Abstract. A number of proposed lidar systems, such as ESA’s AEOLUS (formerly ADM) and DIAL missions (e.g. WALES) are to make use oflidar returns inclearair. How- ever, on average, two-thirds ofthe globe is covered incloud. Hence, there is a strong likelihood that data from these instru- ments may be contaminated by cloud. Similarly, optically thick cloud may not be penetrated by a lidar pulse, resulting in unobservable regions that are overshadowed by thecloud. To address this, it is suggested, for example, in AEOLUS, that a number of consecutive short sections oflidar data (be- tween 1 and 3.5 km in length) be tested for cloud contamina- tion or for overshadowing and only those that are unaffected by cloud be used to derive atmospheric profiles. The prob- ability of obtaining profiles to near ground level using this technique is investigated both analytically and using UV air- bornelidar data recorded during the CLARE’98 campaign. These data were measured inthepresenceofbrokencloud on a number of flights over southern England over a four- day period and were chosen because thelidar used has the same wavelength, footprint and could match the along-track spacing ofthe proposed AEOLUS lidar.
Over the considered period, 6 favorable cases were selected for CALIOP validation, including 3 daytime and 3 night-time cases, and 3 different types of atmospheric aerosol and cloud scenes (Table 1): (case 1) 1 scene of PBL aerosols under clear sky condition, (case 2) 3 scenes of multiple aerosol lay- ers underlying semi-transparent cirrus clouds, and (case 3) 2 scenes of dense clouds. Figure 1 presents the location of SNU-L and CALIPSO ground tracks for the 6 selected cases. To avoid huge sampling volume discrepancies due to dif- ferent vertical resolution and horizontal footprint size of data between the two instruments, we averaged the closest 18 pro- files of CALIOP, as shown in Fig. 1 with closed circles along the tracks. This corresponds to a sampling duration of ∼0.9 s and an horizontal coverage of ∼6.0 km. CALIPSO flies over the SNU-L site at 04:50 UTC (13:50 local time) dur- ing daytime (ascending) and 17:41 UTC (02:41 local time) during night-time (descending). The 5-min averaged SNU- L profiles, comprising 3000 shots, acquired between 04:45 and 04:50 UTC (daytime) or between 17:45 and 17:50 UTC (night-time) are used for comparison.
Since the relationship between zenith radiance and cloud optical depth is not monotonic, the aforementioned retrieval process results in two possible solutions at a given radiance: one corresponds to optically thin clouds, the other corre- sponds to optically thick. To remove this retrieval ambigu- ity, Chiu et al. (2007) applied a manual screening. Here we have developed an objective discrimination method using li- dar backscatter measurements. We calibrated lidar backscat- ter signals inclear-air periods using the known molecular scattering at thelidar wavelength. Since thelidar energy was monitored and thelidar optics were assumed to not vary sig- nificantly, calibration coefficients from a suitable clear-air period were then extrapolated into cloudy periods. Figure 1b shows an example ofthe vertical profiles of calibrated atten- uated backscatter signals for optically thin and thick clouds. For thick clouds, the attenuated backscatter signal drops dra- matically above the apparent cloud top; the mean logarithm (base 10) ofthelidar signal from thecloud top to the layer 1 km above is around −7.5. In contrast, for optically thin clouds, the mean logarithm value above cloud tops is around − 6.0. The difference between these two mean values is sig- nificant, suggesting that this parameter can be used to dis- criminate between optically thin and thick clouds; however, a proper threshold needs to be determined objectively, as described next. For convenience, the mean ofthelidar at- tenuated backscatter signal from the apparent, or detectable, cloud top to the level 1 km above is denoted as β ct,1 km here-
