The Fennec Automatic Weather Station (AWS) Network: Monitoring the Saharan Climate System

Abstract

The Fennec automatic weather station (AWS) network consists of eight stations installed across the Sahara, with four in remote locations in the central desert, where no previous meteorological observations have existed. The AWS measures temperature, humidity, pressure, wind speed, wind direction, shortwave and longwave radiation (upwelling and downwelling), ground heat flux, and ground temperature. Data are recorded every 3 min 20 s, that is, at 3 times the temporal resolution of the World Meteorological Organization’s standard 10-min reporting for winds and wind gusts. Variations in wind speeds on shorter time scales are recorded through the use of second- and third-order moments of 1-Hz data. Using the Iridium Router-Based Unrestricted Digital Internetworking Connectivity Solutions (RUDICS) service, data are transmitted in near–real time (1-h lag) to the United Kingdom, where calibrations are applied and data are uploaded to the Global Telecommunications System (GTS), for assimilation into forecast models. This paper describes the instrumentation used and the data available from the network. Particular focus is given to the engineering applied to the task of making measurements in this remote region and challenging climate. The communications protocol developed to operate over the Iridium RUDICS satellite service is described. Transmitting the second moment of the wind speed distribution is shown to improve estimates of the dust-generating potential of observed winds, especially for winds close to the threshold speed for dust emission of the wind speed distribution. Sources of error are discussed and some preliminary results are presented, demonstrating the system’s potential to record key features of this region.

Meteorology and dust in the central Sahara: Observations from Fennec supersite‐1 during the June 2011 Intensive Observation Period

“…The Fennec supersite‐1 data include the first observations of the diurnal cycle of the boundary layer and surface fluxes in the central Sahara, with the first ground‐based lidar profiles and Sun photometer, nephelometer, reflectometer, dust sampler, and 1 Hz surface meteorology and 20 Hz winds for evaluating satellite retrievals, dust properties, and dust uplift and transport mechanisms. The Fennec automatic weather station network [ Hobby et al ., ] provides a complementary data set with a longer time duration, but no vertical profiles or observations of dust. The Fennec supersite‐2 at Zouerat in Mauritania ( Todd et al ., submitted manuscript) is much more maritime‐influenced with much less active dust uplift and lower dust loads.…”

Optical properties of Saharan dust aerosol and contribution from the coarse mode as measured during the Fennec 2011 aircraft campaign

“…The Fennec project was designed to better understand the Saharan climate system through targeted ground observations Todd et al, 2013;Hobby et al, 2012), aircraft measurements and remote sensing over the remote Sahara in 2011 and 2012. Here we present in-situ aircraft measurements of Saharan dust from the Fennec June 2011 campaign over previously unsampled regions of Mauritania and Mali, and aim to provide a better understanding of the nature and importance of coarse dust particles.…”

The influence of dust optical properties on the colour of simulated MSG-SEVIRI Desert Dust infrared imagery

“…Hobby et al, 2013;Marsham et al, 2013;Todd et al, 2013) and from aircraft (e.g. Rosenberg et al, 2014;Ryder et al, 2015; 2013).…”