Outlook - Surface Based Remote Sensing of the Atmospheric Boundary Layer - page 148

by a ramp-and-fire injection seeding technique. An advanced photodetector archi-
tecture is used incorporating photodiodes in a dual-balanced configuration. This
Doppler LIDAR allows for real-time display of wind and aerosol backscatter
data products. The high-pulse energy and receiver efficiency provides for mea-
surement of wind fields to ranges not seen before with 2

μ m LIDARs (Koch

et al. 2007 ).
Evaluation and comparison of new sounding instruments was performed, e.g.
in the international COST 720 Temperature, hUmidity, and Cloud (TUC) profil-
ing experiment organized in Winter 2003/2004 at Payerne, Switzerland. Various
in situ and active/passive ground-based remote-sensing systems, including three
microwave radiometers, a cloud RADAR, and a windprofiler, were operated in the
same location. Temperature and humidity profiles from two microwave radiometers
were compared with radiosonde profiles (Klaus et al. 2006 ).
Still increasing computer resources allow for a more rapid processing of the
incoming data, e.g. with spectrometers and interferometers. Larger storing devices
permit the prolongation of maintenance intervals. Less energy consumption of mod-
ern electronics cordless data transfer options make more remote installations of the
instruments possible.

5.3 Application Needs

Several new challenges and demands from the application side have been brought up
to the scientific community dealing with boundary layer remote sensing in the past
few years. The latter demands comprise among other issues (i) meteorological input
for planning and conducting electricity generation from renewable natural sources
(wind, solar, water power, Emeis et al. 2007 ; Frehlich and Kelley 2008 ), (ii) the
interrelation between atmospheric boundary layer meteorology and the emission of
greenhouse gases (see Laj et al. 2009 for an update of all kinds of atmospheric
composition measurement techniques including ground-based remote sensing), and
(iii) the interrelation between boundary layer air quality and public health. Here,
especially the aerosol load of near-surface air has got into the focus. See for example
Wu et al. ( 2007 ) for the use of FTIR spectroscopy for aerosol detection or Schäfer
et al. ( 2009 ) for the role of remotely detected mixing layer heights for the assessment
of aerosol concentrations.
The first application demand requires, e.g., very accurate wind measurements for
the operation of wind energy converters, accurate shortwave radiation measurements
for the operation of photovoltaic solar energy converters, and accurate areal precip-
itation measurements for the exploitation of water power. These accurate data are
not only needed for an estimation of the gross amount of the expected energy output
but rather as input values for a short-term prediction of the temporal variation of the
energy output. With the growing fraction of renewable energies in electricity gener-
ation, the perfect organization of power grids connecting producers and consumers
becomes increasingly important, because the production and the consumption of
electrical energy must be balanced at any time.