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ATMOSPHERIC TRANSPORT PROCESSES OVER THE KATHMANDU VALLEY NEPAL ATMOSPHERIC TRANSPORT PROCESSES OVER THE KATHMANDU VALLEY NEPAL ATMOSPHERIC TRANSPORT PROCESSES OVER THE KATHMANDU VALLEY, NEPAL ATMOSPHERIC TRANSPORT PROCESSES OVER THE KATHMANDU VALLEY, NEPAL R P R i d Lk N Jh Ram P. Regmi and Lok N. Jha Ram P. Regmi and Lok N. Jha Central Department of Physics Tribhuvan University Kathmandu Nepal SCIENCE AND TECHNOLOGY 2011 T1 P13 TRIBHUVAN UNIVERSITY Central Department of Physics, Tribhuvan University, Kathmandu, Nepal. SCIENCE AND TECHNOLOGY 2011: T1-P13 TRIBHUVAN UNIVERSITY ABSTRACT 5 Results C Vertical Structure of Wind and Potential Temperature Temporal and Spatial Distribution of Pollutants ABSTRACT Th i t t h t i ti th K th d ll h b t di d t th ti l d t l 5. Results A Ch t i ti f N S f L l Fl C. Vertical Structure of Wind and Potential Temperature Temporal and Spatial Distribution of Pollutants ( ) The air mass transport characteristics over the Kathmandu valley have been studied to assess the spatial and temporal d b f d l f ll h h l fl Th d h b d h h l f A. Characteristics of Near Surface Local Flows 06:45 LST 00:45 LST 18:00 LST • Pollutants (e.g., SO 2 ) released in the southern area builds hi h i h d distributions of decoupling of valley's air mass with the regional flows. The study has been carried out with the applications of 06:45 LST 00:45 LST Near surface wind at 11:45 LST Near surface wind at 05:45 LST high concentration zone near the eastern and th t ti l Mesoscale Meteorological Model (MM5) Weather Research and Forecast (WRF) and a Chemical Transport northeastern mountain slops. Mesoscale Meteorological Model (MM5), Weather Research and Forecast (WRF) and a Chemical Transport Mdl Th dl di ti h b d ith b d dt Th td l th t K th d ll t i ll • The prevailing local flows organize general mass Models. The model predictions have been compared with observed data. The study reveals that Kathmandu valley typically Pa) Pa) transport from west/south to east in the Kathmandu shows a plateau-basin dual nature. The nighttime near surface air mass remains largely calm. However, the intermittent re (h e (hP valley and channel out into eastern valley . The pollutants downslope winds organize a weak flow system that often develops valley wide anti clockwise circulation at about 150 m above the ssur ssure L m) further move towards the Himalayas. downslope winds organize a weak flow system that often develops valley wide anti-clockwise circulation at about 150 m above the fl hh l l b ff l d h h l l f ld d h h T Pres Pres SL m) MSL e (km • SO remains constant around 40 ppb during the floor, which slowly but effectively induces mass exchange in the lower layer of cold air mass during the nighttime. Two very AM e (km m) AM ance • SO 2 remains constant around 40 ppb during the nighttime despite its continuous release in the area gentle wind systems, southwesterly and northwesterly, composed of regional scale deep upslope and plain-to -plateau winds (m) ance n (m ista nighttime despite its continuous release in the area (Imadol) due to the windless surface and presence of gentle wind systems, southwesterly and northwesterly, composed of regional scale deep upslope and plain to plateau winds l l it d it th K th d ll l t ti d ti till th lt i U i f th 3 ion Dista ation th D (Imadol) due to the windless surface and presence of some intermittent wind at about 150 m AGL as regularly intrude into the Kathmandu valley close to noontime and continue till the late evening. Upper air from more than 3 k b h l l d d h ll fl h f S f K h d evati th D leva Nort some intermittent wind at about 150 m AGL as mountain/down‐slope wind. km above the mean sea level comes down and sweeps across the valley floor in the afternoon. Spring season of Kathmandu Ele Nort n El uth-N mountain/down slope wind. Th di t ib ti f ll t t d t t th di l appears to be relatively windy compared to winter No strong decoupling of valley's air mass with the regional air flows appear 12:45 LST 10:45 LST rain uth-N errai Sou • The distribution of pollutants demonstrate the diurnal i di it i it t ith th h t i ti appears to be relatively windy compared to winter . No strong decoupling of valley s air mass with the regional air flows appear t it f th 2 h i d d th ll Th di tit ti l l th t d 12:45 LST 10:45 LST Terr Sou Te S periodicity in consistent with the characteristic meteorology to persist for more than 24 hours or so in and around the valley . The surrounding mountaintops, particularly, the eastern and h b h bl f l b k d l T meteorology . southeastern mountain tops appear to be the most suitable sites for regional background aerosol concentration measurements. • Pollutants may spread over the mixed layer of about 1.2 1 I d i Pa) Pa) km over the valley just before the intrusion of the local 1. Introduction e (hP e (hP flows. Mt. Shivapuri Mt. Nagarkot The atmospheric transport processes over the Kathmandu ssure ssure • In the evening HNO 3 rich air mass comes back over the Mt. Phulchoki 2660 m 2250 m The atmospheric transport processes over the Kathmandu valley located in the Middle Hills of the Central Himalaya Pres Pres West-East Distance (km) West-East Distance (km) In the evening HNO 3 rich air mass comes back over the Kathmandu valley and remains floating at about 350 2762 m valley, located in the Middle Hills of the Central Himalaya, offers rather different characteristics of local flow fields in P P West-East Distance (km) Near surface wind at 14:45 LST Near surface wind at 17:45 LST Kathmandu valley and remains floating at about 350 meters above the valley floor . offers rather different characteristics of local flow fields in comparison to the general mountain valley wind system In Near surface wind at 14:45 LST Near surface wind at 17:45 LST meters above the valley floor . comparison to the general mountain valley wind system. In this region the local circulations associated with a large this region, the local circulations associated with a large number of small scale subdivisions and sub climates interact number of small‐scale subdivisions and sub‐climates interact in a complicated manner Present study assesses the in a complicated manner . Present study assesses the atmospheric conditions prevailing over the Kathmandu valley 17:45 LST atmospheric conditions prevailing over the Kathmandu valley and then examines the extent of decoupling of surface air 17:45 LST 14:45 LST L m) m) and then examines the extent of decoupling of surface air i d d th K th d ll ith th i l MSL (km MSL (km D3 The only Valley Outlet mass in and around the Kathmandu valley with the regional fl d i th d d d it it bl AM nce ) AM nce D3 The only Valley Outlet Bagmati River Gorge flows during the dry season and recommends sites suitable f i l/ l b l l b k d t ti Pa) Pa) (m) stan n (m) stan for regional/global aerosol background concentration t Weak Stability e (hP (hP on ( h Dis tion Dis measurement. Stable Layer( 1km) Weak Stability ssure sure vatio orth evat rth Stable Layer(~1km) Pres Press Elev th-N n Ele Nor P P in E Sout rrain uth- View in Autumn Himalayas rrai S Ter Sou T i h i ht( ) AMSL C Te S Terrain height (m) AMSL 3 D Topographic View of Kathmandu Valley and Its Surroundings Sh ll th t l C B 3‐D Topographic View of Kathmandu Valley and Its Surroundings. ( ) Shallow southwesterly h h l l f l ( ) d d (l ) Bhimsen Tower (54m high) Northwest‐Southeast cross‐sectional plot of potential temperature (contours) and wind vector (along A—B) S 17:45 LST West-East Distance (km) West-East Distance (km) Kathmandu remain relatively clean during Autumn Near surface wind at 20:45 LST Kathmandu remain relatively clean during Autumn Conceptual flow diagram V ti l di i f ll t ti lt i it a) Vertical dispersion of pollutants in late morning winter (hPa Himalayan range as seen from Kathmandu ure ( Hundreds of emitters in operation ressu Pr SL m) AM e (km (m) ance Sodar site N th t l fl b th t l ion ista Northwesterly flows above southwesterly evati th D Southwest‐Northeast cross‐sectional plot of potential temperature ( ) ( ) Photographs of wind/dust storm (upper left picture) and highly Ele Nort Smoke flow pattern in the afternoon Fog and pollutant’s layer blanketing the Kathmandu Valley (contours) and wind vector (along C—D) localized destructions caused by wind storm in last March. rain uth-N Smoke flow pattern in the afternoon Fog and pollutant s layer blanketing the Kathmandu Valley 2 G l li ti f t f K th d ll • Both southwesterly and northwesterly show the nature of the cool