# Freeze–Thaw Cycles DAYMET (`Freeze_Thaw_Cycle_2020_2024`) — EDIS AI Agent Dataset View

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## 1. Dataset Metadata
- **Raster Name**: Freeze–Thaw Cycles DAYMET
- **Slug**: `Freeze_Thaw_Cycle_2020_2024`
- **Units**: `cycles/yr`
- **Spatial Extent**: UL(83.7912118, -180.0) to LR(6.0712118, 180.0)
- **Summary**: North America Freeze–Thaw Cycles raster quantifies the annual number of temperature transition events in which the daily minimum temperature falls below 0 °C and the daily maximum temperature exceeds 0 °C.

This metric represents daily crossings of the freezing point and is intended to characterize environmental stress related to thermal expansion, material fatigue, soil heave potential, and infrastructure durability.
- **Included in Flagship Map Package**: `Global_ISO9223_2020_2024_LE_V4` (`GET https://secure.engineeringdirector.com/api/bundles/Global_ISO9223_2020_2024_LE_V4/point_query`)

### Color Table & Value Breaks
- `(0.0, (34.0, 94.0, 168.0))`
- `(1.5, (35.8, 96.4, 169.5))`
- `(3.0, (37.6, 98.8, 171.0))`
- `(4.5, (39.4, 101.2, 172.5))`
- `(6.0, (41.2, 103.6, 174.0))`
- `(7.5, (43.0, 106.0, 175.5))`
- `(9.0, (44.8, 108.4, 177.0))`
- `(10.5, (46.6, 110.8, 178.5))`
- `(12.0, (48.4, 113.2, 180.0))`
- `(13.5, (50.2, 115.6, 181.5))`
- `(15.0, (52.0, 118.0, 183.0))`
- `(15.0, (52.0, 118.0, 183.0))`

Technical Specification
Freeze–Thaw Cycles Raster
North America – 2020–2024
1. Overview

The Freeze–Thaw Cycles raster quantifies the annual number of temperature transition events in which the daily minimum temperature falls below 0 °C and the daily maximum temperature exceeds 0 °C.

This metric represents daily crossings of the freezing point and is intended to characterize environmental stress related to thermal expansion, material fatigue, soil heave potential, and infrastructure durability.

2. Geographic Coverage

Spatial Domain: North America (Daymet v4 coverage)

Projection (Web Delivery): EPSG:4326 (WGS 84)

Native Projection: Daymet Lambert Conformal Conic (meters)

Spatial Resolution: 30 arc-seconds (~1 km)

Temporal Coverage: 2020–2024

Products Provided:

Annual Freeze–Thaw Cycles (per year)

5-Year Mean Freeze–Thaw Cycles (2020–2024 average)

3. Data Source

Primary Dataset:
NASA ORNL DAAC – Daymet Version 4
https://daymet.ornl.gov

Daily Variables Used:

Minimum Air Temperature (tmin, °C)

Maximum Air Temperature (tmax, °C)

Daymet provides gridded daily meteorological data derived from surface observations and interpolated using terrain-informed modeling techniques.

4. Definition of Freeze–Thaw Event

A freeze–thaw event is defined as a calendar day satisfying:

Tmin < 0 °C

Tmax > 0 °C

This definition represents a daily crossing of the freezing threshold (0 °C).

Units: cycles per year

5. Processing Methodology
5.1 Computational Framework

Python (ArcGIS Pro Notebook environment)

NumPy array-based daily processing

NetCDF4 ingestion of Daymet files

ArcPy for raster generation and reprojection

5.2 Processing Steps

Daily tmin and tmax rasters are read from NetCDF files.

NetCDF _FillValue pixels are masked to exclude missing data.

For each grid cell, daily evaluation is performed:

If Tmin < 0 and Tmax > 0 → increment freeze–thaw counter.

Daily results are accumulated into an annual count raster.

A 5-year mean raster is computed using pixel-wise averaging of annual counts.

Native rasters are projected to EPSG:4326 (30 arc-second resolution).

5.3 Data Types

Annual Freeze–Thaw:

Data Type: Unsigned 16-bit integer (UInt16)

5-Year Mean:

Data Type: 32-bit floating point (Float32)

NoData value: -9999

6. Output Specifications
6.1 Annual Raster

Filename format:

FreezeThaw_Daymet_<YEAR>_count_EPSG4326_30as.tif

Units: cycles/year

Value Range (typical North America):

0–5 (southern U.S., warm coastal areas)

20–80 (northern U.S., southern Canada)

50–120 (continental interior, mountain regions)

0–10 (deep Arctic, persistently below freezing)

6.2 Five-Year Mean Raster

Filename:

FreezeThaw_Daymet_5yrMean_2020_2024_count_EPSG4326_30as.tif

Units: average cycles/year (2020–2024)

Data Type: Float32

NoData: -9999

7. Raster Characteristics
Property	Specification
Resolution	30 arc-seconds (~1 km)
Coordinate System	EPSG:4326 (WGS 84)
Compression	LZW
Internal Tiling	Enabled
Pyramids	Built
Statistics	Calculated
8. Quality Control Measures

NetCDF _FillValue masking to prevent invalid temperature contributions.

Per-pixel accumulation to avoid propagation of missing data.

Post-processing raster statistics calculation.

Visual inspection for:

Striping artifacts

Projection distortion

Unrealistic extreme values

Negative or anomalous counts

9. Intended Applications

Pavement durability assessment

Concrete scaling risk

Frost heave potential analysis

Infrastructure lifecycle modeling

Pipeline and coating stress evaluation

Corrosion–freeze interaction studies

10. Limitations

Based on daily temporal resolution (sub-daily freeze–thaw cycles are not captured).

Derived from modeled climate data (Daymet), not direct station observation at each pixel.

Does not account for soil moisture conditions or snow cover insulation effects.

Represents air temperature transitions, not subsurface temperature.

---

## 2. How to Create an Account, Log In & Query Coordinates

### Step 1: Register with User Email (`POST https://secure.engineeringdirector.com/api/v1/agent/register`) or Sign In at `https://secure.engineeringdirector.com/login`
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```bash
curl -X POST "https://secure.engineeringdirector.com/api/v1/agent/register" \
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  -d '{"email": "engineer@yourcompany.com", "first_name": "Jane", "last_name": "Doe"}'
```

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```bash
curl -s "https://secure.engineeringdirector.com/api/bundles/Global_ISO9223_2020_2024_LE_V4/point_query?latitude={LAT}&longitude={LON}&token=iso9223_YOUR_VERIFIED_KEY"
```

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