specMACS on NARVAL-II campaign

general remarks

Due to the short development time for the specMACS adaption to the downward looking position before the NARVAL-II campaign, some parts of the system were operating suboptimal. Any quick fix during the campaign would have been risky, because taking the system apart and together again needs several days due to the mounting location in the boiler room, which would most likely have affected the flight schedule if done during the campaign. Known issues include the following:

The environmental control system was not able to keep the window ice-free at all times, lower flight altitudes were chosen during the campaign to partially compensate this issue.
The Focus of the VNIR system had accidentally been modified. This results in a spatial blur of the data.
One wire of the VNIR data cable has been damaged, therefore every 2^nd spatial pixel is unuseable. This luckily coincides with the previous problem.
The aperture of the 2D camera was too big for the brightest cloudy scenes, which resulted in several overexposure events.

The above mentioned issues have been fixed for the following campaign (NAWDEX).

summary of research flights

date	name	remarks
2016-08-08	RF01	Transfer from EDMO to TBPB underflight of CALIPSO satellite track north-east of Barbados Due to the high flight altitude, the window was iced most of the time
2016-08-10	RF02	Cross ITCZ flow cloud statistics
2016-08-12	RF03	Test dropsonde methodology for measuring vertical velocity while constraining cloud and humidity field via remote sensing.
2016-08-15	RF04	CALIPSO satellite validation ITCZ crossing The specMACS VNIR shutter has been inoperative (stuck in open position), therefore darkcurrent for the VNIR must be estimated. In the VNIR quicklooks, this is visible as a blueish color, as the estimation is currently not implemented. The system which is responsible for dark current measurements is also responsible for autoexposure. Therfore, the integration time has not been adapted throughout the flight which in turn caused some over exposure events which otherwise could have been prevented.
2016-08-17	RF05	Satellite validation cirrus cloud statistics
2016-08-19	RF06	Estimate wind divergence and surface turbulent fluxes in an area covered by low-clouds compare surface flux estimates with buoys data compare data to CALIPSO and Megha-Tropiques (Megha-Tropiques in the area around 19 UTC and 20:50 UTC)
2016-08-22	RF07	Measurements in the vicinity of deep convective clouds in the inner ITCZ region, where surface winds slacken.
2016-08-24	RF08	Observing the deep convection at the western edge of hurricane Gaston Measuring congestus type convection at the boundaries of the dry inflow region of the hurricane Gaston Sampling clouds and aerosol at dry sector of hurricane Gaston
2016-08-26	RF09	Influence of aerosol and water vapor gradients on shallow cumulus convection in the mixing region south of tropical storm Garson.
2016-08-30	RF10	Transfer from TBPB to EDMO performing a constant bank circle while dropping 12 dropsondes north-east of Madeira Due to the high flight altitude, the window was iced most of the time

Some summary data is also available as KML file. This file is still beeing extended, so be sure to reference it as link and be able to receive further updates automatically. Additionally, there is a second KML file containing only specMACS data.

specMACS products

Products derived from the specMACS data captured during NARVAL-II campaign can be downloaded here.

the specMACS instrument

specMACS is a hyperspectral imager, capturing one image line at a time. It is sensitive in the range of approx. 400nm to 2500nm and has a field of view of approximately 35°. During NARVAL-II it is mounted on the HALO aircraft facing downwards and is accompanied by a 2D RGB camera an an opening angle of 70°. More information can be found in Ewald et al. (2016).

more information

If you have any questions or requests, please contact tobias.koelling@physik.uni-muenchen.de.