This describes the Longwave Component of the JGrass-NewAGE system. Please read the document for more information

1. Formetta
LINKERS
JGrass-NewAGE: LWRB component
Giuseppe Formetta*
Correspondence:
giuseppe.formetta@mines.edu
Dipartimento di Ingegneria Civile
Ambientale e Meccanica, Trento,
Mesiano di Povo, Trento, IT
Full list of author information is
available at the end of the article
*
Code Author
Abstract
This pages teaches how to run the LongWave Radiation Balance (LWRB) component
inside the OMS 3 console. Some preliminary knowledge and installation of OMS is
mandatory (see @Also useful). This component deals with the downwelling (L ↓) and
upwelling (L ↑) longwave atmospheric radiation. Longwave radiation (1-100 µm) is an
important component of the radiation balance on Earth which affects many phenomena
such as evapotranspiration, snow melt , glaciers evolution , vegetation dynamics, plant
respiration, and primary productivity. Many simplified models (SM) have been proposed
in order to model L ↓ and L ↑ by using easily available meteorological observation such
as air temperature, relative humidity, incoming solar radiation, and cloud cover. Ten
SM for estimating L ↓ and one for L ↑ were integrated in the LWRB component. The
package is perfectly integrated in the JGrass-NewAge, and is feeded by other
components, like the one providing the shortwave radiation (SWRB,
(formetta2013modeling)). Once parameters are assigned according to the selected SM,
it can be used for the forecasting longwave radiation, either in points or as maps.
@Version:
0.1
@License:
GPL v. 3
@Inputs:
• The time series of the clearness index [-];
• the Digital Elevation Model of the investigated site;
• the time series of the relative humidity measures [%];
• the raster file containing the skyview factor map;
• the vector file containing the coordinates of the station;
• the time series of the air temperature [◦
C];
• the time series of the soil temperature [◦
C].
@Outputs:
• The time series or the raster map of (L ↓)
• The time series or the raster map of (L ↑)
@References:
• Bancheri 1
• Formetta 1
• Abera 2
Keywords: OMS; JGrass-NewAGE Component Description
Code Information
Executables
This points to the jar file that, once downloaded can be used in the OMS console. https:
//drive.google.com/folderview?id=0B2jvkPOc4ZvnQVgyczhGNzg4cDA&usp=sharing

2. Formetta Page 2 of 8
Developer Info
This contains point to the document that the Info more usable by developers than users,
i.e. information about the code internals, algorithms and the source code http://www.
github.com
Also useful
To run JGrass-NewAGE it is necessary to know how to use the OMS console (information
at: ”How to install and run the OMS console”, http://www.javaforge.com/project/oms).
JGrasstools are required for preparing some input data (information at: http://
abouthydrology.blogspot.it/2012/11/udig-jgrasstools-resources-in-italian.
html
To visualize results you need a GIS. Use your preferred GIS, following its installation
instructions.
To make statistics on the results, you can probably get benefits from R: http://www.
r-project.org/andfollowitsinstallationinstruction.
To whom address questions
marialaura.bancheri@unitn.it
Authors of documentation
Marialaura Bancheri (marialaura.bancheri@unitn.it)
This documentation is released under Creative Commons 4.0 Attribution International

