No abstract

[1] Here we present extensive observations of stratospheric and upper tropospheric water vapor using the balloon-borne Cryogenic Frost point Hygrometer (CFH) in support of the Aura Microwave Limb Sounder (MLS) satellite instrument. Coincident measurements were used for the validation of MLS version 1.5 and for a limited validation of MLS version 2.2 water vapor. The sensitivity of MLS is on average 30% lower than that of CFH, which is fully compensated by a constant offset at stratospheric levels but only partially compensated at tropospheric levels, leading to an upper tropospheric dry bias. The sensitivity of MLS observations may be adjusted using the correlation parameters provided here. For version 1.5 stratospheric observations at pressures of 68 hPa and smaller MLS retrievals and CFH in situ observations agree on average to within 2.3% ± 11.8%. At 100 hPa the agreement is to within 6.4% ± 22% and at upper tropospheric pressures to within 23% ± 37%. In the tropical stratosphere during the boreal winter the agreement is not as good. The ''tape recorder'' amplitude in MLS observations depends on the vertical profile of water vapor mixing ratio and shows a significant interannual variation. The agreement between stratospheric observations by MLS version 2.2 and CFH is comparable to the agreement using MLS version 1.5. The variability in the difference between observations by MLS version 2.2 and CFH at tropospheric levels is significantly reduced, but a tropospheric dry bias and a reduced sensitivity remain in this version. In the validation data set a dry bias at 177.8 hPa of À24.1% ± 16.0% is statistically significant.

[1] We develop a new forward algorithm for the retrieval of effective size and ice water content (IWC) of ice crystals in clouds by using collocated 95-GHz (3.16 mm) cloud radar and lidar with the wavelength of 0.532 mm. Use of radar or lidar alone has a fundamental difficulty to obtain cloud microphysics because of the wide variety of size distributions of cloud particles, though it is effective to obtain cloud macrophysical information such as cloud boundaries. The combined use of radar and lidar can overcome this problem. One unique feature of the algorithm is the attenuation-correction to the lidar signals according to the cloud microphysics determined by look-up tables of backscattering and extinction for the radar and lidar signals. Consequently, the combined system enables the retrieval of vertical profiles of the effective radius (r eff ) and ice water content (IWC). We perform several numerical analyses of the retrieved values for potential sources of errors, that is, the shape of the size distribution, biases in the radar and lidar signals, and the effect of multiple scattering. Then we provide the formulations that describe the retrieval errors as a function of the given bias and optical thickness. Finally, we demonstrate retrieval of microphysics for ground-based observation of cirrus clouds in February 2000 in Kashima, Japan. We examine the vertical distributions of r eff , IWC, fall velocity, and depolarization ratio as well as the interrelationships between them. The radius of the particles turns out to be the largest near the cloud bottom, and the fall velocity also shows a trend consistent with the r eff tendency. There are no in situ measurements to validate the retrieved parameters for the observations. Instead, supporting arguments are given on the basis of information about the expected behavior of the relationships between the cloud microphysical parameters from the literature.

[1] We investigated water vapor variations in the tropical lower stratosphere on seasonal, quasi-biennial oscillation (QBO), and decadal time scales using balloon-borne cryogenic frost point hygrometer data taken between 1993 and 2009 during various campaigns including the Central Equatorial Pacific Experiment (March 1993), campaigns once or twice annually during the Soundings of Ozone and Water in the Equatorial Region (SOWER) project in the eastern Pacific (1998Pacific ( -2003

