The MOPITT Version 6 product for carbon monoxide (CO) incorporates several enhancements. First, a geolocation bias has been eliminated. Second, the new variable a priori for CO concentrations is based on simulations performed with the CAM-Chem chemical transport model for the years 2000-2009. Third, required meteorological fields are extracted from the MERRA reanalysis. Finally, a retrieval bias in the upper troposphere was substantially reduced. Validation results are presented.

We present the new vM21 MIPAS temperatures from 20 to 102km for all of its 2005-2012 MA, UA and NLC measurements. The main upgrades are the update of ESA L1b spectra, spectroscopic database and O and CO2 climatologies, and improvement in Tk-gradient and offset regularizations and apodization accuracy. The vM21 Tk's correct the main systematic errors of previous versions and lead to remarkable improvement in their comparisons with ACE-FTS, MLS, OSIRIS, SABER and SOFIE and the MLO and TMF lidars.

Sea spray aerosol particles represent a system of relatively high chemical complexity. The chemical composition of sea spray aerosol particles was shown in this study to be directly determined by the method used to produce bubbles, which produce aerosol upon bursting at the sea surface. Using methods which deviate from natural breaking waves directly translated into differences in the measured particle sizes and the chemical mixing state of laboratory-generated sea spray aerosol particles.

Two different methods for the determination of the mixing layer height (MLH) are investigated with a one-year data set from central Europe: (i) based on a significant gradient of backscatter and (ii) on the vertical velocity. The aerosol-based method shows significant over-estimation in the morning hours when the ML grows into the residual layer and late afternoon hours when turbulent mixing decays. This results in systematic over-estimation of average characteristcs as e.g. maximum MLH.

Peroxyacetyl nitrate (PAN) plays an important role in the distribution of lower-atmospheric ozone. PAN can be transported far from the original pollution source, leading to ozone formation and degraded air quality in remote areas. Satellite observations from the Tropospheric Emission Spectrometer (TES) are sensitive to PAN at lower altitude than previous global data sets. We describe characteristics of the data and show elevated PAN associated with boreal fires and outflow of Asian pollution.

This paper describes a new airborne instrument for measuring the trace gas composition of the atmosphere.

The paper provides the community with criteria to quantify the value of complementary climate measurements and to assess how the uncertainty in a measurement of an ECV is reduced by measurement complementarity. The study demonstrates the potential of entropy and mutual correlation, defined in information theory as metrics for quantifying synergies, and shows that the random uncertainties of a single instrument time series of TCWV can be strongly reduced by including complementary measurements.

Presented here is the FAME-C (Freie Universität Berlin AATSR and MERIS cloud) algorithm, which uses satellite measurements in the visible, near-infrared and infrared part of the spectrum to retrieve cloud macrophysical properties, such as cloud amount and two independent cloud top heights, and cloud optical and microphysical properties, such as cloud top thermodynamic phase, cloud optical thickness and effective radius, which describes the particle size distribution.

In winter 2011, the Global Hawk unmanned aircraft system (UAS) was deployed over the Arctic to evaluate a UAS dropsonde system at high latitudes. Dropsondes deployed from the Global Hawk successfully obtained high-resolution profiles of temperature, pressure, humidity, and wind speed and direction information between the stratosphere and surface. During the 25-hour polar flight, the Global Hawk released 35 sondes between the North Slope of Alaska and 85° N latitude.

The HelioClim-3 database (HC3v3) provides records of surface solar irradiation every 15 min estimated by processing images from the geostationary meteorological Meteosat satellites using climatological data sets of atmospheric properties. A method is proposed to improve a posteriori HC3v3 by combining it with data records of advanced global aerosol property forecasts and physically consistent total column content in water vapour and ozone produced by the MACC projects.

Radio Occultation (RO) observations featuring high vertical resolution, global availability, and high accuracy were used to investigate global characteristics of the lapse rate tropopause. Climatological tropopause characteristics for the RO record from 2001 to 2013 extend previous studies on tropopause structure and its temporal variability. Latitudinal and longitudinal variations as well as the annual cycle and inter-annual variability were analyzed for the tropopause altitude and temperature.

We systematically explore the cumulative effect of MISR research aerosol retrieval algorithm assumptions, quantifying and correcting the main sources of uncertainty over ocean. High median spectral aerosol optical depth biases of ~0.024 at low AOD are reduced to ~0.01 with an improved, physically based ocean surface model, particle properties and mixtures, adaptive reflectance uncertainty estimates and pixel selection, minor radiometric calibration adjustments and more stringent cloud screening.

- A new algorithm to retrieve nitrogen dioxide by Brewer spectrophotometers was developed. - Direct sun and zenith sky data recorded at the Izaña observatory were processed with the new algorithm and compared to co-located reference instruments. - The measurement uncertainty was thoroughly determined by using a Monte Carlo technique. - The new algorithm can be applied to more than 60 Brewers around the world.