Deriving tropospheric ozone from assimilated profiles

We derived global tropospheric ozone (O3) columns from GOME-2A (Global Ozone Monitoring Experiment) and OMI (Ozone Monitoring Instrument) O3 profiles, which were simultaneously assimilated into the TM5 (Tracer Model, version 5) global chemistry transport model for the year 2008. The horizontal model resolution has been increased by a factor of 6 for more accurate results. To reduce computational cost, the number of model layers has been reduced from 44 to 31. The model ozone fields are used to derive tropospheric ozone, which is defined here as the partial column between mean sea level and 6 km altitude. Two methods for calculating the tropospheric columns from the free model run and assimilated O3 fields are compared. In the first method, we calculate the residual between assimilated total columns and the partial model column between 6 km and the top of atmosphere. In the second method, we perform a direct integration of the assimilated O3 fields between the surface and 6 km. The results are validated against tropospheric columns derived from ozone sonde measurements. Our results show that the residual method has too large a variation to be used reliably for the determination of tropospheric ozone, so the direct integration method has been used instead. The median global bias is smaller for the assimilated O3 fields than for the free model run, but the large variation makes it difficult to make definitive statements on a regional or local scale. The monthly mean ozone fields show significant improvements and more detail when comparing the assimilated O3 fields with the free model run, especially for features such as biomass-burning-enhanced O3 concentrations and outflow of O3 rich air from Asia over the Pacific

Simultaneous assimilation of ozone profiles from multiple UV-VIS satellite instruments

A three-dimensional global ozone distribution has been derived from assimilation of ozone profiles that were observed by satellites. By simultaneous assimilation of ozone profiles retrieved from the nadir looking satellite instruments Global Ozone Monitoring Experiment 2 (GOME-2) and Ozone Monitoring Instrument (OMI), which measure the atmosphere at different times of the day, the quality of the derived atmospheric ozone field has been improved. The assimilation is using an extended Kalman filter in which chemical transport model TM5 has been used for the forecast. The combined assimilation of both GOME-2 and OMI improves upon the assimilation results of a single sensor. The new assimilation system has been demonstrated by processing 4 years of data from 2008 to 2011. Validation of the assimilation output by comparison with sondes shows that biases vary between ĝ'5 and +10ĝ€̄% between the surface and 100ĝ€̄hPa. The biases for the combined assimilation vary between ĝ'3 and +3ĝ€̄% in the region between 100 and 10ĝ€̄hPa where GOME-2 and OMI are most sensitive. This is a strong improvement compared to direct retrievals of ozone profiles from satellite observations

The deep atmospheric boundary layer and its significance to the stratosphere and troposphere exchange over the Tibetan Plateau

In this study the depth of the atmospheric boundary layer (ABL) over the Tibetan Plateau was measured during a regional radiosonde observation campaign in 2008 and found to be deeper than indicated by previously measurements. Results indicate that during fair weather conditions on winter days, the top of the mixed layers can be up to 5 km above the ground (9.4 km above sea level). Measurements also show that the depth of the ABL is quite distinct for three different periods (winter, monsoon-onset, and monsoon seasons). Turbulence at the top of a deep mixing layer can rise up to the upper troposphere. As a consequence, as confirmed by trajectory analysis, interaction occurs between deep ABLs and the low tropopause during winter over the Tibetan Plateau

Versatile QA / Validation system for the evaluation of Copernicus Sentinel-4/5(p) ozone profiling algorithms and data: Demonstration on GOME-2 and IASI

info:eu-repo/semantics/publishe

Meridional cross-section at 84.25° E (over Gerze site) at 20∶00 BST, for the period 25 Feb. to 28 Feb. 2008, derived from ERA interim data, including zonal winds (cyan contours, m/s), potential vorticity (yellow lines, contours of 1, 2, 4 PV units), ozone (solid color, ×10⁶kg/kg) and potential temperature (red contours, K).

<p>The color bar is the scale of ozone concentration. The area in black shows the cross section of the Tibetan Plateau terrain. The red triangles and circles show the position of the LRT and the top of CBL.</p

Application of the Complete Data Fusion algorithm to the ozone profiles measured by geostationary and low-Earth-orbit satellites:A feasibility study

The new platforms for Earth observation from space are characterized by measurements made at great spatial and temporal resolutions. While this abundance of information makes it possible to detect and study localized phenomena, it may be difficult to manage this large amount of data for the study of global and large-scale phenomena. A particularly significant example is the use by assimilation systems of Level 2 products that represent gas profiles in the atmosphere. The models on which assimilation systems are based are discretized on spatial grids with horizontal dimensions of the order of tens of kilometres in which tens or hundreds of measurements may fall in the future. A simple procedure to overcome this problem is to extract a subset of the original measurements, but this involves a loss of information. Another option is the use of simple averages of the profiles, but this approach also has some limitations that we will discuss in the paper. A more advanced solution is to resort to the so-called fusion algorithms, capable of compressing the size of the dataset while limiting the information loss. A novel data fusion method, the Complete Data Fusion algorithm, was recently developed to merge a set of retrieved products in a single product a posteriori. In the present paper, we apply the Complete Data Fusion method to ozone profile measurements simulated in the thermal infrared and ultraviolet bands in a realistic scenario. Following this, the fused products are compared with the input profiles; comparisons show that the output products of data fusion have smaller total errors and higher information contents in general. The comparisons of the fused products with the fusing products are presented both at single fusion grid box scale and with a statistical analysis of the results obtained on large sets of fusion grid boxes of the same size. We also evaluate the grid box size impact, showing that the Complete Data Fusion method can be used with different grid box sizes even if this possibility is connected to the natural variability of the considered atmospheric molecule

Versatile QA/validation system for the evaluation of Copernicus Sentinel-4 and Sentinel-5(p) ozone profiling algorithms and data - Demonstration on MetOp-A GOME-2 and IASI retrievals

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Meridional cross-section at 84.25° E (over Gerze site) at 20∶00 BST, for the period 25 Feb. to 28 Feb. 2008, derived from ERA interim data, including zonal winds (cyan contours, m/s), potential vorticity (yellow lines, contours of 1, 2, 4 PV units), ozone (solid color, ×10⁶kg/kg) and potential temperature (red contours, K).

<p>The color bar is the scale of ozone concentration. The area in black shows the cross section of the Tibetan Plateau terrain. The red triangles and circles show the position of the LRT and the top of CBL.</p

Variation of CBL depth and height of LRT during the three IOPs.

<p>Variation of CBL depth and height of LRT during the three IOPs.</p