density • The relatively cooler south‐ westerly capped by the warmer Terr Sou 2. General climatic feature of Kathmandu valley flow; they intrude into the mixed layer developed over the Kathmandu northwesterly and the development of stable layer aloft just T S The Kathmandu valley possesses a warm temperate semi‐tropical and valley . above the surrounding mountaintops that covers the whole The Kathmandu valley possesses a warm temperate semi tropical and seasonable climate. The winter climate is characterized as dry with an • The southwesterly is driven by a combination of both up slope and plain Kathmandu valley and beyond sets the basic meteorological average maximum and minimum temperatures of 17 and 2°C, • The southwesterly is driven by a combination of both up‐slope and plain‐ to‐plateau winds background for air pollution transport over the valley . respectively . During the winter season, the valley remains mostly clear to‐plateau winds. • This layering flow structure over the valley severely limits the in its skies with calm or windless nights followed by early morning • The northwesterly execute a hydraulic jump like flow and it rides over the This layering flow structure over the valley severely limits the vertical dispersion of pollutants and leads to the formation of West East Distance (km) dense fog lingering up to 09 or 10 Local Standard Time (LST). Very cool southwesterly the depth of which is about 250 m. vertical dispersion of pollutants and leads to the formation of multiple layering of pollutants. West-East Distance (km) gentle wind routinely starts to blow close to the noontime and • The wind storm generally occurs late afternoon and early evening that multiple layering of pollutants. Th i d l ll d l 700 800 b h Nighttime Wind Fields at 02:45 LST at 150m AGL Near surface Potential Temperature at 16:45 LST 7 Observed Local Flow Characteristics in and Around the Valley Local Flows and Observed Pollutant Distribution continue till the evening. The surface wind speeds have been found to The wind storm generally occurs late afternoon and early evening that coincides with the development of stable layer just above the surrounding • The mixed layer generally develops up to 700 to 800m above the ll fl i th ft d i th d 7. Observed Local Flow Characteristics in and Around the Valley Local Flows and Observed Pollutant Distribution be calm (< 1 ms ‐1 ) for about 75 % of the time of a day with max. wind mountaintops. valley floor in the afternoon during the dry season. Wind Speed at Thankot (March) 10.0 1-Mar 2M Wind Speed at NAST (March) 6.0 1-Mar Wind speed at western mountain pass Wind speed at southern area speed generally around 5 ms ‐1 in the afternoon, but could reach as high D Emission Source Distribution in Dry Season 9.0 2-Mar 3-Mar 4-Mar 2-Mar 3-Mar 4-Mar as 15 ms ‐1 in the late spring. Spring months are characterized by D. Emission Source Distribution in Dry Season 8.0 5-Mar 6-Mar 7-Mar 5.0 4 Mar 5-Mar 6-Mar 7 Mar showery and relatively windy weather, increasingly higher humidity d h d ih i l h il Wi d NO TSP SO 7.0 7-Mar 8-Mar 9-Mar 10 Mar 40 7-Mar 8-Mar 9-Mar 10 M and pre‐monsoon thunderstorms with occasional hail. Winter and l i h d it th ti d th NO x TSP SO x ) 6.0 m/s) 10-Mar 11-Mar 12-Mar 4.0 m/s) 10-Mar 11-Mar 12-Mar early spring showers may deposit snow on the mountains around the d f th ll Th id tt l d f ti ll (km m) 5.0 peed ( 13-Mar 14-Mar 15-Mar 3.0 peed (m 13-Mar 14-Mar 15-Mar edges of the valley . The wind patterns, cloud formation, valley ventilation visibility as well as the air mass dispersion characteristics nce ( e (k 4.0 Wind sp 15 Mar 16-Mar 17-Mar 18-Mar Wind Sp 15 Mar 16-Mar 17-Mar 18-Mar ventilation, visibility as well as the air mass dispersion characteristics over the valley in dry season appears distinctly different from the wet A il stan ance 3.0 W 18-Mar 19-Mar 20-Mar 21 M 2.0 W 18-Mar 19-Mar 20-Mar 21 Mar over the valley in dry season appears distinctly different from the wet season The summer monsoon occurs as eastern disturbances The April April h Dis Dista 2.0 21-Mar 22-Mar 23-Mar 10 21-Mar 22-Mar 23-Mar 24 M season. The summer monsoon occurs as eastern disturbances. The annual rainfall generally exceeds 1300 mm of which 70 to 80% rain falls orth rth D 1.0 24-Mar 25-Mar 26-Mar 1.0 24-Mar 25-Mar 26-Mar annual rainfall generally exceeds 1300 mm of which 70 to 80% rain falls during the summer monsoon months Monsoon rains have a tendency h-N -Nor 0.0 0 0 0 0 0 0 0 0 0 0 0 0 26 Mar 27-Mar 28-Mar 29 Mar 0.0 27-Mar 28-Mar 29-Mar during the summer monsoon months. Monsoon rains have a tendency to be more frequent at night whereas the daylight hours are mostly Sout uth- 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 L l St d d Ti (h ) 29-Mar 30-Mar 31-Mar A 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 29 Mar 30-Mar 31-Mar Average to be more frequent at night whereas the daylight hours are mostly sunny Overcast is rather rare over the valley The dry season generally S Sou Local Standard Time (hr.) Average Local Standard Time (hr.) Average sunny . Overcast is rather rare over the valley . The dry season generally persists for 9 months (October to June) with much less precipitation Wind Speed at Babarmahal (March) 4.5 1-Mar 2M Wind Speed at Budanilakantha (March) 5.0 1-Mar Wind speed at northern area Wind speed at central area persists for 9 months (October to June) with much less precipitation (only 10–20 % of the annual total). 4.0 2-Mar 3-Mar 4-Mar 4.5 2-Mar 3-Mar 4-Mar (only 10 20 % of the annual total). 35 4.0 5-Mar 6-Mar 7-Mar 4.0 4-Mar 5-Mar 6-Mar 7 Mar 3. Purpose 30 3.5 7 Mar 8-Mar 9-Mar 10 Mar 3.5 7-Mar 8-Mar 9-Mar 10 M • To understand the mechanism of development of local flows over the Kathmandu valley 25 3.0 (m/s) 10-Mar 11-Mar 12-Mar 13 M 3.0 m/s) 10-Mar 11-Mar 12-Mar • To understand the mechanism of development of local flows over the Kathmandu valley . T d t d h i f i ll ti t t d th i d i th ll 2.5 peed ( 13-Mar 14-Mar 15-Mar 2.5 peed ( 13-Mar 14-Mar 15-Mar • To understand mechanism of air pollution transport and their dynamics over the valley . T d t d th l ti hi bt th l l fl d f ti f th ll t t fi ld i th ll February February West East Distance (km) 2.0 Wind S 16-Mar 17-Mar 18-Mar 2.0 Wind S 15 Mar 16-Mar 17-Mar 18 Mar • To understand the relationship between the local flows and formation of the pollutant fields in the valley . T h il d l di ib i f d li f ll ’ i ih h i l fl West-East Distance (km) West-East Distance (km) 1.5 W 18-Mar 19-Mar 20-Mar 21 Mar 1.5 W 18-Mar 19-Mar 20-Mar 21 M • To assess the spatial and temporal distributions of decoupling of valley’s air mass with the regional flows. f f 2 1 2 1 More Large Scale Flow 1.0 21-Mar 22-Mar 23-Mar 24 M 1.0 21-Mar 22-Mar 23-Mar Ob d NO d SO l l f ll th i ltdl l • Kathmandu valley remains calm during late evening until • To identify the suitable sites for regional background aerosol concentration measurement. NO x (kg-NO 2 km -2 day -1 ) TSP (kg km -2 day -1 ) SO x (kg-SO 2 km -2 day -1 ) More Large Scale Flow 0.5 24-Mar 25-Mar 26-Mar 0.5 24-Mar 25-Mar 26-Mar • Observed NO 2 and SO 2 closely follows the simulated local fl the noon forming a deep cold air lake at night that may 4 Methodology x 2 E Visible Transport Processes 4. Methodology Near Surface Wind Fields at 14:45 LST 0.0 0 0 0 0 0 0 0 0 0 0 0 0 26 Mar 27-Mar 28-Mar 29-Mar 0.0 0 0 0 0 0 0 0 0 0 0 0 0 26 Mar 27-Mar 28-Mar 29 Mar flows. reach 400m in its depth in the early morning. 