A new airborne broadband radiometer system and an efficient method to correct thermal offsets

The instrumentation of the High Altitude and Long Range (HALO) research aircraft is extended by the new Broadband AirCrAft RaDiometer Instrumentation (BACARDI) to quantify the radiative energy budget. Two sets of pyranometers and pyrgeometers are mounted to measure upward and downward solar (0.3&ndash;3 &mu;m) and thermal-infrared (3&ndash;100 &mu;m) irradiances. The radiometers are installed in a passively ventilated fairing to reduce the effects of the dynamic environment, e.g., fast changes of altitude and temperature. The remaining thermal effects range up to 20 W m-2 for the pyranometers and 10 W m-2 for the pyrgeometers; they are corrected using an new efficient method that is introduced in this paper. Using data collected by BACARDI during a night flight, the thermal offsets are parameterized by the rate of change of the radiometer sensor temperatures. Applying the sensor temperatures instead of ambient air temperature for the parameterization provides a linear correction function (200&ndash;600 W m-2 K-1 s), that depends on the mounting position of the radiometer on HALO. Furthermore, BACARDI measurements from the EUREC4A (Elucidating the role of clouds-circulation coupling in climate) field campaign are analyzed to characterize the performance of the radiometers and to evaluate all corrections applied in the data processing. Vertical profiles of irradiance measurements up to 10 km altitude show that the thermal offset correction limits the bias due to temperature changes to values below 10 W m-2. Measurements with BACARDI during horizontal, circular flight patterns in cloud-free conditions demonstrate that the common geometric attitude correction of the solar downward irradiance provides reliable measurements in this typical flight sections of EUREC4A, even without active stabilization of the radiometer.</p

Highly resolved observations of trace gases in the lowermost stratosphere and upper troposphere from the Spurt project: an overview

During SPURT (Spurenstofftransport in der Tropopausenregion, trace gas transport in the tropopause region) we performed measurements of a wide range of trace gases with different lifetimes and sink/source characteristics in the northern hemispheric upper troposphere (UT) and lowermost stratosphere (LMS). A large number of in-situ instruments were deployed on board a Learjet 35A, flying at altitudes up to 13.7 km, at times reaching to nearly 380 K potential temperature. Eight measurement campaigns (consisting of a total of 36 flights), distributed over all seasons and typically covering latitudes between 35° N and 75° N in the European longitude sector (10° W–20° E), were performed. Here we present an overview of the project, describing the instrumentation, the encountered meteorological situations during the campaigns and the data set available from SPURT. Measurements were obtained for N2O, CH4, CO, CO2, CFC12, H2, SF6, NO, NOy, O3 and H2O. We illustrate the strength of this new data set by showing mean distributions of the mixing ratios of selected trace gases, using a potential temperature – equivalent latitude coordinate system. The observations reveal that the LMS is most stratospheric in character during spring, with the highest mixing ratios of O3 and NOy and the lowest mixing ratios of N2O and SF6. The lowest mixing ratios of NOy and O3 are observed during autumn, together with the highest mixing ratios of N2O and SF6 indicating a strong tropospheric influence. For H2O, however, the maximum concentrations in the LMS are found during summer, suggesting unique (temperature- and convection-controlled) conditions for this molecule during transport across the tropopause. The SPURT data set is presently the most accurate and complete data set for many trace species in the LMS, and its main value is the simultaneous measurement of a suite of trace gases having different lifetimes and physical-chemical histories. It is thus very well suited for studies of atmospheric transport, for model validation, and for investigations of seasonal changes in the UT/LMS, as demonstrated in accompanying and elsewhere published studies

Highly resolved observations of trace gases in the lowermost stratosphere and upper troposphere from the Spurt project: an overview

