Vertical Profiles Of Water Vapor Research Articles

Statistical Relationship between ISCCP Cloud Type and Vertical Relative Humidity Profile

The statistical relationship between ISCCP (International Satellite Cloud Climatology Project) cloud type, and the vertical relative humidity profile observed by radiosonde, was studied during the period from August, 1992 to July, 1994. The ISCCP-DX data of GMS (Geostationary Meteorological Satellite) were used to obtain cloud type information over the 1.5 degree grid area centered at the radiosonde station. To obtain the reliable cloud type classification, the data at 00 UTC-when the visible data were available-were used. The radiosonde observations when the 1.5 degree grid area is covered by single cloud type were used to compare the vertical relative humidity profile. Four cloud types of low-level, middle-level, cirrus-type and cumulonimbus-type cloud, and cloud-free case were selected for the comparison. As was expected, the mean relative humidity was largest at all levels when the cumulonimbus-type cloud existed, and was smallest at all levels when no cloud existed. The relative humidity was larger than that of a cloud-free case at middle- and low-level (low-level) when middle-cloud (low-cloud) existed. When cirrus cloud existed, the high level relative humidity was larger than that when low- and middle-cloud existed, and showed local maximum at 400-500 hPa. The feasibility for the use of the statistical relationship in this study in estimating relative humidity profile was shown as a case study by comparing with the current JMA statistical relationship derived from the GMS single infrared data. Cirrus clouds are difficult to be identified objectively from single infrared measurement and are often misclassified as middle- or low-level cloud. The misclassification between cirrus-type cloud and middle-/low- level cloud leads to a different vertical profile of water vapor. However, cirrus-type cloud is reasonably identified in the ISCCP with the use of visible and infrared measurements.

PIn. II. Comparative evaluation of SSM/I and TMI precipitable water estimate for the Mediterranean Sea

For pt.I see ibid., vol.39, no.12, p.2566-74 (2001). To estimate integrated precipitable water vapor along with liquid water path and water vapor effective profile (i.e. standard atmospheric profile approximation), utilizing the Special Sensor Microwave/Imager (SSM/I) and Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) radiometers, an operative procedure was developed and assessed. This procedure is based on a fast nonlinear physical inversion algorithm (PIn) developed by the authors. A large data set of near-coincident TMI and SSM/I data acquisitions were collected and used to supply the procedure. Retrieved parameters were compared against retrievals achieved with well-accepted statistical algorithms, and consistency between TMI and SSM/I retrievals was confirmed. As far as TMI and SSM/I precipitable water retrieving consistency is concerned, this research revealed a linear relationship up to 20 kg/m/sup 2/ and a general overestimate of TMI retrieving, for higher values. A new algorithm for obtaining integrated precipitable water from TMI brightness temperatures was introduced and the goodness of its accuracy was reported. The procedure proved to be reliable and portable and its integrated precipitable water vapor retrieving was assessed to be as accurate as the best radiometric retrieving algorithms, reported in literature. For SSM/I data, developed-procedure liquid water path estimates seemed to be in good agreement with statistical retrievals. Eventually the procedure provided effective water vapor vertical profiles which belong to a deterministic distribution area characterized by an upper and lower limit; it was confirmed that SSM/I and TMI vertical profile distribution areas mainly overlap even if they are characterized by different sensitivities to profile parameters.

The net radiation budget of the northern hemisphere

A radiative transfer model was used together with mean monthly long‐term climatological data to infer the net radiation budget of the Northern Hemisphere for latitudinal zones of 10° width. Most of the data were taken from the International Satellite Cloud Climatology Project and supplemented by data from the collaboration between National Centers for Environmental Prediction and National Center for Atmospheric Research, for the vertical profiles of water vapor and temperature. Seasonal and latitudinal variations of net shortwave, longwave, and all‐wave radiative fluxes and cloud radiative forcings were estimated at the top of the atmosphere (TOA) and at the Earth's surface, and also radiative cooling/heating rates, together with their mean annual and mean hemispherical variations. The validation of the net TOA all‐wave fluxes is based on a comparison with 5 years mean Earth Radiation Budget Experiment data for the shortwave and longwave fluxes in two of our previous studies. The net all‐wave fluxes were found to be mainly determined by the net shortwave fluxes. Near radiative equilibrium was found on a mean annual basis for net all‐wave radiation at TOA, while at the surface a gain of 99 W m−2 was found for the hemisphere. The estimated net all‐wave forcings generally decrease from equator to pole, with local maxima in middle to high latitudes, and from summer to winter. The net shortwave cloud forcings were found to dominate the net longwave ones, by a factor of about 2. Mean annual hemispherical cloud forcings equal to 25 W m−2 and 13 W m−2 were computed at TOA and at the surface, respectively. A net all‐wave atmospheric radiative cooling was computed, which decreases from equator to pole, with a local maximum in the subtropics, and from winter to summer, having a mean annual hemispherical value of 97 W m−2. For all fluxes, forcings, and cooling/heating rates, detailed comparisons with the work of other authors were performed, and the main discrepancies are discussed.