4. Methodology E. Visible Transport Processes 4. Methodology Near Surface Wind Fields at 14:45 LST 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 29-Mar 30-Mar 31-Mar Average 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 L l St d d Ti (h ) 29-Mar 30-Mar 31-Mar A • The April concentrations are significantly higher than the • Intrusion of cooler air masses close to the noontime from Nagarkot Hilltop Local Standard Time (hr.) Average Local Standard Time (hr.) Average The April concentrations are significantly higher than the February but the distribution pattern remains the same. the Indian Plain and the western valley that merge into a A. Air pollution • Upward transport of smoke at the front of local flows reveal the February but the distribution pattern remains the same. This may indicate the atmospheric conditions driving the • Diurnal variation of the observed wind over the valley floor can be characterized with a westerly forming convergence along central west‐east D t il fi ld t f NO2 d SO2 Upward transport of smoke at the front of local flows reveal the passage of the front close to the noontime. This may indicate the atmospheric conditions driving the local flows are rather stable during the dry season and thus long period of the calm situation, from 20:00 LST to 10:00 LST on the next day, and onset line. • Detail field measurement of NO2 and SO2, d PM10 k l i passage of the front close to the noontime. local flows are rather stable during the dry season and thus local flows tend to repeat regularly of the wind at around 12:00 LST, which continues to around 18:00 LST . • The warmer northwesterly flows over the cooler south‐ and PM10 at key locations k k d • The pollutants released into the southwesterly are trapped in its ) local flows tend to repeat regularly . • The calm situation corresponds to the stably stratified cold air lake during the nighttime, westerly in the late afternoon. • Emission estimation 1km x 1km grid net. shallow layer below 250 m high and migrate toward the eastern part of T (m) • Very high concentration of the NO 2 and SO 2 in April and the unset of wind represents arrival of a combined valley and the plain‐to‐plateau d f h hb ll d h h l • Combined plain‐to plateau and valley wind from the • Numerical simulation with Chemical Transport Model. the valley T on ( measurement compared to February suggests the winds form the neighboring valley and the southern plain. Th f l h k bl d d i il i A b li southern plain (southwesterly) and northwesterly form B Meteorology Nagarkot Hilltop the valley . K S atio advection of regional pollutants into the valley with local • The patterns of meteorology have a remarkable day‐to‐day similarity . Any abnormality t i ti l d l d t t ll ti f t ti the western valley strongly dominate the flow system of B. Meteorology Nagarkot Hilltop • The northwesterly captures the urban pollutants in the western part of K eva flows. apparent in a particular day rarely or does not at all continue even for two consecutive d the western valley strongly dominate the flow system of Kathmandu valley (K). • Sodar observation using Monostatic Flat Array Sodar . the valley and flows over the southwesterly layer . n El days. 6 Sit f R i lB k dA l Kathmandu valley (K). • Flow split in the eastern valley (S) appears rather weak • Surface observations in and around the Kathmandu valley . the valley and flows over the southwesterly layer . ain 6. Sites for Regional Background Aerosol 8 Conclusions Flow split in the eastern valley (S) appears rather weak and does not penetrate Kathmandu • Numerical Simulation of local flows with MM5 and WRF . • As a result, multiple pollutant layers develop in the eastern area of the Terr Concentration Measurement 8. Conclusions and does not penetrate Kathmandu. • Local flows appear to follow the terrain elevation KTM valley close to the sunset. Te Tribhuvan University Nagarkot Hilltop • Local flows appear to follow the terrain elevation KTM valley (K) 1350m Sunkoshi (S) 800m Trishuli (T) 600m valley close to the sunset. Tribhuvan University Nagarkot Hilltop • Kathmandu valley regularly develops a deep calm cold air pool during the nighttime. valley (K) 1350m, Sunkoshi (S) 800m, Trishuli (T) 600m valleys; southern plain (~ 100m ) AMSL Finest Domain (D3) 450 50 F Ch i lT tC l l ti Hattiban Hilltop • Two characteristics local flows (southwesterly and northwesterly) regularly intrude into the valleys; southern plain (~ 100m ) AMSL. It itt t ti id i d ti Finest Domain (D3) 450 Tirshuli F. Chemical Transport Calculations h f ll l f l l f ll valley close to the noontime and continue till the evening. • Intermittent mountain winds may organized an anti‐ l k i k fl t th ll b 150 Daytime Characteristic of Pollutant Transport Role of Local Flows for Pollutant Transport • There is little day‐to‐day variation in the local flows over the valley during the dry season. clockwise weak flow system over the valley above 150 m k i h i bl l i dl 07:00 LST 12:00 LST 15:00 LST 15:00 LST • The local flows show the nature of cool density flows intruding into the weakly developed keeping the air mass below almost windless. h d ll l /b d l 07:00 LST 12:00 LST m) m) 360 40 Mt. Shivapuri West East Distance (km) mixed layer over the valley . • Kathmandu valley executes plateau/basin dual nature (km (km TN West‐East Distance (km) mixed layer over the valley . • The relatively warmer northwesterly flows over the cooler and shallow southwesterly during day and nighttime. ce ce ( BU Mt Nagarjun Fulchoki Mountaintop The relatively warmer northwesterly flows over the cooler and shallow southwesterly during the late afternoon leading to the formation of internal thermal boundary layers in B Comparison with Observation anc tanc Mt. Everest NEPAL 270 30 TL MH BA Mt. Nagarjun during the late afternoon leading to the formation of internal thermal boundary layers in the central and eastern area B. Comparison with Observation Dist Dist N E P A L 270 30 TIA TH BT Mt Nagarkot Kathmandu the central and eastern area. Th i f th 3 k b th l l l l d d th D th D Kathmandu TIA KL BS MA BT DA Mt. Nagarkot Bhaktapur D3 • The upper air from more than 3 km above the mean sea level regularly comes down and th ll fl i th ft Nort Nort BK TI KR PU BS MA Bhaktapur Patan D3 sweeps across the valley floor in the afternoon. f h‐N th‐N D2 180 20 BN BK IM HC NK Mt. Champadevi • The downslope winds can organize a weak flow system at about 150m above the valley • Fulchoki Mountaintop (2762 AMSL), located in the X2 outh out D2 180 20 LU IM HC Banepa floor that slowly but effectively induce mass exchange in the lower layer of cold air mass southeastern edge of the Kathmandu valley appears to be 18:00 LST 15:00 LST X2 So So CH Banepa • During the nighttime pollutant accumulates in the shallow layer . during the nighttime. most suitable for the regional aerosol measurement. 18:00 LST 15:00 LST CH River Gorge During the nighttime pollutant accumulates in the shallow layer . ll di idl h i d l l f i • Kathmandu valley regularly flushes its nighttime stagnated air mass to the eastern • The sites such as Nagarkot Hilltop and Hattiban Hilltop and ibh i i l b bl i bl f 90 10 Mt. Fulchoki River Gorge • Pollutants disperse rapidly as the mixed layer evolves after sunrise tt di ii t ti t th neighboring valley in the early afternoon that further moves towards the Himalayas. Tribhuvan University also appear to be reasonably suitable for it i th i l b k d t ti f i K th d ll I N D I A Mt. Fulchoki attending a minimum concentration at the noon. • The western part of the valley appears to be free from daytime stratification. monitoring the regional background concentration of species lik di i t Kathmandu valley D1 • Intrusion of the cooler southwesterly traps the pollutant released within • Occasional decoupling of valley’s surface air mass does not sustain for more than 24 hours. like radioxenon isotopes. 360 its shallow boundary rapidly building up near surface concentration. Occasional decoupling of valley s surface air mass does not sustain for more than 24 hours. • The pollutants from the eastern valley in the evening remain floating over the whole valley W t E t Di t (k ) 90 180 270 360 450 10 20 30 40 50 • The fictitious pollutants (X1 and X2) concentration distribution contours The pollutants from the eastern valley in the evening remain floating over the whole valley at about 250m above the valley floor until the development of mixed layer next day Ak ld t West‐East Distance (km) West‐East Distance (km) • The fictitious pollutants (X1 and X2) concentration distribution contours clearly demonstrate the double layering structure of the southwesterly at about 250m above the valley floor until the development of mixed layer next day . Acknowledgment: •Tohsihiro Kitada Toyohashi University of Technology Japan MM5/WRF/CTM Simulation Domain System D1, D2, and D3 (left) and Air Quality Sampling Sites (Black Circle). clearly demonstrate the double layering structure of the southwesterly and northwesterly winds and formation of the layered pollutants over •Tohsihiro Kitada, Toyohashi University of Technology, Japan •Harry Miley Pacific NW National Laboratory USA Blue and Red boxes show emission areas (right) for the hypothetical species X1 and X2, respectively. and northwesterly winds and formation of the layered pollutants over the central and eastern area of the Kathmandu valley •Harry Miley , Pacific NW National Laboratory, USA. •Anders Ringbon Swedish Defense Research Agency Sweden Contact: regmi rp@hotmail com the central and eastern area of the Kathmandu valley . •Anders Ringbon, Swedish Defense Research Agency, Sweden. Contact: [email protected]

