No abstract

No abstract

The South Asian summer monsoon brings abundant precipitation and associated latent heat release to the south of central Himalaya, and alters hydrothermal conditions of this region. This study explored the impact of South Asian summer monsoon on the elevation‐dependence of meteorological variables along the south slope of Mt. Everest in the central Himalaya, which is crucial to modelling the glacio‐hydrological processes in this elevated region. The data were collected at five stations deployed at 2660–5600 m above sea level (asl) along the slope during 2007–2011. Major findings are the following: (1) The amount of precipitation during the monsoon season usually decreases with elevation but it is relatively uniform between 3600 and 5000 m asl. This uniform profile may be attributed to the monsoon–terrain–land interactions, particularly to the retard effect of glacier cooling on daytime upvalley wind; (2) Cloud shielding effects cause lower solar radiation and higher downward longwave radiation in the monsoon than in the other seasons. In particular, higher elevations have more clouds in the afternoon, resulting in an abnormal elevation‐dependence of solar radiation (i.e. higher elevations receive less solar radiation); (3) Strong daytime upvalley wind and moist convection homogenizes the vertical distributions of air mass along the slope, causing a constant lapse rate of both surface air temperature and dew‐point temperature (representing humidity) during typical monsoon months, but this phenomenon is not found in the other seasons. These findings provide critical guidance for extrapolating the meteorological variables from lower to higher elevations in this region.

Study Design.Cross-sectional study.Objective.To explore the underlying anatomy of May-Thurner syndrome (MTS) using computed tomography (CT) and discuss its clinical significance for typing diagnosis.Summary of Background Data.Because the anatomical position of the corpse cannot fully illustrate the actual clinical situation in vivo, the diversity of MTS has not been fully elucidated yet.Methods.We retrospectively analyzed the data of 69 patients with MTS. By CT showing, patients were categorized to simple MTS (sMTS, 22 patients), lumbar degeneration-related MTS (dMTS, 33 patients) and other causes MTS (oMTS, 14 patients); meanwhile, a healthy control group were set. Evaluated indexes were onset age, course of disease, diameter of the iliac vein tunnel (IVTD), lumbar degeneration-related iliac vein compression (IVC), therapeutic effect, and diagnostic cutoff of risk IVTD prone to MTS.Results.The onset age of sMTS, dMTS, and oMTS were respectively 42.3 ± 6.5 years, 61.5 ± 10.6 years, and 53.1 ± 16.8 years (P < 0.001); courses were respectively 12.1 ± 9.2 days, 22.5 ± 7.6 days, and 6.8 ± 6.7 days (P = 0.002). IVTDs of sMTS, dMTS, oMTS, and the control were respectively 2.52 ± 0.50 mm, 2.29 ± 0.30 mm, 5.93 ± 2.21 mm, and 4.34 ± 1.61 mm (P < 0.001). Lumbar degeneration-related IVC in dMTS occurred at 41 places, including forward bulging or protruding intervertebral discs (51%,17/33), osteophytes (50%,16/33), and spondylolisthesis (19%, 8/33), but none happened in sMTS, oMTS, and the control. Eighty-six percent of sMTSs, 55% dMTSs, and none oMTSs needed intravenous stent-implanted operation to obtain effective treatment. MTS type (Waldχ2 = 6.092, P = 0.009), course (Waldχ2 = 4.618, P = 0.032), and treatment plan (Waldχ2 = 14.748, P < 0.001) markedly influence the therapeutic result. The cutoff of risk IVTD for sMTS and dMTS was 2.98 mm, which diagnostic sensitivity was 90% and specificity 100%.Conclusion.Owing to the distinct pathoanatomy and causes, diagnosis in classification of MTS by CT is helpful in accurate treatment program.Level of Evidence: 3

While the Himalayas act as a natural barrier to water vapor transport to the Tibetan Plateau, many north‐south‐oriented valleys channel moisture onto the Plateau. However, owing to the lack of in situ data, the spatiotemporal characteristics of precipitation remain unclear along these valleys. In this study, a high‐altitude (2,800–4,500 m above mean sea level) rain‐gauge network was established in the Yadong Valley, one of the main valleys in the central Himalayan Region (CHR). New observations from this network are used to evaluate the Integrated Multi‐satellitE Retrieval for Global Precipitation Measurement (IMERG) precipitation product, with results demonstrating that the IMERG data can reproduce the seasonal and diurnal patterns of precipitation seen in the observational data. This combination of in situ and IMERG precipitation data reveals two unique characteristics in the CHR. First, precipitation during the premonsoon season (March‐May) contributes 20–40% of the annual total, from the high altitudes of the CHR to Southeast Tibetan Plateau, due to water vapor flux conveyed by southwesterlies from the Bay of Bengal, whereas this percentage is much lower in the northern Himalaya and South Asia. Second, diurnal variations in precipitation during the monsoon season (June‐September) vary between the low and high altitudes of the north‐south‐oriented valleys in the CHR: Precipitation at high altitudes has two peaks (one in the afternoon and the other at night), which is different from the single nighttime peak in low altitudes that is usually reported. These two notable spatiotemporal characteristics are indicative of the unique climate that exists at the high altitudes of the CHR.