The Polar Ozone and Aerosol Measurement (POAM) III instrument and early validation results

Polar Ozone and Aerosol Measurement (POAM) III, a follow‐on to the successful POAM II, is a spaceborne experiment designed to measure the vertical profiles of ozone, water vapor, nitrogen dioxide, and aerosol extinction in the polar stratosphere and upper troposphere with a vertical resolution of 1–2 km. Measurements are made by the solar occultation technique. POAM III, now in polar orbit aboard the SPOT 4 satellite, is providing data on north‐ and south‐polar ozone phenomena, including the south‐polar ozone hole, and on the spatial and temporal variability of stratospheric aerosols, polar stratospheric clouds, and polar mesospheric clouds. Differences between the POAM III and POAM II instruments are described. First validations of POAM III data products by comparison with Halogen Occultation Experiment and ozonesonde data are presented.

MIRA: Review of inputs from updated results of the PHOBOS mission

The future Mars International Reference Atmosphere (MIRA) is intended to replace the present COSPAR Mars Reference Model compiled in 1979 on the basis of Mariner 9 and Viking 1,2 missions results. At the moment, several sources of the post-Viking data potentially useful for MIRA are available. Among them is a data set obtained during Phobos mission in 1989. The interpretation of these data has undergone thorough refinement, so final recommendations for MIRA can be made. The principal points are: 1) vertical profile of water vapor with a “knee” at the height about 25 km retrieved in the spring equinox season near equator; 2) variations of water vapor column density including peculiarities on the slopes of high mountains; 3) vertical profiles of ozone; 4) new estimates of CO abundance; 5) surface pressure/height mapping (CO 2 altimetry) in selected regions; 6) optical depths of aerosols; 7) vertical profiles of aerosol between surface and 40 km; 8) properties of high altitude ice layers and clouds above mountains; 9) microphysical properties of aerosol particles (size, composition, and number density estimates). The data have been obtained by means of instruments AUGUSTE (UV and NIR spectrometers for limb sounding of the atmosphere using solar occultations), ISM (NIR scanning spectrometer), TERMOSKAN (thermal IR scanning radiometer), KRFM (near-UV and visible multi-band photometer). The observations were performed in equatorial regions during northern spring (solar aerocentric longitudes 8° < L s < 18°).

Broadband lidar measurements of tropospheric water vapor profiles

A new technique has been developed for the measurement of vertical profiles of water vapor in the troposphere. The method, which is also appropriate for the measurement of gases such as ozone and nitrogen dioxide, is based on the application of differential optical absorption spectroscopy (DOAS) to backscattered photons from a broadband lidar (10–20 nm at full width half maximum) operating in the UV‐visible region of the electromagnetic spectrum. A Nd: YAG pumped broadband dye laser is used as the light source, and backscattered photons from the atmosphere are both time and spectrally resolved using an imaging spectrometer with a charge‐coupled device (CCD) detector. The new broadband lidar circumvents many of the difficulties and inaccuracies involved with traditional narrowband differential absorption lidar (DIAL) water vapor observations, for example, the laser bandwidth and wavelength‐positioning requirements demanded by the narrowness of the water vapor transitions. Water vapor mixing ratio profiles measured over Cambridge, England, in 1996 with the new instrument demonstrate good levels of agreement with quasi‐simultaneous radiosonde profiles from nearby weather stations.