ATMOSPHERIC TRANSPORT PROCESSES OVER THE … R... · ATMOSPHERIC TRANSPORT PROCESSES OVER THE KATHMANDU VALLEY NEPAL TRANSPORT PROCESSES OVER THE KATHMANDU VALLEY, NEPAL R P Ri d

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Page 1: ATMOSPHERIC TRANSPORT PROCESSES OVER THE … R... · ATMOSPHERIC TRANSPORT PROCESSES OVER THE KATHMANDU VALLEY NEPAL TRANSPORT PROCESSES OVER THE KATHMANDU VALLEY, NEPAL R P Ri d

ATMOSPHERICTRANSPORTPROCESSESOVERTHEKATHMANDUVALLEYNEPAL ATMOSPHERICTRANSPORTPROCESSESOVERTHEKATHMANDUVALLEYNEPAL ATMOSPHERICTRANSPORTPROCESSESOVERTHEKATHMANDUVALLEY,NEPAL ATMOSPHERICTRANSPORT PROCESSES OVER THE KATHMANDU VALLEY, NEPAL RPRidLkNJh RamP.RegmiandLokN.Jha Ram P. Regmiand LokN. JhaCentralDepartmentofPhysicsTribhuvanUniversityKathmanduNepalSCIENCE AND TECHNOLOGY 2011 T1P13 TRIBHUVANUNIVERSITYCentral Department of Physics, TribhuvanUniversity, Kathmandu, Nepal.SCIENCE AND TECHNOLOGY 2011: T1-P13 TRIBHUVAN     UNIVERSITY

