NARVAL

The NARVAL (Next-generation Aircraft Remote-Sensing for Validation Studies) mission led by MPI-M was the first cloud remote sensing campaign of the novel German research aircraft HALO.

 

The first part of the mission (NARVAL-South) in December 2013 was focused on shallow convection in the trade wind region east of Barbados. During more than 60 flight hours, the following core instruments collected an unique, highly resolved (~ 200m in space and 1s in time) data set. The cloud information of the HAMP instruments was complemented by observations from a differential absorption LIDAR, which obtained water vapor profiles in ambient cloud-free air.  NARVAL-South was a dedicated initiative to broaden the perspective of the long term observation at the Barbados Cloud Observatory by adding spatial information. The statistics obtained by NARVAL South, and hopefully following up campaigns, will allow addressing fundamental question, like e.g. at which thickness a shallow convective cloud starts to form rain.

 

The focus of the second part (NARVAL-North) in January 2014 was again on shallow convection but in post-frontal regimes over the North Atlantic. Satellite climatologies, like e.g. the HOAPS data set of MPI-M, reveal very different precipitation estimates in these regimes and regions. HALO was used as “low flying satellite” to provide validation data with higher sensitivity, accuracy and spatial resolution. As example, Fig. X depicts a cross-section observed by the CLOUDSAT satellite and a collocated underpass by HALO: It is remarkable, how well the overall cloud structures coincide, but at the same time the detailed view of HALO allows identifying the limitation of the satellite observation.


Fig. X: Cross-sections of radar reflectivity at 9 January 2014, 15:30 UTC south of Greenland over the North Atlantic; top 3 pics: HALO cloud radar; bottom: CLOUDSAT. (Stefan Bos, 2014)

 

After years of development, certification and preparation, the NARVAL campaign has proven that HALO with its cloud remote sensing instrumentation is today a valuable and ready-to-use research platform that gives MPI-M the unique opportunity to get strategically selected data sets, like e.g. statics of trade wind convection or references to evaluate satellite products. 

NARVAL II / NAWDEX

NARVAL-II


After the successful first NARVAL campaign in 2013 and 2014, the follow-up mission NARVAL-II led by MPI-M was conducted in August 2016. Again, HALO was deployed to Barbados and equipped with almost the same payload ad during the previous campaign. The HAMP instruments were again mounted in HALO’s belly pod below the fuselage. During three weeks of deployment, 10 flights amounting to about 85 flight hours were conducted. During these flights a broad range of states of convection were observed from suppressed and shallow convection in relatively dry surroundings to deep convection in the ITCZ.

NARVAL-II expanded the observations taken during the previous campaign to and functioned as a precursor for the upcoming EUREC4A mission planned for 2020.

 

NAWDEX


Following the NARVAL-II mission, the same HALO payload was flown during the NAWDEX (North Atlantic Waveguide and Downstream Impact Experiment) campaign led by DLR and ETH Zurich. During five weeks in September and October 2016 HALO, together with up to three other research aircraft, was deployed to Keflavik, Iceland. The HAMP instruments were flown on 13 research flights amounting to about 96 flight hours. The aim of this campaign was to increase the physical understanding and to quantify the effects of diabatic disturbances to the jet stream over the mid-latitude North Atlantic on the development of high impact weather in Europe.

HAMP observations taken during NAWDEX give insight into convective clouds and their surroundings in the frontal regions and warm sector of mid-latitude cyclones.