Estimation of boundary layer humidity fluxes and statistics from airborne differential absorption lidar (DIAL)

The water vapor differential absorption lidar (DIAL) of the German Aerospace Research Establishment (DLR) was flown aboard the National Center for Atmospheric Research (NCAR) Electra research aircraft during the Boreal Ecosystem‐Atmosphere Study (BOREAS). The downward looking lidar system measured two‐dimensional fields of aerosol backscatter and water vapor mixing ratio in the convective boundary layer (CBL) and across the CBL top (zt). We show a case study of DIAL observations of vertical profiles of mean water vapor, water vapor variance, skewness, and integral scale in the CBL. In the entrainment zone (EZ) and down to about 0.3 zi the DIAL observations agree with in situ observations and mixed‐layer similarity theory. Below, the water vapor optical depth becomes large and the DIAL signal‐to‐noise ratio degrades. Knowing the water vapor surface flux and the convective velocity scale w* from in situ aircraft measurements, we derive entrainment fluxes by applying the mixed‐layer gradient (MLG) and mixed‐layer variance (MLV) methods to DIAL mixing ratio gradient and variance profiles. Entrainment flux estimates are sensitive to our estimate of zt. They are shown to be rather insensitive to the input surface flux and to the DIAL data spatial resolution within the investigated range. The estimates break down above about 0.9 zt as the flux‐gradient and flux‐variance relationships were developed to describe the large‐scale mixing in the mid‐CBL. The agreement with in situ entrainment flux estimations is within 30% for the MLV method. On a flight leg with significant mesoscale variability the entrainment flux turns out to be 70% higher than the in situ value. This is in good agreement with the fact that large‐eddy simulations (LES) of mean water vapor profiles and variances, upon which the MLG and MLV methods are based, do not include mesoscale variability. The additional water vapor variance from mesoscales may then lead to the overestimate of the flux. Deviations from the in situ observations may also be due to poor LES resolution of small‐scale mixing in the EZ, similarly coarse resolution of the DIAL data, or a capping inversion in the LES model (8 K) which is significantly stronger than the observed inversion (3–4 K).

Tropospheric water-vapour and ozone cross-sections in a zonal plane over the central equatorial Pacific Ocean

Tropospheric water-vapour and ozone measurements, using calibrated balloon-borne sensors, are reported from the Central Equatorial Pacific Experiment (CEPEX). the sensors were launched from the Research Vessel Vickers along 2°S latitude between 156°E (west of the international date line) and 155°W (east of the date line). These measurements are combined with those from water-vapour sondes launched over the western Pacific warm pool, during the Coupled Ocean-Atmosphere Response Experiment (TOGA-COARE). Taking the two experiments CEPEX and TOGA-COARE together, the sensors included frost-point hygrometers, Humicap-A Väisälä sondes, Humicap-H Väisälä sondes and electrochemical ozone-sondes. Taken together, the CEPEX and TOGA-COARE data provide over 150 vertical profiles of water vapour within the troposphere in varied conditions of convective activity ranging from disturbed to suppressed. the primary motivation behind the present analyses is to understand the role of tropical deep convection in the vertical distribution of water-vapour. With this in mind, the profiles have been analysed in relation to occasions of recent deep convection and occasions when convection was suppressed. We employ three different criteria to identify the profiles influenced by deep convection: brightness temperature in the infrared-window channel of the Japanese Geostationary Meteorological Satellite (GMS); ozone as a quasi-conservative tracer for deep convection; and using water vapour itself, that is the wettest versus the driest soundings. Irrespective of the criteria used, we report here that the atmosphere, while under the influence of active deep convection, was found to have relative humidities in excess of 75% over most of the troposphere between the surface and about 14 km. the sondes were launched routinely over a period of 45 days (between CEPEX and TOGA-COARE), without biasing the sample towards convectively disturbed conditions. A feature of the convectively disturbed profile is a distinct minimum in relative humidity at about 700 hPa, where it was as low as 65%. the low relative humidity was accompanied by relatively high ozone mixing ratios, which raises the possibility of long-range transport of dry sub-tropical air into the warm, convectively disturbed, regions of the equatorial Pacific Ocean. Inspection of the analysed fields, and the wind fields from the sondes, supports this assertion. It then follows that the omnipresent minimum of moist static energy and minimum relative humidity at 700 hPa in the inner tropics may be the result of long-range, inclined, transport of dry air from non-convective regions. This detection suggests a linkage between the large-scale circulation, deep convection and the thermodynamic structure within the equatorial troposphere. The results presented here demonstrate the applicability of ozone as a quasi-conservative tracer of transport in the context of deep convection. The ozone-based criterion is used to diagnose recent deep convection, independent of the GMS satellite observations, and allows one to follow the evolution of relative humidity and of water-vapour mixing ratio after the dissipation of the cloud anvil to optically thin conditions. We show that the troposphere dries to low humidity soon after anvil dissipation. This observation leads to the hypothesis that moistening of the atmosphere, away from the core of Cb convection, occurs by evaporation of precipitation falling out of the anvils. After anvil dissipation, the ensuing subsidence in clear air causes the relative humidity and the water mixing ratio to decrease.