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ThditibtifllttdttthdilappearstoberelativelywindycomparedtowinterNostrongdecouplingofvalley'sairmasswiththeregionalairflowsappear12:45LST 10:45LST rain

uth-N

errai

Sou•Thedistributionofpollutantsdemonstratethediurnalidiitiittiththhtiti appearstoberelativelywindycomparedtowinter.Nostrongdecouplingofvalleysairmasswiththeregionalairflowsappear

titfth2hiddthllThditittillthtd12:45 LST 10:45 LST

Terr

Sou

Te Speriodicityinconsistentwiththecharacteristicmeteorology topersistformorethan24hoursorsoinandaroundthevalley.Thesurroundingmountaintops,particularly,theeasternand

hbhblflbkdl

Tmeteorology.

southeasternmountaintopsappeartobethemostsuitablesitesforregionalbackgroundaerosolconcentrationmeasurements.•Pollutantsmayspreadoverthemixedlayerofabout1.2 pppfgg

1Idi

Pa)

Pa)kmoverthevalleyjustbeforetheintrusionofthelocal1.  Introductione (hP

e (hP

flows.

Mt. ShivapuriMt. Nagarkot TheatmospherictransportprocessesovertheKathmandussure

ssure

•IntheeveningHNO3richairmasscomesbackovertheMt. Phulchoki

2660 m2250 m TheatmospherictransportprocessesovertheKathmanduvalleylocatedintheMiddleHillsoftheCentralHimalayaP

res

Pres

West-EastDistance(km) West-East Distance (km)IntheeveningHNO3richairmasscomesbackovertheKathmanduvalleyandremainsfloatingatabout350 2762 m valley,locatedintheMiddleHillsoftheCentralHimalaya,

offersratherdifferentcharacteristicsoflocalflowfieldsin

P P West-East Distance (km)

Nearsurfacewindat14:45LSTNearsurfacewindat17:45LSTKathmanduvalleyandremainsfloatingatabout350metersabovethevalleyfloor. offersratherdifferentcharacteristicsoflocalflowfieldsin

comparisontothegeneralmountainvalleywindsystemInNear surface wind at 14:45 LSTNear surface wind at 17:45 LSTmetersabovethevalleyfloor.

comparisontothegeneralmountainvalleywindsystem.Inthisregionthelocalcirculationsassociatedwithalarge thisregion,thelocalcirculationsassociatedwithalargenumberofsmallscalesubdivisionsandsubclimatesinteract numberofsmall‐scalesubdivisionsandsub‐climatesinteractinacomplicatedmannerPresentstudyassessesthe inacomplicatedmanner.PresentstudyassessestheatmosphericconditionsprevailingovertheKathmanduvalley17:45LST atmosphericconditionsprevailingovertheKathmanduvalleyandthenexaminestheextentofdecouplingofsurfaceair

17:45 LST 14:45 LST

L m)

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andthenexaminestheextentofdecouplingofsurfaceairiddthKthdlliththilM

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3‐D Topographic View of Kathmandu Valley and Its Surroundings.()

Shallow southwesterly

hhllfl()dd(l) BhimsenTower (54m high)Northwest‐Southeast cross‐sectional plot of potential temperature (contours) and wind vector (along A—B)

S 17:45 LST West-East Distance (km)West-East Distance (km)

KathmanduremainrelativelycleanduringAutumn

()()Near surface wind at 20:45 LST

Kathmandu remain relatively clean during AutumnConceptual flow diagram

Vtildiifllttiltiita)

Vertical dispersion of pollutants in late morning winter

(hPa

Himalayan range as seen from Kathmanduure (

Hundreds of emitters in operation

ressuPr

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ance

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Northwesterly flows above southwesterly

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th D

Southwest‐Northeast cross‐sectional plot of potential temperature ()()

Photographs of wind/dust storm (upper left picture) and highly  Ele

Nort

Smokeflowpatternintheafternoon Fogandpollutant’slayerblanketingtheKathmanduValley(contours) and wind vector (along C—D)localized destructions caused by wind storm in last March.

rain

uth-N

Smoke flow pattern in the afternoon Fog and pollutants layer blanketing  the Kathmandu Valley 

2GllitiftfKthdll•Bothsouthwesterlyandnorthwesterlyshowthenatureofthecooldensity•Therelativelycoolersouth‐westerlycappedbythewarmer Terr

Sou

2.   General climatic feature of Kathmandu valleyyyy

flow;theyintrudeintothemixedlayerdevelopedovertheKathmanduyyppy

northwesterlyandthedevelopmentofstablelayeraloftjustT S

TheKathmanduvalleypossessesawarmtemperatesemi‐tropicalandvalley.abovethesurroundingmountaintopsthatcoversthewhole TheKathmanduvalleypossessesawarmtemperatesemitropicalandseasonableclimate.Thewinterclimateischaracterizedasdrywithan•Thesouthwesterlyisdrivenbyacombinationofbothupslopeandplain

Kathmanduvalleyandbeyondsetsthebasicmeteorological yaveragemaximumandminimumtemperaturesof17and2°C,

•Thesouthwesterlyisdrivenbyacombinationofbothup‐slopeandplain‐to‐plateauwinds

backgroundforairpollutiontransportoverthevalley. gp,respectively.Duringthewinterseason,thevalleyremainsmostlyclear

to‐plateauwinds.•Thislayeringflowstructureoverthevalleyseverelylimitsthe pyg,yy

initsskieswithcalmorwindlessnightsfollowedbyearlymorning•ThenorthwesterlyexecuteahydraulicjumplikeflowanditridesovertheThislayeringflowstructureoverthevalleyseverelylimitstheverticaldispersionofpollutantsandleadstotheformationof WestEastDistance(km)

densefoglingeringupto09or10LocalStandardTime(LST).Verycoolsouthwesterlythedepthofwhichisabout250m.verticaldispersionofpollutantsandleadstotheformationofmultiplelayeringofpollutants.

