The Low- and Mid-Latitude Ionosphere

D. L. Hysell

daveh@geology.cornell.edu

Earth and Atmospheric Sciences, Cornell University, Ithaca, New York

http://landau.geo.cornell.edu

The Low- and Mid-Latitude Ionosphere – p.1/46

Outline�

The geomagnetic field�

Ionospheric structure�

Thermal structure�

Conductivity�

Dielectric properties�

Dynamics and dynamo theory�

Equatorial electrojet�

Equatorial plasma instabilities�

Midlatitude sporadic E and intermediate layers�

Midlatitude plasma instabilities and msTIDs

The Low- and Mid-Latitude Ionosphere – p.2/46

ISRs

The Low- and Mid-Latitude Ionosphere – p.3/46

Geomagnetic field

� � � � ��� �

� � � � ��� � �� � �� ��� � �� � � � ��� � �� ��� � � � � ��� � � ��� � ! "

#%$ � & � �('�*) � � #$ � � +

� ,- .� ��� �Θ

r

m

S

N

The Low- and Mid-Latitude Ionosphere – p.4/46

Non dipole corrections

The Low- and Mid-Latitude Ionosphere – p.5/46

Ionospheric structure

The Low- and Mid-Latitude Ionosphere – p.6/46

Thermal structure

photo-electrons

thermalelectrons

ions neutralsγ

N( D)quenching

2 Coulombcollisions

O fine structureN vibrational2

Induded dip.,charge ex.�

Quasi equilibrium�

Local heating & cooling + photoelectron transport, conduction�

Rates are energy/velocity dependent�

Cooling via elastic and inelastic collisions�

Need to specify solar flux spectrum, absorbtion and ionizationcross sections

The Low- and Mid-Latitude Ionosphere – p.7/46

Ionospheric layers

/10 /2 � 3 � � 0 4 � � 5� ,

5 � 687 9: 01; �< �>= ? @ ABC D; E FG HI FG H � �� J KML N$O L KL � J # PRQ � S L � � L�

&0 &2 � 5� T 0 � 0 U �� � � �WV X L �� Y Z V&0\[ &2 � 5� ] ^ _ � ` 0[ � P$ X JL La V&0 �&2 � ] ^ _ � `bc d ef0[ � T 0 � 0

�5 � �g 0 � �T 0

The Low- and Mid-Latitude Ionosphere – p.8/46

E region density

From Pfaff, J. Atmos. Terr. Phys., 53, 709, 1991 and Prakash et al.,Indian J. Radio Space Phys., 72, 1, 1972.

The Low- and Mid-Latitude Ionosphere – p.9/46

Topside composition

The Low- and Mid-Latitude Ionosphere – p.10/46

Ambipolar field

h � � ij 3 K� 0lk � = m� �k nh � � ij 3 K� 0 .� = m� � . n

0 . � k 0k

0lk 0 . � 0po k 0o .= ? qr stu v � 0po k 0o .= ? v "I r

0 . � 0o . 0Mo ! = ? v "Ixw � 0Mo . 0Mo = ? v "Ixy � 0Mo . 0o = ? v "Ixz

0k � 0po k 0o .= ? v "I r{ 0o . 0po ! = ? v "I|w � 0o . 0po = ? v "I|y � 0po . 0o = ? v "I|z } ! "

The Low- and Mid-Latitude Ionosphere – p.11/46

Temperature , composition,collisionality

The Low- and Mid-Latitude Ionosphere – p.12/46

Plasma as conductor

~ � : � �� � ��� � � �

� : I ��� � � � � ��� � � � � :o ���

: � � = k

0k �k�k � � k � � k �

: I � = k

� 0k �k�k � � k � � k �

:�o � = k

0k �k �k

The Low- and Mid-Latitude Ionosphere – p.13/46

Profiles (twilight)

The Low- and Mid-Latitude Ionosphere – p.14/46

Plasma as dielectric

�o 3 � � � _>�� ` � 3 � � � _ �� ` � 3 � � �o �� �

� � �o 3 K� � � � � � � �

3 � ~ � 3 � �: �� � � :o � � � : I � � � � � � h � �

3 + � � � � 3 � K� : � � � �� 3 +� K� :o � ��� � : I: � � � � 3 � K� : I � ���

3 + � 3 � � :o: � 3� � 3 � � 3 +�

The Low- and Mid-Latitude Ionosphere – p.15/46

Plasma as a dynamo

h dβ β

h dϕ ϕ

h dα

B

α

m�� � m�� < � � : I < f & g � � � : � � � � : I � � � �< � < f & g � & 6 � & �

< � � : � G|� G1�G�� & g

 � � m�� : � � m¡� : I � m � :�¢

The Low- and Mid-Latitude Ionosphere – p.16/46

Dynamical consequences

�

Dawn-dusk electric field�

Prereversal enhancement�

Funtain effect, equatorial anomaly�

Super-rotation�

Shear�

Evening vortex

The Low- and Mid-Latitude Ionosphere – p.17/46

Electric field profiles

£¤ ¤¥¤ ¤

¦¤ ¤§¤ ¤

¨©ª «¬ ­ ®¯° ±

² ³

´ µ¤ ¤·¶´ ¸¤¶

¤¶¸¤·¶

µ ¤ ¤¶

µ µ µ £ µ¹ µ ¥ µ ¸ µ ¦º¼»½¾ ¿ÀÁ ÂÃÄ Å¼Æ » ÂÄ µ µ ´ Ǽ»È ´ £¤ ¤ £É ¹ µ ¸ÊË » Ä µ ¸ ´ Ǽ»È ´ £¤ ¤ £É ¹ µÌ Ê