Tropospheric water‐vapour and ozone cross‐sections in a zonal plane over the central equatorial Pacific Ocean

AbstractTropospheric water‐vapour and ozone measurements, using calibrated balloon‐borne sensors, are reported from the Central Equatorial Pacific Experiment (CEPEX). the sensors were launched from the Research Vessel Vickers along 2°S latitude between 156°E (west of the international date line) and 155°W (east of the date line). These measurements are combined with those from water‐vapour sondes launched over the western Pacific warm pool, during the Coupled Ocean‐Atmosphere Response Experiment (TOGA‐COARE). Taking the two experiments CEPEX and TOGA‐COARE together, the sensors included frost‐point hygrometers, Humicap‐A Väisälä sondes, Humicap‐H Väisälä sondes and electrochemical ozone‐sondes. Taken together, the CEPEX and TOGA‐COARE data provide over 150 vertical profiles of water vapour within the troposphere in varied conditions of convective activity ranging from disturbed to suppressed. the primary motivation behind the present analyses is to understand the role of tropical deep convection in the vertical distribution of water‐vapour. With this in mind, the profiles have been analysed in relation to occasions of recent deep convection and occasions when convection was suppressed.We employ three different criteria to identify the profiles influenced by deep convection: brightness temperature in the infrared‐window channel of the Japanese Geostationary Meteorological Satellite (GMS); ozone as a quasi‐conservative tracer for deep convection; and using water vapour itself, that is the wettest versus the driest soundings. Irrespective of the criteria used, we report here that the atmosphere, while under the influence of active deep convection, was found to have relative humidities in excess of 75% over most of the troposphere between the surface and about 14 km. the sondes were launched routinely over a period of 45 days (between CEPEX and TOGA‐COARE), without biasing the sample towards convectively disturbed conditions.A feature of the convectively disturbed profile is a distinct minimum in relative humidity at about 700 hPa, where it was as low as 65%. the low relative humidity was accompanied by relatively high ozone mixing ratios, which raises the possibility of long‐range transport of dry sub‐tropical air into the warm, convectively disturbed, regions of the equatorial Pacific Ocean. Inspection of the analysed fields, and the wind fields from the sondes, supports this assertion.It then follows that the omnipresent minimum of moist static energy and minimum relative humidity at 700 hPa in the inner tropics may be the result of long‐range, inclined, transport of dry air from non‐convective regions. This detection suggests a linkage between the large‐scale circulation, deep convection and the thermodynamic structure within the equatorial troposphere.The results presented here demonstrate the applicability of ozone as a quasi‐conservative tracer of transport in the context of deep convection.The ozone‐based criterion is used to diagnose recent deep convection, independent of the GMS satellite observations, and allows one to follow the evolution of relative humidity and of water‐vapour mixing ratio after the dissipation of the cloud anvil to optically thin conditions. We show that the troposphere dries to low humidity soon after anvil dissipation. This observation leads to the hypothesis that moistening of the atmosphere, away from the core of Cb convection, occurs by evaporation of precipitation falling out of the anvils. After anvil dissipation, the ensuing subsidence in clear air causes the relative humidity and the water mixing ratio to decrease.

