Using the HALO Microwave Package (HAMP) for cloud and precipitation research
Final Report Abstract
The key achievement of the project was to pioneer in using the novel HALO aircraft as remote sensing platform for cloud research. The proposed NARVAL campaign (Next-generation Aircraft Remote sensing for VALidation Studies) was successful both on a technical level and scientifically. The goal was to improving the understanding of maritime convection in two special regions of interests: The southern component of NARVAL was dedicated to shallow convection in the trade wind region and took place during December 2013 east of Barbados. The northern part focused on post frontal regimes over the extratropical North Atlantic. In total, the campaign collected an extensive data set over more than 120 flight hours. During NARVAL, HALO was equipped as airborne cloud observatory with the HALO Microwave Package (HAMP) as core instrument. HAMP consists of a cloud radar to monitor the vertical cloud structure and three passive microwave radiometers which can be used to retrieve water vapor and temperature profiles as well as condensate loading. This cloud information is complemented by observations from a water vapor differential absorption lidar which obtains water vapor profiles in ambient cloud-free air. A miniDOAS system, spectral resolving radiation measurements by HALO-SR, dropsondes and the basic measurements system BAHAMAS completed the aircraft configuration NARVAL-I has proven our initial research hypothesis that HALO as airborne cloud observatory adds complementary information to the both ground based remote sensing sites and satellite records. At Barbados we were able to extend the spatial perspective of the ground based Barbados observatory and verified that the local cloud statistics are representative for a broader trade wind region. To better understand satellite products, it is important to quantify the variability of clouds at scales smaller than the footprint of the satellite sensors. In this respect, it is important to highlight NARAVAL-I data indicating that 70% of the clouds in the trade wind region are less than 2 km wide. Likewise, NARVAL-I data allows for detailed evaluation of cloud-resolving model simulation to identify model shortcomings, like an overestimation of ice clouds at mid-levels in postfrontal convection over the extra tropical North-Atlantic due to shortcomings in the representation of temperature inversions. All developments in terms of instrument operation, retrieval methods and synergistic data analysis within this project formed the basis for the successful follow-up campaigns NARVAL-II and NAWDEX, which took place in late summer and autumn 2016. Future planning envisions the EUREC4A and (AC)3 campaign to further extend our research efforts by using HALO synergistically in international collaboration with other research aircrafts and research vessels. We conceive NARVAL-I as the beginning of a series of research campaigns spanning a whole decade to establish airborne reference data to improve the understanding of maritime convection.
Publications
- (2013). Combining ground and satellite based measurements in the atmospheric state retrieval: Assessment of the information content, J. Geophys. Res. 18, 6940–6956
Ebell, K., Orlandi E., Hünerbein A., Löhnert U., and Crewell S.
(See online at https://doi.org/10.1002/jgrd.50548) - (2014). HAMP-the microwave package on the High Altitude and LOng range research aircraft HALO. Atmos. Meas. Tech., 7, 4539-4553
Mech, M., Orlandi, E., Crewell, S., Ament, F., Hirsch, L., Hagen, M., Peters, G., and Stevens, B.
(See online at https://doi.org/10.5194/amt-7-4539-2014) - (2014). NARVAL Campaign Report, Reports on Earth System Science, Max-Planck-Institut für Meteorologie
Klepp, C., Ament, F., Bakan, S., Hirsch, L., & Stevens, B.
(See online at https://doi.org/10.17617/2.2129055) - (2015). Capabilities and uncertainties of aircraft measurements for the validation of satellite precipitation products–a virtual case study. Meteorol. Z., 24(5), 495-502
Lammert, A., and Ament, F.
(See online at https://doi.org/10.1127/metz/2015/0663) - (2016). Recommendations for improving US NSF-supported airborne microwave radiometry. Bull. Amer. Meteor. Soc.
Zuidema, P., Haggerty, J., Cadeddu M., Jensen J., Orlandi E., Mech M., Vivekanandan J., and Wang, Z.
(See online at https://doi.org/10.1175/BAMS-D-15-00081.1)
