On the Utility (or Futility) of Using Stable Water Isotopes to Constrain the Bulk Properties of Tropical Convection

TitleOn the Utility (or Futility) of Using Stable Water Isotopes to Constrain the Bulk Properties of Tropical Convection
Publication TypeJournal Article
Year of Publication2018
JournalJournal of Advances in Modeling Earth Systems
Volume10
Number2
Pages516-529
Date Published03/2018
Abstract / Summary

Atmospheric water-vapor isotopes have been proposed as a potentially powerful constraint on convection, which plays a critical role in Earth's present and future climate. It is shown here, however, that the mean tropical profile of HDO in the free troposphere does not usefully constrain the mean convective entrainment rate or precipitation efficiency. This is demonstrated using a single-column analytical model of atmospheric water isotopes. The model has three parameters: the entrainment rate, the precipitation efficiency, and the distance that evaporating condensates fall. At a given relative humidity, the possible range of HDO is small: its range is comparable to both the measurement uncertainty in the mean tropical profile and the structural uncertainty of a single-column model. Therefore, the mean tropical HDO profile is unlikely to add information about convective processes in a bulk-plume framework that cannot already be learned from relative humidity alone.

URLhttp://dx.doi.org/10.1002/2017ms001074
DOI10.1002/2017ms001074
Journal: Journal of Advances in Modeling Earth Systems
Year of Publication: 2018
Volume: 10
Number: 2
Pages: 516-529
Date Published: 03/2018

Atmospheric water-vapor isotopes have been proposed as a potentially powerful constraint on convection, which plays a critical role in Earth's present and future climate. It is shown here, however, that the mean tropical profile of HDO in the free troposphere does not usefully constrain the mean convective entrainment rate or precipitation efficiency. This is demonstrated using a single-column analytical model of atmospheric water isotopes. The model has three parameters: the entrainment rate, the precipitation efficiency, and the distance that evaporating condensates fall. At a given relative humidity, the possible range of HDO is small: its range is comparable to both the measurement uncertainty in the mean tropical profile and the structural uncertainty of a single-column model. Therefore, the mean tropical HDO profile is unlikely to add information about convective processes in a bulk-plume framework that cannot already be learned from relative humidity alone.

DOI: 10.1002/2017ms001074
Citation:
Duan, SQ, JS Wright, and DM Romps.  2018.  "On the Utility (or Futility) of Using Stable Water Isotopes to Constrain the Bulk Properties of Tropical Convection."  Journal of Advances in Modeling Earth Systems 10(2): 516-529.  https://doi.org/10.1002/2017ms001074.