UNIVERSITY OF NAIROBI COLLEGE OF BIOLOGICAL AND PHYSICAL SCIENCES School of Physical Sciences Bachelor of Science in Meteorology Weather Analysis (SMR 204) Practical Manual for Academic Year 2014/15 (ODL GROUP 3L) Written By: Prof. Ininda J. M Department of Meteorology University of Nairobi
INTRODUCTION TO PRACTICALS IN WEATHER ANALYSIS The series of practical in WEATHER ANALYSIS are aimed at equipping the students with practical skills in current practices of weather analysis and computational skills. PRACTICAL TIME TABLE (SMR 204 2014/15) SERIAL NO. DESCRIPTION DATE DUE FOR HANDING IN Practical - 01 Computation of zonal (u) and meridional (v) components Allocation of percentage Marks Practical - 02 Practical - 03 Practical 04 Practical - 05 Practical - 06 Practical - 07 Practical - 08 Computation speed and direction Isogon Streamline Anaysis Streamline-Isotach Analysis Decoding the weather message Plotting SYNOP report on the weather Chart Coding upper air the weather message Plotting the sounding on a T CAT March 2015 TOTAL MARKS Useful websites http://www.wmo.int/pages/prog/www/wmocodes/manual/volume-i-selection/sel2.pdf http://www.metoffice.gov.uk/media/pdf/e/a/no._13_-_upper_air_measurements.pdf http://www.ofcm.gov/fmh3/pdf/13-app-e.pdf (For upper air wind and Temperature coding)
PRACTICAL 1: COMPUTATION OF ZONAL (u) and MERIDIONAL (v) COMPONENTS Objective: The practical is aimed at enabling the student compute the zonal and meridional wind components given the speed and direction. Tools a) A table of speed and direction b) Lecture Notes c) Excel software Procedure: Compute the zonal and meridional wind component at various levels given in table 1 Procedure: Compute the zonal and meridional wind component at various levels given in table 1 The zonal and meridional components are given by u V sin(dir) v V cos(dir) Where V TABLE 1 DATA FOR PRACTICAL NO 1 TABLE 1: Speed and Direction Given station DIR SPEED U V station DIR SPEED U V S01 150.3 16.1 S01 180.0 16.0 S02 252.2 29.4 S02 45.0 18.4 S03 317.7 14.9 S03 51.8 17.8 S04 167.5 9.2 S04 142.1 11.4 S05 137.1 19.1 S05 270.0 16.0 S06 232.1 22.8 S06 68.7 19.3 S07 180.0 18.0 S07 116.6 11.2 S08 233.1 20.0 S08 71.5 19.0 S09 125.6 17.2 S09 233.1 10.0 S10 360.0 11.0 S10 131.2 10.6 S11 137.5 16.3 S11 188.1 21.2 S12 104.1 20.6 S12 237.5 26.1 S13 132.5 16.3 S13 198.4 15.8 S14 111.3 19.3 S14 90.0 17.0
S15 171.3 13.2 S15 142.1 11.4 S16 232.4 16.4 S16 79.3 16.3 S17 14.9 15.5 S17 116.6 11.2 S18 90.0 8.0 S18 172.9 16.1 S19 125.6 17.2 S19 243.4 8.9 S20 97.5 23.2 S20 197.1 13.6 S21 42.5 16.3 S21 180.0 21.0 S22 270.0 16.0 S22 71.5 19.0 S23 239.4 25.6 S23 64.8 18.8 S24 350.1 23.3 S24 116.6 11.2 S25 167.5 9.2 S25 142.1 11.4 S26 112.4 18.4 S26 251.5 15.8 S27 298.8 22.8 S27 241.4 25.1 S28 284.1 24.7 S28 238.4 15.3 S29 100.8 21.4 S29 246.2 27.3 S30 18.4 12.6 S30 116.6 11.2 PRACTICAL 2: COMPUTATION SPEED AND DIRECTION Objective: The practical is aimed at enabling the student compute the speed and direction given the zonal and meridional wind components.. Tools a) A table of zonal and meridional wind components. b) Lecture Notes Procedure: Compute the speed and direction using the zonal and meridional wind component at various levels given in table 2. Use excel Software The speed is given by the equation 2 2 SP u v where SP is the speed, u the zonal wind and v the meridional wind. (a) Computation of Direction
The wind direction is define as the direction from where the wind is coming from. It is measure from the true north clockwise. When the wind is blowing from west (east), the u (zonal) component is positive (negative). While when the wind is blowing from south (north), the v (meridional) component is positive. To compute the direction were consider the four quadrants; Case 1: u<0 and v<0 The angle of the direction is between 0 o and 90 o and is given by 1 u dir tan ABS v or 1 v dir 90 tan ABS u Case 2: u<0 and v>0 The angle of the direction is between 90 o and 180 o and is given by 1 u dir 180 tan ABS v or 1 v dir 90 tan ABS u Case 3: u>0 and v>0 The angle of the direction is between 18 0 o and 270 o and is given by 1 u dir 180 tan ABS v or 1 v dir 270 tan ABS u Case 4: u>0 and v<0 The angle of the direction is between 270 o and 360 o and is given by
