ and Vertical Profiles in polluted regions
Effective Cloud Fraction and Effective Cloud Height
Surface Albedo data at OMI spatial resolution | Ground Truth Standard in-situ detection networks
Total NO2 column network of remote sensing standard (e.g. direct sun)
Tropospheric Columns in polluted regions  |
| Ozone 
(total and trop. O3 column, O3 profiles) | Total O3 columns and profiles at high SZA (SAUNA-III)
Surface Albedo data at OMI spatial resolution | Continuation Brewer network
More Double Brewers at high lat. and in SH
SHADOZ balloons, trop. ozone lidar, MaxDOAS |
| Aerosols
(AOD and SSA) | Microphysics (type, size, chem, phys, distributions)
Aerosols type statistics
Surface Albedo data at OMI spatial resolution | Continuation Aeronet network 
Airborne campaigns gathering aerosol microphysics statistics (in particular, polluted regions) |

**     ****Current OMI Retrieval / Validation Needs**** **

##   Current OMI Retrieval / Validation Needs 

|      Product | Retrieval Needs | Validation Needs |
| --- | --- | --- |
| Sulphur Dioxide
(total SO2 column [PBL, 5 km, 15 km]) | Profiles in polluted regions and regions of outflow
Emphasis on PBL
Volcanic plume tomography
Simultaneous observation of aerosols and SO2 profiles
Surface Albedo data at OMI spatial resolution | Double Brewer instrum.
Advanced Double Brewer SO2 algorithm
MaxDOAS instruments for total column and profiling
Aircraft observations of plumes (volcanic and industrial) |
| Clouds
(effective fraction and height) | Cloud model (LER, MLER, plane parallel)
Surface Albedo data at OMI spatial resolution | More comparisons of cloud fraction by sat-sat comparisons
Effective Cloud Height by ground radar / lidar |
| Minor trace gases
(total BrO, HCHO, CHO-CHO columns)
(slant OClO column) | Surface Albedo data at OMI spatial resolution | MaxDOAS instruments
Satellite data
 |

**  ****Current OMI Retrieval / Validation Needs**** **

##   Current TES Validation Issues / Needs 

|      Product | Validation Issue | Data Source |
| --- | --- | --- |
| L1B Radiances | Radiometric stability, Emissivity issues over cold surfaces | Future Scanning-HIS flights (ARCTAS?) |
| Temperature, Water Vapor | Improving nadir retrievals | More CFH sondes, particularly in clear-sky ocean conditions timed with Aura overpass (Closure experiments) |
| Nadir Ozone | High bias in troposphere | More high latitude sondes  (ARCTAS?) |
| HDO | Lack of validation data | Unknown |
| Methane | High bias | Profile Information
(150 to 500 hPa)
DACOM (ARCTAS) |

**  ****Current TES Validation Issues / Needs**** **

## TES Future Validation Analyses

- High bias in nadir ozone, improvement in nadir temperature profiles
- Use current set of sonde measurements
- TES V004 data  2008
- Continued validation of limb products
- HDO, Methane
- Nadir ozone in the stratosphere, limb ozone using MLS, HIRDLS

##   Recent/New campaigns (Overviews)    

-   - **Large Balloons: Kiruna, Ft. Sumner 2007                                            J. Margitan                **
**     ****and Table Mountain NO****2**** Intercomparison  **
-       > Kiruna, Sweden balloon campaign         2007 Jan 24:  FIRS2/SLS/Ozone
-          2007 Feb. 22: MkIV (ascent data only – balloon burst at float)
-          Flights deep in very cold, perturbed vortex
-          Some recent comparisons have been produced [also, *Stachnik et al.* presentation]
-       > 2007 Sep. 22 Ft. Sumner, NM  balloon campaign
-           MkIV/SLS/FIRS2/BOH/Ozone
-           31 hour flight (but no FIRS2 data due to malfunction)
-   **- WAVES                                                                                                 D. Whiteman**
-      Many coordinated measurements from Beltsville area; clean and polluted conditions
-       WAVES 2006 (June 27 – August 12, 2006)
-       WAVES 2007 (July 14 – August 8, 2007)
-       Sondes (includes PTU, ozonesondes, CFH); Microwave Radiometer, 7 lidar systems
-       O3, H2O, aerosols, Temperature data; coordinated with A-train overpasses.
-       - Some Vaisala sonde calibration issues vs CFH
-       - Precipitable water: AIRS and TES biased high vs MWR (and GPS)
-       - Some airborne lidar data also mentioned for TES/CALIPSO validation
-          (H2O, aerosol variability)
-       Some Aura results included as part of several validation papers (JGR special issue)