A Numerical Microphysical Model of the Condensational Venus Cloud

A numerical microphysical model that treats one-dimensional vertical transport of sulfuric acid/water solution aerosols, their nucleation, growth/evaporation, coagulation, and sedimentation, is applied to the condensational middle and lower Venus clouds. The model predicts the vertical profiles of sulfuric acid gas and water vapor, cloud microphysical properties, and the acid concentration of the aerosol particles. Results of model simulations agree favorably with Pioneer Venus particle size spectrometer data, extinction and backscattering coefficients measured by Pioneer Venus and Venera probes,in situand remote observations of cloud optical depth, and sulfuric acid vapor abundances retrieved from Magellan radio occultation data. It is found that the lower Venus cloud is formed as a consequence of a large upward flux of sulfuric acid vapor from the evaporation region below the cloud base. The mechanism of lower cloud formation is probably heterogeneous nucleation of sulfuric acid and water vapors on soluble nuclei. Model altitude profiles of the abundances of water vapor and gaseous sulfuric acid demonstrate the control of these vapors by the condensational cloud. Cloud processes account for the observed decline in concentration of water vapor with altitude, from ≈30 ppm below the clouds to ≈10 ppm at 60-km altitude. The structure of the lower and middle clouds is strongly dependent on the eddy diffusion coefficient. Hence, changes in transport rates may explain the variations in cloud properties revealed by the Pioneer Venus and Venera probein situmeasurements as well as by Earth-based and Galileo near-infrared observations of the lower part of the Venus cloud.

The wind field around Mauna Loa derived from surface and balloon observations

The mountain wind field in the vicinity of Mauna Loa Observatory is derived by comparing vertical profiles of wind, ozone, and water vapor in the free troposphere to measurements made at the observatory. The wind field near the surface is described by two components: a radiation wind caused by the diurnal heating and cooling of the mountain slope, and a barrier wind caused by the free tropospheric wind flowing around the mountain barrier. The radiation wind is the primary factor in transporting air from different source altitudes in the free‐troposphere to the observatory at 3400 m. At midday, air typically arrives from near the top of the marine boundary layer at 2500 m. After midnight, the average source altitude is 3400 m. The barrier wind field consists of a windward stagnation point, strong cross‐slope and downslope flow in the flanks, and moderate downslope flow in the leeward sectors. The barrier wind field is effective at disrupting the surface temperature inversion and the radiation wind at night. A simple model is presented which relates the average properties and statistical variation of these winds to the vertical transport of air from the free troposphere to the observatory by the mountain wind field.

Atmospheric water vapor estimate by a differential absorption technique with the polarisation and directionality of the Earth reflectances (POLDER) instrument

The polarization and directionality of the Earth reflectances (POLDER) instrument, to be launched in 1996 on the Japanese ADEOS (advanced Earth observing satellite) platform includes a channel which covers the 910 nm water vapor absorption band (near IR), as well as a channel centered at 865 nm. An estimate of the total atmospheric water vapor content can be derived from the ratio of the two reflectance measurements. In addition to the spectroscopic parameterization, the major uncertainties of this estimate result from (1) the surface reflectance spectral signature, (2) scattering by atmospheric aerosol, and (3) the water vapor vertical profile. A radiative transfer model has been developed in order to quantify these uncertainties. From radiative transfer simulations an uncertainty on the order of 10% is expected on the total water vapor amount. An airborne version of the POLDER instrument has been developed and flown over various targets. These targets include semiarid surfaces (Sahel), bog, coniferous and deciduous forest (Boreal forest), and the ocean in the glint direction. Water vapor measurements from radiosondes, concomitant with the POLDER measurements, are available for the method validation. Over water bodies with glint present, an overestimate is found, which is still not understood at present. For other surfaces the comparisons are, in general, in good agreement with the uncertainty analysis.

CO&lt;sub&gt;2&lt;/sub&gt;による気候変化に対する熱帯での積雲対流の効果

CO2-induced climate change related to the effect of cumulus convection on the vertical profile of water vapor was studied using a vertical one-dimensional radiative convective model with the Arakawa-Schubert cumulus parameterization that accounts for the drying effect of cumulus convection. Annual mean tropical solar forcing is used because cumulus convection is most active in the tropics. Since moisture and heat transport by large-scale motion (LS forcing) are important to moisture and heat balance in the tropics, two types of doubling CO2 experiments were conducted with and without considering LS forcing.The increase in specific humidity is small above the middle troposphere without LS forcing and the surface temperature increase is much smaller than that obtained in a three-dimensional CO2 experiment. When LS forcing is specified, however, water vapor increases significantly throughout the troposphere and the surface temperature increase is enhanced to a similar degree as in a three-dimensional experiment. LS forcing of heat enhances cumulus convection under control CO2 concentration, while LS forcing of moisture contributes to enhance changes due to CO2 doubling. Thus, the magnitude of cumulus convection response to change in radiative forcing is very sensitive to LS forcing. This means that it is important to incorporate the effects of moisture and heat transport by large-scale motion when investigating cumulus convection response to climate changes.

