UV-vis data and NORS validation server

NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 1

F. Hendrick, B. Langerock, M. Van Roozendael, and M. De Mazière

Belgian Institute for Space Aeronomy (IASB-BIRA), Brussels, Belgium

Context

NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 2

• To develop and implement a web-based application for validation of MACCII products using the NORS data products (NORS WP8)

MACC output at 0, 6, 12, 18, 24h UT

1. Temporal interpolation

NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 3

For UV-vis data, three different cases need to be considered:

• Total ozone columns (90° SZA AM and PM)

• Stratospheric NO2 columns and profiles (90° SZA AM and PM) + diurnal variation

• Products from MAX-DOAS observations (every ~30’)

Temporal interpolation: total ozone

NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 4

• Choose a characteristic time-window (e.g., 6h as for FTIR):

Time

MACC output

6h6h

90°SZA AM observation

90°SZA PM observation

Temporal interpolation: stratospheric NO2

NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 5

x_MACCII(LTDOAS) = x_MACCII (LTMACCII) . [ x_model(LTDOAS)/x_model(LTMACCII) ]

with x= NO2 VCD or [NO2] at altitude z

Scaling factor

90°SZA AM 90°SZA PM

MACC-II output

NORS NO2 photochemical correction tool

NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 6

‘Off-line’ calculation of look-up tables of NO2 profile diurnal variation using of the BIRA photochemical box model PSCBOX

Model calculations for the following scenarios: altitude (24 levels), latitude (18 values covering 85°N→85°S by 10° step), longitude set to 0, months 1-12

For each month, use of the SLIMCAT chemical and meteorological fields corresponding to the middle of the month averaged over a period of 10 years (2000-2009)

Look-up tables of NO2 profile diurnal variation in ASCII

Creation of an interpolation routine in FORTRAN to extract the needed scaling factors

Sensitivity tests (1)

NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 7

March 15th chemical field and p, T profiles averaged over 10 years (2000-2009)

March 15th 2000 NO2_model(LTDOAS) / NO2_model(LT)

Sensitivity tests (2)

NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 8

March 15th chemical field and p, T profiles averaged over 10 years (2000-2009)

March 15th 2005 NO2_model(LTDOAS) / NO2_model(LT)

Sensitivity tests (3)

NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 9

denoxification

NORS NO2 photochemical correction tool

NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 10

‘Off-line’ calculation of look-up tables of NO2 profile diurnal variation

Use of the photochemical box model PSCBOX

Model calculations for the following scenarios: altitude (24 levels), latitude (18 values covering 85°N→85°S by 10° step), longitude set to 0, months 1-12

For each month, use of the SLIMCAT chemical and meteorological fields corresponding to the middle of the month averaged over a period of 10 years (2000-2009)

For polar regions in late fall, winter, early spring, additional look-up tables are needed for denoxification conditions; the choice of LUTs (denoxification conditions or not) could be based on the measured NO2 columns

Temporal interpolation: MAX-DOAS products

NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 11

• Smaller time-window due to the strong short-term variation:

Time

MACC output

1h

MAX-DOAS observations (every ~ 30’)

1h

2. Spatial interpolation

NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 12

• As for FTIR, calculate the location of the effective airmass of every measurement

• Interpolate the four surrounding MACC-II model data to this effective airmass location:

Is it relevant to proceed like this with UV-vis measurements ?

Do we have tools for such calculations ?

3. Smoothing and vertical gridding

NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 13

• MACC-II profile xMACC must be regridded to the vertical grid of the NORS profile

• The MACC-II data is smoothed with the averaging kernel of the NORS measurement using:

xs,MACC = xa,NORS + ANORS (xMACC – xa,NORS)

• IF DOFS < 5, one defines partial column boundaries in between which there is about one DOF. Partial column boundaries should be defined by the PI of the instrument

Profile comparisons:

• MACC-II profile xMACC must be regridded to the vertical grid of the NORS profile

• The MACC-II data is smoothed with the column averaging kernel of the NORS measurement using:

Cs,MACC = Ca,NORS + (xMACC – xa,NORS)

• Suitable for OEM-based retrievals but what we do for total ozone and stratospheric NO2 column retrievals (no a priori data used) ?

3. Smoothing and vertical gridding

NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 14

Column comparisons:

t

NORSCA

,