1 u dir 360 tan ABS v or 1 v dir 270 tan ABS u Table 2: Zonal and meridional components Given TIME 7.5N 7.5S U V SPEED DIRECTION U V SPEED DIRECTION Jan-12-1.57 3.44 0.0-5.19 Feb-12-3 4.83 0.44-2.79 Mar-12-1.05 3.24 0.29-0.64 Apr-12 1.23 4.04-3.35 4.04 May-2 0.0 1.88-5.19 6.38 Jun-12 2.28-2.35-3.65 7.82 Jul-12 5.47-2.22-3.13 7.75 Aug-12 4.01-2.94-5.58 6.03 Sep-12 2.06 0.0-6.59 5.36 Oct-12-3 2.85-5.32 2.96 Nov-12-2.33 3.63-3.95 1.63 Dec-12-2.06 4.02-3.37 0.0 Jan-13-1.75 4.03-1.43-3.67 Feb-13-2.71 3.46-1.26-2.88 Mar-13-0.96 5.22-3.49 2.54 Apr-13 1.84 3.03-3.81 3.53 May-3 1.25 2.49-4.81 6.9
PRACTICAL 03: ISOGONAL STREAMLINE ANALYSIS Objective: The practical is aimed at enabling the student gain skill in analysing wind using isogonstreamline method. Definition: Streamlines: Streamlines are lines that are tangential to the flow at a given instant of time Isogons: Isogons are lines joining points of equal direction Singular points: Singular points are points to which more than one streamlines can be drawn or about which streamlines form a closed curve. Tools: The data of wind direction is given on the chart (Figure 1) Procedure: (i) Draw isogons for 360 0,90 0, 180 0 and 270 0 (ii) Locate singular points (iii)draw intermediate isogons at 30 0 interval, smoothen the lines (iv) Refine the position of the singular points. (v) Draw short segments of streamlines along each isogon, (vi) Starting at the edge of the chart draw smooth streamlines, ensuring thsat each isogon is parallel to short segments (vii)where two streamlines diverge you may start another between them (viii) Where two streamline flow together join them smoothly
Figure 1. The spatial distribution of wind direction (DATA FOR PRACTICAL 03)
PRACTICAL 04: STREAMLINE-ISOTACH ANALYSIS Objective: The practical is aimed at enabling the student gain skill in analysing wind using streamlineisotach method. Definition: Isotach Isotach are lines joining points of equal wind speed Singular points: Tools: The wind data is given on the chart (Figure 2) Procedure: Draw two sets of lines, the streamlines and isotachs Streamline: Starting at the edge of the chart draw smooth streamlines, ensuring thsat each isogon is parallel to wind vector. Where two streamlines diverge you may start another between them Where two streamline flow together join them smoothly Identify singular points Isotach Determine a suitable interval and draw the isotachs.
Figure 2: The spatial distribution of wind (DATA FOR PRACTICAL 04)
PRACTICAL 5: DECODING THE WEATHER MESSAGE Objective: The practical is aimed at enabling the student decode the weather messages a) A table of coded weather messages b) The lecture notes Tools a) Extract the SYNOP REPORT for the station and date and time allocated to you.. For example to obtain data for 00GMT for 16 th April 2014 enter the information as shown.
Reg. No. Station TIME 1200GMT Lodwar Marsabit Kitale Wajir Kisumu Nyeri Embu Nairobi voi Mombasa Eldoret TIME 1500GMT Lodwar Marsabit Kitale Wajir Kisumu Nyeri Embu Nairobi voi Mombasa Eldoret PRACTICAL 6: PLOTTING THE WEATHER INFORMATION ON A CHART Objective: The practical is aimed at enabling the student plot on a weather chart. Tools a) A table of coded weather messages b) Lecture Notes
