Heechoon Lee

Turbulent exchange of heat, water vapor, and momentum over a Tibetan prairie by eddy covariance and flux variance measurements

[1] Land-atmosphere interactions on the Tibetan Plateau are important because of their influence on energy and water cycles on both regional and global scales. Flux variance and eddy covariance methods were used to measure turbulent fluxes of heat, water vapor, and momentum over a Tibetan shortgrass prairie during the Global Energy and Water Cycle Experiment (GEWEX) Asian Monsoon Experiment (GAME) in 1998. Under unstable conditions during the monsoon period (July-September), the observed standard deviations of temperature and specific humidity (normalized by appropriate scaling parameters) followed the Monin-Obukhov theory. The similarity constants for heat C T and water vapor C q in their dimensionless functions of stability under a free convection limit were both 1.1, unlike the differences (i.e., C T ≤ C q ) reported in other studies. While the transfer efficiency of heat and water vapor exchange generally agreed with the prediction from the Monin-Obukhov theory, momentum exchange was less efficient than predicted. In comparison with the eddy covariance data, the flux variance method (with C T = Cq = 1.1) underestimated both heat and water vapor fluxes by <5%. When the eddy covariance data were absent, the flux variance method was used for gap filling the seasonal flux database. To estimate latent heat flux during the premonsoon period in June, C T /C q was approximated as r Tq (where r Tq is a correlation coefficient for the fluctuations of temperature and water vapor) because of the sensitivity of C q to changes in soil moisture conditions. The dramatic changes in the Bowen ratio from 9.0 to 0.4 indicate the shift of energy sources for atmospheric heating over the plateau, which, in turn, resulted in the shift of turbulent exchange mechanisms for heat and water vapor.

Molecular Epidemiological Study for Tick-Borne Disease (Ehrlichia and Anaplasma spp.) Surveillance at Selected U.S. Military Training Sites/Installations in Korea

Abstract: Vector‐borne diseases are a potential public health threat to U.S. Forces Korea (USFK). Ehrlichia and Anaplasma spp., transmitted by ticks, are only two of several diseases that may affect military readiness and operations. Rodents were collected at selected U.S. military installations and training sites in the Republic of Korea. DNA was extracted from spleen tissues and assayed by PCR methods for Ehrlichia and Anaplasma species. From rodents and mustelids collected during 1999 and 2000, a total of 196 Apodemus agrarius (striped field mouse), 2 Mustela sibirica (weasel), and 1 Cricetulus triton nestor (Korean greater long‐tailed hamster) were assayed for Ehrlichia and Anaplasma species‐specific DNA fragments. Rodent surveillance indicated a very high prevalence of Ehrlichia and Anaplasma spp. at selected training sites. Ehrlichia/Anaplasma DNA were identified from spleen tissue from 157 Apodemus agrarius, 1 Mustela sibirica, and 1 Cricetulus riton nestor. Species‐specific DNA fragments of E. canis (45), E. ewingii (16), A. phagocytophila (5), and A. platys (62) were amplified by PCR techniques. Seventy‐one striped field mice had single infections, while 24 had mixed infections of 2 (17 specimens), 3 (7 specimens), or 4 (1 specimen) pathogens. The striped field mouse plays a role as a reservoir for latent infections of various Ehrlichia or Anaplasma species.

Seasonal prevalence of mosquitoes collected from light traps in the Republic of Korea, 2005

Adult mosquito surveillance was conducted during 2005 at 22 US military installations and two training sites located in six provinces in the Republic of Korea. Adult mosquitoes were collected in New Jersey light traps from 1 May to 15 October to determine threshold levels to initiate pesticide applications based on trap indices. A total of 27 363 adult mosquitoes (22 368 [81.7%] females and 4995 [18.3%] males) comprising 15 species (including five members of the Anopheles sinensis group) belonging to seven genera were collected. The most common species collected were members of the Anopheles sinensis Wiedemann group (50.2%), followed by Culex tritaeniorhynchus Giles (30.6%), Aedes vexans nipponii (Theobald) (11.8%), and Culex pipiens Coquillett (6.3%) females. Trap indices varied widely for species over their range, due in part to geographical distribution and degree of association with urban or rural communities.