West-East Distance (km)

gentlewindroutinelystartstoblowclosetothenoontimeand•Thewindstormgenerallyoccurslateafternoonandearlyeveningthatmultiplelayeringofpollutants.

Thidllldl700800bhNighttime Wind Fields at 02:45 LST at 150m AGL Near surface Potential Temperature at 16:45 LST

7ObservedLocalFlowCharacteristicsinandAroundtheValley LocalFlowsandObservedPollutantDistribution continuetilltheevening.ThesurfacewindspeedshavebeenfoundtoThewindstormgenerallyoccurslateafternoonandearlyeveningthatcoincideswiththedevelopmentofstablelayerjustabovethesurrounding•Themixedlayergenerallydevelopsupto700to800mabovethe

llflithftdithd

7.   Observed Local Flow Characteristics in and Around the Valley  Local Flows and Observed Pollutant Distribution

becalm(<1ms‐1)forabout75%ofthetimeofadaywithmax.windpyjg

mountaintops.valleyfloorintheafternoonduringthedryseason.Wind Speed at Thankot (March)

10.01-Mar2M

Wind Speed at NAST (March)6.01-Mar

Wind speed at western mountain passWind speed at southern area

speedgenerallyaround5ms‐1intheafternoon,butcouldreachashighp

DEmissionSourceDistributioninDrySeason9.0

2-Mar3-Mar4-Mar

2-Mar3-Mar4-Mar

as15ms‐1inthelatespring.SpringmonthsarecharacterizedbyD.   Emission Source Distribution in Dry Season8.0

a5-Mar6-Mar7-Mar

5.04Mar5-Mar6-Mar7Mar

showeryandrelativelywindyweather,increasinglyhigherhumiditydhdihilhilWidNOTSP SO

7.0

7-Mar8-Mar9-Mar10Mar40

7-Mar8-Mar9-Mar10M

andpre‐monsoonthunderstormswithoccasionalhail.Winterandlihditthtidth

NOxTSP SOx )6.0 m/s)10-Mar

11-Mar12-Mar

4.0

m/s)10-Mar

11-Mar12-Mar

earlyspringshowersmaydepositsnowonthemountainsaroundthedfthllThidttldftill(km

m)5.0 peed (13-Mar

14-Mar15-Mar3.0 peed (m

13-Mar14-Mar15-Mar

edgesofthevalley.Thewindpatterns,cloudformation,valleyventilationvisibilityaswellastheairmassdispersioncharacteristicsnce (

e (k

4.0

Wind sp15Mar

16-Mar17-Mar18-MarW

ind Sp15Mar16-Mar17-Mar18-Mar

ventilation,visibilityaswellastheairmassdispersioncharacteristicsoverthevalleyindryseasonappearsdistinctlydifferentfromthewetAil stan

ance

3.0

W18-Mar19-Mar20-Mar21M

2.0

W18-Mar19-Mar20-Mar21Mar overthevalleyindryseasonappearsdistinctlydifferentfromthewet

seasonThesummermonsoonoccursaseasterndisturbancesTheAprilApril

h Dis

Dista

2.021-Mar22-Mar23-Mar

10

21-Mar22-Mar23-Mar24M season.Thesummermonsoonoccursaseasterndisturbances.The

annualrainfallgenerallyexceeds1300mmofwhich70to80%rainfallsorth

rth D

1.024-Mar25-Mar26-Mar

1.024-Mar25-Mar26-Mar

annualrainfallgenerallyexceeds1300mmofwhich70to80%rainfallsduringthesummermonsoonmonthsMonsoonrainshaveatendencyh-N

-Nor

0.0

000000000000

26Mar27-Mar28-Mar29Mar0.0

27-Mar28-Mar29-Mar duringthesummermonsoonmonths.Monsoonrainshaveatendency

tobemorefrequentatnightwhereasthedaylighthoursaremostlySout

uth-0:00

2:00

4:00

6:00

8:00

10:00

12:00

14:00

16:00

18:00

20:00

22:00

LlStddTi(h)

29-Mar30-Mar31-MarA

0:00

2:00

4:00

6:00

8:00

10:00

12:00

14:00

16:00

18:00

20:00

22:0029Mar30-Mar31-MarAverage tobemorefrequentatnightwhereasthedaylighthoursaremostly

sunnyOvercastisratherrareoverthevalleyThedryseasongenerally

S

SouLocal Standard Time (hr.)AverageLocal Standard Time (hr.)Average

sunny.Overcastisratherrareoverthevalley.Thedryseasongenerallypersistsfor9months(OctobertoJune)withmuchlessprecipitation

Wind Speed at Babarmahal (March)4.51-Mar

2M

Wind Speed at Budanilakantha (March)5.01-Mar Wind speed at northern area Wind speed at central area persistsfor9months(OctobertoJune)withmuchlessprecipitation

(only10–20%oftheannualtotal).4.0

2-Mar3-Mar4-Mar4.5

a2-Mar3-Mar4-Mar (only1020%oftheannualtotal).