c) A chart (map) with station indicated on it Procedure: Plot the weather messages for the stations over Kenya date and time you were allocated REG. NO. & NAME MONTH, DATE AND TIME 12 GMT 15 TH APRIL 2014 15 GMT 15 TH APRIL 2014 12 GMT 16 TH APRIL 2014 15 GMT 16 TH APRIL 2014 12 GMT 17 TH APRIL 2014 15 GMT 17 TH APRIL 2014 12 GMT 18 TH APRIL 2014 15 GMT 18 TH APRIL 2014 12 GMT 19 TH APRIL 2014 15 GMT 19 TH APRIL 2014 12 GMT 20 TH APRIL 2014 15 GMT 20 TH APRIL 2014 12 GMT 21 ST APRIL 2014 15 GMT 21 ST APRIL 2014 12 GMT 22 ND APRIL 2014 15 GMT 22 ND APRIL 2014 12 GMT 23 RD APRIL 2014 15 GMT 23 RD APRIL 2014 12 GMT 24 TH APRIL 2014 15 GMT 24 TH APRIL 2014 12 GMT 25 TH APRIL 2014 15 GMT 25 TH APRIL 2014 12 GMT 27 TH APRIL 2014 15 GMT 27 TH APRIL 2014 12 GMT 28 TH APRIL 2014 15 GMT 28 TH APRIL 2014 12 GMT 29 TH APRIL 2014 15 GMT 29 TH APRIL 2014 12 GMT 30 TH APRIL 2014 15 GMT 30 TH APRIL 2014 (N B. You will need to print out the figure1)
Figure 3: The Synoptic stations over Kenya
PRACTICAL 7: CODING THEUPPER AIR OBSERVED WEATHER Objective: The practical is aimed at enabling the student code the observed weather a) A table of observed weather b) The lecture notes Procedure: Code the weather message give in table 2 TABLE 2 Sounding for station 63980 0n 24-04-2012 at 15hr local time and the station is located at 75 O E. The radio sonde launched at 14hr 30min local time. Pressure level(mb) Geopotential Height (m) Temperature o C Dew point Temp C Wind speed Kt Direction 1012 45 23.2 18.6 4 110 1000 112 24.5 20.4 6 160 940 495 25.3 17.5 8 180 925 615 23.8 14.3 12 140 850 1520 22.6 12.4 34 120 800 2030 20.1 15.8 40 100 750 2640 16.0 11.9 60 85 700 3186 10.3 10.7 50 50 650 3819 6.3 5.6 76 55 600 4458 2.4-2.2 84 70 500 5904 0.5-8.2 90 95 400 7634-3.2-15.4 100 120 300 9743-8.4 112 150 250 11002-15.7 120 140 200 12480-25.8 125 200 170 14290-32.3 130 140 150 14550-51.4 120 210 120 15600-51.1 110 295 100 16680-62.6 90 300 90 17280-71.2 95 320 70 18703-82.0 80 310 50 20722-75.1 82 300 30 23400-72.4 60 290 20 25800-66.5 50 330 10 29710-62.8 45 310
PRACTICAL NO. 8: PLOTTING THE SOUNDING ON A T Objective: The practical is aimed at enabling the student to plot the sounding on T And compute the convective parameters. Tools a) Extract the TEMP data for the station and date allocated to you at 00 GMTor 23 GMT For example to obtain data for 23GMT for 14 th April 2010 enter the information as shown. http://www.ogimet.com/sondc.phtml.en a) Using a T (i) Plot the given temperature and dew point temperature a T gram and Indicate the layers that experienced warming/ cooling and moistening / drying. (ii) Determine the LCL, equivalent potential temperature, lifted Index. (iii) Find the mixing ratio, specific humidity,,relative humidity and vapour pressure at surface, 800mb,700mb, 600mb, 500mb, and 400mb
REG. NO. & NAME MONTH, DATE AND TIME 23 GMT 14 TH &15 TH APRIL 2010 23 GMT 14 TH & 15 TH APRIL 2011 23 GMT 16 TH & 17 TH APRIL 2010 23 GMT 16 TH & 17 TH APRIL 2011 23 GMT 18 TH & 19 TH APRIL 2010 23 GMT 18 TH & 19 TH APRIL 2011 23 GMT 20 TH & 21 ST PRIL 2010 23 GMT 20 TH & 21 ST APRIL 2011 23 GMT 22 ND & 23 RD APRIL 2010 23 GMT 22 ND & 23 RD APRIL 2011 23 GMT 24 TH & 25 TH APRIL 2010 23 GMT 24 TH & 25 TH APRIL 2011 23 GMT 26 TH & 27 TH APRIL 2010 23 GMT 26 TH & 27 TH APRIL 2011 23 GMT 28 TH & 29 TH APRIL 2010 23 GMT 28 TH & 29 TH APRIL 2011 23 GMT 30 TH APRIL & 1 ST MAYL 2010 23 GMT 30 TH APRIL & 1 ST MAY 2011 23 GMT 14 TH &15 TH APRIL 2008 23 GMT 14 TH & 15 TH APRIL 2009 23 GMT 16 TH & 17 TH APRIL 2008 23 GMT 16 TH & 17 TH APRIL 2009 23 GMT 18 TH & 19 TH APRIL 2008 23 GMT 18 TH & 19 TH APRIL 2009 23 GMT 20 TH & 21 ST PRIL 2008 23 GMT 20 TH & 21 ST APRIL 2009 23 GMT 22 ND & 23 RD APRIL 2008 23 GMT 22 ND & 23 RD APRIL 2009 23 GMT 24 TH & 25 TH APRIL 2008 23 GMT 24 TH & 25 TH APRIL 2009 (N B. You will need to print out the figure1) Synop of a landstation The basic form of the SYNOP bulletin for a landstation is: AAXX YYGGiw IIiii irixhvv Nddff 1snTTT 2snTdTdTd 4PPPP 5appp 6RRRtR 7wwW1W2 8NhCLCMCH The rain group (6RRRtR) is not plotted. All other groups will be plotted using the plot model in