HACH CMP6 Albedometer Kit

Overview

The HACH CMP6 Albedometer Kit is a dual-pyranometer system engineered for precise, simultaneous measurement of global solar irradiance (downward) and reflected solar irradiance (upward) to calculate surface albedo—the dimensionless ratio of reflected to incident shortwave radiation. Designed around two matched Kipp & Zonen CMP6 thermopile pyranometers, the system leverages the proven stability and spectral fidelity of thermoelectric sensing to deliver high reproducibility in field-deployed environmental monitoring. Each CMP6 sensor conforms to ISO 9060:2018 Class C (Secondary Standard) specifications and is calibrated against NIST-traceable reference standards in an ISO/IEC 17025-accredited laboratory. The kit integrates mechanical alignment fixtures, a rigid mounting frame, and a standardized black anodized anti-reflection housing to minimize thermal offset and directional errors—critical for long-term albedo trend analysis in solar resource assessment, land-surface modeling, and cryosphere studies.

Key Features

• Paired thermopile detectors with identical spectral response (305–2800 nm) and thermal time constant (< 5 s at 95% response), ensuring synchronized dynamic capture of transient irradiance events.
• Integrated anti-glare hood (included) reduces diffuse sky radiation error and suppresses off-axis stray light—particularly beneficial under low sun angles and heterogeneous sky conditions.
• Rugged, weatherproof construction (IP67-rated housing) with stainless-steel body and quartz dome, enabling continuous operation across extreme climatic zones—from Arctic tundra to desert solar farms.
• Zero-offset design minimizes thermal emf drift; each unit undergoes individual thermal offset characterization per ISO 9060 Annex D to support correction algorithms in post-processing.
• Standard 0–25 mV analog output (10 µV per W/m² sensitivity) compatible with most data loggers supporting differential input channels and millivolt-scale resolution (e.g., Campbell Scientific CR6, Delta-T DL6, or HACH HQd platforms).

Sample Compatibility & Compliance

The CMP6 Albedometer Kit is validated for use over natural and engineered surfaces including snowpack, bare soil, vegetation canopies, photovoltaic arrays, asphalt, and oceanic whitecaps. Its cosine and azimuth response characteristics meet WMO CIMO requirements for surface radiation budget networks. All components comply with ISO 9060:2018 Class C performance criteria and are suitable for inclusion in national meteorological networks adhering to GCOS (Global Climate Observing System) metadata standards. The system supports GLP-compliant deployment when paired with audit-trail-capable data loggers and documented calibration certificates (valid for 2 years from date of issue).

Software & Data Management

Raw mV outputs from both sensors are converted to W/m² using individual calibration factors supplied with each unit. Albedo (α) is computed as α = G_up / G_down, where G_up and G_down denote upward- and downward-facing irradiance values. HACH’s AquaSuite™ software (v5.2+) includes dedicated albedometer configuration templates with built-in quality control flags for out-of-range ratios (e.g., α > 1.05 or α < 0.02), nighttime filtering, and cloud-edge artifact detection. Exported datasets include timestamped irradiance pairs, calculated albedo, instrument status flags, and uncertainty propagation based on combined standard uncertainties (k = 2) derived from calibration uncertainty, temperature dependence, and cosine error models.

Applications

• Solar energy site assessment: Quantifying ground reflectance for bifacial PV yield modeling and soiling loss correction.
• Cryospheric science: Monitoring seasonal albedo decay on glaciers and sea ice to constrain radiative forcing in climate models.
• Land surface modeling: Parameterizing surface energy balance in LSMs (e.g., Noah-MP, CLM5) used by NOAA/NCEP and ECMWF forecasting systems.
• Agricultural remote sensing validation: Ground-truthing satellite-derived albedo products (e.g., MODIS MCD43A3, Sentinel-3 SLSTR) across heterogeneous cropland and pasture.
• Ocean color correction: Supporting atmospheric correction of water-leaving radiance measurements in coastal radiometry campaigns.

FAQ

What is the recommended recalibration interval for the CMP6 sensors?
Kipp & Zonen recommends recalibration every 2 years under routine field use; annual verification is advised for high-accuracy applications such as BSRN (Baseline Surface Radiation Network) stations.
Can the CMP6 Albedometer Kit be mounted on a rotating shadowband system?
No—it is designed for fixed, co-planar orientation. For direct/diffuse separation, integrate with a separate shaded/unshaded pyranometer pair or a pyrheliometer + shading assembly.
Is the system compatible with Modbus or SDI-12 communication protocols?
The standard CMP6 outputs analog mV only; digital interface requires external signal conditioning (e.g., HACH DR6000 analog-to-Modbus converter or Campbell Scientific AM16/32B multiplexer).
How is thermal offset corrected during data processing?
Each sensor’s thermal offset coefficient (µV/°C) is provided in its calibration report; correction follows ISO 9060 Annex D methodology using concurrent dome and body temperature measurements.
Does the kit include mounting hardware and leveling base?
Yes—the standard kit comprises dual CMP6 sensors, alignment bracket, adjustable leveling base with bubble vial, anti-glare hood set, and stainless-steel mounting mast clamp.