A polarization lidar was continuously operated aboard the research vessel Mirai in the tropical western Pacific over three northern winters: at 2.0°N, 138.0°E during November and December 2001; at 2.0°N, 138.5°E during November and December 2002; and at 7.5°N, 134.0°E during December 2004 and January 2005. Intensive radiosonde soundings were made from the vessel at 3‐h intervals during all three campaigns. The mechanisms that underlie the observed variations in cirrus in the tropical tropopause layer (TTL) are discussed from the viewpoint of large‐scale dynamics and transport. During the 2001 campaign, the tropopause region was cold, but the TTL was often clear, with only some subvisual cirrus. Potential vorticity data and trajectories show that the TTL during this period was strongly affected by dry air transport from the northern midlatitude lower stratosphere. During the 2002 campaign, a packet of large‐amplitude equatorial Kelvin waves was the primary control on the generation and disappearance of cirrus in the TTL. During the 2004–2005 campaign, a cold phase of large‐scale waves resulted in cirrus generation in the TTL in late December of 2004, similar to that observed during the 2002 campaign. Outflow from the South Pacific Convergence Zone (SPCZ) caused optically thick cirrus in the TTL, particularly during early January 2005, when we also observed regular diurnal variations in cirrus development within the TTL, that is, apparent sedimentation during the nighttime. We investigated two possible controlling processes, namely, horizontal advection together with diurnal variations in convective activity within the SPCZ and diurnal variations in local temperature due to tides and gravity waves. In the equatorial western Pacific, equatorial Kelvin waves are the important dynamical process that controls cirrus variations in the TTL. Dry‐air horizontal transport from the midlatitude lower stratosphere and wet‐air vertical transport near the tropical convergence regions should also be considered in fully explaining the cirrus observations in the TTL.

Abstract. A meteorological balloon-borne cloud sensor called the cloud particle sensor (CPS) has been developed. The CPS is equipped with a diode laser at ∼ 790 nm and two photodetectors, with a polarization plate in front of one of the detectors, to count the number of particles per second and to obtain the cloud-phase information (i.e. liquid, ice, or mixed). The lower detection limit for particle size was evaluated in laboratory experiments as ∼ 2 µm diameter for water droplets. For the current model the output voltage often saturates for water droplets with diameter equal to or greater than ∼ 80 µm. The upper limit of the directly measured particle number concentration is ∼ 2 cm −3 (2×10 3 L −1 ), which is determined by the volume of the detection area of the instrument. In a cloud layer with a number concentration higher than this value, particle signal overlap and multiple scattering of light occur within the detection area, resulting in a counting loss, though a partial correction may be possible using the particle signal width data. The CPS is currently interfaced with either a Meisei RS-06G radiosonde or a Meisei RS-11G radiosonde that measures vertical profiles of temperature, relative humidity, height, pressure, and horizontal winds. Twenty-five test flights have been made between 2012 and 2015 at midlatitude and tropical sites. In this paper, results from four flights are discussed in detail. A simultaneous flight of two CPSs with different instrumental configurations confirmed the robustness of the technique. At a midlatitude site, a profile containing, from low to high altitude, water clouds, mixed-phase clouds, and ice clouds was successfully obtained. In the tropics, vertically thick cloud layers in the middle to upper troposphere and vertically thin cirrus layers in the upper troposphere were successfully detected in two separate flights. The data quality is much better at night, dusk, and dawn than during the daytime because strong sunlight affects the measurements of scattered light.

[1] We show characteristics of a tropical deep convection observed in an experiment employing the A-train constellation, the spaceborne imager Moderate Resolution Imaging Spectroradiometer (MODIS), the sounder Atmospheric Infrared Sounder (AIRS)-advanced microwave sounding unit (AMSU), the cloud radar CloudSat, and the lidar Cloud-Aerosol Lidar with Orthogonal Polarisation (CALIOP). CloudSat and CALIOP measured a vertical cross section of a deep convection at 1.1 km from its center, where the center is defined as the local minimum of the brightness temperature T B (11 mm) measured by using MODIS. This deep convection should be overshooting since its cloud top height measured by using CALIOP was 840 m higher than that of 380 K potential temperature as estimated by using AIRS-AMSU data. The cloud morphology observed by using CALIOP indicates that deep convections raised the isentropic surface in the tropical tropopause layer and that there were downdrafts around the deep convection. The averaged mode radius of ice particles and ice water content (IWC) in the deep convection above 380 K are estimated as 23.0 ± 4.9 mm and 7.2 ± 8.0 mg/m 3 , respectively, by the use of CloudSat and CALIOP data. The volume of the deep convection above a height of 380 K and the averaged IWC, of which the particle size is less than 20 mm, are estimated and the deep convection has the potential to hydrate the stratosphere with about 1 × 10 2 t of water vapor. We also show deep convections above a height of 380 K are not rare phenomena over the tropical land and warm water pool.

No abstract