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High Precision, Absolute Total Column Ozone Measurements from the Pandora Spectrometer System: Comparisons with Data from a Brewer Double Monochromator and Aura OMI
- Source :
- JOURNAL OF GEOPHYSICAL RESEARCH - Atmospheres. 117(D6)
- Publication Year :
- 2012
- Publisher :
- United States: NASA Center for Aerospace Information (CASI), 2012.
-
Abstract
- We present new, high precision, high temporal resolution measurements of total column ozone (TCO) amounts derived from ground-based direct-sun irradiance measurements using our recently deployed Pandora single-grating spectrometers. Pandora's small size and portability allow deployment at multiple sites within an urban air-shed and development of a ground-based monitoring network for studying small-scale atmospheric dynamics, spatial heterogeneities in trace gas distribution, local pollution conditions, photochemical processes and interdependencies of ozone and its major precursors. Results are shown for four mid- to high-latitude sites where different Pandora instruments were used. Comparisons with a well calibrated double-grating Brewer spectrometer over a period of more than a year in Greenbelt MD showed excellent agreement and a small bias of approximately 2 DU (or, 0.6%). This was constant with slant column ozone amount over the full range of observed solar zenith angles (15-80), indicating adequate Pandora stray light correction. A small (1-2%) seasonal difference was found, consistent with sensitivity studies showing that the Pandora spectral fitting TCO retrieval has a temperature dependence of 1% per 3K, with an underestimation in temperature (e.g., during summer) resulting in an underestimation of TCO. Pandora agreed well with Aura-OMI (Ozone Measuring Instrument) satellite data, with average residuals of <1% at the different sites when the OMI view was within 50 km from the Pandora location and OMI-measured cloud fraction was <0.2. The frequent and continuous measurements by Pandora revealed significant short-term (hourly) temporal changes in TCO, not possible to capture by sun-synchronous satellites, such as OMI, alone.
- Subjects :
- Geophysics
Instrumentation And Photography
Subjects
Details
- Language :
- English
- Volume :
- 117
- Issue :
- D6
- Database :
- NASA Technical Reports
- Journal :
- JOURNAL OF GEOPHYSICAL RESEARCH - Atmospheres
- Notes :
- NNG11HP16A, , NNX10AT36A
- Publication Type :
- Report
- Accession number :
- edsnas.20140007386
- Document Type :
- Report
- Full Text :
- https://doi.org/10.1029/2012JD017814