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Weather Analyzer Tutorial

Overview​

The Weather Analyzer downloads and prepares daily meteorological data from NASA's POWER (Prediction Of Worldwide Energy Resources) for agronomic workflows. You pick a location and date range, fetch daily records, preview cleaned data, and export CSV or PCSE‑format files for models such as WOFOST/PCSE. A built‑in map lets you click to select coordinates or search by place name.

Key Features​

  • NASA POWER fetch: Daily point data via POWER API for a selected coordinate
  • Map & search: Leaflet map with click‑to‑select and Nominatim place search
  • Fixed parameter set: TOA_SW_DWN, ALLSKY_SFC_SW_DWN, T2M, T2M_MIN, T2M_MAX, T2MDEW, WS2M, PRECTOTCORR
  • PCSE conversion: Transform to IRRAD/TMIN/TMAX/VAP/WIND/RAIN and fill gaps with moving averages
  • Data preview: Render first rows in an HTML table for quick QA
  • Export: Download cleaned CSV and PCSE‑style CSV (with header block)

Quick Start​

1. Open the App​

Visit /app/weather.

2. Pick Location​

  • Click on the map to set latitude/longitude, or type them directly
  • Use the search box (top of the map) to find places and auto‑set coordinates
  • Optional: Click “Get Current Location” to use browser geolocation (HTTPS required)

3. Set Date Range​

  • Choose start and end dates (start must be before end)
  • POWER typically provides data from 1984 to present

4. Download & Preview​

  • Click “Download NASA Weather Data” to fetch and process records
  • The app converts to PCSE fields and fills missing values using local windows
  • A preview table shows the first rows; status indicates counts and missing fills
  • Use the “Download CSV” and “Download Excel (PCSE Format)” buttons to save files

Notes & Limits​

  • Parameters are fixed to a daily agronomy set; custom selection is not available in this version
  • Charts are not included; use exported data for plotting in your tools (Excel, Python, R)
  • Geolocation requires HTTPS pages or localhost; otherwise browsers may block it

Troubleshooting​

  • “Invalid coordinates” or “End date must be after start date”: correct inputs and retry
  • “No data returned” or empty preview: date range or coordinate may be out of coverage; try nearby land points
  • Slow responses: POWER API latency varies; larger date ranges take longer
    • Zoom and pan capabilities for detailed examination
  1. Statistical Summary
    • Basic statistics (mean, median, standard deviation)
    • Seasonal patterns and trends
    • Anomaly detection relative to long-term averages

Step 5: Data Export​

  1. CSV Format Export

    • Download complete dataset in CSV format
    • Includes all requested parameters with timestamps
    • Compatible with statistical software and spreadsheets

  2. Chart Export

    • Export visualizations as PNG or SVG images
    • High-resolution images for publications
    • Customizable chart dimensions and styles

Technical Specifications​

Data Sources​

  • NASA POWER Database: Primary meteorological data source
  • Satellite Observations: Solar radiation and cloud cover data
  • Global Weather Models: Reanalysis data for comprehensive coverage
  • Ground Station Integration: Quality-controlled station data

Data Parameters​

Core Meteorological Parameters​

  • Temperature: °C, with daily max/min/mean values
  • Precipitation: mm/day, liquid precipitation equivalent
  • Solar Radiation: W/m², daily total and hourly values
  • Relative Humidity: %, at standard measurement heights
  • Wind Speed: m/s, at 10m and 50m heights

Agricultural Parameters​

  • Growing Degree Days: Base temperature accumulation
  • Reference ET: mm/day, Penman-Monteith calculation
  • Soil Temperature: °C, at various depths
  • Frost Probability: % likelihood of frost occurrence

Spatial Resolution​

  • Global Coverage: 1° × 1° grid resolution
  • Interpolation: Bilinear interpolation for specific coordinates
  • Accuracy: Typically within 10% of ground truth measurements

Temporal Resolution​

  • Daily Data: Primary temporal resolution
  • Monthly Aggregates: Monthly averages and totals
  • Historical Records: 1984 to present for most parameters

Best Practices​

Data Quality Assessment​

  1. Validation Checks

    • Compare with local weather station data when available
    • Check for data gaps or anomalous values
    • Verify spatial representativeness for specific locations

  2. Parameter Selection

    • Choose parameters relevant to research objectives
    • Consider parameter interdependencies
    • Account for seasonal variations in data quality

Agricultural Applications​

  1. Crop Modeling

    • Use temperature data for phenology modeling
    • Apply precipitation data for irrigation scheduling
    • Utilize solar radiation for yield prediction

  2. Climate Analysis

    • Analyze long-term climate trends
    • Identify climate change impacts on agriculture
    • Assess climate variability and extremes

Data Integration​

  1. Multi-source Integration

    • Combine with local observation data
    • Integrate with soil and crop data
    • Use for model calibration and validation

  2. Statistical Analysis

    • Apply appropriate statistical methods
    • Account for autocorrelation in time series
    • Use robust methods for outlier detection

Troubleshooting​

Common Issues​

1. Data Retrieval Failure

  • Verify internet connection stability
  • Check NASA POWER service status
  • Ensure coordinate values are within valid ranges

2. Missing Data

  • Some parameters may not be available for all locations
  • Check date range against parameter availability
  • Verify location is over land (NASA POWER covers land areas only)

3. Chart Display Issues

  • Ensure browser supports modern JavaScript features
  • Check for sufficient system memory for large datasets
  • Try refreshing page and re-downloading data

Performance Optimization​

For Large Datasets

  • Limit date ranges to necessary periods
  • Select only required parameters
  • Use monthly aggregates for long-term analysis

For Multiple Locations

  • Process locations sequentially
  • Consider batch processing for efficiency
  • Use appropriate sampling strategies

Technical Support​

If you encounter technical issues:

  1. Check browser console for error messages
  2. Verify coordinate values and date ranges
  3. Ensure NASA POWER service is accessible
  4. Contact support with specific error details and parameters

Author: Liangchao Deng, Ph.D. Candidate, Shihezi University / CAS-CEMPS
This tutorial applies to Weather Analyzer v1.0 Optimized for agricultural and environmental research applications