Abstract. We present the first comparison of a new li- dar technique to measure winds inthe middle atmosphere, called DoRIS (Doppler Rayleigh Iodine Spectrometer), with a rocket-bornein situ method, which relies on measuring the horizontal drift of a target (“starute”) by a tracking radar. The launches took place from the Andøya Space Cen- ter (ASC), very close to the ALOMAR observatory (Arc- tic Lidar Observatory for Middle Atmosphere Research) at 69 ◦ N. DoRIS is part of a steerable twin lidar system in- stalled at ALOMAR. The observations were made simulta- neously and with a horizontal distance between the two lidar beams and the starute trajectories of typically 0–40 km only. DoRIS measured winds from 14 March 2015, 17:00 UTC, to 15 March 2015, 11:30 UTC. A total of eight starute flights were launched successfully from 14 March, 19:00 UTC, to 15 March, 00:19 UTC. In general there is excellent agree- ment between DoRIS and thein situ measurements, con- sidering the combined range of uncertainties. This concerns not only the general height structures of zonal and merid- ional winds and their temporal developments, but also some wavy structures. Considering the comparison between all starute flights and all DoRIS observations in a time period of ±20 min around each individual starute flight, we arrive at mean differences of typically ±5–10 m s −1 for both wind components. Part ofthe remaining differences are most likely due to the detection of different wave fronts of gravity waves. There is no systematic difference between DoRIS and thein situ observations above 30 km. Below ∼ 30 km, winds from DoRIS are systematically too large by up to 10–20 m s −1 , which can be explained by thepresenceof aerosols. This is proven by deriving the backscatter ratios at two different
Abstract. We present initial aerosol validation results ofthespace-bornelidar CALIOP -onboard the CALIPSO satellite- Level 1 attenuated backscatter coefficient profiles, using co- incident observations performed with a ground-based lidarin Athens, Greece (37.9 ◦ N, 23.6 ◦ E). A multi-wavelength ground-based backscatter/Raman lidar system is operating since 2000 at the National Technical University of Athens (NTUA) inthe framework ofthe European Aerosol Re- search LIdar NETwork (EARLINET), the first lidar net- work for tropospheric aerosol studies on a continental scale. Since July 2006, a total of 40 coincidental aerosol ground- based lidarmeasurements were performed over Athens dur- ing CALIPSO overpasses. The ground-based measurements were performed each time CALIPSO overpasses the station location within a maximum distance of 100 km. The duration ofthe ground–based lidarmeasurements was approximately two hours, centred on the satellite overpass time. From the analysis ofthe ground-based/satellite correlative lidar mea- surements, a mean bias ofthe order of 22% for daytime mea- surements and of 8% for nighttime measurements with re- spect to the CALIPSO profiles was found for altitudes be- tween 3 and 10 km. The mean bias becomes much larger for altitudes lower that 3 km (ofthe order of 60%) which is attributed to the increase of aerosol horizontal inhomogene- ity within the Planetary Boundary Layer, resulting to the ob- servation of possibly different air masses by the two instru- ments. In cases of aerosol layers underlying Cirrus clouds, comparison results for aerosol tropospheric profiles become worse. This is attributed to the significant multiple scattering effects in Cirrus clouds experienced by CALIPSO which re- sult in an attenuation which is less than that measured by the ground-based lidar.
Although S-HIS and MAS flew together on the ER-2, the data-recording time ofthe two instruments had different ref- erence, resulting in different time overpass over the same scene. Moreover, it had been noted (R. Holz, University of Wisconsin, Madison, personal communication, 2004) that S- HIS data had wrong geographic data positioning due to use ofthe inertial navigation system ofthe ER-2 as reference, which inthe analyzed mission did not work properly. There- fore a scheme was developed to collocate MAS and S-HIS data using MAS channel 45 (a window centered at 11 µm). This channel performs a relatively more stable measurement ofthe scene radiance with respect to window channels lo- cated in NIR range, which are affected, moreover, by solar contribution. Two sets of virtual measurements are gener- ated, having the spatial resolution of S-HIS and the spec- tral resolution of MAS: MAS pixels are averaged over the S-HIS footprint closest to nadir and the S-HIS data is con- volved over the MAS spectral response function to produce the equivalent MAS spectral bands (Moeller et al., 2003). The minimisation ofthe mean square differences between the convolved S-HIS signal and the averaged MAS signal is performed over a 750 km long ER-2 track (corresponding to flight between 01:06 UTC and 02:00 UTC on 22 February) in which clear sky, broken clouds and overcast situations are present. The mean temporal displacement between MAS and S-HIS data is found to be 41±2 s. The uncertainty of 2 s pro- duces a possible spatial displacement of about 400 m at the nominal ground speed ofthe ER-2, i.e. it is smaller than the linear dimension ofthe S-HIS nadir footprint.
