Geographical Controls of Mountain Meteorological Elements Latitude Continentality Altitude Topography.

Slides:



Advertisements
Similar presentations
AIR POLLUTION AND METEOROLOGY
Advertisements

FILTERED NOCTURNAL EVOLUTION Data from 23 AWS, 22 of them from the official Catalan Met. Service (see black dots in figure) and one from the Spanish Met.
Session 2, Unit 3 Atmospheric Thermodynamics
Transport of Air Pollutants
#4095. How much colder than standard temperature is the actual temperature at 9,000 feet, as indicated in the excerpt from the Winds and Temperature Aloft.
World Pattern of Climate
Dependence of PM on Elevation Background and Rationale Influence of the Seasonal Variation in Mixing Heights on the PM Elevation Dependence Vertical Profile.
Moist Processes ENVI1400: Lecture 7. ENVI 1400 : Meteorology and Forecasting2 Water in the Atmosphere Almost all the water in the atmosphere is contained.
Mountain Climate - Extremes are the norm -Great environmental contrasts in short distances -Large variations in short time spans -High Complexity -Effects.
Chapter 11: Thermally forced orographic circulations
Atmospheric Analysis Lecture 3.
Mesoscale Circulations during VTMX John Horel Lacey Holland, Mike Splitt, Alex Reinecke
Geographical Controls of Mountain Meteorological Elements Latitude Continentality Altitude Topography.
Diurnal circulations in Southern California Mimi Hughes and Alex Hall.
Temperature Lapse rate- decrease of temperature with height:  = - dT/dz Environmental lapse rate (  ) order 6C/km in free atmosphere  d - dry adiabatic.
Observations of Wind in Nares Strait. There is incidental evidence that winds are strong … but how strong? And why? 3 November :06 UTC Observations.
Ang Atmospheric Boundary Layer and Turbulence Zong-Liang Yang Department of Geological Sciences.
Lecture 3 Vertical Structure of the Atmosphere. Average Vertical Temperature profile.
* Reading Assignments:
Warning! In this unit, we switch from thinking in 1-D to 3-D on a rotating sphere Intuition from daily life doesn’t work nearly as well for this material!
Climate Meteorology. Factors Affecting Climate Climate includes not only the average weather conditions of an area, but also any variations from those.
Wind Driven Circulation I: Planetary boundary Layer near the sea surface.
Earth Science 17.3 Temperature Controls
The Air-Sea Momentum Exchange R.W. Stewart; 1973 Dahai Jeong - AMP.
II. Synoptic Atmospheric Destabilization Processes Elevated Mixed Layer (EML) Synoptic Lifting Dynamic Destabilization Differential Advection.
Introduction A new methodology is developed for integrating complementary ground-based data sources to provide consistent ozone vertical distribution time.
Atmospheric pressure and winds
The major wind systems.
*K. Ikeda (CCSR, Univ. of Tokyo) M. Yamamoto (RIAM, Kyushu Univ.)
Weather Temporary behavior of atmosphere (what’s going on at any certain time) Small geographic area Can change rapidly.
Forecast Pressure. Pressure Observations ASOS is the best…the gold standard Ships generally the worst.
Climate of North America 101 What are the major controls on North American climate? What is the dominant flow pattern across North America in winter? How.
Vertical Wavenumber Spectrum of Gravity Waves at the Northern High Latitude Region in the Martian Atmosphere Hiroki Ando.
Diurnal Variations of Tropical Convection Ohsawa, T., H. Ueda, T. Hayashi, A. Watanabe, and J. Matsumoto, 2001 : Diurnal Variations of Convective Activity.
Boundary Layer Evolution Atmos 3200/Geog 3280 Mountain Weather and Climate C. David Whiteman.
What set the atmosphere in motion?
Ocean Currents Ocean Density. Energy in = energy out Half of solar radiation reaches Earth The atmosphere is transparent to shortwave but absorbs longwave.
Transport and dispersion of air pollution
Winds Yin (2000) JAM Annual mean winds. Annual Cycle in Wind Yin (2000) JAM Annual cycle amplitude.
Composition/Characterstics of the Atmosphere 80% Nitrogen, 20% Oxygen- treated as a perfect gas Lower atmosphere extends up to  50 km. Lower atmosphere.
Observed Structure of the Atmospheric Boundary Layer
Validation of Satellite-derived Clear-sky Atmospheric Temperature Inversions in the Arctic Yinghui Liu 1, Jeffrey R. Key 2, Axel Schweiger 3, Jennifer.
Basin-scale nocturnal regimes in complex terrain Maria A. Jiménez and Joan Cuxart Universitat de les Illes Balears Palma de Mallorca, Spain 6th MesoNH.
Diurnal Variations in Southern Great Plain during IHOP -- data and NCAR/CAM Junhong (June) Wang Dave Parsons, Julie Caron and Jim Hack NCAR ATD and CGD.
Weather and Climate Unit Investigative Science. * Meteorologists describe properties of the atmosphere using the following descriptors: * Temperature.
Parameterization of the Planetary Boundary Layer -NWP guidance Thor Erik Nordeng and Morten Køltzow NOMEK 2010 Oslo 19. – 23. April 2010.
Forecast Pressure. Pressure Observations ASOS is the best…the gold standard Ships generally the worst.
Implementation of an improved horizontal diffusion scheme into the Méso-NH Günther Zängl Laboratoire d’Aérologie / University of Munich 7 March 2005.
7 – Group 임지유, 김도형, 방주희. Consider a layer of the atmosphere in which ( Γ
AOSS 401, Fall 2006 Lecture 7 September 21, 2007 Richard B. Rood (Room 2525, SRB) Derek Posselt (Room 2517D, SRB)
AOSC 200 Lesson 27. A Typical Day in a Pollution Episode A common severe pollution weather pattern occurs when high pressure is centered just west of.
The Course of Synoptic Meteorology
TOPOGRAPHICALLY INDUCED CONVECTIVE CLOUD PATTERNS
19.1.
Local Wind Systems and Temperature Structure in Mountainous Terrain
TERRAINS Terrain, or land relief, is the vertical and horizontal dimension of land surface. Terrain is used as a general term in physical geography, referring.
Weather 101 and beyond Edward J. Hopkins
Temperature Variations
5. Temperature Structure
Lecture 8: Atmospheric Circulation Introductive Physical Oceanography
METR March 2004 Thermodynamics IV.
Chapter 3 Thermodynamics.
Fig. 2 shows the relationship between air temperature and relative humidity. 2 (a) (i) Describe the relationship shown in Fig. 2. [3] (ii) State.
Air Pollution and Control (Elective- I)
Lab 2: Vertical Structure of the Atmosphere
Forecast Pressure.
Warm-up 22SEP2014 How are weather and climate similar and different? Which is happening outside right now? Logistics: Biome Presentations T/W/Th next.
Fig. 2 shows the relationship between air temperature and relative humidity. (a) (i) Describe the relationship shown in Fig. 2. [3] (ii) State.
Central California Circulation Study
World Geography 3202 Unit 2 Climate Patterns.
Presentation transcript:

Geographical Controls of Mountain Meteorological Elements Latitude Continentality Altitude Topography

Role of Topography

Topography- Temperature on Mountain Summits

During the eighteenth century there was still considerable controversy as to the cause of the general temperature decrease with height. De Sussure, was the first physical scientist to approach a realistic explanation of the cause of cold in mountains. (Barry, 1978). Read: Barry 1978

Topography- Temperature on Mountain Summits From several studies, the primary control of free air- summit temperature difference seems to be the atmospheric temperature structure. Peppler (1931) found that, in the Alps, mountain temperatures are closest to those in the free air when the lapse rate is nearly adiabatic between 1-3 km. With isothermal or inversion conditions, temperatures in both summer and winter are considerably loweer on mountain summits.

Topography- Temperature on Mountain Summits Pepin et al. (1999) showed for stations in the Pennines, lapse rates are determined by atmospheric temperature and moisture level, cloudiness/solar radiation, and wind speed. Changes in lapse rate can result from changes in the frequency of cyclonic/anticyclonic circulation regimes. Rolland (2003) analyzed 640 stations in the Austrian- Italian Alps and showed that many earlier studies are biased by the use short records and limited number of stations. Rolland, C Spatial and seasonal variations of air temperature lapse rates in alpine regions. Journal of Climate 16:1032–1046.

