Downslope windstorms with WRF. Experiment #5 at end

Transcription

1 Downslope windstorms with WRF Experiment #5 at end 1

2 Basics Introduce the idealized WRF Simula?ons are effec?vely 2D Sounding provided via input file (input_sounding) Change ver?cal profiles of poten?al temperature and horizontal winds Mountain shape mimics terrain across Cuyamaca Peak in San Diego county 2

3 Set up WRF environment mkdir MOUNTAIN! cd MOUNTAIN! cp /home/c115-test/mountain/make_all_links.csh.! cp /home/c115-test/mountain/namelist.input.! cp /home/c115-test/mountain/input_sounding.!! cp /home/c115-test/mountain/control_file*.! cp /home/c115-test/mountain/*.gs.!!!./make_all_links.csh!! 3

4 input_sounding (open in text editor) Sfc. Pressure (mb) sfc. poten?al temp (K) and sfc. mixing ra?o (g/kg) ! E E+00! E E+00! E E+00! E E+00! E E+00! E E+00! 4

5 input_sounding! ! E E+00! E E+00! E E+00! E E+00! E E+00! E E+00! Height (m) Pot. temp. (K) vapor (g/kg) u wind (m/s) v wind (m/s) no moisture in this sounding u wind is set to - 5 m/s (easterly flow), no ver;cal shear v wind is zero because we re 2D with no Coriolis force 5

6 namelist.input! &time_control! run_days = 0,! run_hours = 24,! run_minutes = 0,! run_seconds = 0,! start_year = 0001, 0001, 0001,! start_month = 01, 01, 01,! start_day = 01, 01, 01,! start_hour = 00, 00, 00,! start_minute = 00, 00, 00,! start_second = 00, 00, 00,! end_year = 0001, 0001, 0001,! end_month = 01, 01, 01,! end_day = 01, 01, 01,! end_hour = 00, 00, 00,! end_minute = 00, 00, 00,! end_second = 00, 00, 00,! history_interval = 30, 30, 30,! frames_per_outfile = 1000, 1000, 1000,! 30 min history interval 6

7 namelist.input &domains! time_step = 12,! time_step_fract_num = 0,! time_step_fract_den = 1,! max_dom = 1,! s_we = 1, 1, 1,! e_we = 100, 43, 43,! s_sn = 1, 1, 1,! e_sn = 3, 43, 43,! s_vert = 1, 1, 1,! e_vert = 91, 91, 91,! dx = 2000, , ! dy = 2000, , ! ztop = 18000, 18000, 18000,! One domain (so extra columns irrelevant) 100 x 3 x 91 (x by y by z) domain 2 km horizontal resolu?on 18 km deep 7

8 namelist.input &physics! mp_physics = 1, 1, 1,! ra_lw_physics = 0, 0, 0,! ra_sw_physics = 0, 0, 0,! radt = 30, 30, 30,! sf_sfclay_physics = 1, 1, 1,! sf_surface_physics = 1, 1, 1,! bl_pbl_physics = 1, 1, 1,! warm rain microphysics (but no moisture) no radia?on scheme rudimentary surface scheme on, so there is surface fric?on and a small surface moisture flux 8

9 namelist.input &dynamics! w_damping = 1,! rk_ord = 3,! diff_opt = 2,! km_opt = 2,! damp_opt = 2,!! subgrid turbulent mixing and ver?cal velocity damping are on 9

10 Make control run ulimit s unlimited!./ideal.exe! Reads in input_sounding! Creates wrfinput_d01! nohup./wrf.exe > wrf.out &! Model configured to create one wrfout file, containing all output?mes Simula'on should take 3-5 min on an idle machine 10

11 While your simula?on is running 11

12 Sta?ons in the San Diego Gas & Electric mesonet Cuyamaca Peak 12

13 101 mph gust at Sill Hill (1710Z 30 Apr 2014) Red numbers = gusts in mph 13

14 101 mph gust at Sill Hill (1710Z 30 Apr 2014) SILSD winds/gusts during 29 April 2014 event 90+ mph gusts recorded 32 7mes in 10 h period (of 60 total reports) mph wind speeds (mph) h :00 GMT :00 GMT :00 GMT :00 GMT :00 GMT date SKNT mph GUST mph 14