A trajectory analysis was performed at different levels using FLEXTRA model (Stohl et al., 1995) and ECMWF wind fields. It indicated that the two cirrus layers had different origins, the higher one being generated by a convective outflow and the lower one by a more recent air mass up-lift (Figure 7). There is a striking correspondence between estimated uplift (light colours) and presenceof clouds as revealed by lidar. Both the two layers inthelidar backscattering observations had experienced uplifting: inthe previous 24 hr for the lower layer (11-12 km), and more recently, inthe previous 12 hr, for the higher layer (13-14 km).
ral correlations between SCFs versus vertical velocity and relative humidity indicate that the higher vertical velocity and relative humidity the smaller SCFs. The smaller SCFs are possibly due to strong precipitation exhausting the large supercooled liquid droplets. However, the impacts of LTSS, skin temperature and horizontal wind on SCFs are relatively complex than those of vertical velocity and humidity. Their temporal correlations with SCFs depend on latitude or sur- face type. For example, at the −10 ◦ C isotherm, negative temporal correlations for skin temperature are mainly located in ocean regions between 30 and 60 ◦ for two hemispheres, whereas positive correlations can be found inthe land region of high latitudes. With decreasing temperature (e.g., at the −20 ◦ C isotherm), temporal correlation coefficients between SCFs and skin temperature are almost negative in middle and high latitudes. However, it is clear that their temporal correla- tions vary from positive to negative with decreasing temper- ature at some special regions (e.g., mainland China). By an- alyzing the spatial correlations under different aerosol load- ings, we find that negative correlations also exist between SCF and the vertical velocity (or surface skin temperature), whereas positive spatial correlations can be found between SCF and the U wind. Recently, evidence has shown that a cloud phase feedback occurs, causing more shortwave to be reflected back out to space relative to the state prior to global warming (McCoy et al., 2014, 2015). Our results, which are based on long-term (96 months) global observations, verify the effects of dynamic factors on cloud phase changes and illustrate that these effects are regional, thus having potential implications for further reducing the biases of climate feed- backs and climate sensitivity among climate models.
stock, landfills, waste treatment, biomass burning, and fossil fuel combustion). About 60% ofthe CH 4 released inthe atmosphere is related to human activities in such a way that its concentration has more than doubled since pre-industrial times, reach- ing 1774.62±1.22 ppb in 2005 (Forster et al., 2007). From the 1980’s, the increase in methane has been slowing down, reaching a steady state around the year 2000 (but
Rocks selected by males were thicker than those selected by females, although these differences are not statistically sig- nificant. Females may have chosen thinner rocks than males during the reproductive season to enhance digestive efficiency and drive energy for reproduction during the period of inac- tivity. In this case, warmer shelters might allow females to en- hance their seasonal egg production of (S ABO 2003), and fol- lowing that, egg thermoregulation. The fact that oviparous fe- males of C. vacariensis selected thinner rocks in comparison with non-oviparous females supports this idea. Conversely, males of C. vacariensis, due to their more active lifestyle, prob- ably expend more energy on a daily basis, what allows them to choose colder shelters and to avoid additional metabolic costs during inactivity periods (S ABO 2003).
From the analysis, it was found that lands were acquired majorly by inheritance and the resultant effect of this is the fragmentation of land during the acquisition and sharing of either family or community lands. The evident of this was seen on the sizes ofthe land cultivated by both the male and female farmers of which majority of both sexes cultivate a small farm size of 0.1-2.0ha of land with just a few who cultivate a reasonable land size this can also be seen on the number of bag of both garri and fufu produced yearly. However this Land holding in hectares favors more males than females inthe study area and females had better production in cassava than male.