Topography- Temperature on Mountain Summits Rolland (2003) used stations that ranged in altitude from below 100 m to over 2000 m, and identified valley and slope sites. Lapse rates are calculated using simple linear regression of temperature with altitude in four station groups. Fig. 2.14

Topography- Temperature on Mountain Summits The influence of nocturnal inversions at night and of near- adiabatic conditions by day, in addition to effects of foehn winds and katabatic drainage winds, led von Ficker (1926) to declare that “true” lapse rates cannot be determined in mountain regions. A unique approach of measurement was performed by Brocks (1940) in which he determined density differences in layers over the Austrian Alps. Brocks found that the diurnal amplitude of lapse rate decreases with altitude more rapidly in the free air over the plains than over the mountains. Brock also found that the mountain atmosphere extends above the mean ridge height. Similar to the model by Ekhart (1948).

Topography- Temperature on Mountain Summits Important to distinguish between the effects of local topography which cause diurnal changes in lapse rate and large-scale topographic effects that modify the atmospheric structure. Tabony (1985) outlines three idealized topographic situations: Fig Isolated mountain 2.Plateau of limited extent 3.Extensive plateau

Topography- Temperature on Mountain Summits

1913 von Hahn noted that temperatures observed at summit stations, on average, are lower than those in the free air at the same level. Later studies ( McCutchan 1983; Richner an Phillips 1984) show that mountain peaks are warmer in the afternoon and colder in the early morning.

Topography- Temperature in Mountain Environments Dobrowski, Abatzoglou, Greenberg, and Schladow (2009) suggest that air temperature in mountain environments (in their study area—Lake Tahoe basin) is driven primarily by regional temperature patterns. They mention, but neglect the role of stability and decoupling due to cold air pooling in enclosed terrain. They use “Free Air” estimates from NARR which provides assimilated temperature data at 3 hr and 32 km resolution. Please read and write a discussion on this paper for Monday. Think about techniques used and are these valid when comparing the ideas of Ekhart (1938).

The effect of mountains on wind flow over them has aroused early interest in the topic since peoples have occupied mountainous areas. Georgii (1922) argued that wind speeds on summits generally increase above mountain summits up to a level of 30% of the mountain altitude. He termed this effect as the ‘influence height’. This was argued by A. Wagner that it is not a good generalization. Topography- Wind Speeds on Mountain Summits

Wind observations on mountain summits and in the free air was carried out by Wahl (1966). From data for European stations, in general, speeds on summits average approximately half of the corresponding free-air values. Topography- Wind Speeds on Mountain Summits

There are two basic factors which affect wind speeds on mountain summits (Barry 1992). These operate in opposition to each other. 1.The vertical compression of airflow over a mountain causes acceleration of the air. 2.Frictional effects cause retardation. Frictional drag in the loer layers of the atmosphere is caused partly by ‘skin friction’ (shear stress), due to small-scale roughness elements (< 10 m). Topography- Wind Speeds on Mountain Summits

Additional frictional effects are caused by ‘form drag’ which is due to topographic features km in size that set up dynamic pressure perturbations. In mountain areas, form drag contributes the largest proportion to the total friction. Over simple 2-D terrain, drag increases in proportion to the slope 2, up to the point where flow separation takes place (Taylor et al. 1989). Topography- Wind Speeds on Mountain Summits

Balloon measurements in the central Alps indicate that drag influences extend up to about 1 km above the local mean ridge altitude of 3 km. Special soundings made during ALPEX (Alpine Experiment) show that the airflow over the central Swiss Alps is decelerated up to about 4 km (600 mb). Ohmura (1990) suggests that momentum transfer between the atmosphere and the mountains takes place from about 4 km down to 500 m below ridge tops. Topography- Wind Speeds on Mountain Summits

Many of the wind profiles indicated a wind maximum at 1.5 km above the ridges with speeds greater than over the adjacent lowlands. Schell (1936) attempted to explain contrasting observations with tethered balloons on three summits in the Caucasus at 1300 m. He concluded that in the case of an isolated peak, or and exposed ridge, the compressional effect outweighs frictional retardation. Resulting in stronger winds up to about m over the summit than overlying free air. Topography- Wind Speeds on Mountain Summits