Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 55
Reed, Lanterman, and Trostel
Figure 4.
A radar reflectivity image of a classic supercell containing a violent tornado near Oklahoma City, OK, on May 20, 2013.
where · denotes the expected value of a random variable. Reflectivity factor is given in units of mm6/m3; however, because of the
large range of possible values of reflectivity factor, it is traditionally expressed on a decibel scale, Z = 10 log10 ζ, with units of decibels relative to Z. From this point forward, the reflectivity factor is
simply called reflectivity, as is common in meteorological jargon.
Placing reflectivity in the weather radar range equation yields
2 2
1 PG
θ 3 cτπ 3 | K |2 ζ
Pr =
.
t
2ln ( 2 ) 512λ 2 R 2 L2 ( R ) Ls
(31)
The value of |K|2 in the weather radar equation depends on the
physical state of hydrometeors. For a reasonable range of temperatures (0° to 20° C) and wavelengths (3 to 10 cm), the values of K
are often approximated as
| K |2 ≈ 0.93
(32)
(33)
for ice [2]. The physical state is usually hypothesized based on
factors such as temperature and the altitude of the melting layer
JULY 2017, Part II of II
2. Calculation
Using (31), the power received by the radar in the horizontal channel may be equated to a reflectivity value. To estimate the reflectivity, the average received power is estimated as a linear average
over multiple pulses in one or more range resolution cells [11]:
1
ˆ
Pr =
Np
for water and
| K |2 ≈ 0.197
in stratiform events.10 However, the actual computation usually
assumes a refractive index of water regardless of the conjectured
hydrometeor phase [2].
While the basic spherical model is a good approximation for
the RCS of small raindrops and hail, this model fails to properly
describe other types of hydrometeors. Furthermore, large raindrops
tend to have an oblate shape, resulting in polarization-dependent
RCS properties. In addition, hail can grow large enough in diameter that it falls into the nonlinear Mie scattering regime; i.e., the
Rayleigh scattering approximation is no longer valid.
10
Np
y
i =1
i
2
− σˆ n2 ,
(34)
Stratiform precipitation results from the forced lifting of air.
As the air rises, it cools, causing the air mass to saturate, form
clouds, and eventually precipitate. Stratiform events are most
often characterized as widespread, homogeneous rain events
with a less intense rain rate compared with convective events.
IEEE A&E SYSTEMS MAGAZINE
55
Table of Contents for the Digital Edition of Aerospace and Electronic Systems Magazine July 2017 Tutorial XI
No label
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - No label
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - Cover2
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 1
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 2
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 3
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 4
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 5
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 6
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 7
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 8
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 9
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 10
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 11
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 12
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 13
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 14
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 15
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 16
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 17
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 18
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 19
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 20
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 21
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 22
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 23
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 24
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 25
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 26
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 27
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 28
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 29
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 30
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 31
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 32
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 33
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 34
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 35
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 36
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 37
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 38
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 39
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 40
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 41
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 42
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 43
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 44
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 45
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 46
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 47
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 48
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 49
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 50
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 51
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 52
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 53
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 54
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 55
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 56
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 57
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 58
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 59
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 60
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 61
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 62
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 63
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 64
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 65
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 66
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 67
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 68
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 69
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 70
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 71
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - 72
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - Cover3
Aerospace and Electronic Systems Magazine July 2017 Tutorial XI - Cover4
http://www.brightcopy.net/allen/aesm/34-2s
http://www.brightcopy.net/allen/aesm/34-2
http://www.brightcopy.net/allen/aesm/34-1
http://www.brightcopy.net/allen/aesm/33-12
http://www.brightcopy.net/allen/aesm/33-11
http://www.brightcopy.net/allen/aesm/33-10
http://www.brightcopy.net/allen/aesm/33-09
http://www.brightcopy.net/allen/aesm/33-8
http://www.brightcopy.net/allen/aesm/33-7
http://www.brightcopy.net/allen/aesm/33-5
http://www.brightcopy.net/allen/aesm/33-4
http://www.brightcopy.net/allen/aesm/33-3
http://www.brightcopy.net/allen/aesm/33-2
http://www.brightcopy.net/allen/aesm/33-1
http://www.brightcopy.net/allen/aesm/32-10
http://www.brightcopy.net/allen/aesm/32-12
http://www.brightcopy.net/allen/aesm/32-9
http://www.brightcopy.net/allen/aesm/32-11
http://www.brightcopy.net/allen/aesm/32-8
http://www.brightcopy.net/allen/aesm/32-7s
http://www.brightcopy.net/allen/aesm/32-7
http://www.brightcopy.net/allen/aesm/32-6
http://www.brightcopy.net/allen/aesm/32-5
http://www.brightcopy.net/allen/aesm/32-4
http://www.brightcopy.net/allen/aesm/32-3
http://www.brightcopy.net/allen/aesm/32-2
http://www.brightcopy.net/allen/aesm/32-1
http://www.brightcopy.net/allen/aesm/31-12
http://www.brightcopy.net/allen/aesm/31-11s
http://www.brightcopy.net/allen/aesm/31-11
http://www.brightcopy.net/allen/aesm/31-10
http://www.brightcopy.net/allen/aesm/31-9
http://www.brightcopy.net/allen/aesm/31-8
http://www.brightcopy.net/allen/aesm/31-7
https://www.nxtbookmedia.com