Calculation of near-surface layer turbulent transport and analysis of surface thermal equilibrium features in Nagqu of Tibet

Abstract This study investigates aerodynamic roughness Z0, drag coefficient CD , momentum flux τ , sensible heat flux H and latent heat flux LE in terms of the extended gradient method, followed by dealing with net radiation R and coefficient of soil thermal exchange G with the daily variation by dint of the thermal balance technique and Fourier law. The data used in this analysis are those of the Nagqu near-surface layer flux observations obtained during GAME/Tibet (GEWEX Asian Monsoon Experiments/Tibet) in the period June 1 to July 20, 1998.

Study of roughness lengths and drag coefficients over Nansha Sea region, Gobi, desert, oasis and Tibetan plateau

Abstract Near-surface turbulent fluxes observations from three large-scale surface-atmosphere interaction field experiments are studied. In the context of the extended Monin-Obukhov similarity theory, investigation was performed of aerodynamic roughness (Z0), scalar roughness ( ZT, ZQ), neutral drag coefficient (CDN), bulk transfer coefficient (sensible heat exchange coefficient CHN and vapor analog CEN) from a calm and a rough sea of the Nansha region, separately, and of aerodynamic roughness and drag coefficients from Gobi, desert, oasis and the Tibetan plateau, together with the related distribution of the wind u . Some meaningful results have been derived.

Seasonal prevalence of mosquitoes collected from light traps with notes on malaria in the Republic of Korea, 2004

Adult mosquito surveillance was conducted during 2004 at 29 US military installations and training sites located in six provinces in the Republic of Korea. Adult mosquitoes were collected in New Jersey light traps and Magnet traps from 1 May through 15 October to determine threshold levels to initiate pesticide applications and to identify malaria infection rates at selected army installations and training sites. A total of 89 206 adults (78 454 [87.9%] females and 10 752 [12.1%] males) comprising 20 species (including five members of the Anopheles Hyrcanus Group) and belonging to seven genera were collected. The most common species collected were members of Culex tritaeniorhynchus Giles (49.4%) and Anopheles sinensis Wiedemann complex (39.1%), followed by Culex pipiens Coquillett (6.1%) and Aedes vexans nipponii (Theobald) (4.2%). Trap indices varied widely for species over their range, due in part to geographical distribution and degree of association with urban communities.

Field-User Acceptability of New Camouflage Face Paint Formulations in the Republic of Korea

New formulations of camouflage face paint (CFP), one with 30% N,N-diethyl-3-methylbenzamide (DEET) and the other without DEET, were evaluated for soldier-user acceptability during a military field-training exercise in the Republic of Korea. Soldiers testing the CFP formulations were members of one of four U.S. Army infantry companies (A, B, C, or D). The formulations were evaluated while soldiers participated in simulated combat exercises for 5 days during hot, humid summer weather in Korea. Results showed that soldiers found both of the new formulations easier to apply (91.3% of respondents who used CFP without DEET and 87.9% of respondents who used CFP with DEET) and remove (82.6% without DEET and 81.2% with DEET) than the previous standard military-issue CFP. Soldier acceptability was higher for the new CFP formulation with 30% DEET (70.5%) than for the formulation without 30% DEET (52.9%). Soldiers recommended it more frequently (70.5%) than the formulation without 30% DEET (50.0%). The new CFP formulation with 30% DEET was rated more often (79.5%) as either good or excellent than the new formulation without 30% DEET (67.4%). Soldiers reported that the CFP formulation with 30% DEET more successfully camouflaged the face (92.7%) than the formulation without 30% DEET (80.0%).

The Combined Effect of Sleep Duration and Quality on Mental Health Among Republic of Korea Armed Forces

Sleep problems in the Republic of Korea Armed Forces have increased. This study analyzed the mental health impact of sleep duration and quality on personnel of the Republic of Korea Armed Forces. Data from the 2014 Military Health Survey were used. Degree of sleep duration and quality were measured by this self-reported questionnaire. Analysis of variance was carried out to compare Kessler Psychological Distress Scale 10 (K10) scores. Multiple logistic regression analysis identified associations between sleep duration, quality, and K10 scores. Among the personnel studied, 2.5% reported severe sleep difficulties. The average sleep duration was 6.83 ± 1.12 hours. Short sleep duration and sleep difficulty were associated with poorer K10 scores. Higher K10 scores among individuals with short sleep duration and low sleep quality were identified in the isolated military area group, the over 53 working hours/week group, and the enlisted soldier group. The factors listed were not by themselves associated with poorer mental health scores. Rather, specific workplaces and specific rank groups were more prone to poorer mental health. These results provide helpful information to minimize the negative psychological effects of sleep factors and to promote a sleep problem prevention and management policy.