During SPURT (Spurenstofftransport in der Tropopausenregion, trace gas transport in the tropopause region) we performed measurements of a wide range of trace gases with different lifetimes and sink/source characteristics in the northern hemispheric upper troposphere (UT) and lowermost stratosphere (LMS). A large number of in-situ instruments were deployed on board a Learjet 35A, flying at altitudes up to 13.7 km, at times reaching to nearly 380 K potential temperature. Eight measurement campaigns (consisting of a total of 36 flights), distributed over all seasons and typically covering latitudes between 35° N and 75° N in the European longitude sector (10° W–20° E), were performed. Here we present an overview of the project, describing the instrumentation, the encountered meteorological situations during the campaigns and the data set available from SPURT. Measurements were obtained for N2O, CH4, CO, CO2, CFC12, H2, SF6, NO, NOy, O3 and H2O. We illustrate the strength of this new data set by showing mean distributions of the mixing ratios of selected trace gases, using a potential temperature – equivalent latitude coordinate system. The observations reveal that the LMS is most stratospheric in character during spring, with the highest mixing ratios of O3 and NOy and the lowest mixing ratios of N2O and SF6. The lowest mixing ratios of NOy and O3 are observed during autumn, together with the highest mixing ratios of N2O and SF6 indicating a strong tropospheric influence. For H2O, however, the maximum concentrations in the LMS are found during summer, suggesting unique (temperature- and convection-controlled) conditions for this molecule during transport across the tropopause. The SPURT data set is presently the most accurate and complete data set for many trace species in the LMS, and its main value is the simultaneous measurement of a suite of trace gases having different lifetimes and physical-chemical histories. It is thus very well suited for studies of atmospheric transport, for model validation, and for investigations of seasonal changes in the UT/LMS, as demonstrated in accompanying and elsewhere published studies

Ion beam lithography for Fresnel zone plates in X-ray microscopy

Fresnel Zone Plates (FZP) are to date very successful focusing optics for X-rays. Established methods of fabrication are rather complex and based on electron beam lithography (EBL). Here, we show that ion beam lithography (IBL) may advantageously simplify their preparation. A FZP operable from the extreme UV to the limit of the hard X-ray was prepared and tested from 450 eV to 1500 eV. The trapezoidal profile of the FZP favorably activates its 2nd order focus. The FZP with an outermost zone width of 100 nm allows the visualization of features down to 61, 31 and 21 nm in the 1st, 2nd and 3rd order focus respectively. Measured efficiencies in the 1st and 2nd order of diffraction reach the theoretical predictions

Evaluation of compact hygrometers for continuous airborne measurements

Continuous water vapour measurements in the troposphere and lowermost stratosphere are crucial for the understanding of global water transport processes and climate impact. In the course of the ‘Development and Evaluation of Novel and Compact Hygrometer for Airborne Research’ (DENCHAR) project, water vapour instruments (WaSuL, WVSS‑II, ICH) have been partly newly developed and/or extensively tested in the laboratory as well as onboard of research aircraft. For the blind intercomparisons of the instruments, an MBW DP30 frostpoint mirror and the established FISH Lyman‑α instrument (calibrated versus the MBW DP30) served as reference hygrometers in the laboratory and during the flights, respectively. All DENCHAR-instruments show very consistent behaviour in their respective measuring ranges with deviations of less than about 5–10 %, in‑flight with respect to FISH and in the laboratory with respect to DP30 in the range between 100 and 1000 ppmv, as well as among each other in the range of 100 to 20000 ppmv. At mixing ratios below 100 ppmv, differences between the instruments appear which depend on the individual response times and calibrations. In summary, the WaSul, ICH and WVSS‑II hygrometers can be recommended for continuous water vapour measurements at mixing ratios larger than 10, 30, and 30 ppmv, respectively. For an accurate, reliable, and stable measurement of lower water vapour mixing ratios with a compact hygrometer suitable for autonomous operation, either these instruments need to be improved or new technology would have to be developed. In addition to the instrument evaluation, the performance of different water vapour inlet systems is addressed by comparing a forward-facing Rosemount (TAT housing) and a wall plate inlet. From all in‑flight tests, no measurement artifacts caused by specific characteristics of an inlet could be identified, i.e., forward-facing Rosemount and wall plate inlets can be recommended for use on aircraft for water vapour mixing ratios above 30 ppmv

Probing finescale dynamics and microphysics of clouds with helicopter-borne measurements