Vertical Distribution of Water in the Near-Equatorial Troposphere of Mars: Water Vapor and Clouds

Solar occultation spectrometry of the martian atmosphere was performed during the Phobos mission with the Auguste experiment in the UV, visible, and NIR spectral ranges. The entire domain of data in the range of 1.9 μm has been reanalyzed to retrieve all available information about the water vapor vertical profile. Accurate consideration of the instrumental corrections and a probabilistic concept of the inverse problem provide estimated water vapor contents at the level of 135 ppm with an accuracy of a factor of 2 at 10–25 km. Explicit detection of water above 30 km is proven statistically at the level of 3 ± 2 ppm with a variety of occultations, giving an upper limit of 10 ppm. The vertical structure of the water profiles demonstrates a sharp decrease above 23–25 km, whereas the lower portion has an approximately constant mixing ratio. The assumption that the latter is constant down to the surface results in a total column abundance of 8.3 +2.5 −1.5pr. μm. The temperature profile derived from saturation conditions reveals a gradient of 2 ± 1 km −1at 25–35 km. The vertical distribution of water vapor accounts for the previous study of continuous absorption at 1.9 and 3.7 μm that resulted in vertical profiles and size distributions of dust particles. The upper boundary of the confined part of the water vapor profile coincides with the altitude of considerable enhancement of aerosol extinction. This peculiarity is interpreted as a low level (20–25 km) of clouds formed by condensation of water vapor interacting with dust particles. Microphysical parameters of clouds are estimated with the adopted value of the eddy mixing coefficient, and constraints on size distribution are deduced from the modeling of dust dynamics.

An analysis of POAM II solar occultation observations of polar mesospheric clouds in the southern hemisphere

The second Polar Ozone and Aerosol Measurement (POAM II) instrument is a space‐borne visible/near IR photometer which uses the solar occultation technique to measure vertical profiles of ozone, nitrogen dioxide, and water vapor as well as aerosol extinction and atmospheric temperature in the stratosphere and upper troposphere. Here we report on the detection of polar mesospheric clouds (PMCs) in the high‐latitude southern hemisphere by POAM II during the 1993 and 1994 summer seasons. These measurements are noteworthy because they are the first measurements of PMCs in atmospheric extinction. The POAM II PMC data set has been analyzed using a simple geometric cloud model. We find that mean cloud altitudes deduced from these data are 82–83 km, consistent with previous ground‐based and satellite measurements. In addition, the 0.7 km vertical resolution of POAM II allows for accurate determination of cloud thickness. For the PMCs detected by POAM II we find a mean thickness of 2.4 km. The mean peak slant optical depth was determined to be 1.2×10−3 for the 1993 season and 1.8×10−3 for the 1994 season, corresponding to a cloud extinction coefficient of 3.9×10−6 and 6.1×10−6 km−1, respectively. The multichannel capability of POAM II also makes it possible to study the wavelength dependence of the measured slant optical depth for the clouds with largest extinction. The results of this analysis suggest an upper limit to the modal particle radii for these clouds of approximately 70 nm.

ラマンライダーによる湿度・後方散乱比・偏光解消度の観測

Simultaneous observation of the vertical profiles of tropospheric water vapor and the density and nonsphericity of aerosol particles was made with a Raman lidar at Nagoya (35°N, 137°E). The data from observations made on April 17, 1994 showed the following features of the water vapor and aerosol particles. Temporal and systematic variations of the parameters were observed at the lower altitude range of 1.0-2.2 km, where the mixing ratio of aerosol particles (backscattering ratio) increased and the nonsphericity of the particles (depolarization ratio) decreased with increasing humidity. There was a positive correlation between the vertical profiles of backscattering ratio and the water vapor mixing ratio. The depolarization ratio was positively correlated with the water vapor mixing ratio above 2.2 km and negatively correlated below this level. The altitudes where the discontinuities of the water vapor and aerosol parameters were found and that where the correlation between the depolarization ratio and the water vapor mixing ratio changed showed the correspondences with the temperature inversion or wind shears observed at Hamamatsu (35°N, 138°E).

