What changed?
Four answers, straight from the data.
The record, in plain language.
Median within-month slope: -0.00040 per decade.
Median within-month slope: +0.03950 per decade.
Median within-month slope: +0.04744 per decade.
Observed season-adjusted Sen trends are shown over their supplied records. UV Aerosol Index is increasing (+0.04744 per decade), but its whole-year trend is not statistically significant; winter rises significantly.
69.375°E–75°E, 28°N–34°N. The result is an area average, not a pixel or city value.
Annual check: +0.00015 per decade (p = 0.7212). Methods differ.
0.0000 estimated totalDimensionless units. Total = Sen slope × 20.00 elapsed years, not an endpoint difference.
Two-sided seasonal Mann–Kendall test; the threshold is p < 0.05.
Annual check: +0.00015 per decade (p = 0.7212). Methods differ.
Research summary
2005-01-01 — 2025-12-31 · NASA Giovanni / MERRA-2 / NASA Giovanni / MODIS Aqua / NASA Giovanni / Aura OMI OMAERUVd v003
Of the 3 variables studied, 2 show a statistically significant trend between 2005 and 2025: Surface albedo decreasing, Aerosol optical depth increasing.
Surface albedo
NASA Giovanni / MERRA-2 · Dimensionless fraction (0–1) · 2005-01 to 2025-01 · 241 valid months
Between 2005-01 and 2025-01, how much sunlight the land reflects decreased by about -0.000796 Dimensionless fraction (0–1) (-0.373%), roughly -0.000398 every ten years.
Winter readings are higher on average (0.218 versus 0.214 Dimensionless fraction (0–1)).
Largest seasonal anomalies: 2006-02: -0.00986 Dimensionless fraction (0–1); 2020-01: 0.00966 Dimensionless fraction (0–1); 2022-01: 0.00839 Dimensionless fraction (0–1).
Highest annual mean: 2020 (0.216); lowest: 2018 (0.213). Annual means require at least 9 months.
Aerosol optical depth
NASA Giovanni / MODIS Aqua · Dimensionless at 0.55 μm · 2005-01 to 2025-12 · 252 valid months
Between 2005-01 and 2025-12, how hazy the air is (how much sunlight particles block) increased by about 0.0826 Dimensionless at 0.55 μm (13.9%), roughly 0.0395 every ten years.
Monsoon readings are higher on average (0.855 versus 0.476 Dimensionless at 0.55 μm).
Largest seasonal anomalies: 2008-06: 0.423 Dimensionless at 0.55 μm; 2022-05: 0.254 Dimensionless at 0.55 μm; 2011-07: 0.246 Dimensionless at 0.55 μm.
Highest annual mean: 2018 (0.719); lowest: 2005 (0.542). Annual means require at least 9 months.
UV Aerosol Index
NASA Giovanni / Aura OMI OMAERUVd v003 · Dimensionless UV Aerosol Index · 2005-01 to 2025-12 · 252 valid months
UV Aerosol Index: supplied 2005–2025 findings show no significant whole-year trend (+0.047 per decade, p = 0.089); annual p = 0.291. Winter absorbing haze is rising (+0.218 per decade, p = 0.0004, passes p < 0.0125). Post-monsoon +0.127 per decade, p = 0.043: weak evidence, not significant after four-season correction. Monsoon and pre-monsoon have no significant trend. OLS anomalies +0.045 per decade, p = 0.065, 95% CI −0.003 to +0.093.
Monsoon readings are higher on average (0.626 versus 0.586 Dimensionless UV Aerosol Index).
Largest seasonal anomalies: 2012-03: 0.749 Dimensionless UV Aerosol Index; 2018-01: 0.653 Dimensionless UV Aerosol Index; 2006-05: 0.652 Dimensionless UV Aerosol Index.
Highest annual mean: 2018 (0.904); lowest: 2007 (0.489). Annual means require at least 9 months.
How they relate
| Pair | Pearson r | Spearman ρ | Strength | Months used | Best lag, exploratory |
|---|---|---|---|---|---|
| Surface albedo / Aerosol optical depth | -0.133 | -0.191 | very weak | 241 | 0 months, albedo leading aod |
| Surface albedo / UV Aerosol Index | 0.0228 | 0.121 | very weak | 241 | 1 months, albedo leading aerosol_index |
| Aerosol optical depth / UV Aerosol Index | 0.544 | 0.539 | moderate | 252 | 0 months, aod leading aerosol_index |
Surface albedo / Aerosol optical depth move in opposite directions to a very weak degree (-0.133, 241 overlapping months), after removing the seasonal cycle.
Surface albedo / UV Aerosol Index move together to a very weak degree (0.0228, 241 overlapping months), after removing the seasonal cycle.
Aerosol optical depth / UV Aerosol Index move together to a moderate degree (0.544, 252 overlapping months), after removing the seasonal cycle.
A link between two measurements does not prove one causes the other.
