ppetru/opensprinkler-weather
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Add support for calculating Evapotranspiration

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This commit is contained in:
Samer Albahra
2015-04-23 14:38:14 -05:00
parent 2ce7450d21
commit b4fa0f3350
1 changed files with 126 additions and 11 deletions
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137
application.py
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@@ -1,5 +1,5 @@
#!/usr/bin/python
import urllib, urllib2, cgi, re
import urllib, urllib2, cgi, re, math
import json, datetime, time, sys, calendar
import pytz, ephem
from datetime import datetime, timedelta, date
@@ -33,6 +33,18 @@ def isFloat(s):
return 0
return 1
def F2C(temp):
return (temp-32)*5/9
def C2F(temp):
return temp*9/5 + 32
def mm2in(x):
return x*0.03937008
def ft2m(x):
return x*0.3048
def IP2Int(ip):
o = map(int, ip.split('.'))
res = (16777216 * o[0]) + (65536 * o[1]) + (256 * o[2]) + o[3]
@@ -44,6 +56,78 @@ def getClientAddress(environ):
except KeyError:
return environ['REMOTE_ADDR']
def computeETs(latitude, longitude, elevation, temp_high, temp_low, temp_avg, hum_high, hum_low, hum_avg, wind, solar):
tm = time.gmtime()
dayofyear = tm.tm_yday
latitude = safe_float(latitude, 0);
longitude = safe_float(longitude, 0);
# Converted values
El = ft2m(elevation)
Rs = float(solar) * 0.0864 # W/m2 to MJ/d /m2
Tx = F2C(float(temp_high))
Tn = F2C(float(temp_low))
Tm = F2C(float(temp_avg))
RHx = float(hum_high)
RHn = float(hum_low)
RHm = float(hum_avg)
Td = Tm-(100-RHm)/5 # approx. dewpoint (daily mean)
U2 = float(wind) * 0.44704 # wind speed in m/s
# Step 1: Extraterrestrial radiation
Gsc = 0.082
sigma = 4.90e-9
phi = math.pi * latitude / 180
dr = 1 + 0.033*math.cos(2*math.pi*dayofyear/365)
delta = 0.409*math.sin(2*math.pi*dayofyear/365 - 1.39)
omegas = math.acos(-math.tan(phi)*math.tan(delta))
Ra = (24*60/math.pi)*Gsc*dr*(omegas*math.sin(delta)*math.sin(phi)+math.cos(phi)*math.cos(delta)*math.sin(omegas))
# Step 2: Daily net radiation
Rso = Ra*(0.75 + 2.0e-5 * El) # 5
Rns = (1-0.23)*Rs
f = 1.35*Rs/Rso - 0.35 # 7
esTx = 0.6108*math.exp(17.27*Tx/(Tx+237.3)) # 8
esTn = 0.6108*math.exp(17.27*Tn/(Tn+237.3))
ed = (esTx*RHn/100 + esTn*RHx/100)/2 # 10
ea = (esTx+esTn)/2 # 22
epsilonp = 0.34-0.14*math.sqrt(ea) # 12
Rnl = -f*epsilonp*sigma*((Tx+273.14)**4 + (Tn+273.15)**4)/2 # 13
Rn = Rns + Rnl
# Step 3: variables needed to compute ET
beta = 101.3*((293-0.0065*El)/293)**5.26 # 15
lam = 2.45
gamma = 0.00163*beta/lam
e0 = 0.6108*math.exp(17.27*Tm/(Tm+237.3)) # 19
Delta = 4099*e0/(Tm+237.3)**2 # 20
G = 0
ea = (esTx+esTn)/2
# Step 4: calculate ETh
ETh = 0.408*(0.0023*Ra*(Tm+17.8)*math.sqrt(Tx-Tn)) # 23
# Step 5: calculate ET0
R0 = 0.408*Delta*(Rn-G)/(Delta+gamma*(1+0.34*U2)) # 24
A0 = (900*gamma/(Tm+273))*U2*(ea-ed) / (Delta+gamma*(1+0.34*U2)) # 25
ET0 = R0 + A0
# Step 6: calculate ETr
Rr = 0.408*Delta*(Rn-G) / (Delta+gamma*(1+0.38*U2)) # 27
Ar = (1600*gamma/(Tm+273))*U2*(ea-ed) / (Delta+gamma*(1+0.38*U2)) # 28
ETr = Rr + Ar
return (mm2in(ETh), mm2in(ET0), mm2in(ETr))
def application(environ, start_response):