## Recent/New campaigns (Overviews)

**-  MOHAVE                                                                                                  T.  Leblanc**
*MOHAVE-1* campaign (October 2006)
- > to assess the measuring capabilities of Water Vapor Raman lidars (part of NDACC)
-    5 lidars, 50+ PTU sondes, 10 CFH sondes, 2 GPS, 1 microwave,...
-     wet bias of Raman lidars versus CFH above ~12 km
**   ***Major Finding: Fluorescence in lidar receiver optic fiber, can be removed by blocking.*
*   **Also, Miloshevic’s empirical correction to Vaisala RS92 seems to work well.*
*MOHAVE-2* campaign (October 2007) planned to now refine comparisons, check
-    sensitivity limits (lidars probably need more power, etc... to measure higher up)
-  Note: Short-term variability in H2O observed by lidars                                                                	 complicates Aura validation (some good results anyway, on-going)
**UT/LS H2O validation issues                                                  K. Rosenlof / D. Fahey**
**  ***2 main topics of current interest*** **
- > Establishing the frequency and temperature dependence of supersaturation.
-     Various datasets indicate persistent S > 1.2 inside and S > 1.6 outside clouds
-     Causes under investigation...
- > Establishing instrumental accuracy at low water vapor values and low temperatures
** **   Intercomparison campaign of water vapour measurement techniques to be held in
-     the AIDA  Chamber in Karlsuhe, Germany October 8th - November 2nd, 2007;
-     for wide range of T, P, H2O will be tested (with/without aerosols, ice particles).

## Recent/New campaigns (Overviews)

**TC4  (Costa Rica; mid-July to early August 2007)                               M. Schoeberl  **
-   3 aircraft + sondes
-   > ER2 - mostly full participation - but landed before Aura overpass
-   > DC8 - mostly full participation - bulk of Aura validation
-   > WB57 - Only 3 CR flights near the end of the mission - landed before overpass.
** **Good validation data despite mission problems - SO2, NO2, Ozone
-  Not as much TTL data as we would have liked
-  Workshop early next year**             **
**  ****- SAUNA                                                                                                   R. McPeters**
- For total column O3, satellite measurements agree within 2-3% globally
- Differences at low sun, high column amounts, high reflectivities, etc.
- Need to verify the accuracy of GB measurements for satellite validation purposes
*SAUNA: March-April 2006 ;          SAUNA 2:**	**February-April 2007*
- Combined network instruments: Dobsons, Brewers, DOAS, sondes and LIDAR
- > Conclude that data from double Brewers should be used for Aura O3 val at high SZA
- > The state of the network calibration (Brewer and Dobson) is uncertain
- > With improved GB calibration, differences between OMI and GB most probably due to ozone X-sections uncertainties; high spectral resolution X-sections required which can be used by both satellites and ground-based instruments

##  CESAR                                                                                                     P. Levelt

**  ****> **NO2 and O3 campaign in May 2008, Cabauw, The Netherlands
-      (along with the EUCAARI IOP campaign – clouds and aerosols)
-   > Also intend to play a part in the AMFIC project (SO2 and NO2 in China) with
-      the Mini-MAX DOAS
-   Continuous measurements at De Bilt (KNMI) and / or Cabauw of NO2 and O3
-   **If you wish to get involved, please contact Pieternel**
**- ARCTAS                                                                                                   D. Jacob**
**  *****Planning two 3-week deployments:                                                                                              ***
***  ******April 2008 (Fairbanks/Thule), July 2008   (Edmonton)***
-   Three NASA aircraft: DC-8 (in situ chemistry and aerosols), P-3B (radiation
-   and in situ aerosols), B-200 (aerosol remote sensing & CALIPSO validation)
*  **Science Theme 1: Transport of mid-latitudes pollution to the Arctic*
*  **Science Theme 2: Boreal forest fires** *
*  **Science Theme 3: Aerosol radiative forcing*
**DC-8: in situ chemistry and aerosols**
**Likely Payload: O3, H2O, CO, CO2, CH4,  NOx and HOx chemistry, BrO, mercury, NMVOCs, halocarbons,  SO2. HCN/CH3CN, actinic fluxes, aerosol composition/concentrations/properties, remote ozone and aerosol**
*  ***For relevant (high lat. April / July) Aura Validation needs/wishes,                  **
**  ****please contact Daniel with requests                                                                              **
**  *****[see also Aura needs lists above (some still to come)]***

## ● AVDC Status                                                               C. Retscher / B. Bojkov 

- ● **AVDC Status **                                                              **C. Retscher / B. Bojkov**
-   > ***Support continuing**** ****(Aura teams like this!...)***
-   > HDF5 read/write in final testing for correlative data
-   > Focus shifting to long-term validation
-      Collect and update ground datasets
-      Data completeness
-      Continue ESA/NDACC efforts
-      Share datasets and coordinate submissions
-      Proactive on AVDC side but need support from cal/val and instrument teams
- ● **Please provide inputs to AVWG chairs + Aura instr. val. reps.**
**   ****on future campaign wishes/needs, and AVWG activities & structure               **
**   ****in the future **