Air Temperature Inversions Research Articles

The Influence of Air Temperature Inversions on Snowmelt and Glacier Mass Balance Simulations, Ammassalik Island, Southeast Greenland

Abstract In many applications, a realistic description of air temperature inversions is essential for accurate snow and glacier ice melt, and glacier mass-balance simulations. A physically based snow evolution modeling system (SnowModel) was used to simulate 8 yr (1998/99–2005/06) of snow accumulation and snow and glacier ice ablation from numerous small coastal marginal glaciers on the SW part of Ammassalik Island in SE Greenland. These glaciers are regularly influenced by inversions and sea breezes associated with the adjacent relatively low temperature and frequently ice-choked fjords and ocean. To account for the influence of these inversions on the spatiotemporal variation of air temperature and snow and glacier melt rates, temperature inversion routines were added to MircoMet, the meteorological distribution submodel used in SnowModel. The inversions were observed and modeled to occur during 84% of the simulation period. Modeled inversions were defined not to occur during days with strong winds and high precipitation rates because of the potential of inversion breakup. Field observations showed inversions to extend from sea level to approximately 300 m MSL, and this inversion level was prescribed in the model simulations. Simulations with and without the inversion routines were compared. The inversion model produced air temperature distributions with warmer lower-elevation areas and cooler higher-elevation areas than without inversion routines because of the use of cold sea-breeze-based temperature data from underneath the inversion. This yielded an up to 2 weeks earlier snowmelt in the lower areas and up to 1–3 weeks later snowmelt in the higher-elevation areas of the simulation domain. Averaged mean annual modeled surface mass balance for all glaciers (mainly located above the inversion layer) was −720 ± 620 mm w.eq. yr−1 (w.eq. is water equivalent) for inversion simulations, and −880 ± 620 mm w.eq. yr−1 without the inversion routines, a difference of 160 mm w.eq. yr−1. The annual glacier loss for the two simulations was 50.7 × 106 and 64.4 × 106 m3 yr−1 for all glaciers—a difference of ∼21%. The average equilibrium line altitude (ELA) for all glaciers in the simulation domain was located at 875 and 900 m MSL for simulations with or without inversion routines, respectively.

The influence of atmospheric circulation and cloudiness on the intensity of temperature inversions in Sosnowiec (Upper Silesia, Southern Poland)

The paper presents research results of the thermal structure of the near-ground atmospheric layer (100 m) carried out in the years 1993-2005 in Sosnowiec. It is a city located in the central part of the most urbanised and industrialised Katowice Region in Poland. Research of seasonal changes in the frequency of near-ground inversions of temperature revealed their most frequent occurrence on clear winter days. In this season, temperature inversions can sometimes persist for the whole day and night. Air temperature inversions over Sosnowiec occur mainly during anticyclonic stagnation (Ca-anticyclone centre and Ka-anticyclonic ridge) and in anticyclones with air advection from the south and southwest (Sa and SWa).

The lower limit of mountain permafrost in the Russian Altai Mountains

AbstractPermafrost‐indicator features, such as rock glaciers, pingos and ice‐wedge polygons, exist at many locations in and around the South Chuyskiy Range of the Russian Altai Mountains (∼50°N). The distribution of these features suggests that the altitudinal range of the sporadic/patchy permafrost zones and the widespread discontinuous/continuous permafrost zones are 1800–2000 m ASL and above 2000 m ASL, respectively. The lower limit of discontinuous permafrost is approximately 200 m lower than in the Mongolian Altai, which are at a similar latitude. Cold air drainage and/or temperature inversions during winter within U‐shaped valleys together with a thin snow cover because of low precipitation during the same season likely cause the lower permafrost limit in the study area. The calibrated 14C ages of tree remnants found in a rock glacier front in the lower Akkol valley were 293 ± 21 years BP and 548 ± 21 years BP. Given the time of emergence from beneath the Sofiyskiy glacier, this rock glacier developed between 3800–2600 and 550 years BP. Copyright © 2007 John Wiley & Sons, Ltd.