3. Formetta Page 3 of 8
Component Description
SMs formulation for L ↑ [Wm−2
] and L ↓ [Wm−2
] are based on the Stefan-Boltzmann
equation:
L ↓= all−sky · σ · T4
a (1)
L ↑= s · σ · T4
s (2)
where σ = 5.670 · 10−8
is the Stefan-Boltzmann constant,Ta [K] is the near-surface air
temperature, all−sky [-] is the atmosphere effective emissivity, s [-] is the soil emissivity
and Ts is the surface soil temperature. In order to account for the increase of L ↓ in cloud
cover conditions is formulated according to eq. (3):
all−sky = clear · (1 + a · cb
) (3)
where c [-] is the clearness index and a and b are two calibration coefficients. Ten
literature formulations were implemented for the computation of clear . The complete
list of parameterizations used is presented in table 1 where it is specified: the component
number, the component name, the equation that defines it, and the reference to the paper
from which it is derived. X, Y and Z are the parameters provided in literature for each
model, table 2.
# Component Name Formulation Reference
1 Angstrom clear = X − Y · 10Ze Angstrom [1918]
2 Brunt’s clear = X + Y · e0.5 Brunt’s [1932]
3 Swinbank clear = X · 10−13 · T6
a Swinbank [1963]
4 Idso and Jackson clear = 1 − X · exp(−Y · 10−4 · (273 − Ta)2) Idso and Jackson [1969]
5 Brutsaert clear = X · (e/Ta)1/7 Brutsaert [1975]
6 Idso clear = X + Y · 10−4 · e · exp(1500/Ta) Idso [1981]
7 Monteith and Unsworth clear = X + Y · σ · T4
a Monteith and Unsworth [1990]
8 Konzelmann clear = X + Y · (e/Ta)1/8 Konzelmann et al [1994]
9 Prata clear = [1 − (X + w) · exp(−(Y + Z · w)1/2)] Prata [1996]
10 Dilley and O’brien clear = X + Y · (Ta/273.16)6 + Z · (w/25)1/2 Dilley and O’brien [1998]
Table 1 Clear sky emissivity formulations: Ta is the air temperatue [K], w [kg/m2] is precipitable water
= 4650 [e0/Ta] and e [kPa] screen-level water-vapour pressure.
Component Name X Y Z
Angstrom 0.83 0.18 −0.07
Brunt?s 0.52 0.21 [−]
Swinbank 5.31 [−] [−]
Idso and Jackson 0.26 −7.77 [−]
Brutsaert 1.72 7 [−]
Idso 0.70 5.95 [−]
Monteith and Unsworth −119.00 1.06 [−]
Konzelmann et al 0.23 0.48 [−]
Prata 1.00 1.20 3.00
Dilley and O’brien 59.38 113.70 96.96
Table 2 Models? parameters values as presented in their literature formulation.
The formulation of the L ↑,eq.2, requires the soil emissivity, which usually is a property
of the nature of surface, and the surface soil temperature. Table 3 shows the literature
values of the soil emissivity for different types of surface: s varies from its minimum of
0.95 for the bare soils up to its maximum of 0.99 for the fresh snow.

4. Formetta Page 4 of 8
Nature of surface Emissivity
Bare soil (mineral) 0.95 − 0.97
Bare soil (organic) 0.97 − 0.98
Grassy vegetation 0.97 − 0.98
Tree vegetation 0.96 − 0.97
Snow (old) 0.97
Snow (fresh) 0.99
Table 3 Soil emissivity for each nature of surface (Brutsaert, 2005).
Detailed Inputs description
The clearness index
The clearness index is the ratio between the measured incoming solar radiation (Im) and
the theoretical solar radiation computed at the top atmosphere (Itop), which can be com-
puted using the SWRB component, see http://abouthydrology.blogspot.com/2012/
12/direct-solar-radiation-models-by.html. This quantity is given in time series of
adimensional values between 0 and 1. During night-time c is computed as linear interpo-
lation between value at the last hour of light of the day before and the value of the first
hour of light of the day after.
The Digital Elevation Model
The Digital Elevation Model of the investigated site is given in a regularly spaced grid
representing height information. Each DEM should be in the .asc format and should be
accompanied by its .prj file, containing the projection info about the station.
The time series of the relative humidity measures
The relative humidity is given in time series of [% ] values for the station investigated.
The skyview factor map
The skyview factor represent the fraction of the sky which is visible from a point. It is
given as rester file containing a number between 0 and 1 and it can be obtained from the
DEM, using the JGrasstools.
The coordinates of the station
The coordinates of the station are given in a vector .shp file.
The air temperature
The time series of air temperature should be in [◦
C].The conversion in [K] is directly done
by the component.
The soil temperature [◦
C]
The time series of soil temperature should be in [◦
C].The conversion in [K] is directly
done by the component.
Detailed Outputs description
L ↓
The L ↓ output is given as a time series at a given point or as a raster map. Its units are
[W/m2
]. Figure 1 shows the results of a L ↓ simulation obtained using the (author?) (1)
model and data from a station in Oklahoma.

5. Formetta Page 5 of 8
0 5000 10000 15000 20000 25000
200300400500
Downwelling
Time [h]
Downwelling[W/m^2]
Figure 1 Time series of downwelling radiation for the station ARM USDA UNL OSU Woodward
Switchgrass 1 / US-AR1 in Oklahoma.
L ↑
The L ↓ output is given as a time series at a given point or as a raster map. Its units are
[W/m2
]. Figure 2 shows the results of a L ↑ simulation obtained using the air temperature
data from a station in Oklahoma.

