Measurements of small ice crystals in arctic cirrus: observations from the Indirect and Semi-Direct Aerosol Campaign (ISDAC)

In-situ observations on the size and shape of particles in arctic cirrus are less common than those in mid-latitude and tropical cirrus with considerable uncertainty about the contributions of small ice crystals (maximum dimension D<50 µm) to the mass and radiative properties that impact radiative forcing. In situ measurements of small ice crystals in arctic cirrus were made during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in April 2008 during transits of the National Research Council of Canada Convair-580 between Fairbanks and Barrow, Alaska and during Mixed Phase Arctic Cloud Experiment (MPACE) in October 2004 with the University of North Dakota (UND) Citation over Barrow, Alaska. Concentrations of small ice crystals with D < 50 μm from a Cloud and Aerosol Spectrometer (CAS), a Cloud Droplet Probe (CDP), a Forward Scattering Spectrometer Probe (FSSP), and a two-dimensional stereo probe (2DS) were compared as functions of the concentrations of crystals with D > 100 μm measured by a Cloud Imaging Probe (CIP) and two-dimensional stereo probe (2DS) in order to assess whether the shattering of large ice crystals on protruding components of different probes artificially amplified measurements of small ice crystal concentrations. The dependence of the probe comparison on other variables as CIP N>100 (number concentrations greater than diameter D>100 μm),temperature, relative humidity respect to ice (RHice), dominant habit from the Cloud Particle Imager (CPI), aircraft roll, pitch, true air speed and angle of attack was examined to understand potential causes of discrepancies between probe concentrations. Data collected by these probes were also compared against the data collected by a CAS, CDP and CIP during the Tropical Warm Pool-International Cloud Experiment (TWP-ICE) and by a CAS and 2DS during the Tropical Composition, Cloud and Climate Coupling (TC4) missions. During ISDAC, the CAS and FSSP both overestimated measurements of small ice crystals compared to both the CDP and 2DS by 1-2 orders of magnitude. Further, the amount of overestimation increased with the concentrations from the CIP2 (N>100 > 0.1 L-1). There was an unexplained discrepancy in concentrations of small crystals between the CDP and 2DS during ISDAC. In addition, there was a strong dependence on RHice of the average ratios of the N3-50, CAS/N3-50,CDP, N3-50, FSSP096/N3-50,CDP, N3-50, CAS/N3-50,FSSP096, N10-50, CDP/N3-50,2DS, N10-50, FSSP096/N10-50,2DS. Continued studies are needed to understand the discrepancy of these probes.

Sexuality in the media and emotional well-being among lesbian, gay, & bisexual adolescents

LGB teens’ feelings, desires, and physical attractions run contrary to the heteronormative standards of American society. As such, LGB youth often experience feelings of sadness and dejection that can lead to depression and suicidal tendencies (Russell & Joyner, 2001). Evaluating the factors that could possibly influence the emotional well-being of LGB youth would be an important undertaking given the hindrances LGB adolescents face during sexual socialization. The purpose of this dissertation was to study the portrayal of sexuality in media popular with LGB adolescents and to assess the relationship between media exposure and emotional well-being among LGB teens. In particular, this dissertation distinguished between mainstream media and gay- and lesbian-oriented (GLO) media. GLO media were defined as any media outlet specifically designed, produced, and marketed for gay and lesbian audiences. Two studies were conducted to serve as the initial investigation in a program of research that will be designed to better understand the role of media in the lives of LGB individuals. The first study of this dissertation was a content analysis of the television programs, films, songs, and magazines most popular with LGB teens as determined by self-reports of media consumption in a survey of media use. A total of 96 media vehicles composed the content analysis sample, including 48 television programs, 22 films, 25 musical artists, and 6 magazines. Using a coding scheme that was adapted from previous media sex research, Study 1 measured the frequency of sexual instances as well as the type, nature, and source characteristics for each sexual instance. Results of the content analysis suggest that heterosexuality reigns supreme in mainstream media. When LGB sexuality is depicted in mainstream media, it is often sanitized. LGB sexual talk is rarely sexual; rather it is primarily about the social or cultural components of being lesbian, gay, or bisexual. LGB sexual behavior is also rare in mainstream media, which tend to depict LGB individuals as non-sexually as possible. LGB sexuality in mainstream media exists, but is more about proclaiming LGB identity than actually living it. GLO media depicted LGB sexuality more frequently than mainstream media did. GLO media often depict LGB sexuality in a more realistic manner. LGB sexual talk is about LGB identity, as well as the relational and sexual aspects of being a sexual minority. LGB sexual behavior is commonplace in GLO media, depicting LGB individuals as sexual beings. LGB sexuality in GLO media is prevalent and relatively authentic. The second study was a survey that assessed the relationship between media exposure (both mainstream media and GLO media) and LGB teens’ emotional well-being, considering self-discrepancy as an important mediating variable in that relationship. Study 2 also considered age, sex, and sexual identity commitment as possible moderating variables in the relationship between media exposure and emotional well-being. In Study 2, emotional well-being was defined as lower levels of dejection-related emotions. LGB adolescents (N = 573) completed a questionnaire that was used to investigate the relationships between media exposure and emotional well-being. Results of the survey indicated that mainstream media exposure was not significantly associated with dejection-related emotions. In contrast, GLO media exposure was negatively related to feelings of dejection even when controlling for age, sex, race, perceived social support, school climate, religiosity, geographical location, sexuality of peers, and motivation for viewing LGB inclusive media content. Neither age nor sex moderated the relationships between media exposure variables and dejection, but sexual identity commitment did act as a moderator in the relationship between GLO media exposure and dejection. The negative relationship between GLO media exposure and dejection was stronger for participants lower in sexual identity commitment than for participants higher in sexual identity commitment. In addition, the magnitude of discrepancies between the actual self and the ideal self mediated the relationship between GLO media exposure and dejection for LGB adolescents low in sexual identity commitment. However, self-discrepancy did not mediate the relationship between GLO media exposure and dejection for LGB teens highly committed to their sexual identities. Results of both the content analysis and the survey are discussed in terms of implications for theory and method. Practical implications of this dissertation’s findings are also discussed, as well as directions for future research.