The vertical structure of aerosol and its relationship to boundary‐layer thermodynamics over the rural UK

AbstractThe vertical structure of aerosol, covering sizes from 0.05‐4 μm radius, was examined under conditions of subsidence during winter and summer over the rural UK. Under well‐mixed boundary layer conditions, dry accumulation mode aerosol was found to be well mixed with height. During the winter campaigns, nocturnal cooling resulted in the development of a stable surface layer, typically 100 m in depth, within which the surface emitted pollutants became trapped leading to concentrations significantly greater than that observed in the mixed boundary layer above it. Under stable boundary‐layer conditions, the aerosol and water vapour vertical profiles exhibited strong negative gradients with height and were indicative of suppressed turbulence associated with stable boundary‐layer conditions. During summer, the boundary layer was normally decoupled and possessed two cloud layers: cumuli forming just below, and penetrating the surface‐layer inversion; and stratocumulus occupying the region under the boundary‐layer capping inversion. Aerosol profiles under decoupled conditions exhibited considerable variability with peak concentrations being observed in the vicinity of cloud edges. Average aerosol concentrations in the main boundary‐layer ranged from 209–651 cm−3 and 0.89–4.3 μm−3 cm−3 for dry number and volume respectively, whilst concentrations and volumetric loadings of 239–2430 cm−3 and 1.1–13.5 μm−3 cm−3 were encountered in surface layers. The majority of the aerosol number and mass concentrations were almost exclusively derived from the size range 0.05‐0.2 μm radius with mode radii often occurring at 0.1 μm or larger. By comparison, free tropospheric aerosol possessed typically an order of magnitude lower concentrations and mass with an associated mode radius of 0.05–0.06 μm or less.

The Polar Ozone and Aerosol Measurement instrument

The second Polar Ozone and Aerosol Measurement instrument (POAM II) is a spaceborne experiment designed to measure the vertical profiles of ozone, water vapor, nitrogen dioxide, aerosol extinction, and temperature in the polar stratosphere and upper troposphere with a vertical resolution of about 1 km. Measurements are made by the solar occultation technique. The instrument package, which has a mass of less than 25 kg, is carried on the Satellite Pour l'Observation de la Terre (SPOT) 3 spacecraft and has a design lifetime of 3–5 years. POAM II has provided data on the south polar ozone hole, north and south polar ozone phenomena, the spatial and temporal variability of stratospheric aerosols and polar stratospheric clouds, and has detected polar mesospheric clouds.

The Parameterization of Shortwave and Longwave Radiative Fluxes for Use in Zonally Averaged Climate Models

Abstract The shortwave and longwave fluxes at the top of the atmosphere (TOA) and at the surface are parameterized in term of solar constant, solar zenith angle, cloud parameters (amount, optical depth, height, and emissivity), surface albedo, surface air temperature, surface temperature, and atmospheric CO2 concentration. Detailed radiative models are used to calculate up- and downward radiative fluxes at TOA and at the surface with input from standard vertical atmospheric profiles of temperature, water vapor, and ozone. Expressions for clear-sky and completely overcast conditions are presented. It is shown that there is reasonably good agreement between the radiative fluxes calculated with this parameterization, with the detailed radiation models and with standard radiation codes (ICRCCM). Furthermore, it is shown that the parameterization is able to produce with reasonable accuracy several aspects of the latitudinally and seasonally varying, zonally averaged shortwave and longwave radiative fluxes at T...

Raman Lidar Observations: Simultaneous Measurements of Water Vapor, Temperature and Aerosol Vertical Profiles, Part I.

A Raman lidar was developed to observe vertical profiles of water vapor, temperature and aerosols. The lidar system can detect signal from 5 detectors simultaneously. Two vibrational Raman backscattering echoes from H 2 O and N 2 (or O 2 ) excited by Nd:YAG 3rd harmonics wavelength (355 nm) are used to observe the profiles of water vapor mixing ratio and atmospheric temperature (or density). Nd:YAG fundamental and 2nd harmonics wavelengths (1064 and 532 nm) are used to observe backscattering coefficient profiles of aerosols and clouds at these wavelengths. The scattering at 532 nm is observed in parallel and perpendicular components corresponding to the linear polarization plane of the transmitted linearly-polarized laser pulse to observe depolarization ratio profiles. Observed water vapor and temperature distributions coincide with the simultaneously observed radiosonde sounding data excellently. The Raman lidar makes it possible to observe the vertical profiles of water vapor, temperature, aerosols, and clouds simultaneously.