SEBAL - Dca.ufcg.edu.br

More documents

Recommendations

Info

150y = 0.8694x - 35.286R 2 = 0.8174G (W/m2)1005000 50 100 150 200-50Rn (W/m2)Figure 10.2. A R n -G curve andmeasurements for estimating G for waterduring the January to June period (based onYamamoto and Kondo, 1968).G (W/m2)y = 1.0656x - 114.28R 2 = 0.94725000 50 100 150-50-100-150Rn (W/m2)Figure 10.3. A R n -G curve andmeasurements for estimating G for waterduring the July to December period (based onYamamoto and Kondo, 1968)This data represents the monthly averages and G may be larger if the day time is focusedon.In addition to Yamamoto’s work, Amayreh (1995) measured G for Bear Lake, Idaho/Utahusing eddy covariance and heat storage change and reported that daily values of G duringthe summer and fall could be predicted using: G = 0.984Rn – 62 . This equation does nottake into account the seasonal difference in G since Amayreh’s work was limited tosummer and fall. However, Amayreh’s measurements are similar to those of Kondo’s inboth magnitude and trends and this simple prediction approach based on Rn is thereforeassumed to be valid for deep clear water bodies in general. The following equations weredeveloped for estimating G for water surfaces based on Yamamoto’s and Amayreh’s work:From July to December, the instantaneous G during midday (and at the satellite imagetime):Gwater = Rn – 90 (10.1)and for 24-hours:Gwater = Rn – 100 (10.2)From January to June, the instantaneous G during midday (and at the satellite image time):Gwater = 0.9 Rn – 40 (10.3)88
and for 24-hours:Gwater = 0.9 Rn – 50 (10.4)The penetration of solar radiation into water decreases as the depth of the water bodydecreases and/or as the turbidity of the water increases. Highly turbid bodies of water andvery shallow bodies of water will have a value of G that is close to the value of Rn and theoffsets of the above equations will be r<strong>edu</strong>ced or may completely disappear.2. G equation for shallow (less than 2m) or turbid lakesThe value of G for shallow lakes is estimated to be between the value for deep lakes andfor wetlands. This results in the following equation developed from Table 10.1:for instantaneous at midday:Gwater = 0.50Rn (10.5)and for 24-hours:Gwater = 089
Page 1 and 2:
SEBALSurface Energy Balance Algorit
Page 3 and 4:
6. Tables for surface albedo comput
Page 5 and 6:
δ declination of the earth radians
Page 7 and 8:
INTRODUCTION1. BACKGROUNDLand manag
Page 9 and 10:
THE THEORETICAL BASIS OF SEBAL1. OV
Page 11 and 12:
The surface emissivity is the ratio
Page 13 and 14:
• Reference evapotranspiration, E
Page 15 and 16:
Figure 3. Flow Chart of the Net Sur
Page 17 and 18:
2. The reflectivity for each band (
Page 19 and 20:
and ET are specified for the two ex
Page 21 and 22:
To complete step 2, model F06_surfa
Page 23 and 24:
D. Choosing the “Hot” and “Co
Page 25 and 26:
irrigated crops near Kimberly, Idah
Page 27 and 28:
where; u * is the friction velocity
Page 29 and 30:
Weather stationu, z x, z om, u *H f
Page 31 and 32:
Note: An alternative method used by
Page 33 and 34:
where;⎛ 2 ⎞⎜1+ x(0.1m)Ψ = 2
Page 35 and 36:
where; ET inst is the instantaneous
Page 37 and 38: Figure 6 shows an example of a dail
Page 39 and 40: 1. If there is some cloud cover in
Page 41 and 42: • For all other formats (includin
Page 43 and 44: On the main page, select Type in Pa
Page 45 and 46: These values for z om can vary by r
Page 47 and 48: Appendix 3Reference Evapotranspirat
Page 49 and 50: and click on “Open”3. Provide t
Page 51 and 52: 5. Describe weather station and wea
Page 53 and 54: 8. Save the output file using a nam
Page 55 and 56: 4. Go to the Viewer tool and view t
Page 57 and 58: Appendix 5Time Issues Around Weathe
Page 59 and 60: 2. What time interval does the data
Page 61 and 62: The wind speed is 3.4 m/s for the 1
Page 63 and 64: Table 6.3. ESUN λ for Landsat 5 TM
Page 65 and 66: Table 6.6. Typical albedo values.Fr
Page 67 and 68: 4. Make a first guess for T cold by
Page 69 and 70: Fig.3. P40/R30, Landsat 7 ETM+ 4/8/
Page 71 and 72: Fig.5. P40/R30, Landsat 7 ETM+ 4/8/
Page 73 and 74: We open the image or subset image a
Page 75 and 76: Now, we look at the northwest area
Page 77 and 78: (2) The regional weather or soil co
Page 79 and 80: We conclude that this “heat islan
Page 81 and 82: Part 1: using the manual iteration
Page 83 and 84: Part 2: Using the automatic iterati
Page 85 and 86: Appendix 9SAVI and LAI for Southern
Page 87: equation for G. The following are e
Page 91 and 92: The Stability of the AtmosphereAppe
Page 93 and 94: Appendix 12The SEBAL Mountain Model
Page 95 and 96: where; t is the standard clock time
Page 97: N. Momentum Roughness LengthThe mom
show all

SEBAL - Dca.ufcg.edu.br

Create successful ePaper yourself

Delete template?

Save as template?