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by EarthdataForumContributor » Thu Apr 02, 2020 9:58 am America/New_York

I would like to know what units the NH3 and CO2 TES/Aura L2 data is provided in. I have looked into several web pages and documents and have not found the information.


ASDC - mcook
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by ASDC - mcook » Thu Apr 02, 2020 10:00 am America/New_York

The TES Science team suggested the you should refer to “ User’s Guide “.
The information should be in PPB (Part Per Billion).

TES Level2 User's Guide: https://eosweb.larc.nasa.gov/project/te ... 8_FV-2.pdf

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by jon » Tue Mar 02, 2021 10:38 am America/New_York

Respectfully, CO2 units are NOT not in parts per billion, but rather in parts per million (PPM).

The Tropospheric Emission Spectrometer (TES) on EOS-Aura CO2 is retrieved between 40S and 45N, individual TES soundings have errors of ~6 ppm, ~2.3 ppm for 10-observation averages, ~1.7 ppm for 20-observation averages, dynamic range for CO2 is at 14 levels. For "Lite products" CO2 gas measurements the averaging kernel and errors are corrected to reflect the actual sensitivity. The observation error is increased by a factor of 1.5 (this also affects the total error). There are 3 bias terms included in the product: bias2010 in units ppm, correction after 2010 spatial bias in units ppm. Spatial correction based on year average compared with CarbonTracker bias that is Time Dependent in units ppm. Time dependent bias based on comparisons with SGP aircraft data original_species = retrieved value species = original_species + (bias 2010 + bias Spatial + bias Time Dependent) in VMR. The Carbon tracker fields (prototype only) are ct_pressure, ct_co2, ct_latitude, ct_longitude, and ct_yearfloat, are the closest Carbon Tracker matches from CT2011oi. ncep_temperature (prototype only) is the closest NCEP temperature at the following atmospheric pressures: 1000, 900, 800, 700, 600, 500, 400, 300, 200, 100, 10 hPa.

Averaging over larger areas provides an estimated error of ∼10 ppm for a single geographic location and ~1.3–2.3 ppm for monthly averages on larger spatial scales of 20 degrees × 30 degrees.

Using the MaunaLoa surface stations as a reference, TES measurements show a correlation of 0.92, a standard deviation of 1.3 ppm, a predicted error of 1.2 ppm, and a∼2% low bias.

Additional information on the Characterization of Tropospheric Emission Spectrometer (TES)CO2for carbon cycle science is available at https://www.atmosp.physics.utoronto.ca/ ... 10_ACP.pdf

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