Cold air drainage and modeled nocturnal leaf water potential in complex forested terrain

Spatial variation in microclimate caused by air temperature inversions plays an important role in determining the timing and rate of many physical and biophysical processes. Such phenomena are of particular interest in mountainous regions where complex physiographic terrain can greatly complicate these processes. Recent work has demonstrated that, in some plants, stomata do not close completely at night, resulting in nocturnal transpiration. The following work was undertaken to develop a better understanding of nocturnal cold air drainage and its subsequent impact on the reliability of predawn leaf water potential (Psi(pd)) as a surrogate for soil water potential (Psi(s)). Eight temperature data loggers were installed on a transect spanning a vertical distance of 155 m along a north facing slope in the Mica Creek Experimental Watershed (MCEW) in northern Idaho during July and August 2004. Results indicated strong nocturnal temperature inversions occurring from the low- to upper-mid-slope, typically spanning the lower 88 m of the vertical distance. Based on mean temperatures for both months, inversions resulted in lapse rates of 29.0, 27.0 and 25.0 degrees C km(-1) at 0000, 0400 and 2000 h, respectively. At this scale (i.e., < 1 km), the observed lapse rates resulted in highly variable nighttime vapor pressure deficits (D) over the length of the slope, with variable impacts on modeled disequilibrium between soil and leaf water potential. As a result of cold air drainage, modeled Psi(pd) became consistently more negative (up to -0.3 MPa) at higher elevations during the night based on mean temperatures. Nocturnal inversions on the lower- and mid-slopes resulted in leaf water potentials that were at least 30 and 50% more negative over the lower 88 m of the inversion layer, based on mean and maximum temperatures, respectively. However, on a cloudy night, with low D, the maximum decrease in Psi(pd) was -0.04 MPa. Our results indicate that, given persistent cold air drainage and nighttime stomatal opening, serious errors will result if Psi(s) is estimated from Psi(pd).

PM source apportionment and trace metallic aerosol affinities during atmospheric pollution episodes: a case study from Puertollano, Spain

Source apportionment study was performed, applying principal component analysis to the results of 221 chemical analyses of PM10 and PM2.5 samples collected daily from the industrial (but low traffic) Spanish town of Puertollano over a 14-month period during 2004-2005. Results reveal compositional variations attributable to different mixtures of natural and anthropogenic materials, mainly soil and rock dust (crustal), marine salt (only in PM10), petrochemical refinery emissions, and particles attributed to the combustion of local coal, which is unusually rich in Pb and Sb. During the study period there were 34 pollution episodes when PM10 exceeded 50 tg m(-3), mostly due to winter air temperature inversions, regional atmospheric stagnation, or African dust incursions (North African, NAF days: usually in summer). Whereas the crustal component during NAF episodes averaged 52% with a PM2.5/PM10 ratio of 0.54, this dropped to 29% and a PM2.5/PM10 of 0.67 during non-NAF days when anthropogenic materials predominated. Abnormally enhanced concentrations of pathfinder metallic trace elements provide additional evidence for source apportionment: thus aerosols with raised levels of Pb and Sb are associated with local coal combustion, Ni and V can be linked to petrochemical PM emissions, and Ti, Mn, Rb, and Ce are particularly characteristic of crustal dust incursions.

Modelling the hydrological behaviour of a mountain catchment using TOPMODEL

The mathematical catchment model TOPMODEL was used to simulate the hydrological behaviour of a mountain catchment at Jalovecky Creek, Western Tatras, Slovakia. The model provided adequate results in simulation of daily runoff from the catchment for the period 1 August 1987–31 October 1993. Air temperature inversions, typical of certain periods in mountain catchments, caused overestimation of simulated runoff because of treatment of snowfall as rainfall. A single value of the temperature limit for solid–liquid precipitation was also not appropriate for some events. Similarly, the single value of the degree–day factor for the entire period used in the snow subroutine has led to higher simulated snowmelt runoff in some years. Hourly data were used for runoff simulation during the short period between 15 August and 7 September 1993. The results indicate that more effort will be required to improve the simulation, although the total simulated runoff for the whole period was close to the measured runoff. The areal extent of the saturated area calculated by TOPMODEL for the two short-term events was comparable with the results based on isotopic runoff separation. However, saturated areas estimated by TOPMODEL may provide both event and pre-event water, whereas areas contributing new water estimated by the isotopic method provide pre-event water by definition.