35

4.05-Mar6-Mar7-Mar4.0

4-Mar5-Mar6-Mar7Mar

3.   Purpose30

3.57Mar8-Mar9-Mar10Mar

3.5

7-Mar8-Mar9-Mar10M

•TounderstandthemechanismofdevelopmentoflocalflowsovertheKathmanduvalley25

3.0

(m/s)10-Mar

11-Mar12-Mar13M

3.0 m/s)10-Mar

11-Mar12-Mar

•TounderstandthemechanismofdevelopmentoflocalflowsovertheKathmanduvalley.Tdtdhifilltittdthidithll

2.5

peed (13-Mar14-Mar15-Mar2.5 peed (13-Mar

14-Mar15-Mar

•Tounderstandmechanismofairpollutiontransportandtheirdynamicsoverthevalley.Tdtdthltihibtthllfldftifthllttfildithll

FebruaryFebruary  WestEastDistance(km)

2.0

Wind S16-Mar

17-Mar18-Mar

2.0

Wind S15Mar

16-Mar17-Mar18Mar

•Tounderstandtherelationshipbetweenthelocalflowsandformationofthepollutantfieldsinthevalley.Thildldiibifdlifll’iihhilfl

West-East Distance (km)West-East Distance (km)1.5 W18-Mar19-Mar20-Mar21Mar

1.5

W18-Mar19-Mar20-Mar21M

•Toassessthespatialandtemporaldistributionsofdecouplingofvalley’sairmasswiththeregionalflows.ff21 21 MoreLargeScaleFlow

1.021-Mar22-Mar23-Mar24M

1.021-Mar22-Mar23-Mar

ObdNOdSOllfllthiltdll•Kathmanduvalleyremainscalmduringlateeveninguntil

•Toidentifythesuitablesitesforregionalbackgroundaerosolconcentrationmeasurement.NOx(kg-NO2 km-2day-1)TSP (kgkm-2day-1) SOx(kg-SO2km-2day-1) More Large Scale Flow0.524-Mar25-Mar26-Mar

0.524-Mar25-Mar26-Mar

•Observed NO2and SO2closely follows the simulated local fl

thenoonformingadeepcoldairlakeatnightthatmay

4Methodologyx2

EVisibleTransportProcesses 4.MethodologyNearSurfaceWindFieldsat14:45LST0.0

000000000000

26Mar27-Mar28-Mar29-Mar

0.0

000000000000

26Mar27-Mar28-Mar29Mar

flows. reach400minitsdepthintheearlymorning.4.MethodologyE.   Visible Transport Processes 4.   MethodologyNear Surface Wind Fields at 14:45 LST

0:00

2:00

4:00

6:00

8:00

10:00

12:00

14:00

16:00

18:00

20:00

22:0029-Mar30-Mar31-MarAverage

0:00

2:00

4:00

6:00

8:00

10:00

12:00

14:00

16:00

18:00

20:00

22:00

LlStddTi(h)

29-Mar30-Mar31-MarA •TheAprilconcentrationsaresignificantlyhigherthanthe •Intrusionofcoolerairmassesclosetothenoontimefrom

NagarkotHilltopLocal Standard Time (hr.)AverageLocal Standard Time (hr.)Average TheAprilconcentrationsaresignificantlyhigherthanthe

Februarybutthedistributionpatternremainsthesame. theIndianPlainandthewesternvalleythatmergeintoa

A.Air pollutionNagarkotHilltop

•UpwardtransportofsmokeatthefrontoflocalflowsrevealtheFebruarybutthedistributionpatternremainsthesame.Thismayindicatetheatmosphericconditionsdrivingthe•Diurnalvariationoftheobservedwindoverthevalleyfloorcanbecharacterizedwitha westerlyformingconvergencealongcentralwest‐east p

DtilfildtfNO2dSO2

Upwardtransportofsmokeatthefrontoflocalflowsrevealthepassageofthefrontclosetothenoontime.

Thismayindicatetheatmosphericconditionsdrivingthelocalflowsareratherstableduringthedryseasonandthus

longperiodofthecalmsituation,from20:00LSTto10:00LSTonthenextday,andonset line.•DetailfieldmeasurementofNO2andSO2,

dPM10kli

passageofthefrontclosetothenoontime.localflowsareratherstableduringthedryseasonandthuslocalflowstendtorepeatregularly

ofthewindataround12:00LST,whichcontinuestoaround18:00LST. •Thewarmernorthwesterlyflowsoverthecoolersouth‐andPM10atkeylocations

kkd•Thepollutantsreleasedintothesouthwesterlyaretrappedinits )

localflowstendtorepeatregularly.•Thecalmsituationcorrespondstothestablystratifiedcoldairlakeduringthenighttime, westerlyinthelateafternoon.•Emissionestimation1kmx1kmgridnet.shallowlayerbelow250mhighandmigratetowardtheeasternpartof T(m

)

•VeryhighconcentrationoftheNO2andSO2inAprilandtheunsetofwindrepresentsarrivalofacombinedvalleyandtheplain‐to‐plateaudfhhblldhhl

y•Combinedplain‐toplateauandvalleywindfromthe

•NumericalsimulationwithChemicalTransportModel.yggp

thevalleyT

on (

measurementcomparedtoFebruarysuggeststhewindsformtheneighboringvalleyandthesouthernplain.ThflhkblddiiliAbli

ppysouthernplain(southwesterly)andnorthwesterlyform

BMeteorologyNagarkotHilltop

thevalley.

KSatio

advectionofregionalpollutantsintothevalleywithlocal•Thepatternsofmeteorologyhavearemarkableday‐to‐daysimilarity.Anyabnormalitytitildldttlltiftti

p(y)ythewesternvalleystronglydominatetheflowsystemof B.MeteorologyNagarkotHilltop •Thenorthwesterlycapturestheurbanpollutantsinthewesternpartof Keva

flows.apparentinaparticulardayrarelyordoesnotatallcontinueevenfortwoconsecutived

thewesternvalleystronglydominatetheflowsystemofKathmanduvalley(K).

•SodarobservationusingMonostaticFlatArraySodar.yppp

thevalleyandflowsoverthesouthwesterlylayer. n Eldays.

6SitfRilBkdAl

Kathmanduvalley(K).•Flowsplitintheeasternvalley(S)appearsratherweak

•SurfaceobservationsinandaroundtheKathmanduvalley.thevalleyandflowsoverthesouthwesterlylayer.

ain6.    Sites for Regional Background Aerosol 8Conclusions

Flowsplitintheeasternvalley(S)appearsratherweakanddoesnotpenetrateKathmandu y

•NumericalSimulationoflocalflowswithMM5andWRF.•Asaresult,multiplepollutantlayersdevelopintheeasternareaofthe

TerrConcentration Measurement8.   Conclusions anddoesnotpenetrateKathmandu.

•LocalflowsappeartofollowtheterrainelevationKTMvalleyclosetothesunset.

