 |
| Titel |
Droplet activation parameterization: the population-splitting concept revisited |
| VerfasserIn |
R. Morales Betancourt, A. Nenes |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1991-959X
|
| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 7, no. 5 ; Nr. 7, no. 5 (2014-10-14), S.2345-2357 |
| Datensatznummer |
250115737
|
| Publikation (Nr.) |
 copernicus.org/gmd-7-2345-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| In this work, we postulate, implement and evaluate modifications to
the "population-splitting" concept, introduced by Nenes and Seinfeld (2003), for
calculation of water-condensation rates in droplet-activation
parameterizations. The population-splitting approximation consists of
dividing the population of growing droplets into two categories: those that experience
significant growth after exposed to a supersaturation
larger than their critical supersaturation, and those that do not grow
much larger than their critical diameter. The modifications introduced here lead to an
improved accuracy and precision of the parameterization-derived
maximum supersaturation, smax, and droplet-number
concentration, Nd, as determined by comparing
against those of detailed numerical simulations of the activation
process. A numerical computation of the first-order derivatives
∂ Nd/∂ χj of the parameterized
Nd to input variables χi was performed and
compared against the corresponding parcel-model-derived
sensitivities, providing a thorough evaluation of the impacts of the
introduced modifications in the parameterization ability to respond
to aerosol characteristics. An evaluation of the parameterization computation of
Nd and smax against detailed numerical simulations
of the activation process showed a relative error of −6.0% ± 6.2%
for smax, and −2.7% ± 4.8% for Nd,
which represents a considerable reduction in prediction bias when compared to earlier versions of
the parameterization. The proposed modifications require only minor
changes for their numerical implementation in existing codes based on the
population-splitting concept. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|