Ground-based FTIR soundings of column-average methane from NDACC and TCCON can be combined without the need to apply an overall calibration factor. NDACC and TCCON measurements complement one another and provide valuable information for satellite validation, evaluation of chemical-transport models, and source-sink inversions. The impact of dynamical variability on NDACC and TCCON retrievals of column-average methane is reflected in different smoothing effects.

In this paper, we review the main factors driving the calculation of the tangent height of spaceborne limb measurements: the ray-tracing method, the refractive index model and the assumed atmosphere. We find that commonly used ray-tracing and refraction models are very accurate, at least in the mid-infrared. The factor with the largest effect in the tangent height calculation is the assumed atmosphere, which may cause errors of up to 200m.

In the presented paper, we introduce a method for the density background separation and a methodology for internal gravity waves analysis using the GPS RO density profiles. Various background choices are discussed, and the correspondence between analytical forms of the density and dry temperature background profiles is examined. Finally the advantages of the density instead of dry temperature GPS RO data utilization are listed (e.g. inclusion of non-hydrostatic waves).

An improved glyoxal retrieval for OMI measurements using the DOAS method has been developed. The retrieval is based on sensitivity tests for the selection of most appropriate retrieval parameters. Also, corrections for reduction of interferences with other species have been applied. In addition, the link between pyrogenic emissions and glyoxal over regions with large wildfires have been investigated, and showed that fires are an important source of glyoxal.

This publication intends to prove that a network of low-cost local area weather radars with a time resolution of 30s and range resolution of 60m is a reliable and scientifically valuable comple-ment to nationwide radar networks, especially in urban areas. The advantages of high temporal resolution and multiple coverage in overlapping areas are proven to enhance the quality of pre-cipitation estimates. Long-term comparison with C-band radar confirms very good accordance with POD>90% and FAR<10%.

A new method is presented for the determination of cloud top heights using the footage of a time-lapse camera that is placed above a frequently occurring cloud layer in a mountain valley. Contact points between cloud tops and underlying terrain are automatically detected in the camera image based on differences in the brightness, texture and movement of cloudy and non-cloudy areas. The height of the detected cloud top positions is determined by comparison with a digital elevation model project.

In this study, a correction spectrum accounting for insufficiencies in commonly used liquid water absorption spectra in DOAS applications is retrieved from ship-borne field measurements. The correction spectrum compensates at the same time for broadband parts of vibrational Raman scattering. With this, an entire compensation of liquid water spectral effects in DOAS applications was achieved.

We apply the TES ozone retrieval algorithm to IASI radiances and characterise the uncertainties and information content of the retrieved ozone profiles. We find that our biases with respect to sondes and our degrees of freedom for signal for ozone are comparable to previously published results from other IASI ozone algorithms. We find that predicted and empirical errors are consistent. In general, the precision of the IASI ozone profiles is better than 20%.

The REA technique cannot be applied on grassland shortly after management without the risk of REA-flux errors due to large uncertainties of b-factors and lacking scalar similarity. The NEE flux partitioning model based on REA measurement results is complex but can enhance results of common partitioning by considering ecosystem discrimination of 13C and wind velocity.

An understanding of the biogeochemical cycling of mercury is an important health issue. Exposure to mercury is primarily through fish consumption. The typical background concentration of Hg(0) is ~200 ppq; hence atmospheric measurements represent a significant challenge in ultratrace analytical chemistry. We developed a laser-based sensor for detection of gas-phase elemental mercury, Hg(0), that is capable of fast in-situ measurements at ambient levels and can also measure oxidized mercury.

We present a case study in solar/radiation nowcasting using environmental sensor measurements as inputs. While some sensor readings may oftentimes be missing, predictions need to be output continuously in near real time. We are after linear regression models that would be robust to missing data, i.e., that would perform well with or without data gaps. We recommend using regularized a PCA regression with our established guidelines for building robust regression models.

This paper presents a validated method and data set for new retrievals of trace gas concentrations and temperature from the ARIES infrared spectrometer instrument on the UK Atmospheric Research Aircraft (www.faam.ac.uk). This new capability for the aircraft will allow new science to be done because of the way it can sense information about the atmosphere without having to physically pass through it (remote sensing). This will allow us to better understand the make-up of the lower atmosphere.

We present here a new in situ instrument for ambient measurements of highly polar organic semi-volatile and low-volatility compounds in both the gas and particle phase by gas chromatography. Compounds previously measured only through filter collection and offline analysis can now be measured hourly with, in most cases, less than 20% uncertainty. This instrument provides unprecedented time resolution and the first ever observations of gas-particle partitioning for most of these compounds.

We designed and built a spectrometer, ABsolute Carbon dioxide (ABC), to measure atmospheric concentration of carbon dioxide. This instrument was tested in a forest environment for almost a year. Based on results from this long-term field deployment, we proved that ABC has the capability of performing high-accuracy, unattended, continuous field measurements with minimal use of reference gas cylinders.

Only very few techniques for wind measurements in the upper stratosphere and lower mesosphere exist. Moreover, none of these instruments is running on a continuous basis. This paper describes the development of ground-based microwave Doppler radiometry. Time series of daily wind profile measurements from four different locations at polar, mid- and tropical latitudes are presented. The agreement with ECMWF model data is good in the stratosphere, but discrepancies were found in the mesosphere.

We present stratospheric gravity wave observations from 4.3 micron radiance measurements by the nadir sounders AIRS and IASI. Three case studies demonstrate that AIRS and IASI provide a consistent picture of the temporal development of individual gravity wave events. Statistical comparisons based on five years of data (2008-2012) also showed similar patterns of gravity wave activity. Long-term records from combined satellite data are an exciting prospect for future gravity wave research.

Here the High Altitude and LOng range research aircraft Microwave Package (HAMP) is introduced. The package consists of three passive radiometer modules with 26 channels between 22 and 183 GHz and a 36 GHz Doppler cloud radar. The manuscript describes the instrument specifications, the installation in the aircraft, and the operation. Furthermore, results from simulation and retrieval studies, as well as measurements from a first test campaign, are shown.