The impact of horizontal heterogeneities, cloud fraction, and liquid water path on warm cloud effective radii from CERES-like Aqua MODIS retrievals

The impact of horizontal heterogeneities, liquid water path (LWP from AMSR-E), and cloud fraction (CF) on MODIS cloud effective radius (<i>r</i>_e), retrieved from the 2.1 μm (<i>r</i>_e2.1) and 3.8 μm (<i>r</i>_e3.8) channels, is investigated for warm clouds over the southeast Pacific. Values of <i>r</i>_e retrieved using the CERES algorithms are averaged at the CERES footprint resolution (&sim;20 km), while heterogeneities (<i>H</i>_&sigma;) are calculated as the ratio between the standard deviation and mean 0.64 μm reflectance. The value of <i>r</i>_e2.1 strongly depends on CF, with magnitudes up to 5 μm larger than those for overcast scenes, whereas <i>r</i>_e3.8 remains insensitive to CF. For cloudy scenes, both <i>r</i>_e2.1 and <i>r</i>_e3.8 increase with <i>H</i>_&sigma; for any given AMSR-E LWP, but <i>r</i>_e2.1 changes more than for <i>r</i>_e3.8. Additionally, <i>r</i>_e3.8–<i>r</i>_e2.1 differences are positive (<1 μm) for homogeneous scenes (<i>H</i>_&sigma; < 0.2) and LWP > 45 gm⁻², and negative (up to −4 μm) for larger <i>H</i>_&sigma;. While <i>r</i>_e3.8–<i>r</i>_e2.1 differences in homogeneous scenes are qualitatively consistent with in situ microphysical observations over the region of study, negative differences – particularly evinced in mean regional maps – are more likely to reflect the dominant bias associated with cloud heterogeneities rather than information about the cloud vertical structure. The consequences for MODIS LWP are also discussed

Flower-bud initiation in deciduous fruit trees : with particular reference to apricot

In this thesis the author has two aims: (a) to review the literature on flowering in deciduous fruit trees, and (b) to record and discuss, in the light of previous work, experiments designed to elucidate the role of carbohydrates, and the possible role of hormones, in the process of flower-bud initiation in apricot (Prunus armeniaca, L.). The experiments were conducted over the period December 1968, to February 1970. The review is more detailed than may be required for an introduction to the experimental section. This is because most previous work on flower-bud initiation in deciduous fruit trees was carried out some time ago, and there are no recent large reviews on the subject. The review also illustrates how little is known on the process in stone fruits , as most investigations have centred on initiation in apple. The author in the experimental section has looked at the following factors affecting flower-bud initiation in apricot; shading, defoliation, temperature, light, level of carbohydrate metabolites, level of nitrogen compounds. In further experiments the herbicide diuron (DCMU) was used to inhibit photosynthesis and so determine the importance of leaf-produced carbohydrates on initiation of flower-buds in the axil of that leaf. The isotope Carbon-14 was also used to substantiate the results of diuron treatment and to demonstrate translocation patterns within the apricot tree. The experimental results are not recorded chronologically but appear in the following order: Part 1 : Determination of the importance of shading and defoliation on flower-bud initiation in apricot. Part 2: The role of temperature and light in flower-bud initiation in apricot. Part 3 : The role of carbohydrates in flower-bud initiation in apricot

Risk factors for vulnerable youth in urban townships in South Africa: the potential contribution of reactive attachment disorder

Reactive attachment disorder (RAD) is a psychiatric disorder developing in early or middle childhood as a consequence of significant failures in the caregiving environment. RAD results in children failing to relate socially, either by exhibiting markedly inhibited behaviour or by indiscriminate social behaviour and is associated with significant socio-behavioural problems in the longer term. This study examined RAD in South Africa, a setting with high environmental risks. We recruited a sub-sample of 40 10-year-old children from a cohort enrolled during pregnancy for whom early attachment status was known. Children were purposefully selected to represent the four attachment categories using the data available on the strange situation procedure (SSP) at 18 months. The Manchester Child Attachment Story Task (MCAST) assessed current attachment and RAD was diagnosed using a standardised assessment package. A high proportion of the children (5/40% or 12.5%) fulfilled diagnostic criteria for RAD; all were boys and were displaying the disinhibited type. SSP classification at 18 months was not significantly associated with RAD symptoms at age of 10 years, while current MCAST classifications were. This suggests that children in this sample are at much higher risk of RAD than in high-income populations, and despite a fairly typical attachment distribution in this population at 18 months, RAD was evidenced in later childhood and associated with current attachment disorganisation. The strengths of this research include its longitudinal nature and use of diagnostic assessments. Given increasing evidence that RAD is relatively stable over time and introduces longer term socio-behavioural risks; the high rate of RAD in this sample (12.5%) highlights potential developmental threats to children in low- and middle-income countries (LMICs). Our results should be interpreted with caution given sample size and risk of selection bias. Further research is needed to confirm these findings

