Oxford MIPAS meeting#82
06 Sep 05

Present

Oxford: Alastair Burgess, Anu Dudhia, Gareth Thomas, Joanne Walker, Claire Waymark.

Instrument Status [Prev] [Next]

Currently (30Aug-19Sep) switched off to allow recovery from increasing Interferometer Drive Unit (IDU) errors.

Some details on the Envisat Web-Site including Instrument Availability web-site
Latest version of Mission Planning Document covering 1 Jan 05 to 26 Sep 05: [.xls] [.html]
Mission_Plan_V4.2.pdf (15JUL05), describing various modes and overall strategy.

SF6 (AB) [Prev] [Next]

Retrieving SF6 from MIPAS 0.025cm^-1 data.

'Removed' a priori bias in order to try and retrieve more accurate values at high altitude (effectively substituting original a priori with different value) [Plot]
This allows SF6 to be used as an 'age of air' tracer for higher altitudes when data are averaged [Plot - NB: scale is years not pptv]

Error Analyses (AD)

Microwindow error analyses have been updated for the off-line products

Errors in pT retrieval now modelled using a priori pointing covariance based on the same formulation as in the ORM/ESA retrieval
pT propagation errors in VMR retrievals now modelled using full pT random error covariance from pT error analysis rather than simple assumption of fixed 1K, 2% uncorrelated errors (hence there is only a single "pT" systematic error term in the plots now, compared to separate "TEM" and "PRE" errors previously

Compared to previous version, errors are not significantly different.

Field of View (AD)

Plot shows calculated distortion effects for a 3km-high FOV at tangent heights 6, 9 and 12km. Diamonds show geometric (ie unrefracted tangent points), + signs show refracted tangent points and black rectangles represent the 'ESA' assumption of no FOV shape distortion. Dashed boxes in colour show calculated distortions for each FOV (also expanded horizontally for clarity)
The effect of the distortion is to expand the FOV by up to +/-150m for the 6km tangent height.
The x signs show centre of distorted FOV - these are almost coincident with the + signs implying that the vertical expansion is reasonably symmetric about the nominal FOV centre.
Although the vertical displacement of the FOV centre due to distortion seems negligible, the non-linear variation of radiance across the expanded FOV may still produce a significant impact on the retrieved value.

CFC-11 (JW) [Prev] [Next]

Running CFC-11 retrievals for comparison with DESCARTES balloon measurements (Feb 2004) (part of HIBISCUS campaign)

Currently MIPAS values differ significantly and have large error bars compared with DESCARTES.
Try switching continuum retrieval off to see if this has any effect
Try removing masks to improve S/N

MLS Comparisons (CW)

H2O2 (EP) [Prev]