Such mediums are the best cover media to hide messages. Digital images are the most widespread cover files used for SG, due to their high embedding efficiency and the insensitivity ofthe human visual system (HVS) . It is not necessary that the cover and message have a homogeneous structure. For example, it is possible to embed a recording of an audio stream message inside a digital image . The simplest steganographic techniques embed the bits ofthe message directly into the least significant bit (LSB) plane ofthe cover image in a deterministic sequence [5, 6]. Different steganographic techniques focus on a variety of requirements such as robustness, tamper resistance, imperceptibility, security and capacity [7-10]. Our technique is focused on providing high security and high speed operation while maintaining imperceptibility. We are using here Galois Encoder to provide high operational speed while maintaining the security intensively. The 2BC (two bit code) technique is the basic steganography technique we are using with the Galois Operation. Galois field arithmetic has received considerable attention in recent years due to their application in public-key cryptography schemes and error correcting codes. We are here using the 2BC(two bit code) and Galois Field algorithm to achieve the goal ofthe maximum reception ofthe original message signal while maintaining the losses and enhancing the speed of operation. Different steganographic techniques focus on a variety of requirements such as robustness, tamper resistance, imperceptibility, security and capacity. Our embedding technique is focused on providing security while maintaining imperceptibility. Our method can work in any transform domain, but we are illustrating the ideas inthe spatial domain for convenience. The rest ofthe paper is divided among the following sections: section 2 explains the existing passcode based technique which involves the matching process and the embedding techniques, section 3 describes the Galois operation, section 4 and 5 explains the data transmission and retrieval process using the Galois Encoder and decoder, section 6 contains simulation result and section 7 summarizes the Conclusion.
of social commitments and values such as social justice and equity, which are stated in their constitutions, signed treaties and conventions. Ministries of health oversee the overall development of health systems using their governance function, which includes policy analysis and formulation, regulating service delivery between partners, developing norms and standards for quality assurance and ensuring the implementation of agreed upon policies and strategies. The importance of ICTs in development process was long recognized and access to ICTs has even been made one ofthe targets ofthe Millennium Development Goal No. 8 (MDG 8),which emphasizes the benefits of new technologies, especially ICTs inthe fight against poverty . Inthe implementation of mHealth, ICT is a key component therefore policies on penetration, adoption and utilization of ICT inthe health sector play a key role in enhancing mHealth adoption. The telecommunications sector of some countries such as Ghana, Kenya, Nigeria and Senegal, are very dynamic. Yet, as shown inthe introductory section, Africa as a whole continues to lag behind other regions ofthe world. This is primarily as a result ofthe high cost of services . Based on a review conducted across 17 Sub-Saharan African countries, Calandroet. al. argue that the national objectives of achieving universal and affordable access to the full range of communications services have been undermined either by poor policies constraining market entry and the competitive allocation of available resources; weak institutional arrangements with a dearth of technical capacity and competencies; and, in some instances, regressive taxes on usage. Gillwald  argues that in addition to competition and open access regimes, effective regulation of other factors such as spectrum and interconnection and tariffs are required to stimulate market growth, improve access, and lower prices. This is because: many competitive markets with several players have experienced spectrum allocation problems high cost of services as a result of retrogressive tax on mobile communications despite having an open market with several operators such as Uganda and expensive leased lines generally available from incumbent operators which hare mostly unregulated contributed to the high cost of doing business and inhibited growth and employment opportunities .
