# Dew-Point Anchor Hypothesis (DPAH): Application to the Indian Summer Monsoon and Thar Desert Heat Low

**Repository / Deposit**: https://zenodo.org/communities/dpah/  
**Version**: Master Workflow (Runs 4001–Master)  
**Date**: 11 June 2026

## Overview

The **Dew-Point Anchor Hypothesis (DPAH)** posits that the lifting condensation level (LCL) controlled by surface dewpoint serves as the fundamental thermodynamic anchor for convective processes, rather than surface temperature alone. This deposit presents a complete open-source Python workflow exploring DPAH in the context of the **Indian Summer Monsoon** and the **Thar Desert thermal low-pressure cell**.

### Key Features Demonstrated

- Thermodynamic vertical profiles (temperature, dewpoint, pressure) with explicit LCL anchoring
- Quantitative validation against idealized radiosonde-style soundings (low RMSE achieved)
- Conceptual rainfall probability linked to LCL depth and moisture
- Markov chain time-series model showing sensitivity of monsoon rainfall frequency to Thar heat low strength
- Visual and functional analogy of the Thar heat low as a thermal "eye" driving organized moist inflow and peripheral convection

## Scientific Context

The Thar Desert develops a prominent summer heat low that drives cross-equatorial moisture convergence into the monsoon trough. DPAH provides a clean thermodynamic framework for understanding how intense sensible heating in the dry core (high LCL, subsidence, persistent low dewpoints) organizes inflow and convection on the margins (rapidly lowering LCL).

This work is offered as an open contribution particularly relevant to researchers at the **Centre for Climate Studies, Indian Institute of Technology Bombay (IIT Bombay)**.

## Key References

- Paul, S., Ghosh, S., Oglesby, R., Pathak, A., Chandrasekharan, A., & Ramsankaran, R. (2016). Weakening of Indian Summer Monsoon Rainfall due to Changes in Land Use Land Cover. *Scientific Reports*, 6, 32177. https://doi.org/10.1038/srep32177

- Devanand, A., Roxy, M. K., & Ghosh, S. (2018). Coupled Land-Atmosphere Regional Model Reduces Dry Bias in Indian Summer Monsoon Rainfall Simulated by CFSv2. *Geophysical Research Letters*, 45(5), 2476–2486. https://doi.org/10.1002/2018GL077218

- Pathak, A., Ghosh, S., Martinez, J. A., Dominguez, F., & Kumar, P. (2017). Role of Oceanic and Land Moisture Sources and Transport in the Seasonal and Interannual Variability of Summer Monsoon Rainfall over India. *Journal of Climate*, 30(5), 1839–1859. https://doi.org/10.1175/JCLI-D-16-0156.1

## Repository Contents

- `RunMaster.pv` – Main consolidated script (recommended starting point)
- Individual development scripts (`Run4001.pv` … `Run4012.pv`)
- All generated plots (vertical profiles, sounding comparisons with RMSE, rainfall probability, Markov rainfall time-series)
- Summary CSV files with metrics

## How to Run

1. Ensure you have Python 3.x with `numpy`, `matplotlib`, and `pandas` installed.
2. Run:
   ```bash
   python RunMaster.pv