Retrievals of thick cloud optical depth from the Geoscience Laser Altimeter System (GLAS) by calibration of solar background signal

Laser beams emitted from the Geoscience Laser Altimeter System (GLAS), as well as other spaceborne laser instruments, can only penetrate clouds to a limit of a few optical depths. As a result, only optical depths of thinner clouds (< about 3 for GLAS) are retrieved from the reflected lidar signal. This paper presents a comprehensive study of possible retrievals of optical depth of thick clouds using solar background light and treating GLAS as a solar radiometer. To do so one must first calibrate the reflected solar radiation received by the photon-counting detectors of the GLAS 532-nm channel, the primary channel for atmospheric products. Solar background radiation is regarded as a noise to be subtracted in the retrieval process of the lidar products. However, once calibrated, it becomes a signal that can be used in studying the properties of optically thick clouds. In this paper, three calibration methods are presented: (i) calibration with coincident airborne and GLAS observations, (ii) calibration with coincident Geostationary Opera- tional Environmental Satellite (GOES) and GLAS observations of deep convective clouds, and (iii) cali- bration from first principles using optical depth of thin water clouds over ocean retrieved by GLAS active remote sensing. Results from the three methods agree well with each other. Cloud optical depth (COD) is retrieved from the calibrated solar background signal using a one-channel retrieval. Comparison with COD retrieved from GOES during GLAS overpasses shows that the average difference between the two retriev- als is 24%. As an example, the COD values retrieved from GLAS solar background are illustrated for a marine stratocumulus cloud field that is too thick to be penetrated by the GLAS laser. Based on this study, optical depths for thick clouds will be provided as a supplementary product to the existing operational GLAS cloud products in future GLAS data releases

Validation of GOES-10 Satellite-derived Cloud and Radiative Properties for the MASRAD ARM Mobile Facility Deployment

This poster presentation reviews the process used to validate the GOES-10 satellite derived cloud and radiative properties. The ARM Mobile Facility (AMF) deployment at Pt Reyes, CA as part of the Marine Stratus Radiation Aerosol and Drizzle experiment (MASRAD), 14 March - 14 September 2005 provided an excellent chance to validate satellite cloud-property retrievals with the AMF's flexible suite of ground-based remote sensing instruments. For this comparison, NASA LaRC GOES10 satellite retrievals covering this region and period were re-processed using an updated version of the Visible Infrared Solar-Infrared Split-Window Technique (VISST), which uses data taken at 4 wavelengths (0.65, 3.9,11 and 12 m resolution), and computes broadband fluxes using improved CERES (Clouds and Earth's Radiant Energy System)-GOES-10 narrowband-to-broadband flux conversion coefficients. To validate MASRAD GOES-10 satellite-derived cloud property data, VISST-derived cloud amounts, heights, liquid water paths are compared with similar quantities derived from available ARM ground-based instrumentation and with CERES fluxes from Terra

Nitric Acid Particles in Cold Thick Ice Clouds Observed at Global Scale: Link with Lightning, Temperature, and Upper Tropospheric Water Vapor

Signatures of nitric acid particles (NAP) in cold thick ice clouds have been derived from satellite observations. Most NAP are detected in the Tropics (9 to 20% of clouds with T less than 202.5 K). Higher occurrences were found in the rare mid-latitudes very cold clouds. NAP occurrence increases as cloud temperature decreases and NAP are more numerous in January than July. Comparisons of NAP and lightning distributions show that lightning is the main source of the NOx, which forms NAP in cold clouds. Qualitative comparisons of NAP with upper tropospheric humidity distributions suggest that NAP play a role in the dehydration of the upper troposphere when the tropopause is colder than 195K

Corrigendum to "Detection of dust aerosol by combining CALIPSO active lidar and passive IIR measurements" published in Atmos. Chem. Phys., 10, 4241–4251, 2010

No abstract available