Death Zone Weather Extremes Mountaineers Have Experienced in Successful Ascents.

BACKGROUND: Few data are available on mountaineers' survival prospects in extreme weather above 8000 m (the Death Zone). We aimed to assess Death Zone weather extremes experienced in climbing-season ascents of Everest and K2, all winter ascents of 8000 m peaks (8K) in the Himalayas and Karakoram, environmental records of human survival, and weather extremes experienced with and without oxygen support. MATERIALS AND METHODS: We analyzed 528 ascents of 8K peaks: 423 non-winter ascents without supplemental oxygen (Everest-210, K2-213), 76 ascents in winter without oxygen, and 29 in winter with oxygen. We assessed environmental conditions using the ERA5 dataset (1978-2021): barometric pressure (BP), temperature (Temp), wind speed (Wind), wind chill equivalent temperature (WCT), and facial frostbite time (FFT). RESULTS: The most extreme conditions that climbers have experienced with and without supplemental oxygen were: BP 320 hPa (winter Everest) vs. 329 hPa (non-winter Everest); Temp -41°C (winter Everest) vs. -45°C (winter Nanga Parbat); Wind 46 m⋅s-1 (winter Everest) vs. 48 m⋅s-1 (winter Kangchenjunga). The most extreme combined conditions of BP ≤ 333 hPa, Temp ≤ -30°C, Wind ≥ 25 m⋅s-1, WCT ≤ -54°C and FFT ≤ 3 min were encountered in 14 ascents of Everest, two without oxygen (late autumn and winter) and 12 oxygen-supported in winter. The average extreme conditions experienced in ascents with and without oxygen were: BP 326 ± 3 hPa (winter Everest) vs. 335 ± 2 hPa (non-winter Everest); Temp -40 ± 0°C (winter K2) vs. -38 ± 5°C (winter low Karakoram 8K peaks); Wind 36 ± 7 m⋅s-1 (winter Everest) vs. 41 ± 9 m⋅s-1 (winter high Himalayan 8K peaks). CONCLUSIONS: 1.The most extreme combined environmental BP, Temp and Wind were experienced in winter and off-season ascents of Everest.2.Mountaineers using supplemental oxygen endured more extreme conditions than climbers without oxygen.3.Climbing-season weather extremes in the Death Zone were more severe on Everest than on K2.4.Extreme wind speed characterized winter ascents of Himalayan peaks, but severely low temperatures marked winter climbs in Karakoram.

Comparison of Environmental Conditions on Summits of Mount Everest and K2 in Climbing and Midwinter Seasons.

(1) Background: Today's elite alpinists target K2 and Everest in midwinter. This study aimed to asses and compare weather at the summits of both peaks in the climbing season (Everest, May; K2, July) and the midwinter season (January and February). (2) Methods: We assessed environmental conditions using the ERA5 dataset (1979-2019). Analyses examined barometric pressure (BP), temperature (Temp), wind speed (Wind), perceived altitude (Alt), maximal oxygen uptake (VO2max), vertical climbing speed (Speed), wind chill equivalent temperature (WCT), and facial frostbite time (FFT). (3) Results: Most climbing-season parameters were found to be more severe (p < 0.05) on Everest than on K2: BP (333 ± 1 vs. 347 ± 1 hPa), Alt (8925 ± 20 vs. 8640 ± 20 m), VO2max (16.2 ± 0.1 vs. 17.8 ± 0.1 ml·kg-1·min-1), Speed (190 ± 2 vs. 223 ± 2 m·h-1), Temp (-26 ± 1 vs. -21 ± 1°C), WCT (-45 ± 2 vs. -37 ± 2 °C), and FFT (6 ± 1 vs. 11 ± 2 min). Wind was found to be similar (16 ± 3 vs. 15 ± 3 m·s-1). Most midwinter parameters were found to be worse (p < 0.05) on Everest vs. K2: BP (324 ± 2 vs. 326 ± 2 hPa), Alt (9134 ± 40 vs. 9095 ± 48 m), VO2max (15.1 ± 0.2 vs. 15.3 ± 0.3 ml·kg-1·min-1), Speed (165 ± 5 vs. 170 ± 6 m·h-1), Wind (41 ± 6 vs. 27 ± 4 m·s-1), and FFT (<1 min vs. 1 min). Everest's Temp of -36 ± 2 °C and WCT -66 ± 3 °C were found to be less extreme than K2's Temp of -45 ± 1 °C and WCT -76 ± 2 °C. (4) Conclusions: Everest presents more extreme conditions in the climbing and midwinter seasons than K2. K2's 8° higher latitude makes its midwinter BP similar and Temp lower than Everest's. K2's midwinter conditions are more severe than Everest's in the climbing season.

Correlations between 7Be, 210Pb, dust and PM10 concentrations in relation to meteorological conditions in northern Poland in 1998-2018.

Analysis of a twenty-year (1998-2018) data series on 7Be concentrations in weekly collected aerosol samples in northern Poland showed a clear pattern of seasonal changes in 7Be with a maximum in the summer period associated with the most intensive thermal convection and vertical mixing. Activity concentrations of 7Be ranged from 480 µBq m-3 to 9370 µBq m-3. A strong relationship has been shown between 7Be concentrations observed in years and the activity of the Sun related to the sunspot number. Activity concentrations of 210Pb in aerosol ranged from 17 µBq m-3 to 1490 µBq m-3 with maximum occurring in the winter. The difference in the seasonal pattern in 7Be and 210Pb concentrations were directly related to the different sources of both isotopes, as an additional source of 210Pb was the products of combustion during the heating season. Similar pattern with maximum concentrations in winter was observed for PM10, as the main source is the same as in the case 210Pb. A content of PM10 was in the range from 6.5 to 81.7 µg m-3. A statistically significant correlation between both isotopes occurs. At the same time, 7Be, 210Pb and PM10 are visibly related to the dust concentrations ranged from 7.3 µg m-3 in winter to 134.8 µg m-3 in spring. Statistical analysis carried out with simple regression model, stepwise multiple regression, and Random Forest models showed that the sunspots number, air temperature and sunshine duration have the most substantial impact on transport, and hence the concentration of 7Be in the surface layer of the atmosphere. The increase in relative humidity and precipitation and higher wind speed have a statistically significant effect on the reduction of 7Be concentrations in surface air.

The variability of PM10 and PM2.5 concentrations in selected Polish agglomerations: the role of meteorological conditions, 2006-2016.

The research focuses on the analysis of PM10 and PM2.5 concentrations variability at 11 stations in selected urbanized areas of Poland (Tricity, Poznan, Lódz, Kraków). Methods comprised: the analysis of basic statistical characteristics in yearly/monthly/daily/hourly scale and threshold exceedance frequencies. Also, correlations between PM10 and meteorological variables were investigated. GEV distribution analysis allowed the estimation of the return levels of monthly maxima of PM10 and PM2.5. Results show that in Tricity there are fewer than 5 % of days with PM10 and PM2.5 threshold exceedance. In Kraków, the standards are only met during summer and the frequency of daily PM limit exceedance in winter was around 65-90 %. GEV analysis indicates that 10y return level of PM10 monthly maximum daily average do not usually exceed 250 µg/m3 at most of the stations (Kraków agglomeration is an exception here). In winter, the meteorological conditions unfavourable to the pollutant's dispersion comprise: high-pressure systems, stable equilibrium in the atmosphere and limited turbulence occur quite often together with low wind speed and reduced height of the planetary boundary layer.