Bottom line
Between 2005-01 and 2025-01, how much sunlight the land reflects decreased by about -0.000796 Dimensionless fraction (0–1) (-0.373%), roughly -0.000398 every ten years. Between 2005-01 and 2025-12, how hazy the air is (how much sunlight particles block) increased by about 0.0826 Dimensionless at 0.55 μm (13.9%), roughly 0.0395 every ten years. UV Aerosol Index: supplied 2005–2025 findings show no significant whole-year trend (+0.047 per decade, p = 0.089); annual p = 0.291. Winter absorbing haze is rising (+0.218 per decade, p = 0.0004, passes p < 0.0125). Post-monsoon +0.127 per decade, p = 0.043: weak evidence, not significant after four-season correction. Monsoon and pre-monsoon have no significant trend. OLS anomalies +0.045 per decade, p = 0.065, 95% CI −0.003 to +0.093. These area averages describe relationships, not causes.
ORBIT · 2026-11-15 · Albedo/AOD calculated from observations; UVAI uses supplied 2005–2025 findings
Methodology How the answers are calculated
UV Aerosol Index uses the supplied cleaned OMI series and supplied 2005–2025 statistics and OLS confidence band. Its increasing whole-year slope is not significant (p = 0.089); its winter rise is significant. Albedo and AOD monthly records use seasonal Sen slopes within each calendar month and a seasonal Mann–Kendall test whose monthly scores and tie-corrected variances are summed. Charts remove each calendar month’s mean before fitting OLS; the band is a pointwise 95% large-sample confidence band for the mean fit, not a prediction interval. Serial correlation is not corrected.
Follow each finding to its evidence.
Surface albedo, 2005 – 2025
Monthly · MERRA-2 · M2TMNXRAD 5.12.4Deseasonalized monthly values · dimensionless · 241 observations
The area-averaged record shows a decreasing season-adjusted Sen trend of -0.00040 per decade, with a seasonal Mann–Kendall p-value of 0.0054.
Why it mattersSurface reflectivity influences how much incoming solar energy is reflected. This area average can guide further investigation, but it cannot identify city-level changes or causal processes.
Aerosol optical depth, 2005 – 2025
Monthly · MODIS Aqua · MYD08_M3 V6.1Deseasonalized monthly values · dimensionless · 252 observations
The area-averaged record shows an increasing season-adjusted Sen trend of +0.03950 per decade, with a seasonal Mann–Kendall p-value of 0.0002.
Why it mattersAerosol optical depth describes atmospheric extinction by aerosols and provides atmospheric context for the surface record. It does not by itself establish a surface-albedo response or identify a cause.
UV Aerosol Index, 2005 – 2025
Monthly · Aura OMI · OMAERUVd v003Deseasonalized monthly values · dimensionless · 252 observations
The area-averaged record shows an increasing season-adjusted Sen trend of +0.04744 per decade, with a seasonal Mann–Kendall p-value of 0.0892.
Why it mattersUV Aerosol Index detects sunlight-absorbing particles. The supplied whole-year slope is positive but not statistically significant; winter rises significantly (+0.218 per decade, p = 0.0004). These observations do not identify a source or cause.
Surface albedo: monsoon versus winter
Means of valid monthly observations · winter Dec–Feb · monsoon Jun–Sep
Trend per grid cell
Not available from the supplied area averages
Albedo · All months. A trend map requires georeferenced observations for individual grid cells. The current files contain one area-averaged value per month, so no cells, significant stippling, or opposing subregional trends can be calculated.
Opposite-direction areas: not available.Largest seasonal anomaly
Beyond ±2 standard deviations of the same calendar month’s climatology.
- Month
- 2022-07
- Observed
- 0.213055
- Monthly baseline
- 0.214871
- Z-score
- -2.53
This lower-than-baseline surface albedo observation deserves investigation. It does not establish a cause.
Inspect the same month across variables.
Hover a loaded chart to link the time series. Correlation is not causation.
Surface albedo MERRA-2 · M2TMNXRAD 5.12.4
Aerosol optical depth MODIS Aqua · MYD08_M3 V6.1
UV Aerosol Index Aura OMI · OMAERUVd v003
Computed only where both months are valid. Correlation is not causation; different products and extraction extents limit comparison.
Computed only where both months are valid. Correlation is not causation; different products and extraction extents limit comparison.
Computed only where both months are valid. Correlation is not causation; different products and extraction extents limit comparison.
Questions with traceable answers.
MODIS Aqua · MYD08_M3 V6.1 has the larger absolute season-adjusted Sen slope: +0.03950 per decade (2005-01-01 to 2025-12-01; seasonal Mann–Kendall p 0.0002). This compares numerical dimensionless rates, not environmental importance. MERRA-2 albedo and MODIS Aqua AOD are computed app results.
What supports the answers—and what does not.
Datasets and period
MERRA-2 M2TMNXRAD 5.12.4 albedo: 2005-01-01 — 2025-01-01.
MODIS Aqua MYD08_M3 V6.1 AOD: 2005-01-01 — 2025-12-01.
UV Aerosol Index: 2005-01-01 — 2025-12-01.
Spatial resolution
MERRA-2: 0.5° × 0.625° source grid, supplied as an area average.
MODIS Aqua monthly Level 3: 1° × 1° product grid, supplied on a different extraction extent.
Known limitations
No pixel-level quality flags, official province mask, serial-correlation correction, or independent ground validation. Albedo 2025 contains January only.
Area averages cannot support subregional, zonal, or city conclusions.
Sanity check
All supplied albedo values are between 0 and 1, and all AOD values are non-negative.
Independent published-reference check: not available.