Validation of 10-year SAO OMI Ozone Profile (PROFOZ) product using ozonesonde observations
We validate the Ozone Monitoring Instrument (OMI) Ozone Profile (PROFOZ) product from October 2004 through December 2014 retrieved by the Smithsonian Astrophysical Observatory (SAO) algorithm against ozonesonde observations. We also evaluate the effects of OMI row anomaly (RA) on the retrieval by...
| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-07-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://www.atmos-meas-tech.net/10/2455/2017/amt-10-2455-2017.pdf |
| Summary: | We validate the Ozone Monitoring Instrument (OMI) Ozone Profile (PROFOZ)
product from October 2004 through December 2014 retrieved by the Smithsonian
Astrophysical Observatory (SAO) algorithm against ozonesonde observations. We
also evaluate the effects of OMI row anomaly (RA) on the retrieval by
dividing the dataset into before and after the occurrence of serious OMI RA,
i.e., pre-RA (2004–2008) and post-RA (2009–2014). The retrieval shows good
agreement with ozonesondes in the tropics and midlatitudes and for pressure
< ∼ 50 hPa in the high latitudes. It demonstrates clear improvement
over the a priori down to the lower troposphere in the tropics and down to an
average of ∼ 550 (300) hPa at middle (high) latitudes. In the tropics
and midlatitudes, the profile mean biases (MBs) are less than 6 %, and
the standard deviations (SDs) range from 5 to 10 % for pressure < ∼ 50 hPa to less than 18 % (27 %) in the tropics (midlatitudes)
for pressure > ∼ 50 hPa after applying OMI averaging kernels to
ozonesonde data. The MBs of the stratospheric ozone column (SOC, the ozone
column from the tropopause pressure to the ozonesonde burst pressure) are
within 2 % with SDs of < 5 % and the MBs of the tropospheric ozone
column (TOC) are within 6 % with SDs of 15 %. In the high latitudes,
the profile MBs are within 10 % with SDs of 5–15 % for pressure < ∼ 50 hPa but increase to 30 % with SDs as great as 40 % for
pressure > ∼ 50 hPa. The SOC MBs increase up to 3 % with SDs as
great as 6 % and the TOC SDs increase up to 30 %. The comparison
generally degrades at larger solar zenith angles (SZA) due to weaker signals
and additional sources of error, leading to worse performance at high
latitudes and during the midlatitude winter. Agreement also degrades with
increasing cloudiness for pressure > ∼ 100 hPa and varies with
cross-track position, especially with large MBs and SDs at extreme off-nadir
positions. In the tropics and midlatitudes, the post-RA comparison is
considerably worse with larger SDs reaching 2 % in the stratosphere and
8 % in the troposphere and up to 6 % in TOC. There are systematic
differences that vary with latitude compared to the pre-RA comparison. The
retrieval comparison demonstrates good long-term stability during the pre-RA
period but exhibits a statistically significant trend of
0.14–0.7 % year<sup>−1</sup> for pressure < ∼ 80 hPa,
0.7 DU year<sup>−1</sup> in SOC, and −0. 33 DU year<sup>−1</sup> in TOC during the
post-RA period. The spatiotemporal variation of retrieval performance
suggests the need to improve OMI's radiometric calibration especially during
the post-RA period to maintain the long-term stability and reduce the
latitude/season/SZA and cross-track dependency of retrieval quality. |
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| ISSN: | 1867-1381 1867-8548 |