# rTemp Validation Documentation

This directory contains comprehensive validation results comparing the Python implementation with the original VBA rTemp model.

## Validation Summary

The Python implementation has been rigorously validated against the original VBA model over a 3-month period (October-December 2003, 8,828 timesteps):

- **Water Temperature RMSE**: 0.13°C (excellent agreement)
- **Solar Radiation RMSE**: 6.82 W/m² (2.4% error)
- **Test Coverage**: 346 automated tests passing
- **Status**: ✅ Production-ready

## Validation Documents

### Primary Validation Results

**[SOLAR_RADIATION_FIX_SUMMARY.md](SOLAR_RADIATION_FIX_SUMMARY.md)**
- Comprehensive summary of solar radiation validation
- Bug fixes and corrections made
- 24-hour and long-term validation results
- Edge cases and limitations

**[COMPREHENSIVE_VALIDATION_RESULTS.md](COMPREHENSIVE_VALIDATION_RESULTS.md)**
- Complete validation methodology
- All heat flux components
- Statistical analysis
- Comparison tables

**[VBA_VALIDATION_RESULTS.md](VBA_VALIDATION_RESULTS.md)**
- Direct VBA comparison results
- Method-by-method validation
- Accuracy metrics

### Additional Validation Documents

**[VBA_COMPARISON_SUMMARY.md](VBA_COMPARISON_SUMMARY.md)**
- Summary of VBA comparison approach
- Key findings
- Recommendations

**[VALIDATION.md](VALIDATION.md)**
- General validation information
- Testing approach
- Quality assurance

**[BUG_FIXES_SUMMARY.md](BUG_FIXES_SUMMARY.md)**
- Summary of bugs found and fixed
- Impact analysis
- Before/after comparisons

## Validation Test Scripts

Validation scripts are located in `../../tests/validation/`:

**Key Scripts:**
- `validate_24hr.py` - 24-hour detailed validation
- `long_term_validation.py` - 3-month validation
- `diagnose_solar_position_dec3.py` - Solar position diagnostic
- `investigate_solar_radiation.py` - Solar radiation investigation

**Test Data:**
- `../../tests/fixtures/vba_ts_input.csv` - VBA input time series
- `../../tests/fixtures/vba_ts_output.csv` - VBA output time series
- `../../tests/fixtures/vba_params.csv` - VBA parameters

## Running Validation Tests

### Quick Validation

```bash
# 24-hour validation (fast)
python tests/validation/validate_24hr.py

# Long-term validation (3 months)
python tests/validation/long_term_validation.py
```

### Detailed Diagnostics

```bash
# Solar position diagnostic
python tests/validation/diagnose_solar_position_dec3.py

# Solar radiation investigation
python tests/validation/investigate_solar_radiation.py
```

### All Tests

```bash
# Run all automated tests
pytest

# Run with coverage
pytest --cov=rtemp --cov-report=html
```

## Validation Results by Component

### Water Temperature
- **RMSE**: 0.13°C
- **Mean Difference**: 0.096°C (< 2% error)
- **Maximum Difference**: 0.39°C (1 day out of 92)
- **Status**: ✅ Excellent

### Solar Radiation
- **RMSE**: 6.82 W/m²
- **Mean Difference**: 2.4%
- **Maximum Difference**: 132 W/m² (5 timesteps, 0.06% of data)
- **Status**: ✅ Excellent

### Longwave Atmospheric
- **RMSE**: 0.13 W/m²
- **Mean % Error**: 0.07%
- **Status**: ✅ Excellent

### Longwave Back
- **RMSE**: 0.60 W/m²
- **Mean % Error**: 0.59%
- **Status**: ✅ Excellent

### Convection
- **RMSE**: 0.64 W/m²
- **Status**: ✅ Good

### Evaporation
- **RMSE**: 0.71 W/m²
- **Status**: ✅ Good

### Sediment Conduction
- **RMSE**: 5.44 W/m²
- **Status**: ✅ Acceptable

### Solar Position
- **Elevation Difference**: 0.02-0.09°
- **NOAA Algorithm**: Verified correct
- **Status**: ✅ Excellent

## Key Improvements

### 1. Bras Solar Radiation Formula Corrections

Three bugs were found and fixed:

1. **Extraterrestrial Radiation**: Changed from `I0 * cos(zenith)` to `I0 * sin(elevation)`
2. **Molecular Scattering**: Changed from constant `0.128` to `0.128 - 0.054 * log10(air_mass)`
3. **Air Mass Formula**: Updated to match VBA implementation

### 2. Measured Solar Radiation Support

- Model now uses measured solar radiation when available
- Applies appropriate corrections (cloud, shade, albedo)
- Matches VBA behavior

### 3. Enhanced Validation

- Comprehensive input checking
- Informative warnings
- Better error messages
- Stability criteria checking

## Known Limitations

1. **Maximum Temperature Difference**: 0.39°C occurs on 1 day (December 3, 2003)
   - Caused by accumulated small differences
   - Solar position algorithm is accurate
   - Acceptable for most applications

2. **Edge Cases**: Small differences near sunrise/sunset
   - When sun elevation < 2°
   - Affects < 0.1% of timesteps
   - Does not impact overall accuracy

3. **Long-Term Accumulation**: Small errors can accumulate
   - Over periods > 3 months
   - Recommend periodic reinitialization

## Confidence Levels

Based on validation results:

| Application | Expected Accuracy | Confidence |
|-------------|------------------|------------|
| Daily mean temperature | ± 0.1°C | High |
| Hourly temperature | ± 0.2°C | High |
| Peak temperature | ± 0.4°C | Medium-High |
| Long-term statistics | ± 0.15°C | High |

## References

### Primary Reference
- **Edinger, J.E., Brady, D.K. and Geyer, J.C.** (1974). *Heat exchange and transport in the environment*. EPRI publication no. 74-049-00-3, Electric Power Research Institute, Palo Alto, CA.

### Original VBA Implementation
- **Greg Pelletier**, Washington State Department of Ecology
- Concept by **J.E. Edinger Associates**

## Support

For questions about validation:
- See [User Guide - Validation Results](../USER_GUIDE.md#validation-results)
- See [Developer Guide - Validation](../DEVELOPER_GUIDE.md#validation)
- Open a GitHub issue for specific questions

---

**Last Updated**: December 2024  
**Validation Period**: October-December 2003  
**Status**: Production-ready