Roscoe, H. K., Van Roozendael, M., Fayt, C., du Piesanie, A., Abuhassan, N., Adams, C., Akrami, M., Cede, A., Chong, J., Clémer, K., Friess, U., Gil Ojeda, M., Goutail, F., Graves, R., Griesfeller, A., Grossmann, K., Hemerijckx, G., Hendrick, F., Herman, J., Hermans, C., Irie, H., Johnston, P. V., Kanaya, Y., Kreher, K., Leigh, R., Merlaud, A., Mount, G. H., Navarro, M., Oetjen, H., Pazmino, A., Perez-Camacho, M., Peters, E., Pinardi, G., Puentedura, O., Richter, A., Schönhardt, A., Shaiganfar, R., Spinei, E., Strong, K., Takashima, H., Vlemmix, T., Vrekoussis, M., Wagner, T., Wittrock, F., Yela, M., Yilmaz, S., Boersma, F., Hains, J., Kroon, M., Piters, A., and Kim, Y. J.: Intercomparison of slant column measurementsof NO 2 and O 4 by MAX-DOAS and zenith-sky UV and visible spectrometers, Atmos. Meas. Tech., 3, 1629–1646, doi:10.5194/amt-3-1629-2010, 2010. Sarkissian, A., Pommereau, J.-P., and Goutail, F.: Identification of
Explanations. Height: flight altitude from Global Positioning System data, GPS. Aitken-Mode: 10–160 nm. Accu- mulation mode: from instrument Grimm OPC 1.129, 0.25–1.0 µm. Coarse mode: from FSSP-300 channels 13–29, 2–50 µm for analysis A, absorbing refractive index value, m=1.59+0.004i, and 2–25 µm for analysis N, non-absorbing index m=1.59+0.0i . Super coarse mode: from FSSP-300 channels 18–29, 6.5–50 µm for A, 5–25 µm for N. Mass conc.: mass concentration for non-absorbing (N) and absorbing (A) refractive index values. Max MC: Maximum of 10-s mean values of mass concentration for material N and A. D eff =3×specific volume/(2×specific cross-section area)=effective diameter, for non-absorbing (N) and absorbing refractive index (A). Age= plume age from backward trajectories (resolution of FLEXPART: 0.5 ◦
As the multinomial model is non-linear, the marginal effect ofthe treatment in a DID model is not the marginal impact ofthe interaction between time and treatment, but the difference ofthe cross-differences, as described by Puhani (2012). The results of Table 7 (in terms of marginal effects) show that the BVJ has a significant effect on the probability studying and working at the same time, but not on the other outcome variables. The estimated marginal effects mean that the probability of a youngster studying and working increases by 4.2 percentage points with the BVJ, compared with a baseline of 30% inthe control group in 2006. The estimated coefficients for the categories ‘studying only’ and ‘working only’ were negative but not statistically significant. It seems, therefore, that treated adolescents do not quit their jobs to study because ofthe program, but do both activities at the same time. This raises questions about the long run impacts ofthe program, since the quality ofthe night classes is notoriously low in Brazil.
means that any cloud layer temperature change will affect the balance of their phases (ice or water or mixed) with a potentially large radiative impact in local regions (Sassen and Khvorostyanov, 2007). In addition, over some deserts (such as the Sahara Desert), the most prevalent cloud type is a low level cloud (stratocumulus and stratus) in ISCCP D1 rather than a high cloudin our results. This discrepancy may be due to inadequate
Numerous studies have been conducted all over the world focusing on the characters of submicron particles, including their chemical composition and size distribution as well as their formation and growth inthe atmosphere (e.g., Woo et al., 2001; Birmili et al., 2003; Engler et al., 2007; Zhang et al., 2007; Dal Maso et al., 2008; Laakso et al., 2008; Jimenez et al., 2009; Komppula et al., 2009; Asmi et al., 2011; Ker- minen et al., 2012; Vakkari et al., 2013; Kulmala et al., 2014; Nie et al., 2014; Nieminen et al., 2014). In China, studies on submicron particles started about a decade ago. How- ever, to the best of our knowledge, there are only three stud- ies in China providing more than 1 year ofmeasurementsof aerosol size distributions, two of them conducted inthe North China Plain (Wu et al., 2007; Shen et al., 2011) and one at Mount Waliguan in remote western China (Kivekäs et al., 2009). Therefore, knowledge about the temporal vari- ation of submicron particles and their relationship to mete- orology and human activities in China is rather poor, even in some well-developed regions such as Yangtze River Delta (YRD) in eastern China.
Experimental measurementsin terrestrial laboratory, space and astrophysical observations of variation and fluctuation of nuclear decay constants, measurementsof large enhancements in fusion reaction rate of deuterons implanted in metals and electron capture by nuclei in solar core indicate that these processes depend on the envi- ronment where they take place and possibly also on the fluctuation of some extensive parameters and eventually on stellar energy production. Electron screening is the first important environment effect. We need to develop a treatment beyond the Debye-H¨uckel screening approach, commonly adopted within global thermodynamic equilibrium. Advances inthe description of these processes can be obtained by means of q-thermostatistics and/or superstatistics for metastable states. This implies to handle, without ambiguities, the case q < 1. Keywords: Astrophysics plasma, Nuclear reactions, Nonextensive statistical mechanics