MeteoSwiss Aerological Station
MeteoSwiss Aerological Station
Huang G.,Harvard - Smithsonian Center for Astrophysics |
Liu X.,Harvard - Smithsonian Center for Astrophysics |
Chance K.,Harvard - Smithsonian Center for Astrophysics |
Yang K.,University of Maryland University College |
And 49 more authors.
Atmospheric Measurement Techniques | Year: 2017
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 <∼ 50g 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 applyin OMI averagin 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, leadin to worse performance at high latitudes and durin the midlatitude winter. Agreement also degrades with increasin 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 reachin 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 durin the pre-RA period but exhibits a statistically significant trend of 0.14-0.7 % year-1 for pressure <∼ 80 hPa, 0.7 DU year-1 in SOC, and -0.33 DU year-1 in TOC durin the post-RA period. The spatiotemporal variation of retrieval performance suggests the need to improve OMI's radiometric calibration especially durin the post-RA period to maintain the long-term stability and reduce the latitude/season/SZA and cross-track dependency of retrieval quality. © 2017 Author(s).
Thompson A.M.,Pennsylvania State University |
Miller S.K.,Pennsylvania State University |
Tilmes S.,U.S. National Center for Atmospheric Research |
Kollonige D.W.,Pennsylvania State University |
And 29 more authors.
Journal of Geophysical Research: Atmospheres | Year: 2012
We present a regional and seasonal climatology of SHADOZ ozone profiles in the troposphere and tropical tropopause layer (TTL) based on measurements taken during the first five years of Aura, 2005-2009, when new stations joined the network at Hanoi, Vietnam; Hilo, Hawaii; Alajuela/Heredia, Costa Rica; Cotonou, Benin. In all, 15 stations operated during that period. A west-to-east progression of decreasing convective influence and increasing pollution leads to distinct tropospheric ozone profiles in three regions: (1) western Pacific/eastern Indian Ocean; (2) equatorial Americas (San Cristóbal, Alajuela, Paramaribo); (3) Atlantic and Africa. Comparisons in total ozone column from soundings, the Ozone Monitoring Instrument (OMI, on Aura, 2004-) satellite and ground-based instrumentation are presented. Most stations show better agreement with OMI than they did for EP/TOMS comparisons (1998-2004; Earth-Probe/Total Ozone Mapping Spectrometer), partly due to a revised above-burst ozone climatology. Possible station biases in the stratospheric segment of the ozone measurement noted in the first 7 years of SHADOZ ozone profiles are re-examined. High stratospheric bias observed during the TOMS period appears to persist at one station. Comparisons of SHADOZ tropospheric ozone and the daily Trajectory-enhanced Tropospheric Ozone Residual (TTOR) product (based on OMI/MLS) show that the satellite-derived column amount averages 25% low. Correlations between TTOR and the SHADOZ sondes are quite good (typical r2 = 0.5-0.8), however, which may account for why some published residual-based OMI products capture tropospheric interannual variability fairly realistically. On the other hand, no clear explanations emerge for why TTOR-sonde discrepancies vary over a wide range at most SHADOZ sites. © 2012. American Geophysical Union. All Rights Reserved.
Stickler A.,ETH Zurich |
Grant A.N.,ETH Zurich |
Ewen T.,ETH Zurich |
Ross T.F.,National Oceanic and Atmospheric Administration |
And 12 more authors.
Bulletin of the American Meteorological Society | Year: 2010
A new dataset, Comprehensive Historical Upper-Air Network (CHUAN), has been developed as a systematic compilation of the different sources in only three standard formats. The first includes the data that come on pressure levels from all platforms except radiosondes, second for the data on geometrical altitude levels, and third with four additional pressure levels for the radiosonde data. The pilot balloon data are given predominantly on geometrical altitude levels above mean sea level, but some observations are given on levels above ground level or on pressure levels. The radiosonde data are given solely on pressure (p) levels whereas the kite, aircraft, and registering balloon data are either on pressure or geometrical altitude levels. CHUAN data have been reformatted into three simple ASCII formats, one each for pressure level and geometrical altitude level data, and one with four additional pressure levels for the radiosonde data.