Origin of Ionospheric Hot Spots During Quiet Times J. Raeder, W. Li Space Science Center, UNH D. Knipp NCAR/HAO MURI/NADIR Workshop, Boulder, CO, October 27, 2010

AMIE Joule Heat Poynting Flux-DMSP IMF and Solar Wind Bz By Bx |V| Introduction 2 High Poynting flux into the polar ionosphere is expected during storms = strong southward IMF. However, there are times when the IMF is not southward (= quiet magnetosphere, Kp<2), but strong, localized Poynting flux is observed.

CHAMP Data: Neutral Density Enhancement Shock Arrival Northward Turning, SW Density Increase DMSP Poynting Flux 3 The localized energy input has a profound effect on neutral density.

OpenGGCM: Global Magnetosphere Modeling Personnel: J. Raeder, D. Larson, W. Li, A. Vapirev, K. Germaschewski, L. Kepko, H.-J. Kim, M. Gilson, B. Larsen (UNH), T. Fuller- Rowell, N. Muriyama (NOAA/SEC), F. Toffoletto, A. Chan, B. Hu (Rice U.), M.-C. Fok (GSFC), A. Richmond, A. Maute (NCAR) The Open Geospace General Circulation Model: Coupled global magnetosphere - ionosphere - thermosphere model. 3d Magnetohydrodynamic magnetosphere model. Coupled with NOAA/SEC 3d dynamic/chemistry ionosphere - thermosphere model (CTIM). Coupled with inner magnetosphere / ring current models: Rice U. RCM, NASA/GSFC CRCM. Model runs on demand (>300 so far) provided at the Community Coordinated Modeling Center (CCMC at NASA/GSFC). Fully parallelized code, real-time capable. Runs on IBM/datastar, IA32/I64 based clusters, PS3 clusters, and other hardware. Used for basic research, numerical experiments, hypothesis testing, data analysis support, NASA/THEMIS mission support, mission planning, space weather studies, and Numerical Space Weather Forecasting in the future. Funding from NASA/LWS, NASA/TR&T, NSF/GEM, NSF/ITR, NSF/PetaApps, AF/MURI programs. Aurora Ionosphere Potential

OpenGGCM Simulations of Three Events 2004 November January August 24 5 These events happen frequently (see afternoon session). OpenGGCM can reproduce them. Which allows us to study their causes.

North Polar Cap Distribution of Joule Heating and FAC Small clock angle & large B yz -> large hot spot of JH & FAC -> large Poynting flux DMSP f15 Positive FAC is downward +Ygse +Zgse 23nT SM Northern Hemisphere NH JH: 651 GW; Global: 1161GW 6

North Polar Cap Distribution of Joule Heating and FAC small clock angle & small B yz -> small area of enhanced JH & FAC -> small Poynting flux +Ygse +Zgse AMPERE/Iridium statistical FAC for northeast IMF [Anderson et. Al. 2008]  DMSP f15 Positive FAC is downward 9.4nT AMPERE: Positive FAC is upward NH JH: 182 GW; Global: 336GW 7

North Polar Distributions of Joule Heating and FAC small clock angle & large B yz -> small hot spot; missed by DMSP +Ygse +Zgse Iridium statistical FAC for northeast IMF [Anderson et. Al. 2008] DMSP f15 Positive FAC is downward 22nT Positive FAC is upward NH JH: 352GW; Global: 717GW 8

North Polar Distributions of Joule Heating and FAC Hot spot moves in response to IMF clock angle: DMSP missed hot spot DMSP f15 Positive FAC is downward Fast Rotating +Ygse +Zgse Iridium statistical FAC for northwest IMF [Anderson et. Al. 2008] Positive FAC is upward NH JH: 260GW; Global: 510GW 9

South Polar Distributions of Joule Heating and FAC IMF clock angle controls total energy input, |B| is less important. DMSP f15 Positive is downward 16nT +Ygse +Zgse SH JH: 992GW; Global: 1611GW 10

