The MLS Temperature Product
Basic Information
Temperature plays central roles throughout atmospheric science. It is a
key parameter in the radiative balance of the atmosphere.
Temperature at a given pressure determines density and thus
buoyancy, driving dynamics on all scales. Temperature controls
chemical reaction rates and radiative transfer. Temperature is
critically important in the hydrological cycle, controlling of
cloud formation and the distribution of humidity. MLS measurements of atmospheric composition require
knowledge of temperature, but at atmospheric temperatures, and
at the frequencies of MLS observations, thermal emission is
roughly linear in gas temperature, so small fractional errors
in inferred absolute temperature generally lead to
correspondingly small errors in inferred constituent
abundance.
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MLS Tempearature Map
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How it is part of MLS Science Objectives
Temperature is vitally important
in understanding the questions of radiative balance involved in
climate change. Upper tropospheric temperature is particularly
important to climate feedbacks involving the regulation of humidity
and clouds. Some models show temperature in the mesosphere to be
particularly sensitive to climate change. Temperatures required for
the formation of polar stratospheric clouds (PSCs) are at the
extreme low end of those found in the northern polar winter. PSCs
play multiple roles in the catalytic destruction of ozone, and here
MLS mission objectives of understanding stratospheric ozone layer
stability and climate change are linked through temperature.
How EOS MLS measures Temperature
MLS measures
temperature - primarily - from thermal emission by
oxygen, which is well mixed with a known atmospheric mixing
ratio. The standard product for temperature is taken for the Core
retrieval (118 GHz only) from 316 - 1.41 hPa and from the Core+R2A
(118 GHz and 190 GHz) retrieval from 1 hPa to 0.001 hPa. Preliminary
validation shows Core+R2A temperature to be somewhat more prone to
vertical oscillation than Core temperature at the lowest retrieval
levels (316 - 100 hPa), however its superior vertical resolution
(~5.5 km vs. ~8 km) may make it preferable for some uses. There is
little to choose between these phases in the mid stratosphere.
Core+R3 temperature is significantly more susceptible to vertical
oscillation and has persistent biases in the lowest retrieval
levels.
(map from 2005d264)
Quick Product Information for data version v3.3
- Swath Name: Temperature
- Vertical Resolution:
~5 km from 261 - 100 hPa
~4 km at 56.2 - 3.16 hPa
~7.2 km at 1 - 0.316 hPa
~10 km at 0.1 - 0.001 hPa
- Useful Range: 261 - 0.001 hPa
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- DAAC Short Name: ML2T
- Precision: ~+/- 1K at 261-0.1 hPa
~+/- 2.3K at at 0.01 - 0.001 hPa
- Quality Threshold: 0.65
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Simulations show retrieval scatter typically comparable to, or
slightly less than the estimated retrieval precision throughout the
stratosphere, with values generally less than 1 K, and with a
minimum of approximately 0.5 K in the lower stratosphere.
Performance is poorer in the winter polar bin for both simulation
days. Simulations also show retrieval instability leading to
vertical oscillations. Vertical oscillations in Core+R2 and Core+R3
temperatures in the stratosphere and upper troposphere are larger,
leading to the use of Core Temperature as the standard v1.5 product
at these levels despite its poorer vertical resolution.
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v3.3 Temperature Averaging Kernel
colored lines are individual kernels; thick dashed line is full width at half maximum, thick solid is integrated kernel value
Publications related to the MLS Temperature data product
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