15 PX/ACM2 May 2014 Bernardo fire NBCSD 10m winds 20 mph 15

16 NBCSD 16

17 Ver?cal cross- sec?on WRBSD KRNM NBCSD 17

18 Anima?on WRBSD KRNM NBCSD 18

19 Finished running? 19

20 Post- process control run w2g control_file.z windz05 Note control_file.z has been changed to refer to the wrfout files created by this model run, to declare the model output as ideal rather than real and to turn the map off This creates a GrADS file that interpolates to higher resolu?on below 5 km height, but cuts off there w2g control_file wind05 This version of the control file has lower resolu?on near surface but retains the en?re domain depth 20

21 From wind05 GrADS file ga-> open wind05! ga-> set display color white! ga-> set t 1! ga-> set x 1! ga-> d theta! ga-> draw xlab pot. temp. (K)! ga-> draw ylab height (km)! 21

22 Easily manipulated in input_sounding! 22

23 Wind flow at 0 h ga-> set t 1! ga-> ww_color.gs! 23

24 Plots theta (black contours) and wind speed (colored field) and topography (grey) (looks a liwle bewer in the windz05 file) 24

25 set t 2 ww_color.gs 25

26 set t 3 ww_color.gs 26

27 set t 4 ww_color.gs 27

28 set t 5 ww_color.gs 28

29 set t 49 [final ;me] ww_color.gs 29

30 Stepping and anima?on ga-> step.gs u ! ga-> step.gs theta ! [hit return to move on to next time]! ga-> vert_movie.gs! [wind speed thin contours,! theta thick contours,! Richardson number shaded.! If you save gif files, they are named/ numbered movie_###.gif]!! 30

31 U, theta and Ri at 24 h. Why is the Richardson number so low here? 31

32 Anima;on created using vert_movie.gs 32

33 Change name of movie s7ll images here vert_movie.gs! if(frame < 10)! 'printim movie_00'frame'.gif gif '! else! if(frame < 100)! 'printim movie_0'frame'.gif gif '! else! 'printim movie_'frame'.gif gif '! endif! endif! frame=frame+1! endif! pull dummy! To avoid himng return between frames, comment out this line with an asterisk; i.e., * pull dummy 33

34 ! Conver?ng a series of *.gif images into a movie! convert -delay 30 -loop 0 movie_*.gif OUT.GIF! Uses ImageMagick convert program - loop = 0 endless looping - loop = 1 just play once - delay ## decrease to speed up play You can play the movie OUT.GIF in a web browser 34

35 Hovmoller diagram ga-> c! ga-> reset! ga-> set t 1 49! ga-> hov.gs! [by default, a contour x vs. t diagram! of near-surface 10m wind speed]!!! 35

36 36

37 Edi?ng input_sounding to make new cases 37

38 Cases to explore Change the wind speed Control run is - 5 m/s (east to west) What does stronger or weaker easterly flow do? You can guess what making the wind westerly would do, right? What happens if you force wind shear on the ini?al wind profile? Change the poten?al temperature profile Create a less stable layer aloq Change the height of the lower, more stable layer Add moisture (be careful) Feel free to edit the GrADS scripts, or make new ones 38

39 input_sounding z theta N = Average tropospheric and stratospheric N values are 0.01 and 0.02, respec?vely. N = You can change the heights, too, and add levels, but I d keep the lowest level at 10 m and highest at 20 km 39

40 A possible sounding This sounding puts a more stable layer beneath 2.5 km and a less stable (neutral layer) between km. How does this alter the downslope flow? If the depth of the lower stable layer is changed, how would that alter the downslope flow? If the easterly wind speed is altered, how does that affect the downslope flow? 40

41 Experiment #5 Alter the input_sounding in some fashion and observe how it changes the flow over the mountain rela;ve to the control run Think about crea'ng a parameter space and exploring it. Example: changing depth of lower stable layer and wind speed. Write a report that describes your results. Include figures. Cap?on your figures appropriately. Due: December 19 th (end of finals week). More comments: Changing the surface pressure is not relevant Keep the poten?al temperature of the surface and lowest level in sounding equal to each other (presently both are 291 K) What happens if you make the lower layer less stable and the upper layer more stable? There is a small moisture source from the surface that isn t turned off You can add atmospheric moisture but make sure vapor mixing ra?os are realis?c. Once moisture is added, mp_physics is relevant and may be altered as well. Since flow may become much more vigorous, time_step may have to be reduced. Using the no_mp_heating = 1 flag may help keep things under control. 41