Heterogeneity and chemical reactivity of the remote troposphere defined by aircraft measurements – corrected
<p>The NASA Atmospheric Tomography (ATom) mission built a photochemical climatology of air parcels based on in situ measurements with the NASA DC-8 aircraft along objectively planned profiling transects through the middle of the Pacific and Atlantic oceans. In this paper we present and analyze...
| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-01-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/23/99/2023/acp-23-99-2023.pdf |
| Summary: | <p>The NASA Atmospheric Tomography (ATom) mission built a
photochemical climatology of air parcels based on in situ measurements with
the NASA DC-8 aircraft along objectively planned profiling transects through
the middle of the Pacific and Atlantic oceans. In this paper we present and
analyze a data set of 10 s (2 km) merged and gap-filled observations of the
key reactive species driving the chemical budgets of O<span class="inline-formula"><sub>3</sub></span> and CH<span class="inline-formula"><sub>4</sub></span>
(O<span class="inline-formula"><sub>3</sub></span>, CH<span class="inline-formula"><sub>4</sub></span>, CO, H<span class="inline-formula"><sub>2</sub></span>O, HCHO, H<span class="inline-formula"><sub>2</sub></span>O<span class="inline-formula"><sub>2</sub></span>, CH<span class="inline-formula"><sub>3</sub></span>OOH,
C<span class="inline-formula"><sub>2</sub></span>H<span class="inline-formula"><sub>6</sub></span>, higher alkanes, alkenes, aromatics, NO<span class="inline-formula"><sub><i>x</i></sub></span>, HNO<span class="inline-formula"><sub>3</sub></span>,
HNO<span class="inline-formula"><sub>4</sub></span>, peroxyacetyl nitrate, and other organic nitrates), consisting of
146 494 distinct air parcels from ATom deployments 1 through 4. Six models
calculated the O<span class="inline-formula"><sub>3</sub></span> and CH<span class="inline-formula"><sub>4</sub></span> photochemical tendencies from this
modeling data stream for ATom 1. We find that 80 %–90 % of the
total reactivity lies in the top 50 % of the parcels and 25 %–35 % in the top 10 %, supporting previous model-only studies that
tropospheric chemistry is driven by a fraction of all the air. Surprisingly,
the probability densities of species and reactivities averaged on a model
scale (100 km) differ only slightly from the 2 km ATom 10 s data, indicating
that much of the heterogeneity in tropospheric chemistry can be captured
with current global chemistry models. Comparing the ATom reactivities over
the tropical oceans with climatological statistics from six global chemistry
models, we find generally good agreement with the reactivity rates for
O<span class="inline-formula"><sub>3</sub></span> and CH<span class="inline-formula"><sub>4</sub></span>. Models distinctly underestimate O<span class="inline-formula"><sub>3</sub></span> production
below 2 km relative to the mid-troposphere, and this can be traced to lower
NO<span class="inline-formula"><sub><i>x</i></sub></span> levels than observed. Attaching photochemical reactivities to
measurements of chemical species allows for a richer, yet more
constrained-to-what-matters, set of metrics for model evaluation. This paper
presents a corrected version of the paper published under the same authors
and title (sans “corrected”) as <a href="https://doi.org/10.5194/acp-21-13729-2021">https://doi.org/10.5194/acp-21-13729-2021</a>.</p> |
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| ISSN: | 1680-7316 1680-7324 |