South Polar Distributions of Joule Heating and FAC DMSP f15 Positive FAC is downward 19nT +Ygse +Zgse For ~90 o clock angle power input becomes large, but also more spread out; DMSP missed hot spot GSE 90 o ≠ GSM 90 o IMF may be slightly southward Iridium statistical FAC for dawnward and duskward IMF in north polar [Anderson et. Al. 2008] SH JH: 708GW; Global: 1604GW 11

North Polar Distributions of Joule Heating and FAC - Brief Southward IMF DMSP f15 Positive FAC is downward 9.7nT +Ygse +Zgse Iridium statistical FAC for southeast IMF [Anderson et. Al. 2008] Positive FAC is upward NH JH: 543GW; Global: 1226GW 12

South Polar Distributions of Joule Heating and FAC Brief Southward IMF: total power input less than during E-W IMF period! DMSP f15 Positive FAC is downward 24nT +Ygse +Zgse Iridium statistical FAC for southward IMF [Anderson et. Al. 2008] SH JH: 661GW; Global: 1065GW 13

Relation to Cusp Reconnection traced from DMSP and nearby points near SM lat. 70 o Field lines traced from SM latitude 80 o Traced from SM latitude 60 o +Ygse +Zgse 23nT 14

Relation with Cusp Reconnection Origin, evolution, and motion of open field lines, fluid element tracing Path of a fluid element Newly created open line moving westward IMF +Ygse +Zgse 23nT Cyan field lines Traced to R=5RE Blue field lines traced from SM latitude 80 o 15

Relation to Cusp Reconnection Field lines traced from DMSP and nearby points Southern Hemisphere Newly created open line moving eastward +Ygse +Zgse Blue field lines traced from SM latitude 60 o 16 Freshly reconnected field lines are dragged east-west:

Field Line Dragging, FACs, and Flow Channels From Tanaka Mechanical view (V/B, are primary variables): field lines are dragged through the ionosphere, along with ionospheric plasma. Friction between plasma and neutrals causes heating. Electrical view (J/E are primary variables): reconnection causes B shear  FAC  resistive closure in the ionosphere  Joule heating. These views are equivalent. E/J easier to observe/compute; V/B more fundamental.

E×B flow channels and FAC [Anderson et. Al. 2008] Eriksson et.al found sunward E×B flow between two adjacent & opposite FACs Clock angle SYM-H Maximum Cross-track E×B (Vy) at dot 18

OpenGGCM/CTIM Neutral Density 2005 January 21 16:00 – 21:00 UT Northern Hemisphere 19

CTIM Neutral Density: latitude versus time 2005 January 21 16:00 – 21:00 UT 00:00 LT 03:00 LT 06:00 LT 09:00 LT12:00 LT15:00 LT 18:00 LT 21:00 LT 20

Summary Strong Joule heating is unexpectedly observed in the dayside high latitude region between 60 o (-60 o ) and 80 o (-80 o ) SM latitude in the Northern (Southern) Hemisphere for northward IMF conditions. These “hot spots” extend from noon to dawn (dusk) for positive (negative) IMF By in the Northern Hemisphere, and extends to an opposite direction in the Southern Hemisphere. Total energy input correlates with IMF clock angle and often exceeds energy deposition during southward IMF (storm main phase). A stronger IMF or a higher solar wind speed may also lead to increased Joule heating. The “hot spots” are sandwiched by two adjacent and opposite high- latitude FACs. For northern and southern hemispheres, downward FAC locates equatorward (poleward) of upward FAC with respect to the “hot spot” in the afternoon (morning) sector. Open field lines created by cusp reconnection drive drive the FAC that dissipates in the ionosphere and creates the hot spots. OpenGGCM has reproduced observed PF and Joule heating in several cases. A new NSF/GEM challenge is planned to test the fidelity of these predictions. 21

South Polar Distributions of Joule Heating and FAC Big clock angle & big B yz -> large hot area of JH & FAC -> large Poynting flux DMSP f15 Positive is downward FAC 45nT +Ygse +Zgse SH JH: 488GW; Global: 964GW 22