6. Formetta Page 6 of 8
0 5000 10000 15000 20000 25000
300400500600
Upwelling
Time [h]
Upwelling[W/m^2]
Figure 2 Time series of upwelling radiation for the station ARM USDA UNL OSU Woodward
Switchgrass 1 / US-AR1 in Oklahoma.
Examples
The fallowing .sim file is customized for the use of the LWRB component.
import oms3.SimBuilder as OMS3
def home = oms_prj
def statID =8
NewAge = OMS3.sim_run(name:"NewAge", {
model () {
components {
def HM = "org. jgrasstools . hortonmachine .modules"
def GEARS = "org.jgrasstools.gears.io"
// Raster reader component
"reader_dem" "${GEARS }. rasterreader . OmsRasterReader "
// Lwrb component
"l" "${HM}. hydrogeomorphology .lwrb. OmsLongwaveRadiationBalance "
// Vector reader component
" vreader_station " "${GEARS }. vectorreader .
OmsVectorReader "
}
parameter{
// path to DEM
"reader_dem.file" "${home }/ data/${statID }/ dtm1.asc"
// path to shape file with the station coordinate
" vreader_station .file" "${home }/ data/${statID }/
stazioni_tagliate .shp"
// ID of the station in the shape file
"l. fStationsid" "cat"

7. Formetta Page 7 of 8
// Path to humidity
"l. inPathToHumidity " "${home }/ data/${statID }/H.csv"
// Path to air temperature
"l. inPathToTemp " "${home }/ data/${statID }/ Taria.csv"
// Path to clearness index
"l. inPathToClearness " "${home }/ data/${statID }/ ClearnessIndex .
csv"
// Path to soil temperature
"l. inPathToSoilTemp " "${home }/ data/${statID }/ Taria.csv"
// number of the rows in the input file
"l.pDimMeas" 2628800
// Timestep between the measures
"l.inTimestep" 60
// DOWNWELLING .csv is the output of the simulation for the
Longwave Downwelling ,
// according to the model used.
"l. pathToLongwaveDownwelling " "${home }/ output/ Upwelling_Taria /${
statID }/ DOWNWELLING.csv"
// UPWELLING .csv is the output of the simulation for the Longwave
Upwelling ,
// according to the model used
"l. pathToLongwaveUpwelling " "${home }/ output/ Upwelling_Taria /${
statID }/ UPWELLING.csv"
// LONGWAVE .csv is the sum of the ouputs of the Longwave
Downwelling and Longwave Upwelling .
"l. pathToLongwave " "${home }/ output/ Upwelling_Taria /${statID }/
LONGWAVE.csv"
// ModeDownCLR 1 : Angstrom (1918)
"l. pModeDownCLR " 1
// Downwelling model parameters
"l.pA_Cloud" 0.0
"l.pB_Cloud" 0.00
"l.pXs" 0.942
"l.pYs" 0.3292
"l.pZs" " -0.221"
// Upwelling parameters
"l.pEpsilonS" 0.99
"l.pC_up" 0
"l.pD_up" 1.0
"l. workWithRaster " false
// Start and end date of the simulation
"l.tStartDate" "2004 -06 -10 00:00"
"l.tEndDate" "2010 -01 -01 00:00"
}
connect {
" vreader_station .outVector" "l.inStations"
"reader_dem.outRaster" "l.inElev"
}
}
})

8. Formetta Page 8 of 8
Data and Project
The following link is for the download of the input data necessaries to execute the LWRB
component. https://drive.google.com/folderview?id=0B2jvkPOc4ZvnXy12eXdERUxLNDQ&
usp=sharing
The following link is for the download of the OMS project for LWRB component. https:
//drive.google.com/folderview?id=0B2jvkPOc4ZvnOUp1RFd2QTBVOW8&usp=sharing
(2)
%
References
1. ˚Angstr¨om, A.K.: A Study of the Radiation of the Atmosphere: Based upon Observations of the Nocturnal Radiation
During Expeditions to Algeria and to California vol. 65. Smithsonian Institution, ??? (1915)
2. Formetta, G., Bancheri, M., Rigon, R., David, O.: On site specific parameterizations of longwave radiation. Geoscientific
Model Development (2015)