KRC for Europa

Latest revision as of 16:24, 14 May 2020

[edit] Notes

Water ice is the default material for Europa (Mat1 = "H2O"), and T_user = 100 (temperature at which the inertia is defined).

Some parameters are set to realistic values by default, including:

Mat1 = "H2O" which assigns water ice Cp, Density, and Conductivity properties

Mat2 = "H2O" which assigns water ice Cp, Density, and Conductivity properties

ALBEDO = 0.67

PTOTAL = 0 which eliminates the atmosphere (ELEV, TAU, etc. unused)

When running the DaVinci interface, default Mars atmospheric values might be printed on the screen but not effectively used (PTOTAL = 0.)

[edit] Simple Cases

Basic surface temperatures for Europa:

OUT = krc(lat=0,INERTIA=45.,body="Europa",ALBEDO=.55,LKofT="F")

Example of simple diurnal temperature curve

labelxy("LTST","Temperature [K]")
plot(OUT.tsurf[,1,1],xaxis=OUT.time,"45 Kieffer, No Flux",w=2,color=2)

[edit] Planetary Flux (From Jupiter)

To include the visible and thermal infrared flux from Jupiter, three approaches are possible:

1: Use default built-in parameters, set PFlux = "T", and Lon_Hr

Lon_Hr [0-24] is the surface longitude relative to the sub-Jupiter point, expressed in hours.

When Lon_Hr < 6, the surface point is on the Antijovian hemisphere => No flux contributed.

When 6 < Lon_Hr < 18, the surface point is on the subjoin hemisphere => Flux is contributed (max at Lon_Hr = 12.).

When Lon_Hr > 18, the surface point is on the Antijovian hemisphere => No flux contributed.

dv> OUT  = krc(lat=0.,INERTIA=70.,body="Europa",ALBEDO=.55,PFlux="T",Lon_Hr=12.,LKofT="F")

2: Provide values for all the necessary input parameters, and set PFlux = "T" (Default provided for common bodies)

BT_Avg  : Average Brightness Temperature [K]

BT_Min  : Min Brightness Temperature, if diurnal cycle [K]

BT_Max  : Max Brightness Temperature [K]

Dis_AU  : Distance from Sun in AU

Geom_alb  : Geometric Albedo [1]

Mut_Period : Mutual Period [?]

Orb_Radius : Orbiting Radius [km]

Radius  : Radius of the Obiting body [km]

Lon_Hr  : Longitude Hour of the surface point (see above)

OUT  = krc(lat=0.,INERTIA=70.,body="Europa",ALBEDO=.55,PFlux="T",BT_Avg=127.,BT_Min=127.,BT_Max=127.,Dis_AU=5.203,Geom_alb=0.52,Mut_Period=3.55,Orb_Radius=670900,Radius=670900,Lon_Hr=12.,LKofT="F")

3: Provide Visible and IR flux tables vs. LTST, and set PFlux = "T"

The interface fits sin functions through the table values, and extracts parameters required by KRC (amplitude, phase, etc.). For Europa, this is not the preferred option.

IR: A 2 x n x 1 array with IR flux (1st col.) vs. LTST (2nd col.)

Vis: A 2 x n x 1 array with Vis flux (1st col.) vs. LTST (2nd col.)

dv> OUT  = krc(lat=0.,INERTIA=70.,body="Europa",ALBEDO=.55,PFlux="T",Lon_Hr=12.,LKofT="F")

Comparison between simple diurnal temperature curves (with vs. without Jupiter flux)

OUT_2 = krc(lat=0,INERTIA=70.,body="Europa",ALBEDO=.55, LKofT="F")
OUT_3  = krc(lat=0.,INERTIA=70.,body="Europa",ALBEDO=.55,PFlux="T",Lon_Hr=12.,LKofT="F")
labelxy("LTST","Temperature [K]")
plot(OUT_2.tsurf[,1,1],xaxis=OUT_2.time,"70 Kieffer, No Flux",w=2,color=2,OUT_3.tsurf[,1,1],xaxis=OUT_3.time,"70 Kieffer,With Flux",w=2,color=3)

[edit] Eclipse by Jupiter

To include an Eclipse by Jupiter, set Eclipse = "T" and specify the following parameters:

Eclipse = "T" forces an eclipse (Default = "F")

body = "Europa"

Eclipser = "Jupiter" Eclipser name, for Example "Jupiter" or "Mars"

Eclipse_Style = 1 because eclipses are assumed to occur daily; see dedicated Eclipse Section [Build Link Here]

Ecl_Cent_Hr: Eclipse central hour [subjovian point => =12.; Antijovian point => =0.]

Bias = 0.0: Eclipse Bias (0 => perfect alignement; 1 => partial eclipse); see dedicated Eclipse Section [Build Link Here]

Date: ???

 OUT = krc(lat=0.,INERTIA=45.,N1=32,body="Europa",N24=96,Eclipse="T",Eclipser="Jupiter",Ecl_Cent_Hr=12.,Bias=0.,Eclipse_Style=1.,Date=5000.)

Example of Europa diurnal curve with Jupiter Eclipse centered at Noon

labelxy("LTST","Temperature [K]","45 Kieffer, Eclipse centered at Noon")
plot(OUT.tsurf[,1,1],xaxis=OUT.time,"Noon Eclipse")

[edit] Defining a Date

Seasons can be defined as Ls (ls), Julian Date (JD), and Gregorian Date (GD):

 OUT = krc(body="Europa",lat=25.,ls=90.)

For a specific Gregorian Date, GD (currently ranging from 1990-Jan-01 to 2040-Jan-01), the format is ????-Mmm-DD, with Mmm:Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec;

 OUT = krc(body="Europa",lat=12.,GD="2010-Jan-05")

or a specific Julian Date JD:

 OUT = krc(body="Europa",lat=12.,JD=2455201)

Note: the possibility to specify the date with GD is only currently available for Mars, the Moon, Bennu, and Europa.