 |
| Titel |
Comparative Characterisation of Maritime Clouds between Dry and Wet Season Over the Tropical North Atlantic by Airborne Observations |
| VerfasserIn |
Marek Jacob, Felix Ament, Susanne Crewell, André Ehrlich, Kevin Wolf, Mario Mech, Emiliano Orlandi, Sabrina Schnitt |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250151379
|
| Publikation (Nr.) |
 EGU/EGU2017-15950.pdf |
|
|
|
|
|
| Zusammenfassung |
| Trade wind clouds are a major uncertainty in climate models. The observation of these clouds
by satellites is limited by the satellite resolution and detailed ground-based observations are
lacking. Therefore, the series of Next-Generation Aircraft Remote-Sensing for Validation
campaigns (NARVAL) using the High Altitude LOng range research aircraft (HALO)
was initiated to assess North Atlantic trade clouds on an appropriate scale. In this
presentation, we take the advantage of the synergy of the HALO active and passive
Microwave Package (HAMP) in combination with the solar radiation measured by the
Spectral Modular Airborne Radiation measurement system (SMART) to characterize
shallow clouds in the Caribbean. The two NARVAL campaigns in December 2013
and August 2016 offer the opportunity to study clouds during dry and wet season,
respectively.
Based on a cloud mask derived from SMART spectral solar measurements, about 12000
cloudy profiles describing 4100 individual clouds could be detected during the dry
season (NARVAL-I) with about 70% of the clouds having a length of less than 2 km.
Corresponding retrieval of the liquid water path (LWP) using passive microwave
measurements reveals that these small clouds contain little water with a third of the clouds
having a LWP of less than 50 g m−2. Such small clouds are difficult to measure
by the spaceborne Special Sensor Microwave Imager/Sounder (SSMIS) due to
its coarse resolution while precipitable water vapor agrees rather well between
airborne and satellite measurements. Using a simple reflectivity threshold, 7%
of the clouds were identified as precipitating. Precipitation did not show a strong
dependence on LWP and there were also precipitating clouds showing a LWP lower than
100 g m−2. While the Moderate Imaging Spectroradiometer (MODIS) is able to
identify smaller clouds (∼ 1 km), it shows deficits in terms of LWP for drizzling
clouds.
This presentation addresses differences in cloud characteristics between the tropical dry
and wet seasons as revealed based on measurements of 70 flight hours during the dry season
and 85 flight hours during the wet season. |
|
|
|
|
|
|