Atmospheric Instrument Systems and Technology in the Goddard Earth Sciences Division

Studies of the Earths atmosphere require a comprehensive set of observations that rely on instruments flown on spacecraft, aircraft, and balloons as well as those deployed on the surface. Within NASAs Goddard Space Flight Center (GSFC) Earth Sciences Division-Atmospheres, laboratories and offices maintain an active program of instrument system development and observational studies that provide: 1) information leading to a basic understanding of atmospheric processes and their relationships with the Earths climate system, 2) prototypes for future flight instruments, 3) instruments to serve as calibration references for satellite missions, and 4) instruments for future field validation campaigns that support ongoing space missions. Our scientists participate in all aspects of instrument activity, including component and system design, calibration techniques, retrieval algorithm development, and data processing systems. The Atmospheres Program has well-equipped labs and test equipment to support the development and testing of instrument systems, such as a radiometric calibration and development facility to support the calibration of ultraviolet and visible (UV/VIS), space-borne solar backscatter instruments. This document summarizes the features and characteristics of 46 instrument systems that currently exist or are under development. The report is organized according to active, passive, or in situ remote sensing across the electromagnetic spectrum. Most of the systems are considered operational in that they have demonstrated performance in the field and are capable of being deployed on relatively short notice. Other systems are under study or of low technical readiness level (TRL). The systems described herein are designed mainly for surface or airborne platforms. However, two Cubesat systems also have been developed through collaborative efforts. The Solar Disk Sextant (SDS) is the single balloon-borne instrument. The lidar systems described herein are designed to retrieve clouds, aerosols, methane, water vapor pressure, temperature, and winds. Most of the lasers operate at some wavelength combination of 355, 532, and 1064 nm. The various systems provide high sensitivity measurements based on returns from backscatter or Raman scattering including intensity and polarization. Measurements of the frequency (Doppler) shift of light scattered from various atmospheric constitutes can also be made. Microwave sensors consist of both active (radar) and passive (radiometer) systems. These systems are important for studying processes involving water in various forms. The dielectric properties of water affect microwave brightness temperatures, which are used to retrieve atmospheric parameters such as rainfall rate and other key elements of the hydrological cycle. Atmosphere radar systems operate in the range from 9.6 GHz to 94 GHz and have measurement accuracies from -5 to 1 dBZ; radiometers operate in the 50 GHz to 874 GHz range with accuracies from 0.5 to 1 degree K; conical and cross-track scan modes are used. Our passive optical sensors, consisting of radiometers and spectrometers, collectively operate from the UV into the infrared. These systems measure energy fluxes and atmospheric parameters such as trace gases, aerosols, cloud properties, or altitude profiles of various species. Imager spatial resolution varies from 37 m to 400 m depending on altitude; spectral resolution is as small as 0.5 nm. Many of the airborne systems have been developed to fly on multiple aircraft

User requirements for monitoring the evolution of stratospheric ozone at high vertical resolution (‘Operoz’: Operational ozone observations using limb geometry)

The purpose of the Operoz study has been threefold: (i) To establish the user requirements for an operational mission targeting ozone profiles at high vertical resolution, (ii) To identify the observational gaps with respect to these user requirements taking into account planned operational missions and observational ground networks, and (iii) To perform a reality check on the observational requirements based on proven concepts and present-day knowledge of potentially available measurement techniques and to identify options for a small to medium size satellite mission

Improvement and interpretation of the tropospheric ozone columns retrieved based on SCIAMACHY Limb-Nadir Matching approach

Tropospheric ozone, one of the most important green-house gases and one of the most essential components of photochemical smog, has been monitored from space by different retrieval techniques since the late 1980s. Satellite measurements are well suitable to investigate sources and transport mechanisms of tropospheric ozone, as well as its atmospheric chemistry on regional and global scales. Nevertheless, the retrieval of tropospheric ozone columns (TOCs) from satellite data constitutes a big challenge since approximately 90% of the total ozone amount is located in the stratosphere, and only the remaining 10% is located in the troposphere. The Limb-Nadir Matching technique is one of the methods that has been widely used to re-trieve TOCs from space borne measurements. In previous studies, this approach has been applied to measurements from the SCIAMACHY instrument, which alternates limb and nadir geometry. An accurate tropopause height, retrieved from the ECMWF database, was used to subtract the stratospheric ozone column from the total ozone column. In this thesis, a three-step approach is shown that was developed to improve the current Limb-Nadir Matching TOC retrieval technique, and resulted in the new database version 1.2. Several improvements in the V1.2 TOC data have been achieved. The obtained amount of TOC V1.2 data has increased by a factor of two in comparison to the original dataset. Fur-thermore, the data quality has improved in many aspects. First of all, the V1.2 TOC data set reduces the negative (>10 DU) and positive (~10 DU) biases over tropics and high latitudes, respectively. The reduction is achieved by use of the improved limb ozone data set V3.0, which was tested and validated against the previous version V2.9 in this thesis. The TOC values were also optimized over the midlatitudes by decreasing its positive biases. The yearly averaged V1.2 TOC data set agrees well with ozonesonde measurements within 5 DU globally. More details on the TOC distribution were successfully captured because of the improved accuracy of the data. The clear observation of the spring TOC maxima (~42 DU) over the Arabian Sea (AS) during the pre-monsoon is one of the benefits of using the V1.2 TOC product. In the present thesis, the potential sources of the AS spring ozone pool are investigated by use of multiple data sets (e.g., SCIAMACHY Limb-Nadir-Matching TOC, OMI/MLS TOC, TES TOC, MACC reanalysis data, MOZART-4 model and HYSPLIT model). 3/4 of the enhanced ozone concentrations are attributed to the 0-8 km height range. The main source of the ozone enhancement is considered to be caused by long range transport of pollutants from India (~ 50% contributions to the lowest 4 km, ~ 20% contributions to the 4-8 km height range), the Middle East, Africa and Europe (~30% in total). In addition, the vertical pollution accumulation in the lower troposphere, especially at 4-8 km, was found to be important for the AS spring ozone pool. Local photochemistry, on the other hand, plays a negligible role in producing ozone at the 4-8 km height range. In the 0-4 km height range, ozone is quickly removed by wet-deposition. The AS spring TOC maxima are influenced by the dynamical variations caused by the sea surface temperature (SST) anomaly during the El Nino period in 2005 and 2010 with a ~5 DU decrease. The Limb-Nadir Matching retrieval improvement scheme developed in this thesis leads to a much more accurate TOC product measured by SCIAMACHY and a better understanding of tropospheric ozone distributions

The Ozone Monitoring Instrument: Overview of 14 years in space

This overview paper highlights the successes of the Ozone Monitoring Instrument (OMI) on board the Aura satellite spanning a period of nearly 14 years. Data from OMI has been used in a wide range of applications and research resulting in many new findings. Due to its unprecedented spatial resolution, in combination with daily global coverage, OMI plays a unique role in measuring trace gases important for the ozone layer, air quality, and climate change. With the operational very fast delivery (VFD; direct readout) and near real-time (NRT) availability of the data, OMI also plays an important role in the development of operational services in the atmospheric chemistry domain