Ice thickness and accumulation balance
For effectively constant-density ice, depth-integrated mass conservation is H_t+∇_h·(Hū)=a_s−m_b.
Key knowledge
For effectively constant-density ice, depth-integrated mass conservation is H_t+∇_h·(Hū)=a_s−m_b. H is thickness, ū the depth-averaged horizontal velocity, a_s surface net accumulation and m_b basal melt, both in ice-equivalent length per time. A locally thinning glacier can therefore reflect flux divergence as well as surface or basal mass balance.
Values and equations
H_t+∇_h·(Hū)=a_s−m_b
- H
- ice thickness m
- ū
- depth-averaged horizontal ice velocity m s⁻¹
- a_s,m_b
- net surface accumulation and basal melt in ice-equivalent units m s⁻¹
- t
- time s
Conditions and scope
- Surface accumulation is positive for net addition, basal melt positive for loss. Convert snow/water/ice equivalent units consistently and provide boundary and initial geometry.
- Density-changing firn, calving/frontal loss and moving grounding boundaries need consistent additional treatment. A mass balance does not itself determine velocity or future sea level.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read actual thickness equation4.16 and surface/basal signs plus inflow-boundary requirements. Retained no numerical stabilization or software command claims; excluded the nearby thermal-equation sign/energy-density ambiguities rather than silently adopting them.
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Entry details
Permanent link to this entry ↗- Record identity
- uni-earth-ice-thickness-continuity
- Revision
- core.1
- Structured reference record
- University core expansion