Te

TribhuvanUniversityNagarkotHilltop•LocalflowsappeartofollowtheterrainelevationKTMvalley(K)1350mSunkoshi(S)800mTrishuli(T)600mvalleyclosetothesunset.TribhuvanUniversityNagarkotHilltop•Kathmanduvalleyregularlydevelopsadeepcalmcoldairpoolduringthenighttime. valley(K)1350m,Sunkoshi(S)800m,Trishuli(T)600mvalleys;southernplain(~100m)AMSL

FinestDomain(D3) 45050FChilTtCllti

HattibanHilltop•Twocharacteristicslocalflows(southwesterlyandnorthwesterly)regularlyintrudeintothe valleys;southernplain(~100m)AMSL.Itittttiididti Finest Domain (D3) 450TirshuliF.    Chemical Transport Calculations

hflllfllfll

pvalleyclosetothenoontimeandcontinuetilltheevening. •Intermittentmountainwindsmayorganizedananti‐

lkikfltthllb150Daytime Characteristic of Pollutant Transport Role of Local Flows for Pollutant Transport•Thereislittleday‐to‐dayvariationinthelocalflowsoverthevalleyduringthedryseason.clockwiseweakflowsystemoverthevalleyabove150mkihibllidl

07:00LST12:00LST15:00 LST15:00 LSTyyygy

•Thelocalflowsshowthenatureofcooldensityflowsintrudingintotheweaklydevelopedkeepingtheairmassbelowalmostwindless.

hdlll/bdl07:00 LST12:00 LST

m)

m) 36040Mt. Shivapuri

WestEastDistance(km)

ygypmixedlayeroverthevalley. •Kathmanduvalleyexecutesplateau/basindualnature

(km

(kmTNWest‐East Distance (km)mixedlayeroverthevalley.•Therelativelywarmernorthwesterlyflowsoverthecoolerandshallowsouthwesterly

duringdayandnighttime.

ce   

ce (

BUMtNagarjunFulchokiMountaintop

Therelativelywarmernorthwesterlyflowsoverthecoolerandshallowsouthwesterlyduringthelateafternoonleadingtotheformationofinternalthermalboundarylayersin BComparisonwithObservation

anc

tanc

Mt. EverestNEPAL 27030

TL MH BAMt. Nagarjunpduringthelateafternoonleadingtotheformationofinternalthermalboundarylayersin

thecentralandeasternarea

B. Comparison with Observation

Dist

Dist N E P A L 27030

TIA THBTMtNagarkot

Kathmanduthecentralandeasternarea.Thifth3kbthlllldd

th D

th D

KathmanduTIA

KLBS MA

BTDAMt. NagarkotBhaktapur D3

•Theupperairfrommorethan3kmabovethemeansealevelregularlycomesdownandthllflithft

Nort

Nort

BKTI KRPUBS MABhaktapur

Patan D3sweepsacrossthevalleyfloorintheafternoon.f

h‐N

th‐N

D2 18020BN BK

IM HCNK Mt. Champadevi•Thedownslopewindscanorganizeaweakflowsystematabout150mabovethevalley •FulchokiMountaintop(2762AMSL),locatedinthe

X2 outh

out D2 18020LU IM HC

Banepafloorthatslowlybuteffectivelyinducemassexchangeinthelowerlayerofcoldairmass southeasternedgeoftheKathmanduvalleyappearstobe

18:00LST 15:00LSTX2

SoSo

CH

Banepa•Duringthenighttimepollutantaccumulatesintheshallowlayer.duringthenighttime. mostsuitablefortheregionalaerosolmeasurement.

18:00 LST 15:00 LST CHRiverGorge

Duringthenighttimepollutantaccumulatesintheshallowlayer.

lldiidlhidllfi•Kathmanduvalleyregularlyflushesitsnighttimestagnatedairmasstotheeastern •ThesitessuchasNagarkotHilltopandHattibanHilltopand

ibhiilbbliblf 9010Mt.FulchokiRiver Gorge•Pollutantsdisperserapidlyasthemixedlayerevolvesaftersunrise

ttdiiittitthneighboringvalleyintheearlyafternoonthatfurthermovestowardstheHimalayas. TribhuvanUniversityalsoappeartobereasonablysuitablefor

itithilbkdttifi

Kthdll INDIAMt. Fulchokiattendingaminimumconcentrationatthenoon.

ggyyy•Thewesternpartofthevalleyappearstobefreefromdaytimestratification.

monitoringtheregionalbackgroundconcentrationofspecieslikdiit Kathmandu valley D1•Intrusionofthecoolersouthwesterlytrapsthepollutantreleasedwithin

pyppy•Occasionaldecouplingofvalley’ssurfaceairmassdoesnotsustainformorethan24hours.

likeradioxenonisotopes.

360

yppitsshallowboundaryrapidlybuildingupnearsurfaceconcentration.

Occasionaldecouplingofvalleyssurfaceairmassdoesnotsustainformorethan24hours.•Thepollutantsfromtheeasternvalleyintheeveningremainfloatingoverthewholevalley

WtEtDit(k)901802703604501020304050•Thefictitiouspollutants(X1andX2)concentrationdistributioncontours

Thepollutantsfromtheeasternvalleyintheeveningremainfloatingoverthewholevalleyatabout250mabovethevalleyflooruntilthedevelopmentofmixedlayernextday Akldt West‐East Distance (km) West‐East Distance   (km)•Thefictitiouspollutants(X1andX2)concentrationdistributioncontours

clearlydemonstratethedoublelayeringstructureofthesouthwesterlyatabout250mabovethevalleyflooruntilthedevelopmentofmixedlayernextday. Acknowledgment:

•TohsihiroKitadaToyohashiUniversityofTechnologyJapanMM5/WRF/CTM Simulation Domain System D1, D2, and D3 (left) and Air Quality Sampling Sites (Black Circle).

clearlydemonstratethedoublelayeringstructureofthesouthwesterlyandnorthwesterlywindsandformationofthelayeredpollutantsover

•TohsihiroKitada, Toyohashi University of Technology, Japan•HarryMileyPacificNWNationalLaboratoryUSA

Blue and Red boxes show emission areas (right) for the hypothetical species X1 and X2,  respectively.andnorthwesterlywindsandformationofthelayeredpollutantsoverthecentralandeasternareaoftheKathmanduvalley

•Harry Miley, Pacific NW National Laboratory, USA.•AndersRingbonSwedishDefenseResearchAgencySwedenContact:regmirp@hotmailcom (g)ypppythecentralandeasternareaoftheKathmanduvalley.•Anders Ringbon, Swedish Defense Research Agency, Sweden.Contact:  [email protected]

Transport processes – Part 3a - users.abo.fiusers.abo.fi/rzevenho/trp-slides-3a-2018.pdf · Transport processes(TRP) VST rz18 Transport processes – Part 3a Ron Zevenhoven Åbo

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