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Interaction with the ongoing satellite measurements programs is an important goal of ICARTT. The Terra/MOPITT instrument has now been making global measurements of the tropospheric carbon monoxide (CO) distribution for 4 years, and is in a unique position to provide valuable support during the field campaign. CO is an important trace gas in tropospheric chemistry due to its role in determining the atmospheric oxidizing capacity, as an ozone precursor, and as an indicator and tracer of both natural and anthropogenic pollution arising from incomplete combustion. The satellite perspective also provides the more general temporal and spatial context to the aircraft and ground-based measurements during the subsequent scientific analysis. Our aim is to provide expedited MOPITT data processing in near real-time, and to ensure maximum exploitation of the satellite information, we also plan to have a scientist in the field to present and interpret the MOPITT data for the INTEX team, and to assist in flight planning.
Under usual operation, the raw MOPITT data, in the form of instrument counts, are transferred to NCAR from the NASA LaRC DAAC after download from the Terra satellite. These data are accompanied by supplemental files on instrument pointing and geo-location. The Level 0-1 data processing delivers geo-located calibrated instrument radiances from the instrument count data. These are then fed to the Level 2 processor. This algorithm is composed of the following principal components: the radiative transfer forward model which provides a full physical description of the measurements process, a cloud detection module to identify cloudy pixels, and the maximum-likelihood retrieval. The cloud-detection algorithm combines information from the MOPITT radiances with the MODIS operational cloud mask product to determine if the MOPITT pixel is cloud contaminated and whether a retrieval can be performed. The forward model requires supplemental NCEP (National Center Environmental Prediction) atmospheric information which is obtained from the NASA GSFC DAAC. The output of the Level 2 processor are CO total column and mixing ratio profiles reported at seven levels through the troposphere for each geo-located 22 km by 22 km pixel. Validation activities show data accuracy to be about 10%. It is important to note that the mixing ratio at a given level reflects the vertical resolution of the measurement as defined by the retrieval averaging kernel and a priori profile [for further information, follow the Data link on the main MOPITT web page]. The Level 0-2 processing normally takes about 4 days due to the time required to stage and transfer the MOPITT and MODIS data and for computer run-time.
For field campaign support, we are also maintaining a dedicated second processing stream. For the Pacific, North American, and Atlantic regions of interest to ICARTT, the corresponding MOPITT count and supplemental data are transferred from NASA using an expedited data protocol. Once at NCAR, they are priority-processed. Because of the time required to produce the MODIS cloud mask product, only MOPITT input is used in the cloud detection.
In addition to MOPITT data processing, a chemical assimilation and forecast system is run daily. MOPITT data is transferred in near real-time to Toulouse, France, in the context of a close collaboration with CNRS-Laboratoire d'Aerologie and Meteo-France. CO profile data is assimilated within the MOCAGE global Chemistry and Transport Model, running at an horizontal resolution of 2 degrees and extending up to 5 hPa with 47 vertical levels. MOCAGE presents a comprehensive representation of physical and chemical processes in the planetary boundary layer, tropoposphere and lower stratosphere. 120 chemical species or group of species are taken into account. Assimilation is performed using the Kalman filter algorithm of MOPITT data. MOCAGE meteorological forcings are provided by Meteo-France Numerical Weather Prediction forecasts (ARPEGE, 4D-var meteorological assimilation system), available operationally up to 96h ahead. MOCAGE 6-hourly images of CO analyses and forecasts are sent daily to NCAR and are accessible from the Data Product Page. For more information on the MOCAGE chemical assimilation and forecast system, you can contact Jean-Luc.Attie@aero.obs-mip.fr or Vincent-Henri.Peuch@meteo.fr
Overpass Table: This provides information on each pass of the Terra satellite over the ICARTT region of interest. Plots showing the satellite ground track and time are available for download. This will be particularly useful for validation activities.
Daily plots of the CO distribution for the field project region: These show a half degree gridded composite of all MOPITT swaths for the given day and are available for 2 of the MOPITT standard Level 2 product retrieval levels (700 hPa and 350 hPa) and total column. It should be noted from the outset that these do not necessarily represent completely independent information and are indicative of average mixing ratios over broad atmospheric layers. The user is referred to the Data link on the main MOPITT web page for further information.
Global 3-day plots: MOPITT uses a cross-track scan, and in the absence of persistent cloud cover, the instrument achieves close to global coverage in 3 days. These plots are available at the same retrieval levels as detailed above, but show global data collected over the previous 3-day period.
Regional 3-day Plots: Same as above, only showing the ICARTT region of interest in greater detail.
Downloadable Field Project Data: Links are provided to
MOCAGE Forecasts and Assimilations: Images created by assimilating MOPITT data into a French chemical transport model and forecasts.
Animations: MPEG animations are created that show the time progression of the data. There are animations of the daily images at several pressure levels and animations of three-day composites. Animations of the MOCAGE data are also available.
Science Log: Narrative entries by the MOPITT Science Team.
|David Edwards||PI MOPITT INTEXfirstname.lastname@example.org|
|Dallas Masters||MOPITT Data Manageremail@example.com|
|Louisa Emmons||INTEX Campaign Scientistfirstname.lastname@example.org|
|John Gille||MOPITT US PIemail@example.com|