£¤ ¤¥¤ ¤

¦¤ ¤§¤ ¤

¨©ª «¬ ­ ®¯° ±

² ³

´ £¤ ¤·¶´ µ¤ ¤·¶

¤¶µ ¤ ¤¶

£¤ ¤¶

The Low- and Mid-Latitude Ionosphere – p.18/46

Equatorial anomal y

Courtesy C. E. Valladares

The Low- and Mid-Latitude Ionosphere – p.19/46

Evening vor tex

The Low- and Mid-Latitude Ionosphere – p.20/46

Equatorial electr ojet

The Low- and Mid-Latitude Ionosphere – p.21/46

Jicamar ca magnetometer

The Low- and Mid-Latitude Ionosphere – p.22/46

Lower thermospheric winds

The Low- and Mid-Latitude Ionosphere – p.23/46

Wind shear

Courtesy

M. F. Larsen

The Low- and Mid-Latitude Ionosphere – p.24/46

Wind effects (noon)

The Low- and Mid-Latitude Ionosphere – p.25/46

Twilight

The Low- and Mid-Latitude Ionosphere – p.26/46

Electr ojet plasma waves

The Low- and Mid-Latitude Ionosphere – p.27/46

FBGD instability

n>0δ n<0δ n>0δ

Eδ Eδ

EδB

n

δExB

J

δExBδExB

The Low- and Mid-Latitude Ionosphere – p.28/46

Disper sion relation

Í � Î � �Ï Ð .� Ï ÐÑ �� � � Ò � � � � Ó o � Ó � � Î � Ï ÐÑ

] � Ò � �Ñ� � Ò � � Í� Î � Ï ÐÑ � � Ó ÕÔ Ö � � Óo Ó � Í� Î � Ï ÐÑ �� � T 0o

Óo Ó � �� � Ò Ó �Ó , �Ñ � Ñ Q Ò � � . �Ñ� . � Ñ

The Low- and Mid-Latitude Ionosphere – p.29/46

Type I and type II spectra

The Low- and Mid-Latitude Ionosphere – p.30/46

150 km echoes

The Low- and Mid-Latitude Ionosphere – p.31/46

150 km echo drifts

The Low- and Mid-Latitude Ionosphere – p.32/46

Equatorial spread F

The Low- and Mid-Latitude Ionosphere – p.33/46

Equatorial spread F

The Low- and Mid-Latitude Ionosphere – p.34/46

Inter chang e instability

n>0δ n<0δ n>0δ

Eδ Eδ

EδB

n

δExB

J

δExBδExB

The Low- and Mid-Latitude Ionosphere – p.35/46

Inter chang e instability

] � � Ø×ÚÙÛ � � ×ÚÙ, Ó ÜÓ n� ×ÚÙ � m� � � v - � � ×ÚÙ Ó Ý [ � � ×ÚÙ�

- � ÞWßÞáà � Þáß

�

Finite

,

correction; fastest growing modes â 1 km�

Shear flow, transient waves�

Anomalous effects�

Seeding

The Low- and Mid-Latitude Ionosphere – p.36/46

Mid-latitude ionosphere

�

(-) Electrojet�

(-) Prereversal enhancement�

(-) Shear flow�

(-) Evening vortex�

(+) He+�

(+) Sporadic E layers�

(+) Intermediate layers�

(+) midlatitude spF and msTIDs

The Low- and Mid-Latitude Ionosphere – p.37/46

Ionization layers

The Low- and Mid-Latitude Ionosphere – p.38/46

QP echoes

The Low- and Mid-Latitude Ionosphere – p.39/46

2D maps

The Low- and Mid-Latitude Ionosphere – p.40/46

2D maps

The Low- and Mid-Latitude Ionosphere – p.41/46

2D maps

The Low- and Mid-Latitude Ionosphere – p.42/46

Midlatitude spread F

The Low- and Mid-Latitude Ionosphere – p.43/46

630 nm airglo w

The Low- and Mid-Latitude Ionosphere – p.44/46

MsTID

The Low- and Mid-Latitude Ionosphere – p.45/46

ReferencesFejer, B. G., and M. C. Kelley, Ionospheric irregularities, Rev. Geophys., 18, 401, 1980.

Forbes, J. M., The equatorial electrojet, Rev. Geophys., 19, 469, 1981.

Kelley, M. C., The Earth’s Ionosphere, Academic, New York, 1989.

Kelley, M. C. et al., Caribbean Ionosphere Campaign, Year One: Airglow and plasmaobservations during two intense midlatitude spread F events, 27, 2825, 2000.

Rees, M. H., Physics and Chemistry of the Upper Atmosphere, Cambridge UniversityPress, Cambridge, UK, 1989.

Rishbeth, H. and O. K. Garriot, Introduction to Ionospheric Physics, Academic, NewYork, 1969.

Schunk, R. W., and A. F. Nagy, Ionospheres — Physics, Plasma Physics, andChemistry, Cambridge Universtiy Press, Cambridge, UK, 2000.

Shiokawa, K. et al., Ground and satellite observations of nighttime medium scaletraveling ionospheric disturbances at midlatitude, J. Geophys. Res., 108, 1145, 2003.

Stenning, R. J., Model of the low latitude F region ionosphere, J. Atmos. Terr. Phys.,54, 1387, 1992.

Swartz, W. E. et al., Coherent and incoherent scatter radar observations duringintense midlatitude spread F, Geophys. Res. Lett., 27, 2829, 2000.

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