Helicopter-based measurements provide an opportunity for probing the finescale dynamics and microphysics of clouds simultaneously in space and time. Due to the low true air speed compared with research aircraft, a helicopter allows for measurements with much higher spatial resolution. To circumvent the influence of the helicopter downwash the autonomous measurement pay-load Airborne Cloud Turbulence Observation System (ACTOS) is carried as an external cargo 140 m below the helicopter. ACTOS allows for collocated measurements of the dynamical and cloud microphysical parameters with a spatial resolution of better than 10 cm. The interaction between turbulence and cloud microphysical processes is demonstrated using the following two cloud cases from recent helicopter measurements: i) a cumulus cloud with a low degree of turbulence and without strong vertical dynamics, and, in contrast, ii) an actively growing cloud with increased turbulence and stronger updrafts. The turbulence and microphysical measurements suggest that entrainment at the tops of these two clouds occurs by inhomogeneous and homogeneous mixing, respectively. ©2006 American Meteorological Society

DENCHAR-Assessment Report on the Performance of a New Suite of Hygrometers for EUFAR

&lt;p&gt;Continuous water vapour measurements in the troposphere and lowermost stratosphere are crucial for the understanding of global water transport processes and climate impact. In the course of the 'Development and Evaluation of Novel and Compact Hygrometer for Airborne Research' (DENCHAR) project, water vapour instruments (WaSuL, WVSS-II, ICH) have been partly newly developed and/or extensively tested in the laboratory as well as onboard of research aircraft. For the blind intercomparisons of the instruments, an MBW DP30 frostpoint mirror and the established FISH Lyman-α instrument (calibrated versus the MBW DP30) serve as reference hygrometers in the laboratory and during the flights.&nbsp;&lt;/p&gt;&lt;p&gt;All DENCHAR-instruments show very consistent behaviour in their respective measuring ranges with deviations of less than about 5-10 %, in-flight with respect to FISH and in the laboratory with respect to DP30 in the range between 100 and1000 ppmv, as well as among each other in the range of 100 to 20000 ppmv. At mixing ratios below 100 ppmv, differences between the instruments appear which depend on the individual response times and calibrations. In summary, the WaSul, ICH and WVSS-II hygrometers can be recommended for continuous water vapour measurements at mixing ratios larger than 10, 30, and 200 ppmv, respectively. For an accurate, reliable, and stable measurement of lower water vapour mixing ratios with a compact hygrometer suitable for autonomous operation, either these instruments need to be improved or new technology would have to be developed.&lt;/p&gt;&lt;p&gt;In addition to the instrument evaluation, the performance of different water vapour inlet systems is addressed by comparing a forward-facing Rosemount (TAT housing), and a wall plate inlet. From all in-flight tests, no measurement artifacts caused by specific characteristics of an inlet could be identified, i.e., forward-facing Rosemount and wall plate inlets can be recommended for use on aircraft for water vapour mixing ratios above 30 ppmv.&lt;/p&gt

Highly resolved observations of trace gases in the lowermost stratosphere and upper troposphere from the Spurt project: an overview

ISSN:1680-7375ISSN:1680-736

Characterization of a HKT-type transporter in rice as a general alkali cation transporter

Golldack D, Su H, Quigley F, et al. Characterization of a HKT-type transporter in rice as a general alkali cation transporter. The Plant Journal. 2002;31(4):529-542.We report the characterization of rice OsHKT1 (Oryza sativa ssp. indica) homologous to the wheat K+/ Na+-symporter HKT1. Expression of OsHKT1 in the yeast strain CY162 defective in K+-uptake restored growth at mM and muM concentrations of K+ and mediated hypersensitivity to Na+. When expressed in Xenopus oocytes, rice OsHKT1 showed uptake characteristics of a Na+-transporter but mediated transport of other alkali cations as well. OsHKT1 expression was analysed in salt-tolerant rice Pokkali and salt-sensitive IR29 in response to external cation concentrations. OsHKT1 is expressed in roots and leaves. Exposure to Na+, Rb+, Li+, and Cs+ reduced OsHKT1 transcript amounts in both varieties and, in some cases, incompletely spliced transcripts were observed. By in situ hybridizations the expression of OsHKT1 was localized to the root epidermis and the vascular tissue inside the endodermis. In leaves, OsHKT1 showed strongest signals in cells surrounding the vasculature. The repression of OsHKT1 in the two rice varieties during salt stress was different in various cell types with main differences in the root vascular tissue. The data suggest control over HKT expression as a factor that may distinguish salt stress-sensitive and stress-tolerant lines. Differences in transcript expression in space and time in different lines of the same species appear to be a component of ion homeostasis correlated with salt sensitivity and tolerance