path = environ.get('PATH_INFO')
uwt = re.match('/weather(\d+)\.py',path)
@@ -72,8 +156,8 @@ def application(environ, start_response):
else:
fwv = ''
restrict, maxh, minh, meant, pre, pre_today, h_today, sunrise, sunset, scale, toffset = [0, -1, -1, -500, -1, -1, -1, -1, -1, -1, -1]
solar, wind, avehumidity, minhumidity, maxhumidity, maxt, mint, elevation, restrict, maxh, minh, meant, pre, pre_today, h_today, sunrise, sunset, scale, toffset = [0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -1, -500, -1, -1, -1, -1, -1, -1, -1]
ET = [0,0,0]
eip = IP2Int(getClientAddress(environ))
# if loc is GPS coordinate itself
@@ -94,30 +178,55 @@ def application(environ, start_response):
# if loc is pws, query wunderground geolookup to get GPS coordinates
if loc.startswith('pws:') or loc.startswith('icao:'):
try:
req = urllib2.urlopen('http://api.wunderground.com/api/'+key+'/geolookup/q/'+urllib.quote(loc)+'.json')
req = urllib2.urlopen('http://api.wunderground.com/api/'+key+'/conditions/forecast/q/'+urllib.quote(loc)+'.json')
dat = json.load(req)
if dat['location']:
v = dat['location']['lat']
if 'current_observation' in dat:
v = dat['current_observation']['observation_location']['latitude']
if v and isFloat(v):
lat = v
v = dat['location']['lon']
v = dat['current_observation']['observation_location']['longitude']
if v and isFloat(v):
lon = v
v = dat['location']['tz_long']
v = dat['current_observation']['observation_location']['elevation']
if v:
elevation = safe_int(int(v.split()[0]), 0)
v = dat['current_observation']['solarradiation']
if v:
solar = safe_int(v, 0)
v = dat['current_observation']['local_tz_long']
if v:
tzone = v
else:
v = dat['location']['tz']
v = dat['current_observation']['local_tz_short']
if v:
tzone = v
forecast = dat['forecast']['simpleforecast']['forecastday'][0]
v = forecast['high']['fahrenheit']
if v:
maxt = safe_int(v, 0)
v = forecast['low']['fahrenheit']
if v:
mint = safe_int(v, 0)
v = forecast['avehumidity']
if v:
avehumidity = safe_int(v, 0)
v = forecast['maxhumidity']
if v:
maxhumidity = safe_int(v, 0)
v = forecast['minhumidity']
if v:
minhumidity = safe_int(v, 0)
v = forecast['avewind']['mph']
if v:
wind = safe_int(v, 0)
except:
lat = None
lon = None
tzone = None
#loc = loc.replace(' ','_')
# now do autocomplete lookup to get GPS coordinates
if lat==None or lon==None:
try:
@@ -195,6 +304,7 @@ def application(environ, start_response):
if v:
h_today = safe_float(v, h_today)
# Check which weather method is being used
if ((uwt & ~(1 << 7)) == 1):
# calculate water time scale, per https://github.com/rszimm/sprinklers_pi/blob/master/Weather.cpp
hf = 0
@@ -217,6 +327,11 @@ def application(environ, start_response):
if (scale>200):
scale = 200
elif ((uwt & ~(1 << 7)) == 2):
ET = computeETs(lat, lon, elevation, maxt, mint, meant, maxhumidity, minhumidity, avehumidity, wind, solar)
# TODO: Actually generate correct scale using ET (ET[1] is ET0 for short canopy)
scale = safe_int(ET[1] * 100, -1)
# Check weather modifier bits and apply scale modification
if ((uwt>>7) & 1):
# California modification to prevent watering when rain has occured within 48 hours